Surgical guide for improved angulation control

Abstract

A surgical guide includes a base having a first body having a proximal opening, a distal opening and an internal chamber therebetween. The proximal opening has a plurality of recesses disposed along an inner perimeter of the proximal opening. A first insert includes a second body having a proximal end, a distal end, and a channel extending therebetween. The proximal end has a plurality of protrusions disposed along an outer perimeter and configured to interface with the plurality of recesses. The channel is angled away from a central vertical axis by a first angle. A surgical guide kit and a method for guiding an external ventricular drain are also described.

Description

SURGICAL GUIDE FOR IMPROVED ANGULATION CONTROLCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 585,248 filed on September 26, 2023, incorporated herein by reference in its entirety.BACKGROUND OF THE INVENTION

[0002] Placement of an external ventricular drain (EVD) is a common / routine neurosurgical procedure used for drainage of cerebrospinal fluid (CSF), most commonly to manage and monitor elevated intracranial pressure (ICP) [Ganti L., Atlas of Emergency Medicine Procedures. Springer New York; 2016:241 -245], The most common method for external ventricular drain placement is the free-hand (FH) approach, with significant reported inaccuracy rates, particularly for altered ventricular anatomy. Current assistive devices require added time or equipment or do not account for shifted ventricles. Elevated ICP can result from a wide variety of pathological conditions, including trauma, spontaneous hemorrhage and mass lesions. EVDs can be performed anywhere from the operating room to the bedside in the emergency department. The procedure involves burr-hole creation and placement of a catheter into one of the lateral ventricles of the brain to drain CSF. This allows for both CSF diversion and monitoring of the ICP.

[0003] The main method for EVD placement is the free-hand (FH) approach, where the insertion point on the skull and angle of insertion of the catheter are chosen using anatomical landmarks [Ganti L., Atlas of Emergency Medicine Procedures. Springer New York; 2016:241-245], In particular, a burr-hole is drilled at Kocher’s point, which is located 11 cm back from the nasion and 3 cm to the right of midline in the mid-pupillary line [Mortazavi et al., Childs Nerv Syst. 2014 Jan;30(1 ): 19-35], The catheter is then aimed using the ipsilateral medial canthus and ipsilateral tragus to guide. While the FHapproach is generally considered reliable, there are significant reported inaccuracy rates, ranging from 12.3% - 44.9% [Huyette et al., J Neurosurg 108:88-91 , 2008; Saladino et al., Neurocrit Care 10:248-252, 2009; Shtaya et al., J Neurosurg. Published online May 1 , 2018:1 -6; Kakarla et al., Neurosurgery. 2008;63(1 Suppl 1 ):ONS162-166; discussion ONS 166-167], Accurate EVD placement is more technically challenging in patients with distorted ventricular anatomy. Complications from inaccurate EVD placement include hemorrhage, infection, and drain failure.

[0004] Several studies have evaluated the use of new technologies to improve the accuracy of EVD placement. Neuronavigation (NN), for example, is a technique involving computer-assisted navigation using image guidance that was demonstrated to improve the accuracy of EVD placement for patients with traumatic brain injury (TBI) [AlAzri et al., Acta Neurochir (Wien). 2017; 159(8): 1399-1411 ], XperCT (XCT) is another image-guided fluoroscopy-based technique that has been demonstrated to improve accuracy and safety of EVD placement relative to the FH approach [Gautschi et al., Acta Neurochir (Wien). 2014; 156(4): 777-785],

[0005] Although these technologies improve the accuracy of EVD placement relative to the FH approach, they have significant drawbacks to widespread use. Highly specialized equipment is required, and many hospitals do not have access to these types of instruments readily, if at all. In addition, a longer procedure time is required relative to the FH approach, severely limiting the use of these more advanced techniques in emergent settings at the bedside [Gautschi et al., Acta Neurochir (Wien). 2014;156(4):777-785; discussion 785], As described by Gautschi et al. [Gautschi et al., Acta Neurochir (Wien). 2014; 156(4): 777-785], this creates a dilemma of “accuracy versus urgency” when an emergent bedside EVD needs to be placed in a patient who has altered ventricular anatomy. Using newer techniques such as NN or XCT can improve accuracy, but the procedure time is prolonged relative to the FH approach [Gautschi et al., Acta Neurochir (Wien). 2014;156(4):777-785], For patients with altered ventricular anatomy where an EVD must be placed emergently, neither accuracy nor urgency can be sacrificed.

[0006] In addition to EVD placement, various other procedures require accurate positioning and / or neuronavigation within the skull, particularly those performed with real-time imaging or complex frame-based systems [Bjartmarz H, Rehncrona S., Stereotact Funct Neurosurg. 2007;85(5):235-42], For example, procedures involving guiding a biopsy needle to a particular location within a subject. Previously shown by Muller was a patient-specific 3D-printed stereotactic frame, however the device and method are complicated to use and non-adjustable [Muller et al., Journal of Personalized Medicine. 2024; 14(2): 180],

[0007] A Ghajar Guide is a commonly used surgical guide for the placement of a ventricular catheter. Yoon et al. designed an adjustable Ghajar Guide [Yoon et al., J Korean Neurosurg Soc. 2017;60(5):604-609], however the device is placed directly into an open burr-hole and only allows adjustment of the insertion angle in the coronal plane.

[0008] Deep brain stimulation requires precise placement of electrodes within the brain, currently performed during lengthy surgeries requiring live imaging guidance and a frame or robotic assistance to ensure accuracy of electrode placement [Burchiel et al., Journal of Neurosurgery JNS, 119(2), 301-306; VanSickle et al., Ann Biomed Eng 47, 1212-1222 (2019)]. In many cases live imaging and / or robotic assistance is not available to aid in the accurate placement of such electrodes.

[0009] An improved surgical guide is needed in the art for improving efficiency and accuracy of emergent device placement (e.g., EVD placement) in various settings such as altered ventricular anatomy. Embodiments described herein fit this need.SUMMARY OF THE INVENTION

[0010] In some embodiments, a surgical guide includes a base comprising a first body having a proximal opening, a distal opening and an internal chamber therebetween, the proximal opening having multiple recesses disposed along an inner perimeter of the proximal opening; and a first insert comprising a second body having aproximal end, a distal end, and a channel extending therebetween, the proximal end having multiple protrusions disposed along an outer perimeter and configured to interface multiple recesses, the channel angled away from a central vertical axis by a first angle. In some embodiments, the surgical guide includes a tubular structure extending proximally away from the proximal end and distally away from the distal end with the channel extending therethrough. In some embodiments, the proximal opening is circular and centered on the central vertical axis. In some embodiments, the outer perimeter is circular and centered on the central vertical axis. In some embodiments, the central vertical axis intersects with the channel axis in a distal plane of the base. In some embodiments, the internal chamber tapers distally. In some embodiments, the second body tapers distally. In some embodiments, the internal chamber and second body taper distally at a common angle. In some embodiments, the surgical guide includes at least three legs extending distally from the base. In some embodiments, the at least three legs are spaced equally apart. In some embodiments, the multiple each have the same dimension. In some embodiments, the multiple recesses are spaced equally apart. In some embodiments, the multiple recesses are spaced about 15 degrees apart. In some embodiments, the multiple recesses are spaced between 10 and 15 degrees apart. In some embodiments, the multiple recesses are spaced between 5 and 10 degrees apart. In some embodiments, the multiple recesses are spaced between 3 degrees and 20 degrees apart. In some embodiments, multiple protrusions each have the same dimension. In some embodiments, the multiple protrusions are spaced equally apart. In some embodiments, the multiple protrusions are spaced about 15 degrees apart. In some embodiments, the multiple protrusions are spaced between 10 and 15 degrees apart. In some embodiments, the multiple protrusions are spaced between 5 and 10 degrees apart. In some embodiments, the multiple protrusions are spaced between 3 degrees and 20 degrees apart.

[0011] In some embodiments, a surgical guide kit includes the surgical guide; and a second insert comprising a third body having a proximal end, a distal end, and a channel extending therebetween, the proximal end having multiple protrusions disposed along an outer perimeter and configured to interface with the multiple recesses, the channel angled away from a central vertical axis by a second angle. In someembodiments, the surgical guide kit includes a third insert comprising a third body having a proximal end, a distal end, and a channel extending therebetween, the proximal end having multiple protrusions disposed along an outer perimeter and configured to interface with the multiple recesses, the channel angled away from a central vertical axis by a third angle.

[0012] In some embodiments, a method for guiding a device (e.g., an external ventricular drain) includes the steps of providing the kit; imaging a patient’s head; determining an insertion parameter based on the imaging; selecting one of the first, second or third insert based on the determined insertion parameter; and inserting the selected insert into the base at a rotated position based on the determined insertion parameter. In some embodiments, determining an insertion parameter includes determining a coronal adjustment angle and sagittal adjustment angle. In some embodiments, determining further comprises comparing the coronal adjustment angle and the sagittal adjustment angle to predetermined values.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The foregoing purposes and features, as well as other purposes and features, will become apparent with reference to the description and accompanying figures below, which are included to provide an understanding of the invention and constitute a part of the specification, in which like numerals represent like elements, and in which:

[0014] FIG. 1 A is a perspective view of a guide (e.g., a surgical guide) having a base and one or more inserts according to some embodiments. FIG. 1 B is a perspective view of a base with one or more inserts having different channel angles included in a surgical guide kit according to some embodiments. FIG. 1 C is a perspective view of a guide with labelled dimension lines. FIG. 1 D is a perspective view of an insert with labelled dimension lines. FIG. 1 E is a perspective view of an insert with labelled dimension lines.

[0015] FIG. 3A is a diagram depicting an exemplary method for guiding an external ventricular drain according to aspects of the present invention.

[0016] FIG. 3B is a diagram depicting a computer architecture for a computer for practicing the various embodiments of the invention.

[0017] FIGs. 4A & 4B are images depicting a CT scan exemplifying extremely altered ventricular anatomy with calculated adjustment angles in the coronal (FIG. 4A) and sagittal (FIG. 4B) planes. FIG. 4A shows a coronal plane view. FIG. 4B shows a sagittal plane view.

[0018] FIGs. 5A-5C are a series of images depicting an exemplary patient-specific external ventricular drain (PS-EVD) placement method using a disclosed guide according to aspects of the present invention. The series of images depict an exemplary method performed on a phantom skull model. FIG. 5A depicts an initial CT scan for PS-EVD guide use. FIG. 5B depicts a CT scan with perpendicular and adjustment trajectories in the coronal and sagittal planes. FIG. 5C depicts the resulting CT scan after catheter placement, showing the catheter is in the central ventricle in both the frontal and sagittal planes.

[0019] FIGs. 6A-6F are images depicting an exemplary guide kit and 3D printed prototype, a CAD design of a phantom skull, and simulated positions provided by the guide based on the chosen insert. FIG. 6A depicts a CAD rendering of tripod base and three inserts using standard color code of red for the 6° insert, blue for the 12° insert, and gold for the 18° insert forming a kit. The arrow on top of the inserts is used to aid in determining the rotational setting. The label on top of the inserts is used to aid in identifying the insert. FIG. 6B depicts a PLA 3D-printed prototype for an exemplary guide kit, including all three inserts. FIG. 6C depicts a CAD design of the phantom skull used for testing, with an insert portion of the skull removed. FIG. 6D depicts a CAD design of assembled phantom skull with the PS-EVD guide in place over the burr-hole and the 6° insert in use. FIG. 6E depicts a rendering of a guide showing all possible entry positions in colors corresponding to the insert used (red for the 6° insert, blue for the 12° insert, and gold for the 18°). It should be noted that all trajectories travelthrough the same entry point without needing to reposition the guide. FIG. 6F depicts a bottom view of the rendering of FIG. 6E showing exemplary trajectories of the guide.

[0020] FIGs. 7A-7F are a series of images showing the results for a comparison between a simulated Ghajar guide and the disclosed guide and method. FIG. 7A shows the result in the coronal plane for a trial where the positioning of the device mimics the perpendicular trajectory of a Ghajar Guide. FIG. 7B shows the result in the coronal plane of the same phantom skull as in FIG. 7A using the disclosed guide and method showing accurate positioning and insertion into the ventricle. FIG. 7C is an overlay of FIGs. 7A & 7B, demonstrating the improvement in placement using the disclosed guide and method. FIG. 7D shows the result of using a zero-degree insert, simulating a Ghajar Guide in a simulation of severely altered anatomy in which the perpendicular entry from a Ghajar Guide would not have been sufficient to reach the ventricle. FIG. 7E shows the result on the same phantom skull of FIG. 7D but using the disclosed guide and method with an 18-degree insert rotated at zero degrees, resulting in accurate insertion into the ventricle. FIG. 7F is an overlay of FIGs. 7C & 7D, demonstrating the improvement in placement using the disclosed guide and method.

[0021] FIGs. 8A-8D are a series of images showing the results in the coronal and sagittal planes from two trials using the disclosed guide and method. FIG. 8A & FIG. 8B show sagittal and coronal planes of a subject’s skull for a first trial. The measured angles were 13.90° and 0.91 ° in the (FIG. 8A) coronal and (FIG. 8B) sagittal planes. The gold insert rotated 30° was chosen, which gave calculated adjustment angles of 15.72° and 9.23° in the frontal and sagittal planes, respectively. The result was accurate insertion in the central ventricle. FIG. 8C & FIG. 8D show sagittal and coronal planes of a subject’s skull for a second trial. The measured angles were 5° and -2.69° in the (FIG. 8C) coronal and (FIG. 8D) sagittal planes. The red insert rotated -30° was chosen, which gave calculated adjustment angles of 5.20° and -3.01 ° in the coronal and sagittal planes, respectively. The result was accurate insertion in the ventral ventricle.

[0022] FIGs. 9A-9H are a series of images showing an exemplary method for guiding a device using a surgical guide. FIG. 9A shows a base of a surgical guide positionedabove and coaxial with a burr hole in a subject’s skull. FIG. 9B shows that a specific insert (e.g., a gold colored 18 deg insert) comprising an angled tubular structure is chosen based on the target, area or region in the subject’s skull. FIG. 9C shows that the insert is aligned with the base. FIG. 9D shows that the insert is rotated to an appropriate setting (e.g., rotated 2 notches or 30 deg) based on the target in the subject’s skull. FIG. 9E shows that insert has notches that interface with grooves in the base when inserted. FIG. 9F shows an exemplary device (e.g., a catheter) aligned with the tubular structure of the insert. FIG. 9G shows a device guided by the tubular structure of the insert into the burr hole and towards a target in the subject’s skull. FIG. 9H shows a device positioned at a target in the subject’s skull.DETAILED DESCRIPTION OF THE INVENTION

[0023] It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a more clear comprehension of the present invention, while eliminating, for the purpose of clarity, many other elements found in external ventricular guide systems and methods. Those of ordinary skill in the art may recognize that other elements and / or steps are desirable and / or required in implementing the present invention. However, because such elements and steps are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements and steps is not provided herein. The disclosure herein is directed to all such variations and modifications to such elements and methods known to those skilled in the art.

[0024] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described.

[0025] As used herein, each of the following terms has the meaning associated with it in this section.

[0026] The articles “a” and “an” are used herein to refer to one or to more than one ( / .e., to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element.

[0027] “About” as used herein when referring to a measurable value such as an amount, a temporal duration, and the like, is meant to encompass the specified value and variations of ±20%, ±10%, ±5%, ±1 %, and ±0.1% from the specified value, as such variations are appropriate.

[0028] The terms “patient,” “subject,” “individual,” and the like are used interchangeably herein, and refer to any animal amenable to the systems, devices, and methods described herein. The patient, subject or individual may be a mammal, and in some instances, a human.

[0029] Ranges: throughout this disclosure, various aspects of the invention can be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Where appropriate, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1 , 2, 2.7, 3, 4, 5, 5.3, and 6. This applies regardless of the breadth of the range.

[0030] Referring now in detail to the drawings, in which like reference numerals indicate like parts or elements throughout the several views, in various embodiments, presented herein is a guide in some examples referred to as an external guide, a surgical guide, an external ventricular drain (EVD) guide, and / or a patient-specific extra ventricular drain (PS-EVD) guide.

[0031] Embodiments of the guide described herein aid a surgeon placing an external device, such as an EVD, a catheter used to drain excess cerebrospinal fluid from the brain to relieve elevated intracranial pressure. However, it should be appreciated that the disclosed guide may aid in placing or locating any device such as a drain, catheter, biopsy tool, electrode, transducer, light source, radiation source, sensor, surgical tools, instruments, guided devices, or the like. Embodiments of the guide ensure that the device is inserted at the angle necessary to reach the desired target (e.g., within a skull), target area, area of interest, or region of a brain. Methods of using the device include the steps of examining a patient’s head CT scan in order to determine the required insertion point and angle for the EVD. The device will then be positioned on the head and set to the determined correct setting and used to place the EVD.

[0032] More specifically, embodiments of the surgical guide device place an EVD at a specifical angle with respect to both the coronal (frontal) and sagittal (longitudinal) planes of the patient’s head. The device is non-invasive, only coming into contact with the patient’s head externally, requiring no contact within the body. Embodiments of the device include at least two parts: a base with legs that sit on the surface of the head, and one or more insert pieces that may be set into that base, which have the guide tube used for the EVD placement. The initial design and prototype have been 3D printed, but may be made of any plastic, metal, or composite material deemed safe for external body contact. The base is meant to be placed on the patient’s head, centered over a surgically drilled hole (e.g., a burr hole) at the insertion site for EVD placement. An insert piece is then placed into the base and used to place the EVD. The insert may be rotated step-wise 360 degrees around a central, vertical axis. Each insert has a tube as a guide for placing the EVD, and this tube is tilted at a specified angle from vertical axis. Multiple inserts, each with the guide tube at a different angle, allow for a greater range of placement positions.

[0033] One embodiment for the base uses three legs, taking advantage of the natural stability gained by using a tripod design, but could potentially use more legs. Supported by the legs is a circular cup the tapers inward at the bottom with a symmetrical groove pattern used for the placement of an insert piece. This cup can bewide enough to allow for the angled insert guide tube to remain within the cup, and also tall enough to provide leverage to prevent the insert from coming out.

[0034] The insert piece is designed to sit inside the cup of the base, with an outer, circular ring with grooves the inverse of those found on the inside of the base. These grooves allow the insert to be positioned at any rotational position. One embodiment has positions for every 15 degrees of rotation, but other increments can be adopted. The guide tube in the insert can extend 2 cm above the cup of the insert and 0.5 cm below the cup portion. These lengths can be changed, but longer allows for more accurate EVD alignment. In some embodiments, the interior or inner diameter of the tube can be about 3.4 mm, to allow for a close fit of the standard catheter used for EVD procedures (3.33 mm outer diameter), although other inner diameters are contemplated herein.

[0035] No matter the rotational position or angle of the insert, the guide tube should in most embodiments always be directed at the center of the base, at the surface of the skull, to allow for correct placement. This requirement, along with the desire to not interact with any internal part of the body, prevents the use of a simple ball and socket joint, as the pivot point for this joint would need to be at the surface of the skull, with material touching the inside of the hole. A more complex mechanism could be employed in certain embodiments to achieve motion about this pivot point without touching the skull. The design in several depicted embodiments utilizes a simpler, multi-component design. This allows for easier and less expensive manufacturing. It should be noted that the inserts and tubes are designed such that all trajectories travel through the same entry point (e.g., burr hole) without needing to reposition the base of the guide (see FIG. 6E).

[0036] Accordingly, with reference now to FIG. 1A, the surgical guide 100 in some embodiments includes a base 110 having a first body 112 with a proximal opening 114, a distal opening 116 and an internal chamber 118 therebetween. The proximal opening 114 has a plurality of recesses 120 disposed along an inner perimeter 122 of the proximal opening 114. An insert 150 includes a second body 152 having a proximalend 154, a distal end 156, and a channel 160 extending therebetween. The proximal end 154 has multiple protrusions 170 disposed along an outer perimeter 172, configured to interface with the recesses 120 and arrest movement and rotation of the insert 150 when placed in the base 110. The channel 160 is angled away from a central vertical axis 190 by a first angle.

[0037] A tubular structure 180 extends proximally away from the proximal end 182 and distally away from the distal end 184 with the channel 160 extending therethrough. The proximal opening 114 is round (e.g., circular, ovular) and centered on the central vertical axis 190. The outer perimeter 172 is circular and centered on the central vertical axis 190. The central vertical axis 190 intersects with a channel axis 192 in a distal plane of the base. This may be for example the plane that is the footprint of the base, or another plane parallel to the footprint plant, or otherwise a distal plane perpendicular to the central vertical axis 190. The channel position can be further offset from center as the angle increases (shown e.g. in the inserts of FIG. 1 B). The internal chamber 118 and second body 152 taper distally. This cup shaped geometry helps stabilize the insert when resting in the base. The internal chamber 118 and second body 152 can taper distally at a common angle.

[0038] At least three legs extend distally from the base. The at least three legs 124 extending distally from the first body 112 can be spaced equally apart, or unequally apart. In some embodiments, each leg comprises a foot portion configured to interface with, abut, or make contact with the skull of a subject. In some embodiments, the foot portion is angled to accommodate for the curvature of a skull. In some embodiments, each foot comprises an anti-slip material, a rubber footing, or may terminate in a point in order to resist movement of base 110 along the skull of the subject.

[0039] The recesses 120 can each have the same dimension, spaced equally apart, at about 15, 10 or 5 degrees, or between 3 degrees and 20 degrees apart or some other increment. Likewise, the protrusions 170 can each have the same dimension, spaced equally apart, at about 15, 10 or 5 degrees, or between 3 degrees and 20 degrees apart or some other increment. The protrusions 170 relative to the recesses120 are sized to interface with each other and lock a rotational position of the insert 150 into the base 110.

[0040] Guide 100 may include various markings or rules on insert 150 and / or base 110 for identification of specific inserts and / or rotational indexing of the insert to the base. In some embodiments, base 110 and / or insert 150 comprise one or more markings, labels, or directional arrows. For example, in some embodiments, the one or more markings are embossed or debossed on a surface (e.g., top surface 155) of insert 150 and / or a surface (e.g., top surface 115, a side surface) of base 110. In some embodiments, the one or more markings comprises a directional arrow 186 on top surface 155 for rotating or indexing insert 150 to align with base 110. In some embodiments, base 110 comprises one or more markings or orienting lines that correspond to notches (e.g., recesses 120), degrees, positions or an index of base 110 for orienting or rotating insert 150 to a specific rotation or position in the base. For example, in some embodiments base 110 comprises a bezel, or one or more marking or orienting lines surrounding or around inner perimeter 122 and / or on a surface (e.g., top surface 115 and / or side surface) of base 110. In some embodiments, the one or more markings on insert 150 comprises a label 188, indicating or describing the specific insert 150, or the specific angle of channel axis 192, channel 160 and / or tubular structure 180 for the respective insert 150. The one or more markings may be alphanumeric markings, or other markings indexing a numeric degree or orientation. In some embodiments, the one or more markings can be any character, symbol, shape or color.

[0041] Guide 100 may be formed from or comprise any suitably rigid and non-porous material. In some embodiments, base 110 and insert 150 are formed from the same material, or different materials. In some embodiments, portions of base 110 and / or insert 150 are transparent, translucent or opaque. In some embodiments, tubular structure 180 may be formed of a clear tube with marking or graduations to aid in device or catheter placement. In some embodiments, guide 100 comprises any of a biocompatible material, a sterilizable material, composite material, plastic, metal, alloy or the like.

[0042] Further, guide 100 may include a means for controlling depth of placement, plunge depth or extension of any device passing through the tubular structure 180 and / or channel 160 towards a target in a subject. For example, in some embodiments guide 100 comprises a depth stop, collar, or the like, that may be affixed to a device to arrest distal movement of the device at one or more positions or depths. Further, guide 100 may comprise one or more sensors (e.g., magnetic sensor, optical sensor, camera, hall effect sensor) for measuring markings, graduations or increments on a device (e.g., an EVD or catheter) for aiding in controlling the depth of placement, with an alert (audible, visual, tactile alert) when an intended target has been reached by the device. For example, a sensor positioned within or at one end of channel 160 and / or tubular structure 180 configured to view and / or measure the device passing through the channel.

[0043] Referring now to FIG. 1 C, shown is an exemplary guide 100 with labelled dimension lines. In some embodiments, base 110 has a height 200 ranging between 2 cm and 8 cm, or about 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm, 5 cm, 5.5 cm, 6 cm, 6.5 cm, 7 cm, 7.5 cm, or 8 cm. In some embodiments, first body 112 has a height 202 ranging between 2 cm and 4 cm, or about 2 cm, 2.5 cm, 3 cm, 3.5 cm, or 4 cm. In some embodiments, first body 112 has a first or top width or diameter 204 ranging between 2 cm and 6 cm, or about 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm, 5 cm, 5.5 cm, or 6 cm. In some embodiments, first body 112 has a second or bottom width or diameter 206 ranging between 2 cm and 4 cm, or about 2 cm, 2.5 cm, 3 cm, 3.5 cm, or 4 cm.

[0044] In some embodiments, each leg of the at least 3 legs 124 have a length 208 ranging between 2 cm and 6 cm, or about 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm, 5 cm, 5.5 cm, or 6 cm. In some embodiments, each leg of the at least 3 legs 124 are separated by a distance 210 ranging between 2 cm and 6 cm, or about 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm, 5 cm, 5.5 cm, or 6 cm.

[0045] Referring now to FIGs. 1 D & 1 E, shown is an exemplary insert 150 with labelled dimension lines. In some embodiments, second body 152 of insert 150 has aheight 220 ranging between 2 cm and 4 cm, or about 2 cm, 2.5 cm, 3 cm, 3.5 cm, or 4 cm. In some embodiments, second body 152 has a first or top width or diameter 222 ranging between 2 cm and 6 cm, or about 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm, 5 cm, 5.5 cm, or 6 cm. In some embodiments, second body 152 has a second or bottom width or diameter 224 ranging between 2 cm and 4 cm, or about 2 cm, 2.5 cm, 3 cm, 3.5 cm, or 4 cm.

[0046] In some embodiments, tubular structure 180 has a length 226 ranging between 2 cm and 6 cm, or about 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, 4.5 cm, 5 cm, 5.5 cm, or 6 cm. In some embodiments, tubular structure 180 has an inner diameter 228 ranging between 1 mm and 15 mm, or about 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, or 15 mm. In some embodiments, tubular structure 180 has an outer diameter 230 ranging between 1 mm and 20 mm, or about 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm or 20 mm. In some embodiments, tubular structure 180 may be described as having a major and minor axis, wherein each axis has a length ranging between 1 mm and 20 mm, or about 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm or 20 mm.

[0047] In some embodiments, tubular structure 180 is titled or angled at an angle 232 (e.g., a first angle) from central vertical axis 190. For example, in some embodiments, angle 232 ranges between 1 ° and 60°, or about 1 °, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11 °, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, 20°, 21 °, 22°, 23°, 24°, 25°, 26°, 27°, 28°, 29°, 30°, 31 °, 32°, 33°, 34°, 35°, 36°, 37°, 38°, 39°, 40°, 41 °, 42°, 43°, 44°, 45°, 46°, 47°, 48°, 49°, 50°, 51 °, 52°, 53°, 54°, 55°, 56°, 57°, 58°, 59°, or 60°. In some embodiments, angle 232 is 6°, 12°, or 18°, or any increment of 6°.

[0048] Each insert 150 comprises a tubular structure 180 positioned and angled in a specific configuration to form channel 160 and align channel axis 191 . In some embodiments, the position of tubular structure 180 on top surface 155 of first body 112 is proportional to angle 212. In some embodiments, tubular structure 180 and / orchannel 160 are positioned a distance 191 from central axis 190 on top surface 155 of second body 152 (see FIG. 1 B). In order to maintain correct alignment of a device (e.g., a catheter) with an entry point (e.g., a burr hole) distance 191 must increase as angle 212 increases, and vice versa. Distance 191 may range between 0.1 mm and 4 cm, or 1 mm and 2 cm, or about 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm,10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, 30 mm,31 mm, 32 mm, 33 mm, 34 mm, 35 mm, 36 mm, 37 mm, 38 mm, 39 mm, or about 40 mm.

[0049] A surgical guide kit can include multiple inserts with channels at different angles as shown in FIG. 1 B, allowing surgeons various options for selecting the correct angular approach for insertion. In some embodiments, the surgical guide kit may comprise any of a guide 100, base 110, one or more of insert 150, and a calculation means such as a software having a graphical user interface (GUI), a table, a calculator, a slide calculator, or the like. In some embodiments, the surgical guide kit comprises a plurality of inserts 150. In some embodiments, a first insert 150 is provided with the kit having a tubular structure 180 at a first angle (e.g., angle 232), a second tubular structure 180 having a tubular structure 180 at a second angle, and a third insert 150 having a tubular structure 180 at a third angle. Any number of insert 150 may be provided with the kit, each having a tubular structure 180 at a specific angle relative to central vertical axis 190. The surgical kit may further comprise any device such as a drain, catheter, biopsy tool, electrode, transducer, sensor, surgical tools, instruments, guided devices, or the like. The surgical kit may further comprise an alignment means, tool or device for aligning base 110 with an entry point (e.g., a burr hole). For example, in some embodiments, the kit comprises an insert 150 with a channel 160 having a channel axis 192 that is colinear or coaxial with central vertical axis 190, or a tubular structure 180 that is positioned centrally and vertically passing through second body 152. In some embodiments, the alignment means comprises a tool, guidelight, and / or laser that can be positioned in a vertical channel 160 or extend through the channel to align base 110 with the entry point or burr hole. In some embodiments, base 110 comprises a laser or light source attached to first body 112 configured to produce anillumination, cross-hair or guidelines on the subject (e.g., on the skull) centered on the entry point or burr hole. In some embodiments, the laser or light source is removably attached to a portion of base 110, or positioned inside first body 112 of base 110 and producing an illumination through an opening or aperture in a bottom portion of the body. In some embodiments, the laser or light source is attached to or positioned in at least one of the at least three legs 124.

[0050] Referring now to FIG. 3A, shown is a diagram depicting an exemplary method 300 for guiding a device (e.g., an external ventricular drain) according to aspects of the present invention. In some embodiments, method 300 comprises the steps of 301 providing a surgical kit, 302 imaging a patient’s head, 303 determining an insertion parameter based on the imaging, 304 selecting one of the first, second or third insert based on the determined insertion parameter, and 305 inserting the selected insert into the base at a rotated position based on the determined insertion parameter. In some embodiments, the step of determining an insertion parameter comprises determining a coronal adjustment angle and sagittal adjustment angle. In some embodiments, the step of determining an insertion parameter comprises comparing the coronal adjustment angle and the sagittal adjustment angle to predetermined values. In some embodiments, the method further comprises aligning base 110 with an entry point or burr hole with an alignment means.

[0051] In some embodiments, determining an insertion parameter includes determining a coronal adjustment angle and sagittal adjustment angle. This is achieved either through the use of manual determination of angles on images of the patient head, or through the use of automated software able to measure these angles and determine the insertion parameter, as well as the specific insert and rotational position required. Methods for determining insertion parameters are also disclosed. In some embodiments, the method includes the steps of manually determining angles of insertion in the coronal and sagittal planes and comparing to a given table. In some embodiments, a physical device is utilized for determining angles, similar to a slide rule, or through the use of software. The software in some embodiments is custom designed 1to automate the entire process to allow a user to input a CT scan and receive instructions for insert and rotational position as an output.

[0052] FIGs. 9A-9H are a series of images showing an exemplary method for guiding a device using a surgical guide. FIG. 9A shows a base of a surgical guide positioned above and coaxial with a burr hole in a subject’s skull. FIG. 9B shows that a specific insert (e.g., a gold colored 18 deg insert) comprising an angled tubular structure is chosen based on the target, area or region in the subject’s skull. FIG. 9C shows that the insert is aligned with the base. FIG. 9D shows that the insert is rotated to an appropriate setting (e.g., rotated 2 notches or 30 deg) based on the target in the subject’s skull. FIG. 9E shows that insert has notches that interface with grooves in the base when inserted. FIG. 9F shows an exemplary device (e.g., a catheter) aligned with the tubular structure of the insert. FIG. 9G shows a device guided by the tubular structure of the insert into the burr hole and towards a target in the subject’s skull. FIG. 9H shows a device positioned at a target in the subject’s skull.

[0053] Embodiments of the device guide have several advantages over existing alternatives. Embodiments of the device guide can be applied at the bedside. While other devices such as the neuronavigation (NN) and XperCT (XCT) approaches require complex machinery and are useful in the operating room angiography suite, embodiments of the method described herein can be performed in the emergency room or intensive care unit (ICU). These locations are not very conducive to bulky equipment. As a result, the freehand (FH) approach using anatomic landmarks is usually applied in these settings. Embodiments of the device guide have the potential to improve accuracy in the specific patient population of patients with altered brain ventricular anatomy, where the FH approach would be less accurate, in settings such as the emergency department and ICU, where an EVD must be placed rapidly. In addition, embodiments of the device can be produced at a very low cost. 3D-printed material is inexpensive, and pieces of the device can be packaged in a pre-sterilized kit ready for use at the bedside.

[0054] The device also has the advantage of maintaining the same time of procedure as the FH approach. While other methods such as XCT and NN require a prolonged procedure time, embodiments of the device have the potential of zero increase in procedure time, and possibly even decreasing it. Once an optimal workflow is established for measuring the angles of insertion of the EVD catheter and choosing the best insert and angle combination for the device, the process could be as rapid as the FH approach. With the FH approach, surgeons usually spend a bit of time studying the CT scan of the patient before actually placing the EVD, so as long as the workflow of using the device does not exceed the normal time of planning the trajectory, the method will require at most as much time as the conventional FH approach. Embodiments of the device do not require placement of the device within the skull, presenting safety concerns and more regulatory approvals.

[0055] Embodiments described herein maintain a tripod base, which does not require placing the device itself within the skull. In addition, while conventional devices require adjusting the angle of insertion of the catheter relative to the coronal plane alone, embodiments of the device described herein involve adjusting the angle in the sagittal and coronal plane. Allowing for the insertion angle adjustment in both planes is important for cases of extreme ventricular shift and abnormal ventricular anatomy, where the catheter trajectory predicted by the FH approach would result in extremely inaccurate EVD placement. Another advantage of the method described herein is that it can be performed using any computed topography (CT) software that has the capability of performing angle measurements and drawing lines. This allows the device to be used in a wide variety of hospitals, anywhere from level 1 trauma centers to a community hospital, that use different CT software platforms.

[0056] Embodiments of the disclosed guide are primarily for placement of an external ventricular drain (EVD), most useful is for emergent bedside EVD placement in a patient with significantly altered ventricular anatomy. The disclosed guide would also result in accurate EVD catheter placement at the bedside for patients with normal ventricular anatomy. The guide is useful in other surgical contexts as well. For example, any procedure where a targeted catheter must be placed in a precise locationwould benefit from the guide. In addition, the guide is useful in the setting of electrode placement, such as during functional neurosurgical procedures used to treat epilepsy. The disclosed guide is also helpful with brain and tumor biopsies, where small pieces of tissue must be extracted and sent to a pathologist to determine the specific disease process occurring.

[0057] The disclosed guide also paves the way for patient-specific 3D-printed devices. Currently, the process of 3D printing takes too much time to allow for an EVD guide to be printed de novo and used rapidly at the bedside. As 3D-printing technology continues to improve, a guide similar to the embodiments described herein could be printed rapidly and processed immediately after obtaining an initial CT scan of the patient. This is significant because it would allow for the guide to be 3D-printed at the point of care.

[0058] Aspects of the present invention relate to a software or GUI to be used in conjunction with guide 100. In some embodiments, the software is designed to assist surgeons in accurately inserting a device to reach a target within a patient's skull using the disclosed guide. In some embodiments, the software provides a solution for difficulties that arise for entry point determination when aligning subject imaging (CT scan) and "real-life" registration. The primary function of the software is the determination of an optimal guide setting, a determination that can be calculated either manually (e.g., with a tablet or slide calculator) or through the software’s algorithms. In some embodiments, the software is deployed as a phone app, an online module, a standalone application, or a plugin integrated with standard imaging systems. During the procedure, the surgeon selects an entry point on the patient's skull on a CT scan, and the software calculates the perpendicular angle from this point. Once the target point is chosen, the software then calculates the necessary entry angle and determines the appropriate device settings (e.g., as specific insert 150, and the rotation or indexing of insert 150 in base 110), ensuring accurate and efficient catheter placement.

[0059] In some embodiments, in addition to its core functionality, the software could be enhanced with several advanced features to further assist surgeons. In someembodiments, the software provides the ability to either manually select or automatically determine entry points. In some embodiments, the software automatically identifies entry points based on specific anatomical sites, such as Kocher’s, Fraser’s, or Keene’s points, and / or provider-determined locations. In some embodiments, the software provides options for ipsilateral versus contralateral entry points, with the ability to finetune these automatically determined points manually. In some embodiments, the software calculates device depth (e.g., catheter depth) to ensure accurate depth of placement.

[0060] In some embodiments, the software or algorithm thereof accepts one or more inputs and produces or calculates one or more outputs. For example, in some embodiments, the one or more inputs are selected from: subject sex, age, ethnicity, skull size, target, target area, entry point, anatomical site, burr hole size, and / or device depth. In some embodiments, the one or outputs are selected from: entry point, ipsilateral entry point, contralateral entry point, perpendicular angle relative to entry point, device depth, entry angle, angle of insertion, coronal adjustment angle, sagittal adjustment angle, correction angle, Frontal Component (e.g., with Equation 1 below), Sagittal Component (e.g., with Equation 2 below) a specific insert 150, one or more insert 150, rotation or indexing of insert 150 in base 110, a virtual representation of the skull of the subject and / or the guide 100, and / or a virtual representation of device path for a device using the guide 100 with specific insert.

[0061] In some embodiments, the software calculates a margin of error for each insertion, helping to evaluate the likelihood of successful placement of the catheter, needle, or other device. In cases where is little room for error, in some embodiments the software may alert the surgeon, suggesting alternate entry points or device settings to improve the chances of success. Additionally, in some embodiments, the software may provide warnings for dangerous scenarios, such as when an insertion trajectory crosses the midline. In some embodiments, the software provides alternative strategies or device settings to avoid complications.

[0062] In some embodiments, the software provides a virtual surgery preview that allows surgeons to visualize the guide in place on the patient's head and / or the path of the device, aiding in the accurate positioning of the tripod on the skull and ensuring both the device’s orientation and the entry point are accurate. In some embodiments, the software provides virtual reality or augmented reality tools to further assist in entry point registration. It should be appreciated that the software ensures that patient data is handled appropriately, adhering to privacy and security standards while managing sensitive information.

[0063] In some aspects of the present invention, software executing the instructions provided herein may be stored on a non-transitory computer-readable medium, wherein the software performs some or all of the steps of the present invention when executed on a processor.

[0064] Aspects of the invention relate to algorithms executed in computer software. Though certain embodiments may be described as written in particular programming languages, or executed on particular operating systems or computing platforms, it is understood that the system and method of the present invention is not limited to any particular computing language, platform, or combination thereof. Software executing the algorithms described herein may be written in any programming language known in the art, compiled, or interpreted, including but not limited to C, C++, C#, Objective-C, Java, JavaScript, MATLAB, Python, PHP, Perl, Ruby, or Visual Basic. It is further understood that elements of the present invention may be executed on any acceptable computing platform, including but not limited to a server, a cloud instance, a workstation, a thin client, a mobile device, an embedded microcontroller, a television, or any other suitable computing device known in the art.

[0065] Parts of this invention are described as software running on a computing device. Though software described herein may be disclosed as operating on one particular computing device (e.g. a dedicated server or a workstation), it is understood in the art that software is intrinsically portable and that most software running on a dedicated server may also be run, for the purposes of the present invention, on any of awide range of devices including desktop or mobile devices, laptops, tablets, smartphones, watches, wearable electronics or other wireless digital / cellular phones, televisions, cloud instances, embedded microcontrollers, thin client devices, or any other suitable computing device known in the art.

[0066] Similarly, parts of this invention are described as communicating over a variety of wireless or wired computer networks. For the purposes of this invention, the words “network”, “networked”, and “networking” are understood to encompass wired Ethernet, fiber optic connections, wireless connections including any of the various 802.11 standards, cellular WAN infrastructures such as 3G, 4G / LTE, or 5G networks, Bluetooth®, Bluetooth® Low Energy (BLE) or Zigbee® communication links, or any other method by which one electronic device is capable of communicating with another. In some embodiments, elements of the networked portion of the invention may be implemented over a Virtual Private Network (VPN).

[0067] FIG. 3B and the following discussion are intended to provide a brief, general description of a suitable computing environment in which the invention may be implemented. While the invention is described above in the general context of program modules that execute in conjunction with an application program that runs on an operating system on a computer, those skilled in the art will recognize that the invention may also be implemented in combination with other program modules.

[0068] Generally, program modules include routines, programs, components, data structures, and other types of structures that perform particular tasks or implement particular abstract data types. Moreover, those skilled in the art will appreciate that the invention may be practiced with other computer system configurations, including handheld devices, multiprocessor systems, microprocessor-based or programmable consumer electronics, minicomputers, mainframe computers, and the like. The invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices.

[0069] FIG. 3B depicts an illustrative computer architecture for a computer 400 for practicing the various embodiments of the invention. The computer architecture shown in FIG. 3B illustrates a conventional personal computer, including a central processing unit 450 (“CPU”), a system memory 405, including a random access memory 410 (“RAM”) and a read-only memory (“ROM”) 415, and a system bus 435 that couples the system memory 405 to the CPU 450. A basic input / output system containing the basic routines that help to transfer information between elements within the computer, such as during startup, is stored in the ROM 415. The computer 400 further includes a storage device 420 for storing an operating system 425, application / program 430, and data.

[0070] The storage device 420 is connected to the CPU 450 through a storage controller (not shown) connected to the bus 435. The storage device 420 and its associated computer-readable media provide non-volatile storage for the computer 400. Although the description of computer-readable media contained herein refers to a storage device, such as a hard disk or CD-ROM drive, it should be appreciated by those skilled in the art that computer-readable media can be any available media that can be accessed by the computer 400.

[0071] By way of example, and not to be limiting, computer-readable media may comprise computer storage media. Computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, RAM, ROM, EPROM, EEPROM, flash memory or other solid state memory technology, CD-ROM, DVD, or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can be accessed by the computer.

[0072] According to various embodiments of the invention, the computer 400 may operate in a networked environment using logical connections to remote computersthrough a network 440, such as TCP / IP network such as the Internet or an intranet. The computer 400 may connect to the network 440 through a network interface unit 445 connected to the bus 435. It should be appreciated that the network interface unit 445 may also be utilized to connect to other types of networks and remote computer systems.

[0073] The computer 400 may also include an input / output controller 455 for receiving and processing input from a number of input / output devices 460, including a keyboard, a mouse, a touchscreen, a camera, a microphone, a controller, a joystick, or other type of input device. Similarly, the input / output controller 455 may provide output to a display screen, a printer, a speaker, or other type of output device. The computer 400 can connect to the input / output device 460 via a wired connection including, but not limited to, fiber optic, Ethernet, or copper wire or wireless means including, but not limited to, Wi-Fi, Bluetooth, Near-Field Communication (NFC), infrared, or other suitable wired or wireless connections.

[0074] As mentioned briefly above, a number of program modules and data files may be stored in the storage device 420 and / or RAM 410 of the computer 400, including an operating system 425 suitable for controlling the operation of a networked computer. The storage device 420 and RAM 410 may also store one or more applications / programs 430. In particular, the storage device 420 and RAM 410 may store an application / program 430 for providing a variety of functionalities to a user. In particular, the storage device 420 and RAM 410 may store an application / program 430 for providing a variety of functionalities to a user via a user interface (III) and / or graphical user interface (GUI). For instance, the application / program 430 may comprise many types of programs such as a word processing application, a spreadsheet application, a desktop publishing application, a database application, a gaming application, internet browsing application, electronic mail application, messaging application, and the like. According to an embodiment of the present invention, the application / program 430 comprises a multiple functionality software application for providing mathematical calculation functionality, disclosed guide calculationfunctionality, word processing functionality, slide presentation functionality, spreadsheet functionality, database functionality and the like.

[0075] The computer 400 in some embodiments can include a variety of sensors 465 for monitoring the environment surrounding and the environment internal to the computer 400. These sensors 465 can include a Global Positioning System (GPS) sensor, a photosensitive sensor, a gyroscope, a magnetometer, thermometer, a position sensor, magnetic sensor, optical sensor, camera, a Hall effect sensor, a proximity sensor, an accelerometer, a microphone, biometric sensor, barometer, humidity sensor, radiation sensor, or any other suitable sensor.EXPERIMENTAL EXAMPLES

[0076] The invention is now described with reference to the following Examples. These Examples are provided for the purpose of illustration only and the invention should in no way be construed as being limited to these Examples, but rather should be construed to encompass any and all variations which become evident as a result of the teaching provided herein.

[0077] Without further description, it is believed that one of ordinary skill in the art can, using the preceding description and the following illustrative examples, make and utilize the present invention and practice the claimed methods. The following working examples therefore, specifically point out the preferred embodiments of the present invention, and are not to be construed as limiting in any way the remainder of the disclosure.

[0078] Disclosed herein is experimental proof of concept for a patient-specific EVD (PS-EVD) guide and method. Using patient-derived models (digital models from patient anonymized data as well as 3D-printed models), the disclosed PS-EVD guide and method is shown to allow efficient and accurate EVD placement. In some embodiments, the disclosed device and method may be used in emergent situations for patients with altered ventricular anatomy.

[0079] A PS-EVD Guide was prototyped, having a tripod base and series of differently angled inserts that lock in place at multiple rotational positions, allowing for numerous insertion angles (see FIG. 6B). For testing, a 3D-printed phantom skull was designed with a gelatin brain analog containing ventricles simulating normal and altered ventricular anatomy. Low resolution CT images of the phantom were obtained and used to calculate the insertion angle in relation to the standard perpendicular entry. The corresponding insert at the correct rotational position within the base unit was positioned over the entry point on the phantom and the catheter was inserted. Accuracy was evaluated with repeat CT images. With normal ventricular anatomy as well as abnormal shifted ventricles, the PS-EVD guide resulted in accurate catheter insertion into the ventricle on 10 / 10 (100%) trials confirmed on coronal and sagittal CT images. In the following example, the disclosed PS-EVD guide displays consistent and accurate EVD placement in phantom skulls with both normal and altered ventricular anatomy.

[0080] The PS-EVD guide was designed using CAD software with 3D-printing in mind for rapid prototyping and fabrication. In some embodiments, the guide comprises a tripod base that sits on the patient’s head and an insert that can be placed into the tripod. This insert has an angled canula that can be rotated in increments (e.g., 15- degre increments) and locked in place, allowing for alteration of coronal and sagittal angles of the guiding cannula relative to perpendicular. Prior to designing the angulation and number of inserts required, measurements were performed on deidentified patient CT scans to capture the range of angles that would be physiologically possible and necessary for ventricle canulation. Extreme examples of altered ventricular anatomy were selected, including scans of traumatic brain injury, cerebral hemorrhage and large brain tumors with different extents of ventricular shift (see FIGs. 4A & 4B).

[0081] FIGs. 4A & 4B are images depicting a CT scan exemplifying extremely altered ventricular anatomy with calculated adjustment angles in the coronal (FIG. 4A) and sagittal (FIG. 4B) planes.

[0082] Three different angled inserts (Red, Blue, and Gold) were made corresponding to 6, 12, and 18 degree cannulas, which can be rotated at 15-degree 1increments to create a total of 72 different coronal and sagittal angle combinations to accommodate shifted ventricles and abnormal anatomy (see FIG. 6A). Each rotation alters both the frontal and sagittal correction angle, and the use of multiple inserts allows for a range of angles sufficient for our goals to be reached. Adjustment angles for each plane are calculated for each position, as shown in Table 1 below and discussed herein.

[0083] Table 1: Table of possible adjustment angles reachable by the disclosed device and method

[0084] Table 1 shows exemplary adjustment angles reachable by the disclosed guide. Columns 2-4 indicate frontal adjustment angles, and columns 5-7 indicate sagittal adjustment angles. In the disclosed example, if the measured adjustment angles were 13.90 and 0.91 ° in the frontal and sagittal planes, respectively, the chosen insert and rotation angle of the device would be the gold (18-degree) insert rotated 30°. This insert and rotation angle corresponds to adjustment angles of 15.72 and 9.23° in the frontal and sagittal planes, respectively. The frontal adjustment angle requires more precision in matching the calculated and measured adjustment angles, whereas a wider range of adjustment angles in the sagittal plane is usually sufficient

[0085] Device fabrication: All parts of the guide were 3D-printed using either Formlabs Durable Resin on a Form 2 SLA printer, or polylactic acid (PLA) filament onan Ender 3v2 printer. Resin parts were then fully cured in a UV oven for 1 hour at 50°C. Supports on all prints were then cut off and any excess material was removed by hand. All parts were inspected for any printing errors or defects before use.

[0086] Phantom skull design: Testing was performed using custom 3D-printed skull phantoms. The top portion of a skull was created based on a simplified skull file from a 3D model repository (e.g., the National Institutes of Health (NIH) 3D-Print Exchange). Using a CAD software, a portion of the top of the skull was replaced with an insert covering the area of interest for testing. The insert had a rubber balloon filled with air or iodine (to mimic a ventricle) suspended in the center before being filled with a 4% gelatin, 0.25% glutaraldehyde solution to mimic brain matter, allowing the fake “ventricle” to show up on the CT with sufficient contrast. The position of the “ventricle” could be adjusted within the insert to approximate many different normal and altered anatomies. Five distinct skulls with varying anatomy were used throughout testing.

[0087] Angle calculations: The 0° rotation angle assumes the full angle for each insert is aligned with the coronal plane. The matching notches on the insert and tripod base correspond to 15° of rotation. The correction angles can be calculated using the equations:

[0088] Frontal Component = tan-1(tan(insert angle) * cos(rotation angle))Equation 1

[0089] Sagittal Component = tan-1(tan(insert angle) * sinfrotation angle))Equation 2

[0090] where “insert angle” is the angle of the inserted piece off the perpendicular axis (Red = 6°, Blue = 12°, Gold = 18°).

[0091] Device Usage: The methodology for using the disclosed PS-EVD guide involves obtaining an initial CT scan with sagittal and coronal reconstructions, similar tostandard FH approach [Shih et al., J Am Coll Radiol. 2021 May;18(5S):S13-S36] (see FIG. 5A).

[0092] The next step involves determining the perpendicular trajectory of catheter entry based on the patient’s skull anatomy on the CT scan, marked by the red lines in Fig. 5B. The angle that would result in appropriate catheter placement is then calculated as an “adjustment angle” relative to the perpendicular trajectory using ImageJ, or similar image analysis software. Based on these adjustment angles, the table of inserts and rotation combinations is consulted, and the insert and rotation angle combination is selected that produces coronal and sagittal angles that most closely approximate the measured adjustment angles. The coronal correction angle is prioritized due to the wide range of angles that are appropriate in the sagittal plane based on the anatomy of the lateral ventricle. After device parameter selection, a burrhole is drilled into the skull at Kocher’s Point, as in the FH approach. The tripod base is then placed over the burr hole with two legs facing medially, parallel to the sagittal axis of the skull. The selected insert is placed inside the tripod base and then rotated the prescribed number of notches (which are also labeled for convenience) from the starting position and locked in place using the matching grooves on the tripod and insert. The catheter is passed through the inner canula of the insert, following the pre-measured angle. A repeat CT scan is performed to assess the accuracy of catheter placement. A demonstration of the process for using the disclosed guide is shown in FIGs. 9A-9H.

[0093] Example Case (see FIGs. 5A-5C): A CT scan of a phantom skull was performed (FIG. 5A). The perpendicular line to the skull was established, shown as the red line in FIG. 5B. The “correction angle” was measured with a coronal adjustment angle of 13.90° and sagittal adjustment angle of 0.91 ° (FIG. 5B green lines). From Table 1 , the gold (18-degree) insert rotated 30° (turned 2 notches) was selected. This gave calculated adjustment angles of 15.72° and 9.23° in the coronal and sagittal planes, respectively. The calculated coronal adjustment angle of 15.72° closely matched the measured adjustment angle of 13.90°. The calculated and measured sagittal adjustment angles of 9.23° and 0.91 °, respectively, notably differ. As demonstrated in FIG. 5B, there is room for error in the sagittal plane, as the dimensionsof the ventricle extend across a relatively wide range of angles in the sagittal plane. The resulting CT scan for the disclosed example is shown in FIG. 5C, with accurate catheter insertion.

[0094] FIGs. 5A-5C are a series of images depicting an exemplary PS-EVD placement workflow method using the disclosed guide according to aspects of the present invention. The disclosed images depict the method performed on a phantom skull model. FIG. 5A depicts an initial CT scan for PS-EVD guide use. FIG. 5B depicts a CT scan with perpendicular and adjustment trajectories in the coronal and sagittal planes. FIG. 5C depicts the resulting CT scan after catheter placement, showing the catheter is in the central ventricle in both the frontal and sagittal planes.

[0095] Practical trial methods: Practical EVD implementation trials were performed using the phantom skulls, fabricated as described above. Initial CT scans were performed on the skulls, followed by the workflow method as described above. The disclosed trials were performed by inserting the catheter on either side, including both ipsilateral and contralateral to the direction of midline shift, each on a separate iteration. An approach from both sides was chosen as a challenge to see if the disclosed guide could accommodate even the most difficult angles. Trials were also performed on the same models using the zero-degree insert, which represents the perpendicular trajectory that a Ghajar Guide would provide, in order to serve as a head-to-head comparison between the disclosed guide and the Ghajar Guide.

[0096] The PS-EVD guide was developed to aid in the placement of EVD catheters, especially in altered anatomies. FIG. 6A shows a CAD rendering of the device, which consists of the tripod and 3 inserts of varying angles. The angled inserts have ridges that fit snugly into the grooves on the inside ring of the tripod, which allows the inserts to only be positioned at discrete rotational positions and locked into place at the prescribed angle. The guide tube for catheter insertion is designed such that it passes directly through the center of the tripod base to ensure that no matter which rotational position is chosen, the catheter will be inserted through the burr-hole without needing to reposition the tripod. The pre-set trajectories pivot around the entry site at the skull allowing use ofany angle without need to move the tripod base away from Kocher’s point. This is an important requirement, as repositioning the tripod could alter the perpendicular angle from which the “adjustment angle” is calculated, thus changing the required device setting or accuracy. An alternative design using a ball and socket joint with a pivot point above the skull would not work as simply, as any angle adjustment would move the trajectory of the catheter away from the burr-hole. After analysis of the CT images, the optimal insert and rotational position may be determined using Table 1 , which will allow for quick catheter insertion at the desired position. This process can be seen in full in FIGs. 9A-9H. FIG. 6B shows a 3D-printed tripod and set of inserts used for testing.

[0097] FIGs. 6A-6F are images depicting an exemplary guide, a CAD design of a phantom skull, and simulated positions provided by the guide based on the chosen insert. FIG. 6A depicts a CAD rendering of tripod base and three inserts using standard color code of red for the 6° insert, blue for the 12° insert, and gold for the 18° insert. The arrow on top of the inserts is used to aid in determining the rotational setting. The label on top of the inserts is used to aid in identifying the insert. FIG. 6B depicts a PLA 3D-printed prototype for an exemplary guide, including all three inserts. FIG. 6C depicts a CAD design of the phantom skull used for testing, with the insert removed. FIG. 6D depicts a CAD design of assembled phantom skull with the PS-EVD guide in place over the burr-hole and the 6° insert in use. FIG. 6E depicts a rendering of a guide showing all possible entry positions in colors corresponding to the insert used (red for the 6° insert, blue for the 12° insert, and gold for the 18°). It should be noted that all trajectories travel through the same entry point without needing to reposition the guide. FIG. 6F depicts a bottom view of the rendering of FIG. 6E.

[0098] A custom 3D-printed skull phantom was designed for laboratory testing of the device. The main skull and insert portion for holding the brain-analog are pictured in FIG. 6C. The skull was printed separate from ventricle inserts, as described in the Methods section. The varying blue ventricle insert portions fit tightly within the skull, allowing rapid exchange of five different inserts portions with varying ventricular anatomies. FIG. 6D shows the assembled skull phantom with the PS-EVD in place.

[0099] Simulated Angle Measurement Results: A total of 8 de-identified patient CT scans showing severe examples of midline shift and altered ventricular anatomy were used to demonstrate the feasibility of the PS-EVD to target the ventricles in a large variety of ventricular configurations and degrees of shifted anatomy. The 8 scans were evaluated for PS-EVD placement following the methods disclosed in this example. Table 2 shows the calculated coronal and sagittal angle ranges needed to reach the ventricle and the theoretical discrete PS-EVD settings that will place a device (e.g., a catheter) within the corrected coronal and sagittal angles from perpendicular. The mean calculated adjustment angles in the frontal and sagittal planes for all scans combined are shown at the bottom of Table 2. An example CT scan with the adjustment angle calculations is shown in FIGs. 4A & 4B. The Ghajar Guide would hypothetically result in accurate EVD insertion in just 3 of these 8 example scans, as demonstrated in Table 2.

[0100] Table 2: Calculation results from CT images demonstrating severely altered ventricular anatomy(CT - computed tomography, N / A - not applicable)

[0101] Table 2 shows calculation results from CT images demonstrating severely altered ventricular anatomy. The frontal adjustment angle and range of possible adjustment angles in the sagittal plane are shown, with the ideal insert and rotation angle of the guide that would most closely approximate the measured adjustment angles. Mean measured coronal and sagittal adjustment angles for this set of example CT scans are shown in the bottom row of the table.

[0102] Phantom Skull Trials: 14 total trials were performed on 5 phantom skulls, each skull with a different simulated anatomy. The first 3 trials were initial testing to clarify the device protocol, then 5 trials used an ipsilateral approach, 4 used the contralateral approach, and 2 were used to mimic using a perpendicular trajectory (similar to that of a Ghajar Guide). The first few trials allowed streamlining of the process and established a seamless workflow to allow for high accuracy. The optimal configuration of the guide involves placing the tripod base with two legs in the sagittal plane and the arrow (starting point) of the insert pointed 180° from the midpoint of the two legs. The directionality of the device rotation was also established (i.e., right is positive, and left is negative). The overall range of measured coronal angles was 8 to 23.64 degrees, and the range of measured sagittal angles was -2.69 to 11 .07 degrees. All inserts (red, blue, and gold) were used at least once during the 14 trials at varying rotational angles. Excluding the 3 trials used to establish protocols for positioning the device and the 2 trials mimicking the perpendicular trajectory of a Ghajar Guide, catheter insertion exactly matched the predicted trajectory on 9 of 9 trials following established protocols.

[0103] FIGs. 7A-7C as discussed herein demonstrate a comparison trial. Catheter insertion at a simple perpendicular plane (mimicking the approach of the Ghajar Guide) placed the catheter on the medial edge or missing the ventricle medially (FIG. 7A). FIG. 7B shows the result of using the PS-EVD guide following proper protocols. Coronal and sagittal angles adjusted from perpendicular were measured at 12.43°and 9.6°, respectively. The blue insert was used at 30° rotation, corresponding to 10.43° and 6.07° angles in the coronal and sagittal plane, respectively, resulting in accurate catheter placement. FIGs. 7D-7F demonstrate another comparison trial, with anexample of severe midline shift. The zero-degree insert was first used (FIG. 7D), which resulted in inaccurate catheter placement. A trial was then conducted using this same phantom skull using the optimal device setting to accommodate for the severe midline shift (FIG. 7E). The 18-degree insert rotated 0° was used, resulting in accurate catheter insertion into the ventricle.

[0104] FIGs. 7A-7F are a series of images showing the results for a comparison between a simulated Ghajar guide and the disclosed guide and method. FIG. 7A shows the result in the coronal plane for a trial where the positioning of the device mimics the perpendicular trajectory of a Ghajar Guide. FIG. 7B shows the result in the coronal plane of the same phantom skull as in FIG. 7A using the disclosed guide and method showing accurate positioning and insertion into the ventricle. FIG. 7C is an overlay of FIGs. 7A & 7B, demonstrating the improvement in placement using the disclosed guide and method. FIG. 7D shows the result of using a zero-degree insert, simulating a Ghajar Guide in a simulation of severely altered anatomy in which the perpendicular entry from a Ghajar Guide would not have been sufficient to reach the ventricle. FIG. 7E shows the result for same phantom skull of FIG. 7D, but using the disclosed guide and method with an 18-degree insert rotated at zero degrees, resulting in accurate insertion into the ventricle. FIG. 7F is an overlay of FIGs. 7C & 7D, demonstrating the improvement in placement using the disclosed guide and method.

[0105] FIGs. 8A & 8B as discussed herein demonstrate another trial exemplifying accurate catheter placement using the PS-EVD technique. FIGS. 8C & 8D represents a trial performed for a challenging example of extreme angulation targeting a very small ventricle. A contralateral approach was used to mimic severe ventricular shift. FIG. 80 & 8D demonstrate that catheter insertion was accurate, even in this difficult example mimicking a small target with severe shift, suggesting that using the disclosed guide and method is possible in even the most extreme cases of ventricular anatomy.

[0106] FIGs. 8A-8D are a series of images showing the results in the coronal and sagittal planes from two trials using the disclosed guide and method. For the trial demonstrated in FIGs. 8A & 8B, the measured angles were 13.90° and 0.91 ° in the(FIG. 8A) coronal and (FIG. 8B) sagittal planes. The gold insert rotated 30° was chosen, which gave calculated adjustment angles of 15.72° and 9.23° in the frontal and sagittal planes, respectively. The result was accurate insertion in the central ventricle. For the trial represented in FIGs. 8C & 8D, the measured angles were 5° and -2.69° in the (FIG. 8C) coronal and (FIG. 8D) sagittal planes, the red insert rotated -30° was chosen, which gave calculated adjustment angles of 5.20° and -3.01 ° in the coronal and sagittal planes, respectively. The result was accurate insertion in the ventral ventricle.

[0107] The FH approach for EVD placement, despite inaccuracy rates of 12.3%- 44.9% [Huyette et al., J Neurosurg 108:88-91 , 2008; Saladino et al., Neurocrit Care 10:248-252, 2009; Shtaya et al., J Neurosurg. Published online May 1 , 2018:1 -6; Kakarla et al., Neurosurgery. 2008;63(1 Suppl 1 ):ONS162-166; discussion ONS166- 167], is the most well-known and commonly used approach for bedside EVD placement [Ganti L., Atlas of Emergency Medicine Procedures. Springer New York; 2016:241-245], These alarming rates of misplacement should receive more recognition and EVD placement should garner the same level of attention as other bedside procedures in medicine. For example, a position statement from the Society of Hospital Medicine in 2019 included recommendations for providers to exclusively utilize real-time ultrasound guidance for internal jugular vein catheterization as opposed to landmark-based approaches [Franco-Sadud et al., Journal of Hospital Medicine. 2019;14(9):E1-E22], The authors describe that ultrasound-based approaches decrease the number of needle passes and time to cannulation and increase the overall procedure success rate [Franco-Sadud et al., Journal of Hospital Medicine. 2019;14(9):E1 -E22], One study cited by the authors demonstrates that the success rate of subclavian vein cannulation with ultrasound versus landmark-based approaches was 92% vs 44% [Franco-Sadud et al., Journal of Hospital Medicine. 2019;14(9):E1 -E22; Gualtieri et al., Critical Care Medicine. 1995;23(4):692], Placement of a catheter in the brain should have no less accuracy and the current misplacement rate cannot be tolerated. Through innovation, we aspire to improve bedside EVD accuracy in a similar manner.

[0108] The PS-EVD guide allows for accurate EVD insertion into phantom skulls with normal and abnormal ventricular anatomy. The trials corresponding to FIGs. 7A-7Fand FIGs. 8A-8D exemplify accurate EVD placement for skulls with normal and altered ventricular anatomy. When the methodology of calculating the adjustment angles, choosing the device settings, and placing the device on the skull is performed correctly, the ventricular insertion point matches the predicted point of entry reliably. The trial corresponding to FIGs. 8C & 8D exemplifies accurate EVD placement in the experimental setting of a small ventricle and by using the contralateral approach, mimicking severely shifted anatomy. These results demonstrate that accuracy of EVD placement can be significantly improved using the disclosed guide and method, even in examples of very difficult angles in extreme experimental clinical situations. With further automation of the methodology, such as having a computer program analyze the CT images to find the perpendicular positions, calculate the adjustment angles, and choose the correct insert and rotation angle for the user, the disclosed guide and method will allow rapid and accurate placement of EVD for patients with altered ventricular anatomy in need of emergent placement at the bedside.

[0109] For the disclosed guide, a tripod base design was implemented similar to that of the Ghajar Guide [Ghajar JBG, Technical note. J Neurosurg. 1985;63(6):985- 986], a previously approved device which has served as a guide for catheter insertion in the setting of normal ventricular anatomy for decades. Use of a tripod gives an advantage over other designs in that a tripod will always sit stably, even if there are local irregularities, such as variations in the hair and scalp. The disclosed guide performs at least as well as the traditional Ghajar Guide with respect to stability and consistency of placement, while also providing the many improvements related to angulation described herein.

[0110] Yoon et al. designed an adjustable Ghajar Guide [Yoon et al., J Korean Neurosurg Soc. 2017;60(5):604-609], however their device did not use a tripod base and instead was placed directly into the open burr-hole and only allowed adjustment of the insertion angle in the coronal plane. The disclosed guide has several advantages over the adjustable Ghajar Guide of Yoon et al. [Yoon et al., J Korean Neurosurg Soc. 2017;60(5):604-609], such as the use of a tripod base to suspend the guide mechanism above the skull, allowing for ease of securing the catheter after placement andpotentially decreasing the rate of infections. In addition, the insertion angle for the disclosed guide is adjustable in both the coronal and sagittal planes. The disclosed results demonstrate that the coronal adjustment angle needs to be more precise than the sagittal angle, such as in the trial corresponding to FIGs. 8A & 8B, where the ventricle was still accurately reached despite some variation in the sagittal angle. However, sagittal adjustment can still be important for reaching the ventricle, particularly in cases of extremely altered ventricular anatomy. The trial corresponding to FIGs. 8C & 8D demonstrates that being able to adjust the sagittal insertion angle is particularly important for a case of small ventricular anatomy. The adjustable Ghajar Guide of Yoon et al. [Yoon et al., J Korean Neurosurg Soc. 2017;60(5):604-609] was tested only in the setting of normal ventricular anatomy, where adjustment in the frontal plane is largely sufficient.

[0111] The disclosed guide and method can serve as a desirable alternative to existing technology. The calculations using example CT-scans, as described in Table 2, demonstrate that the Ghajar Guide would only result in accurate catheter insertion in 3 / 8 (37.5%) of these extreme examples of altered ventricular anatomy. On the other hand, the disclosed guide provides positions or settings that accommodated all 8 / 8 (100%) of the scans. In the shown results, the disclosed guide has improved accuracy over the Ghajar Guide, as demonstrated in FIGs. 7D & 7F. The experiment involving a phantom skull with severe midline shift the zero-degree insert, representing the original Ghajar Guide with a perpendicular angle of entry, results in inaccurate catheter insertion medial to the ventricle. Using the disclosed guide and method, with the 18-degree insert rotated zero degrees, resulted in accurate catheter insertion into the ventricle, as seen in FIG. 7E. Image analysis resulted in a measured angle of 21 degrees, though this coronal adjustment was considered to be an extreme example of altered ventricular anatomy that one would not see frequently in patients receiving an EVD. Although 18- degree adjustments for the guide and inserts should be sufficient for even extreme real- life examples, it should be noted that including an additional insert at a larger angle would account for even more extreme altered anatomies.

[0112] Another advantage of the disclosed guide is that the rotational pivot point is centered at the insertion site and not at the level of the guide. This allows placement of the tripod in a single location directly over the insertion site with the inserts guiding catheter placement at angles always centered at the burr hole (see FIGs. 6E & 6F). Thus, after placement, the disclosed guide may be adjusted to any of the 72 possible settings, and every setting will still lead to entry through the original burr hole, without having to move the tripod base. It should be noted that the use of a pivot point at some height above the insertion site, such as a simple ball-and-socket joint, would mean that any angular adjustment would reposition the catheter such that it was no longer aimed at the center of the tripod base, requiring repositioning of the tripod. However, since the adjustment angles are calculated off the perpendicular of the original insertion point, changing the location of the base could alter the angles to the target. This could then require a recalculation of angles at the new position, leading to a more complicated and less accurate process than the disclosed guide and method.

[0113] The disclosed guide as designed allows for 72 combinations of coronal and sagittal angles that can accommodate for even the most severely distorted anatomy. In some embodiments, additional inserts to increase the number and combinations of angles that can be reached may be included.

[0114] Accurately choosing the insertion point and accurately setting the angle of insertion of the catheter are two separate issues with the FH approach for EVD placement. The disclosed guide and method addresses the latter, but not the former. In some embodiments, this could be overcome by obtaining a CT scan after placement of the burr hole to allow precise calculations from the exact point of entry. However, this would add time, cost, radiation exposure and would be cumbersome. In some embodiments, a software or user interface (III) aids in improving the accuracy of identifying and confirming the correct insertion point.

[0115] For the disclosed guide and method to be clinically useful, it will need to involve a procedure time that is comparable in efficiency to the FH approach. A challenge with NN or XCT methods is their need for specialized equipment andincreased procedural time for usage [AlAzri et al., Acta Neurochir (Wien).2017; 159(8): 1399-1411 ; Gautschi et al., Acta Neurochir (Wien). 2014;156(4):777-785], The time needed to calculate the adjustment angles to appropriately use the disclosed guide may be longer when performed manually or with a chart. In some embodiments, a software or Ul automatically calculates the adjustment angle relative to the perpendicular trajectory and automatically chooses the most optimal insert and rotation angle for the device. This can streamline use of the disclosed guide and allow it to be the most efficient and accurate means of catheter placement. Compared to the amount of equipment needed for NN or XCT7-8, the disclosed guide is compact and cost- effective. In some embodiments, the disclosed guide is packaged in a pre-sterilized kit, immediately ready for use at the bedside with no additional assembly required.

[0116] FIGs. 9A-9H are a series of images showing an exemplary method for guiding a device using a surgical guide. FIG. 9A shows a base of a surgical guide positioned above and coaxial with a burr hole in a subject’s skull. FIG. 9B shows that a specific insert (e.g., a gold colored 18 deg insert) comprising an angled tubular structure is chosen based on the target, area or region in the subject’s skull. FIG. 9C shows that the insert is aligned with the base. FIG. 9D shows that the insert is rotated to an appropriate setting (e.g., rotated 2 notches or 30 deg) based on the target in the subject’s skull. FIG. 9E shows that insert has notches that interface with grooves in the base when inserted. FIG. 9F shows an exemplary device (e.g., a catheter) aligned with the tubular structure of the insert. FIG. 9G shows a device guided by the tubular structure of the insert into the burr hole and towards a target in the subject’s skull. FIG. 9H shows a device positioned at a target in the subject’s skull.

[0117] This example demonstrated that the disclosed guide and method is patientspecific, accurate and consistent. It can be used for normal or extremely shifted ventricular anatomy. It has the potential to be even more efficient with automation of the process of measuring adjustment angles and choosing the most optimal guide settings for the user.

[0118] In addition to the placement of EVD, the disclosed guide may be used for various other procedures requiring accurate positioning / neuronavigation within the skull, particularly those where real-time imaging guidance is unavailable. For example, brain biopsy procedure, typically performed with either real-time imaging or complex framebased systems [Bjartmarz H, Rehncrona S., Stereotact Funct Neurosurg.2007;85(5):235-42], may be accurately performed using the disclosed guide. Following the same protocol as for EVD placement, the disclosed guide may be used to guide a biopsy needle to a particular location. While there have been methods previously proposed for patient-specific 3D-printed stereotactic frames [Muller et al., Journal of Personalized Medicine. 2024; 14(2): 180], there does not exist a simple, adjustable, tripod-based product similar to the disclosed guide to perform such procedures. Deepbrain stimulation requires precise placement of electrodes within the brain, currently performed during lengthy surgeries requiring live imaging guidance and frame or robotic assistance to ensure accuracy of electrode placement [Burchiel et al., Journal of Neurosurgery JNS, 119(2), 301 -306; VanSickle et al., Ann Biomed Eng 47, 1212-1222 (2019)]. The disclosed guide may also be used to aid in the accurate placement of such electrodes, especially in situations where live imaging or robotic assistance is not available.

[0119] The disclosures of each and every patent, patent application, and publication cited herein are hereby incorporated herein by reference in their entirety. While this invention has been disclosed with reference to specific embodiments, it is apparent that other embodiments and variations of this invention may be devised by others skilled in the art without departing from the true spirit and scope of the invention.

Claims

CLAIMSWhat is claimed is:

1. A surgical guide comprising: a base comprising a first body having a proximal opening, a distal opening and an internal chamber therebetween, the proximal opening having a plurality of recesses disposed along an inner perimeter of the proximal opening; and a first insert comprising a second body having a proximal end, a distal end, and a channel extending therebetween, the proximal end having a plurality of protrusions disposed along an outer perimeter and configured to interface with the plurality of recesses, the channel angled away from a central vertical axis by a first angle.

2. The surgical guide of claim 1 further comprising: a tubular structure extending proximally away from the proximal end and distally away from the distal end with the channel extending therethrough.

3. The surgical guide of claim 1 , wherein the proximal opening is circular and centered on the central vertical axis.

4. The surgical guide of claim 3, wherein the outer perimeter is circular and centered on the central vertical axis.

5. The surgical guide of claim 4, wherein the central vertical axis intersects with the channel axis in a distal plane of the base.

6. The surgical guide of claim 1 , wherein the internal chamber tapers distally.

7. The surgical guide of claim 6, wherein the second body tapers distally.

8. The surgical guide of claim 1 , wherein the internal chamber and second body taper distally at a common angle.

9. The surgical guide of claim 1 further comprising: at least three legs extending distally from the base.

10. The surgical guide of claim 9, wherein the at least three legs are spaced equally apart.11 . The surgical guide of claim 1 , wherein the plurality of recesses each have the same dimension.

12. The surgical guide of claim 1 , wherein the plurality of recesses are spaced equally apart.

13. The surgical guide of claim 1 , wherein the plurality of recesses are spaced about 15 degrees apart.

14. The surgical guide of claim 1 , wherein the plurality of recesses are spaced between 10 and 15 degrees apart.

15. The surgical guide of claim 1 , wherein the plurality of recesses are spaced between 5 and 10 degrees apart.

16. The surgical guide of claim 1 , wherein the plurality of recesses are spaced between 3 degrees and 20 degrees apart.

17. The surgical guide of claim 1 , wherein the plurality of protrusions each have the same dimension.

18. The surgical guide of claim 1 , wherein the plurality of protrusions are spaced equally apart.

19. The surgical guide of claim 1 , wherein the plurality of protrusions are spaced about 15 degrees apart.

20. The surgical guide of claim 1 , wherein the plurality of protrusions are spaced between 10 and 15 degrees apart.21 . The surgical guide of claim 1 , wherein the plurality of protrusions are spaced between 5 and 10 degrees apart.

22. The surgical guide of claim 1 , wherein the plurality of protrusions are spaced between 3 degrees and 20 degrees apart.

23. A surgical guide kit comprising: the surgical guide of claim 1 ; and a second insert comprising a third body having a proximal end, a distal end, and a channel extending therebetween, the proximal end having a plurality of protrusions disposed along an outer perimeter and configured to interface with the plurality of recesses, the channel angled away from a central vertical axis by a second angle.

24. The surgical guide kit of claim 23 further comprising: a third insert comprising a third body having a proximal end, a distal end, and a channel extending therebetween, the proximal end having a plurality of protrusions disposed along an outer perimeter and configured to interface with the plurality of recesses, the channel angled away from a central vertical axis by a third angle.

25. A method for guiding a device comprising: providing the kit of claim 24; imaging a patient’s head;determining an insertion parameter based on the imaging; selecting one of the first, second or third insert based on the determined insertion parameter; and inserting the selected insert into the base at a rotated position based on the determined insertion parameter.

26. The method of claim 25, wherein determining an insertion parameter includes determining a coronal adjustment angle and sagittal adjustment angle.

27. The method of claim 26, wherein determining further comprises comparing the coronal adjustment angle and the sagittal adjustment angle to predetermined values.

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