Pituitary fossa locator device

Abstract

The present invention relates to a device for locating (100) pituitary fossa in veterinary medicine and a method for locating the pituitary fossa in veterinary medicine by means of such a device.

Description

[0001] PITUITARY FOSSA LOCATOR DEVICE

[0002] The pituitary gland is a gland of primary importance as, by producing and / or releasing circulating hormones, it is able to regulate the hormonal activity of other glands (such as the thyroid and adrenals) and the body's water balance.

[0003] In the veterinary population, with particular reference to companion animals such as dogs and cats, pituitary neoplasms account for approximately 25% of intracranial tumours in dogs and can be -secreting; or -non-secreting .

[0004] The most frequent pituitary-secreting tumours produce an excessive amount of adrenocorticotropic hormone (ACTH) and are responsible for Cushing's syndrome

[0005] (hyperadrenocorticism) . These are usually pituitary adenomas with benign behaviour, but adenocarcinomas or infiltrating adenomas are described more rarely.

[0006] For example, in the cat, pituitary macroadenoma is in most cases associated with increased GH hormone secretion, which over time leads to the development of diabetes mellitus, increased IGF-1 over baseline ranges and morphological changes such as acromegaly.

[0007] In order to identify pituitary tumours in veterinary (and other) settings, various methodologies are known. For example, advanced imaging, such as computed tomography (CT) and nuclear magnetic resonance (NMR), is essential for:

[0008] - confirming the diagnosis,

[0009] - identifying the best therapeutic strategy and for

[0010] - planning the eventual surgery.

[0011] On the basis of the CT / RMN, it is possible to calculate the ratio between the height of the pituitary gland and the brain area, a ratio defined by the P / B (Pituitary / Brain) value. This P / B value makes it possible to differentiate

[0012] A)MICROADENOMAS: pituitary glands that have not increased in size (P / B ≤ 0.31); such adenomas also respond to medical or radiotherapy therapy as they are able to control symptoms;

[0013] B) MACROADENOMAS: pituitary glands increased in size (P / B > 0.31); to date, the only definitive curative treatment for these adenomas is hypophysectomy surgery, as these adenomas can lead to mass effect and neurological symptoms (in addition to symptoms related to ACTH excess).

[0014] In the case of surgery, it aims at the complete removal of the pituitary gland, making it possible to:

[0015] - remove the cause of hormonal hypersecretion, if present, and to

[0016] - eliminate the mass effect on the encephalon.

[0017] Hypophysectomy surgery is now considered the treatment of first choice for pituitary neoplasms and, although many clinicians still reserve this option only in the event of failure of medical therapy or at the onset of neurological symptoms, the trend is changing in some countries (e.g. the United States).

[0018] To date, this surgery is only performed in a few specialised veterinary centres (the Netherlands, England, the United States, Japan and Italy). This depends above all on the availability of a multidisciplinary team trained to manage these patients; in fact, the simultaneous presence of a well- equipped intensive care unit, endocrinologists, anaesthetists as well as duly trained surgeons is necessary, considering a physiological learning curve to correctly learn the technique and good patient management. This makes the surgical option little available internationally to date.

[0019] This surgery, however, involves the complete removal of the pituitary gland, a gland located at the base of the encephalon and placed in a sort of bony 'cradle' of the sphenoid, which is called the pituitary fossa.

[0020] Due to its anatomical position, surgical access to the pituitary gland, for example and with particular reference to the case of dogs and cats, is trans-oral and transsphenoidal, as described by Meij in 1997 (Meij et al; Transsphenoidal Hypophysectomy in beagle dogs: evaluation of a microsurgical technique. Vet.Surg. Jul-Aug; 26(4):295-309; doi:10.1111 / j1532-950x;1997 .tb01502.x.PMID:9232788 / / Meij BP; Transsphenoidal Hypophysectomy for Treatment of Pituitary-Dependent Hyperadrenocorticism in Dogs. Utrecht: Universiteit Utrecht-Thesis, 1997;1-257).

[0021] One of the main intraoperative difficulties is, however, to correctly locate the access point to the pituitary fossa of the sphenoid bone, due to subjective anatomical variability. For this reason, in addition to exploiting the subjective conformation of the ventral face of the sphenoid bone and the amular processes of the pterygoid bone, several techniques have been proposed to confirm the access point. They include:

[0022] - Intraoperative Computed Tomography (CT),

[0023] - CT-guided neuro-navigation, or

[0024] - the development of a 3-D printed guide customised for each patient.

[0025] Such techniques, known and described in the literature, while effective, present a number of problems, including:

[0026] - prolonged surgical time,

[0027] - operational difficulties,

[0028] - expensive and highly specialised instrumentation.

[0029] US2014 / 343561 describes an apparatus for measuring a distance between implanted bone anchors comprising a gauge with one longitudinal axis; a gauge arm slidingly coupled to the gauge and having a second longitudinal axis; and a second gauge arm rotatably coupled to the gauge body and having a third longitudinal axis.

[0030] DE10312755A1 describes a sliding caliper typically used in surgery to measure the dimensions of cervical vertebrae, where said caliper has an extended linear calibration scale and a pair of long and short jaws connected to the scale and cursor with a nonius.

[0031] None of the cited documents describe a locating device such as the one of the present invention, i.e., where the presence of at least one rod and one grasping organ makes it possible to locate the pituitary fossa accurately and quickly in order to perform veterinary hypophysectomies.

[0032] The aim of the present invention is to provide a method and device for identifying the pituitary fossa to perform a hypophysectomy in the veterinary field that advantageously overcomes the above-mentioned problems, providing a faster and easier way to precisely identify surgical access to the pituitary fossa

[0033] In particular, the aim of the invention is to offer a device, of the type mentioned above, which locates the pituitary fossa in animals and which is easy to use and ensures correct detection of this fossa.

[0034] Another aim is to offer a device of the type mentioned that is lightweight and can be used by only one doctor performing the hypophysectomy operation.

[0035] Another aim is to offer a method for locating the pituitary fossa in a particular animal in order to subsequently perform a hypophysectomy, said method using the above-mentioned locating device in order to effectively identify this pituitary fossa safely and quickly.

[0036] These and other purposes that will be apparent to the person skilled in the art are achieved by a pituitary fossa locating device and a method for identifying that pituitary fossa for the purpose of performing a hypophysectomy using that locating device, according to the independent claims of the present invention.

[0037] DESCRIPTION OF THE FIGURES

[0038] For a better understanding of this invention, the following drawings are attached for illustrative purposes only, but not limited to:

[0039] Figure 1 shows an embodiment of a pituitary fossa locator device according to the invention;

[0040] Figure 2 represents a longitudinal CT scan of the head of a dog in which a hypophysectomy is to be performed; and

[0041] Figure 3 represents a 3D reconstruction of the pituitary neoformation using a CT study.

[0042] DETAILED DESCRIPTION OF THE INVENTION

[0043] In an embodiment, the present invention relates to a pituitary fossa locator device 100 (or also simply pituitary fossa "locator") comprising at least one rod 1, presenting a portion IF at least partially graduated and superficially comprising a millimetre scale 2. Said rod presents, at a first free end 1A, a fixed tip 3 (or equivalent first organ projecting from the rod 1) and orthogonal to said rod 1.

[0044] Along the rod there is a movable slider 8 carrying a tip (or second organ protruding from the rod 1) 4 which is therefore movable along the millimetre scale 2. The slider has a locking / unlocking organ 6 for sliding along the rod 1 and being lockable in a desired position thereof; said locking / unlocking organ 6 is, for example, a usual screw ring orthogonal to said rod 1 and cooperating with it. Obviously, other known organs can be provided to lock / unlock the movement of said slider 8 on said spindle 1.

[0045] This screw ring 6 is integral with the movable slider 8 and is designed to lock the aforementioned (movable) tip 4 in a desired position on the rod portion IF, as will be described. The graduation of the millimetre scale 2 begins at a longitudinal axis N of said fixed point 3, passing through the free end 3A of the latter.

[0046] Said pituitary fossa localiser 100 comprises a second rod 7 connected by means of a joint 5 and pin 9 to a second end IK of the first rod 1. In this way, the pituitary fossa localiser 100 is easily manipulated through the use of the second rod 7; at the same time, the localising device advantageously allows for adaptability to the anatomical conformation of the patient animal.

[0047] By way of example, said at least one millimetre scale 1 has a length in the range of 0.5-20 cm, preferably equal to 10 cm; furthermore, said millimetre scale 2 has a length in the range of 0.5-20 cm, preferably equal to 9 cm.

[0048] Again as an example, the fixed tip 3 has a length in the range of 0.5-4 cm, preferably 2 cm; the movable tip 4 has a length in the range of 0.5-2 cm, however less than the length of the fixed tip and preferably 1 cm.

[0049] Advantageously, said pituitary fossa localiser 100 is made of surgical steel. Thus, said pituitary fossa locator is advantageously autoclavable and reusable, thus reducing the environmental impact in disposal compared to the proposed guides.

[0050] The Pituitary Fossa 100 locator is used in veterinary settings preferably comprising a pet population selected from the group consisting of cats and dogs.

[0051] The present invention also relates to the locating device of the present invention for locating a pituitary fossa in a hypophysectomy on an animal; said hypophysectomy comprising:

[0052] A) first preoperative planning phase: in this phase a Computed Tomography (CT) scan is performed on the patient, and the distance between the caudal margin K of the palatine bones of the animal's skull and the centre Z of the pituitary fossa on the ventral cortical of the sphenoid is measured. The measurement is obtained on a longitudinal sagittal section of said CT scan (as shown in Figures 2 and 3) after centring the plane and verifying the symmetry of the patient's positioning in the scan;

[0053] B) a second, operative, step comprising the positioning of the movable tip 4 of said pituitary fossa locator 100 on said millimetric scale 2 at a distance from the fixed tip 3 equal to the measurement obtained preoperatively. Due to the fact that the millimetric scale starts at the N-axis, said positioning can effectively correspond to the datum measured on the CT scan.

[0054] C) in a third step, the pituitary fossa locator 100 is positioned in the patient's mouth, resting the movable tip 4 at the caudal margin of the palatine bones indicated with K in Figure 3. The patient's pituitary fossa on the sphenoid Z is thus identified with the position of the fixed tip 3;

[0055] D) a fourth stage in which the sphenoid Z is drilled at the point indicated by fixed tip 3 of said pituitary fossa locator.

[0056] It should be noted that placement of said fossa locator pituitary 100 is done after incision of the soft palate, identification of the amular processes, incision of the mucoperiosteum, according to procedures known to the branch technician. Access to the sphenoid bone is accomplished by milling the sphenoid using standard procedures known to the branch technician; and

[0057] E) a final stage involving the removal of the pituitary gland (hypophysectomy) . This procedure follows methods and techniques known to the branch technician.

[0058] It can be seen, therefore, that the pituitary fossa locator of the present invention facilitates and locates with extreme precision the point of access to the pituitary fossa, thus guiding the operator in obtaining the correct perpendicularity to drill the hole.

[0059] Such an instrument can reduce surgical time by 30%.

[0060] As a variant, the locator device 100 can comprise a single rod 1 with a fixed gripping element at the second end IK In intraoperative use, the pituitary fossa localiser of the present invention is also particularly handy, unobtrusive, does not obstruct the view, and allows it to be used during the various surgical stages to ensure that the access hole to the sphenoid is always performed correctly.

[0061] Moreover, the pituitary fossa localiser of the present invention allows for targeted access that not dependent on intraoperative advanced diagnostic instrumentation, nor on each subject's anatomical landmarks alone, which may be difficult or inaccurate to locate intraoperatively.

[0062] By simplifying the surgical technique, it makes it easier to perform the procedure in specialised veterinary centres, reducing possible complications and potentially increasing the number of patients who can benefit from it.

[0063] Advantageously, the pituitary fossa locator of the present invention contributes significantly in reducing the duration of the learning curve in the acquisition of the transoral transsphenoidal hypophysectomy surgical technique. Indeed, its ease of use facilitates the learning of the surgical technique for those undergoing training, leading to greater safety when accessing the pituitary fossa, and extending this surgery to facilities where it is not yet implemented. The pituitary fossa localiser of the present invention is effective in 100 per cent of cases, with significant improvements in surgical timing and patient outcomes due to the use of said pituitary fossa localiser.

[0064] The pituitary fossa 100 locator of the present invention was used in an experimental phase; it was made of surgical steel and used to report a known measurement intraoperatively between two fixed and characteristic bony points for each subject, which could be identified by CT examination during preoperative planning.

[0065] The hypophyseal fossa localiser used in this experimental phase was constructed as shown in Figure 1, i.e. it consisted of two rods with an interposed joint, with the rod having a millimetre scale with a maximum length of 9 cm, a fixed tip 3 and a movable tip 4, the latter having an adjustable position along the IF portion of the rod with a Z millimetre scale. Once the above-mentioned measurement had been taken in the preoperative planning phase, the movable tip 4 was clamped on the rod (by means of the locking of the slider 6) at the distance thus defined from the fixed tip 3 by means of the locking of the slider 3A on the rod 1.

[0066] In the preoperative planning, the shape, thickness and length of the pituitary fossa, its relationship to the pituitary gland and anatomical landmarks such as the amular processes of the pterygoid bone (Hamulus pterygoideus) and the ventral surface of the sphenoid were assessed as per conventional surgery. The thickness of the sphenoid bone at the pituitary fossa was also measured.

[0067] As an aid to performing the surgery, a 3D reconstruction of the pituitary neoformation was carried out from the CT study to relate it to the surrounding bony structures (Figure 3). On this 3D reconstruction, the distance between the caudal margin K of the palatine bones and the centre W of the pituitary fossa on the ventral cortical of the sphenoid was calculated.

[0068] The measurement obtained on a CT scan was reported on the pituitary fossa locator of the present invention (defined by the distance between tips 3 and 4) and by means of the instrument was applied to the respective subject intraoperatively, after the traditional anatomical landmarks had been identified.

[0069] The method as found has been applied for several cases of veterinary hypophysectomy on dogs and cats.

[0070] A test phase of the 100 locator device will be described below

[0071] To be included in such a test, patients had to have

[0072] - confirmation of the diagnosis of pituitary neoformation by advanced imaging (CT examination); and

[0073] - undergo transoral transsphenoidal hypophysectomy surgery for therapeutic purposes.

[0074] All subjects, dogs and cats, with secreting or non-secreting pituitary neoformation could be candidates for hypophysectomy . Each subject then underwent a CT scan to confirm the presence of the pituitary neoformation and to study each anatomical location of the pituitary gland in order to assess the possibility of surgery and draw up a preoperative plan.

[0075] The characteristics of the hypophyseal neoformation (size, contrast enhancement, infiltrative features) were assessed by means of this CT examination in order to admit the patient for surgery.

[0076] The shape, thickness and length of the pituitary fossa, its relationship to the pituitary gland and anatomical landmarks such as the amular processes of the pterygoid bone and the ventral surface of the sphenoid were also assessed. The distance between the caudal margin of the palatine bones and the centre of the pituitary fossa on the ventral cortical surface of the sphenoid bone was identified on the CT study in order to bring them into place intraoperatively using the "Pituitary Fossa Locator".

[0077] We then proceeded with the surgery and application of the pituitary fossa locator of the present invention.

[0078] However, since hypophysectomy is an endocranial surgery, the patient had to undergo general anaesthesia to be performed. The surgery was performed in a manner known in itself, but also reporting the measurement detected by the CT study on the pituitary fossa locator.

[0079] Briefly, each patient was positioned in sternal decubitus with the head elevated and the jaw fixed to a support bow (horizontal bar). The neck was supported with soft supports.

[0080] A full-thickness incision of the soft palate was made in the median plane starting from the caudal margin of the hard palate until accessing the nasopharynx and visualising the mucoperiosteum lining the sphenoid bone.

[0081] After visualising and palpating the amular processes and, after incising the mucoperiosteum, the bony sutures of the sphenoid and the morphology of the external cortical bone were identified in order to identify the possible access point to the pituitary fossa.

[0082] At this point, the measurement corresponding to the distance from the caudal margin K of the palatine bones to the pituitary fossa W of the sphenoid, obtained during preoperative planning on the CT study, was reported on the pituitary fossa locator of the present invention.

[0083] The instrument was applied to the patient by placing the mobile tip, appropriately positioned on the millimetre rod, at the caudal margin of the palatine bones, thus observing the point indicated by the fixed tip of the instrument on the sphenoid.

[0084] At this point, access was made to the pituitary fossa by milling the sphenoid bone using a pneumatic drill for a surface area established in the preoperative planning phase. Once the pituitary fossa was entered and the pituitary gland was observed, a small biopsy was taken for extemporaneous cytological analysis to ensure accuracy of access. Once the presence of the pituitary gland was confirmed, a hypophysectomy was performed. The access site was then reconstructed by applying bone wax, suturing the mucusperiosteum and reconstructing the soft palate in two planes. The excised pituitary gland underwent histo-pathological examination to confirm the diagnosis.

[0085] Each patient was admitted to the intensive care unit for monitoring and necessary therapies, including hormone replacement therapy and post-operative analgesia.

[0086] In some cases, a follow-up CT examination was performed in the post-operative period, which was also used to verify the access to the pituitary gland through the sphenoid and possible post-operative intracranial changes.

[0087] During the implementation of the procedure to prepare the hypophysectomy, the use of the 100 locator device did not prove critical, always allowing good visualisation of the surgical site and being unobtrusive. In 19 / 19 cases (100%), it was possible to drill the hole at the level of the pituitary fossa, thanks to the pituitary fossa localiser, allowing the pathological gland to be visualised and removed. The use of the Pituitary Fossa 100 locator device resulted in an average surgical time reduction of 32% compared to similar procedures performed without the use of the pituitary fossa locator device as found.

Claims

CLAIMS1) A pituitary fossa locator device (100) in an animal for performing a subsequent hypophysectomy operation, characterised in that it comprises at least one rod (1), having at least one portion (IF) on which a millimetre scale (2) is provided, at a first end (1A) of said rod being provided a fixed organ projecting orthogonally to said rod (1), being provided for a second protruding organ (4) orthogonal to said rod (1) and parallel to said first protruding organ (3), the position of said second protruding organ on said rod (1) being adjustable so as to be able to define different distances from said first fixed protruding organ (3), said distance defining the position of said patient's pituitary fossa, said locating device comprises a second end (IK), wherein said rod (1) has a gripping organ (7) hinged to the rod (1) provided with the protruding organs (3, 4).2) The locator device of claim 1, characterised by the fact that said first and second protruding organs (3, 4) have a pointed shape.3) The locator device of claim 1, characterised in that said second protruding organ (4) is integral with a movable slider (8) sliding along the rod (1), said movable slider (8) being lockable along the portion (IF) provided with a millimetre scale (2) at different distances from the first protruding organ (3).4) The locator device of claim 3, characterised by the fact that said movable cursor (8) is screw-lockable on the rod (1)•5) The locator device according to one or more of the preceding claims characterised by the fact that(i) said rod (1) with protruding organs (3, 4) has a length of between 0.5 and 20 cm, preferably 10 cm;(ii) said portion (IF) fitted with a millimetre scale (2) has a length between 0.5 and 20 cm, preferably 9 cm;(iii) said fixed protruding organ (3) has a length of between 0.5 and 4 cm, preferably 2 cm;(iv) said mobile protruding organ (4) has a length of between 0.5 and 2 cm, preferably 1 cm.6) The locator device of claim 1, characterised by the fact that it is made of surgical steel.7) A locator device of claim 1 for use in locating a pituitary fossa in a hypophysectomy on an animal, said hypophysectomy comprising: i) preoperative planning, where said preoperative planning includes carrying out a Computerized Tomography (CT) scan on the patient, and a measurement of the distance between the caudal margin of the palatine bones and the centre of the pituitary fossa on the ventral cortical of the sphenoid, said measurement being obtained on a longitudinal sagittal section of said CT scan after centring the plane and verifying the symmetry of the positioning of the patient in the scan; ii) surgical intervention, where the said surgical intervention includesI)fix the movable tip (4) of said hypophyseal fossa localising device (100) onto said millimetre scale (2) by means of the screw ring (6), reporting the measurement obtained in the preoperative phase;II)placement of said pituitary fossa locator device (100) in the patient, said placement including the step of resting the movable tip (4) at the caudal margin of the palatine bones; andIII) milling of the sphenoid at the point indicated by the fixed tip (3) of the pituitary fossa locating device.

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