Neurosurgical pointer for electromagnetic navigation

Abstract

The present invention relates to a neurosurgical pointer for electromagnetic navigation, characterised in that it comprises a base from which a cylindrical rod protrudes equipped with a rounded distal end, the rod comprising an open blind longitudinal hole at the proximal end of the base, the rod being configured for insertion through the tube of the sheath of a ventriculoscope such that it protrudes from the distal end of said tube, and the open blind longitudinal hole being configured to receive the needle of a stylus of an electromagnetic navigation system, the base comprising a cavity shaped as a cylindrical portion having a circular longitudinal cross section and open toward the proximal end of said base into which a stylus body fits.

Description

[0001] NEUROSURGICAL POINTER FOR ELECTROMAGNETIC NAVIGATION

[0002] DESCRIPTION

[0003] OBJECT OF THE INVENTION

[0004] The present invention belongs to the field of neurosurgery, and more particularly to the instruments used to identify patient tissues.

[0005] The object of the present invention is a new neurosurgical pointer suitable for navigation using an electromagnetic navigation system.

[0006] BACKGROUND OF THE INVENTION

[0007] There are four anatomical cavities in the brain, called cerebral ventricles, which are interconnected and constitute the ventricular system through which cerebrospinal fluid circulates. Certain conditions, such as hydrocephalus, require access to the cerebral ventricles. A surgical instrument called a "ventriculoscope" is used for this purpose.

[0008] A ventriculoscope is a neurosurgical instrument designed for performing interventions in the ventricular cavities of the brain. Fig. 1A shows a ventriculoscope, in this case specifically the LOTTA model ventriculoscope manufactured by Karl Storz. As can be seen, the ventriculoscope (100) has a main tube (110) along which several ducts (not visible in the figure) extend that are used for vision, irrigation / suction, as well as for the introduction of specific instruments for each intervention. However, the tube (110) of the ventriculoscope (100), being traversed by the aforementioned ducts, has a tip with relatively sharp edges that are not ideal for moving it through brain tissue until reaching the ventricular space.

[0009] For this reason, to ensure that no damage is caused to the patient's brain tissue during the introduction of the ventriculoscope into the ventricular cavity, two auxiliary elements specifically designed for this purpose are commonly used: the sheath and the trocar.

[0010] Fig. 1B shows an example of a sheath (200, top) and a trocar (300, bottom) used in conjunction with the aforementioned ventriculoscope (100). The sheath (200) essentially comprises a hollow tube (210) with a diameter larger than the diameter of the tube (110) of the ventriculoscope (100). As with the tube (110) of the ventriculoscope (100), the edges of the distal end of the tube (210) of the sheath (200) are also not suitable for introduction through brain tissue, since they could cause tissue damage. The trocar (300), on the other hand, comprises a solid shaft (310) having a diameter smaller than the diameter of the tube (210) of the sheath (200) and a length slightly greater than the length of the tube (210) of the sheath (200). In addition, the tube (310) of the trocar (300) has an anatomically shaped distal end (320) formed by smooth curves.When the trocar (300) is inserted into the sheath (200), the tip of the tube (310) of the trocar (300) protrudes from the distal end of the tube (210) of the sheath (200).

[0011] The sheath (200) and trocar (300) are used in combination to facilitate the introduction of the tube (110) of the ventriculoscope (100) into the ventricular cavity. First, the trocar (300) is inserted into the sheath (200) until the anatomical distal end (320) of the tube (310) of said trocar (300) protrudes through the end of the sheath (200). The sheath (200) is then introduced into the patient's brain cavity until it reaches the ventricle using a suitable navigation system. Because the distal end (320) of the trocar is anatomical, tissue damage along the way is minimized. Once the sheath-trocar assembly has reached the ventricular space, the trocar (300) is removed and the tube (110) of the ventriculoscope (100) is introduced in its place. This procedure allows the ventriculoscope (100) to be introduced into the surgical field in an atraumatic manner.

[0012] Once the sheath has been navigated until its distal end is introduced into the ventricular space, in addition to introducing the ventriculoscope, it can also be used to introduce auxiliary instruments into the ventricular cavity. Specifically, it would be desirable to have a surgical instrument that can be introduced through the sheath to mark (i.e., graze with its distal end) a specific tissue for the purpose of identifying said tissue through the images of a medical imaging system. DESCRIPTION OF THE INVENTION

[0013] The inventors of the present application have developed a pointer that can be introduced into the cerebral ventricle through the sheath of a ventriculoscope and that is also configured to be navigated using an electromagnetic navigation system.

[0014] Indeed, electromagnetic navigation is advantageous over other navigation systems, such as optical navigation, for several reasons. For example, the reference structures that must be attached to the base of the navigated element make it difficult to operate. In any case, the main concept underlying electromagnetic navigation is the introduction of a well-known element called a stylet, which, through certain electromagnetic means, is visible in a medical image using a specially designed system.

[0015] Fig. 2 shows, by way of example, the Medtronic S8 Stealthsystem stylet. The stylet (400) essentially comprises a metallic needle (410) protruding from a flat circular body (420) which, in turn, is connected by a cable (430) to certain electronic means. The electromagnetic navigation system is designed so that the needle (410) is visible in real time through a medical imaging system.

[0016] The pointer of the present invention is designed to allow electromagnetic navigation using a suitable stylet and can also be inserted along the sheath used to introduce a ventriculoscope. Specifically, the pointer of the present invention is intended to be used in conjunction with the sheath of a Karl Storz LOTTA ventriculoscope and the Medtronic S8 Stealthsystem stylet.

[0017] In short, the present invention is directed to a neurosurgical pointer for electromagnetic navigation comprising a base from which a cylindrical-shaped shaft with a rounded distal end protrudes. The shaft is configured for insertion through the sheath tube of a ventriculoscope such that it protrudes beyond the distal end of said tube. For example, according to preferred embodiments of the invention, the shaft may have a diameter between 2.4 mm and 2.6 mm and a length between 280 mm and 300 mm. In particular, a diameter of 2.5 mm and a length of 290 mm allow the shaft of the pointer of the invention to fit specifically into the sheath tube of a Karl Storz LOTTA model ventriculoscope.

[0018] The shaft further comprises a blind longitudinal bore open at a proximal end of the base. This blind longitudinal bore is configured to receive the needle of a stylet used in an electromagnetic navigation system. To this end, the blind longitudinal bore may have a diameter of between 1.8 mm and 2.2 mm and a length of between 260 mm and 280 mm. Particularly preferably, a diameter of 2 mm and a length of 270 mm allow the Medtronic S8 Stealth stylet to be specifically inserted into the bore.

[0019] The base further comprises a cavity in the form of a cylindrical portion with a circular longitudinal section and open toward the proximal end of said base, such that a stylet body fits into the cavity. The cavity may have a radius of between 124 mm and 126 mm, with 125 mm being a particularly preferred radius, as it specifically allows the body of a Medtronic S8 Stealth stylet to be inserted. The thickness of the base may be between 11 mm and 13 mm, preferably 12 mm. The aforementioned stem and bore lengths do not include the base.

[0020] In principle, the pointer of the invention can be made of various materials, such as stainless steel or similar. However, in a particularly preferred embodiment of the invention, the pointer is manufactured using 3D printing. In this case, the material it is made of is polypropylene.

[0021] BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Fig. 1A shows an example of a prior art ventriculoscope, namely a Karl Storz LOTTA model ventriculoscope.

[0023] Fig. 1B shows a sheath (top) and trocar (bottom) used for insertion of the ventriculoscope tube of Fig. 1A.

[0024] Fig. 2 shows a stylet of an electromagnetic navigation system according to the prior art, namely the Medtronic S8 Stealthsystem stylet.

[0025] Fig. 3 shows a perspective view of the neurosurgical pointer according to the present invention.

[0026] Fig. 4 shows a longitudinal section of the neurosurgical pointer according to the present invention.

[0027] Fig. 5 shows a perspective view of the pointer of the invention with a stylet for surgical navigation partially inserted into its longitudinal hole.

[0028] PREFERRED EMBODIMENT OF THE INVENTION

[0029] A particular example of a neurosurgical pointer (1) according to the present invention is described below with reference to the figures.

[0030] Figs. 3 and 4 respectively show a perspective view of the pointer (1) where its different parts can be appreciated. The pointer (1) has a proximal base (11) from which a rod (12) emerges in a distal direction. The rod (12) has a cylindrical shape, with a length of 290 mm and a diameter of 2.5 mm, which allows it to be inserted through the tube (210) of the sheath (200) of a Karl Storz LOTTA ventriculoscope as shown in Fig. 1B. When fully inserted, the distal end (13) of the rod (12) protrudes through the tip of the tube (210). For this reason, to avoid causing damage to the tissues when marking them, the distal end (13) of the rod (12) has a rounded shape.

[0031] The base (11), which is 12 mm thick, has a substantially larger diameter than the stem (12), such that it abuts the proximal end of the tube (210) of the sheath (200). In addition, the base (11) comprises at its proximal end a cavity (15) intended to house the body (420) of a stylet (400) that will be used in combination with the pointer (1) of the invention. Specifically, the cavity (15) in this example is shaped like a portion of a cylinder with a longitudinal section in the form of a circular arc with a diameter of 125 mm. This will allow the body (420) of a Medtronic S8 Stealth stylet, which is shaped like a circular pill with a slightly smaller diameter, to be specifically fitted inside. Fitting the body (420) of the stylet (400) into the cavity (15) prevents one element from being fixed to the other with greater precision, also preventing relative rotation between the two.

[0032] The shaft (12) of the pointer (1) of the invention is further traversed by a blind longitudinal hole (14). This longitudinal hole (14) is open towards the proximal end of the pointer (1), that is, the proximal mouth of the hole (14) is inside the cavity (15) of the base (11) of the pointer (1). The distal end of the hole (14), in turn, is blind and is located at some point along the length of the shaft (12). Specifically, the blind longitudinal hole (14) has a length of 270 mm and a thickness of 2 mm. The distance between the distal end of the hole (14) and the distal end (13) of the shaft (12) is therefore approximately 20 mm.

[0033] This configuration allows the pointer (1) of the invention to be used to mark tissues located inside the ventricular cavity of a patient. To do this, the needle (410) of an electromagnetic navigation stylet (400) is first introduced into the blind longitudinal hole (14) of the pointer (1), as shown in Fig. 5. The needle (410) is inserted as far as it will go, with the body (420) of the stylet (400) fitted inside the cavity (15) of the base (11) of the pointer (1).

[0034] Once this has been done, the functions of the electromagnetic navigation system are used to draw an imaginary straight line between the end of the needle (410) of the stylet (400), which is located at an intermediate point of the shaft (12), specifically 20 mm from the end of its distal end (13) of said shaft (12). For this purpose, known references are taken in a manner known in the art.

[0035] Next, once the sheath (200) has been introduced until it reaches the patient's ventricular cavity using the prior art procedure described above in this document, the stem (12) of the pointer (1) of the invention is introduced through the tube (210) of said sheath (200). The stem (12) is introduced until its distal end (13) protrudes from the tip of said tube (210), thus remaining inside the ventricular cavity. Once the previous steps have been carried out, the medical professional is in a position to mark the tissues with the pointer (1), visualizing through medical images and in real time the position of the distal end (13) of the pointer (1) and, therefore, facilitating the identification of the tissues.

Claims

CLAIMS 1. Neurosurgical pointer (1) for electromagnetic navigation, characterized in that it comprises a base (11) from which a cylindrical rod (12) provided with a rounded distal end (13) protrudes, the rod (12) comprising a blind longitudinal hole (14) open at a proximal end of the base (11), where the rod (12) is configured for introduction through the tube (210) of the sheath (200) of a ventriculoscope (100) in such a way that it protrudes through the distal end of said tube (210), and where the blind longitudinal hole (14) is configured to receive the needle (410) of a stylet (400) of an electromagnetic navigation system, the base (11) comprising a cavity (15) in the form of a cylindrical portion with a circular longitudinal section and open towards the proximal end of said base (11) in which a body (420) of the stylet fits (400).

2. Pointer (1) according to claim 1, wherein the stem (12) has a diameter of between 2.4 mm and 2.6 mm.

3. Pointer (1) according to claim 2, wherein the stem (12) has a diameter of 2.5 mm.

4. Pointer (1) according to any of the preceding claims, wherein the stem (12) has a length between 280 mm and 300 mm.

5. Pointer (1) according to claim 4, wherein the stem (12) has a length of 290 mm.

6. Pointer (1) according to any of the preceding claims, wherein the blind longitudinal hole (14) has a diameter of between 1.8 mm and 2.2 mm.

7. Pointer (1) according to claim 6, wherein the blind longitudinal hole (14) has a diameter of 2.0 mm.

8. Pointer (1) according to any of the preceding claims, wherein the blind longitudinal hole (14) has a length between 260 mm and 280 mm.

9. Pointer (1) according to claim 8, wherein the longitudinal hole blind (14) has a length of 270 mm.

10. Pointer (1) according to any of the preceding claims, wherein the cavity (15) of the proximal end of the base (11) has a radius of between 124 mm and 126 mm.

11. Pointer (1) according to claim 10, wherein the cavity (15) of the proximal end of the base (11) has a radius of 125 mm.

12. Pointer (1) according to any of the preceding claims, which is manufactured by 3D printing.

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