Cranial fixation device for decompression / augmentative craniectomy

Abstract

A cranial fixation device for decompressive / augmentative craniectomy is described, comprising a lid and a plurality of brackets (3A, 3B, 3C, 3D, 3E, 3F), the device being designed for treating pathologies that cause herniation of the brain with consequent increase in intracranial pressure, of the type that involves the creation of an opening in the skull, by milling along a craniotomy edge, suitable to allow the expansion of the brain and the application of said lid at a certain distance vertically from said craniotomy edge with functions of protection and containment of the brain, the lid being connected to the craniotomy edge by the plurality of brackets (3A, 3B, 3C, 3D, 3E, 3F) which are fixed 20 simultaneously to the lid and to the craniotomy edge.

Description

[0001] CRANIAL FIXATION DEVICE FOR DECOMPRESSION /

[0002] AUGMENTATIVE CRANIECTOMY

[0003] The present invention refers to a cranial fixation device for decompressive / augmentative craniectomy .

[0004] The skull is a rigid and non-expandable shell and the increase in volume of its contents due to the presence of a brain tumour , an infection, a haemorrhage , a hydrocephalus , causes an increase in intracranial pressure . The increase in intracranial pressure beyond certain limits is a harmful and potentially fatal condition, capable of triggering cascade phenomena that result in cerebral ischemia and necrosis .

[0005] The treatment of intracranial hypertension involves the use of certain drugs and sedation and ventilation techniques , as well as the removal of CSF or space-occupying lesions ( tumours , hematomas ) . In many cases , however, this is not enough to bring the intracranial pressure back to acceptable values and it is necessary to resort to decompressive craniectomy . This technique involves removing a large portion of the skullcap and opening the dura mater, allowing the swollen brain to herniate outward through the surgical defect in the skull . Decompressive craniectomy improves clinical outcome in many situations , through dif ferent mechanisms : it reduces intracranial pressure , improves cerebral perfusion and reduces the risk of brain herniation and the consequent compression of vital structures such as the brainstem . Patients who survive the acute phase of intracranial hypertension will subsequently undergo a cranioplasty operation which consists of the repositioning of the previously removed bony operculum or the positioning of a cranial theca prosthesis made of synthetic material . The period between the decompressive craniectomy and the subsequent cranioplasty, of the order of weeks or months , exposes the brain to the risk of damage from trauma, and therefore it is necessary for the patient to use protection such as helmets or helmets . There are also other complications linked to the absence of the bony operculum such as the " trephined syndrome" , caused by the ef fects of atmospheric pressure which are transmitted directly to the brain tissue , and those linked to the adhesions created between the subcutaneous soft tissues and the dura mater and the brain, with the possibility of bleeding and increased operating times and surgical risks in the bone repositioning step .

[0006] In order to reduce the risks deriving from the absence of the bony operculum and the cranioplasty operation, alternative solutions to the classic decompressive craniectomy have been conceived . These alternative techniques have in common the fact that the bony operculum, after being cut and separated from the remaining cranial theca, is left in place .

[0007] These techniques are called "hinged craniectomy" , when the bony operculum is fixed only on one side so as to be hinged and open like a door under the pressure of the cerebral oedema ( see for example patent US 8439956B2 by Kathryn Ko ) or " floating craniectomy" , when the bone flap is left free to float on the herniated brain .

[0008] These techniques require precautions to avoid the sinking of the bone once the cerebral oedema and the consequent centri fugal thrust have ceased .

[0009] There are also telescopic fixing systems that allow the lifting and subsequent re-entry of the bony operculum towards its original position once the outward thrust of the brain tissue has ceased (of this type there are several patents by Khanna, for example US9603626B2) .

[0010] In the systems described above (hinged, telescopic or floating) , the increase in intracranial volume, which occurs with the herniation of the brain tissue through the craniotomy gap, occurs thanks to the push of the brain on the bone itself. The brain must therefore overcome the resistance, not at all modest, of the skin and muscle flap. In case of hinged craniectomies, the push must overcome the resistance of the musculocutaneous flap through the bone which can only be separated on one side. In all cases, part of the volume that could be used for brain expansion is occupied by the volume of the bone operculum itself, potentially reducing the effectiveness of the intervention.

[0011] The Applicant of the present invention filed, on 03.02.2022, Italian patent application no. 102022000003821 which uses an innovative device to solve the problems mentioned above.

[0012] This device, however, still needs to be perfected, given that , at the end of its operational insertion, it tends to curve and does not provide ef fective spacing between the two parts of the skull .

[0013] The obj ect of the present invention is overcoming the reported drawback through the use o f a device which allows the bone operculum to be left in place but , unlike the classic decompressive craniectomy technique , it is based on a concept completely di f ferent from that of the other systems , which could be defined as augmentative craniectomy, which instead involves expanding the skull in a stable manner . The improved device of the present invention provides various operating configurations which allow for a more immediate and simple use , some of them equipped with folding inserts which facilitate the operation of surgeons during craniectomy operations .

[0014] The one described and other obj ects , as will be explained below, are achieved with the use of a cranial fixation device , for decompressive / augmentative craniectomy, compliant with claim 1 , which allows the brain to herniate freely, while providing ef fective protection to the brain itsel f .

[0015] This device , suitable for the treatment of pathologies that cause herniation of the brain with consequent increase in intracranial pressure , is of the type that provides :

[0016] - the creation of an opening in the skull , by milling along a craniotomy edge , to allow the expansion of the brain; and

[0017] - the application of a cover with functions of protection and containment of said brain; wherein the lid is connected to the craniotomy edge by a plurality of brackets which are simultaneously fixed to the lid and to the craniotomy edge and which constitute the device of the present invention .

[0018] The length of these brackets determines the increase in volume available for the herniating brain .

[0019] According to a preferred embodiment , said lid can be made of biocompatible synthetic material or the same bone operculum removed by craniotomy . In this case , the bone must be milled following a cutting guide in order to have coherence between the opening and the synthetic lid .

[0020] The lid is therefore kept raised by the brackets , overcoming the resistance of the musculocutaneous flap . These brackets have the characteristic of being suf ficiently resistant to guarantee a seal even in the event of trauma to the head and of being suf ficiently malleable with special pliers so as to be able to adapt at the time of implantation to the synthetic material lid or to the bone operculum to be li fted .

[0021] This system is based on the observation of numerous patients undergoing classic decompressive craniectomy . The analysis of the radiological images made it possible to quanti fy the degree o f herniation and this formed the basis for determining the volume that the device according to the invention must leave available to the brain to allow free herniation .

[0022] Since cerebral oedema and intracranial hypertension are dynamic processes , it was possible to evaluate and quanti fy the maximum degree of expansion, allowing the height of the stirrups to be designed accordingly .

[0023] The device according to the invention, consisting of the brackets indicated above , allows the brain to be provided with the space it needs to herniate and therefore allows it to expand freely within this space .

[0024] According to a preferred embodiment , said brackets are made of titanium and have a central body, with the function of a spacer, and two shelves which stabili ze them at the anchoring point on the skull and prevent the bony operculum from sinking .

[0025] Preferred embodiments and non-trivial variations of the present invention form the subj ect matter of the dependent claims .

[0026] It is understood that all attached claims form an integral part of this description .

[0027] The present invention solves the mentioned drawbacks as the brain is completely free to herniate , without having to overcome any resistance for the movement of the operculum, as said operculum is already positioned in such a way as to provide the brain with all the space it needs .

[0028] It will be immediately obvious that countless variations and modi fications can be made to what i s described ( for example relating to shape , dimensions , arrangements and parts with equivalent functionality) without departing from the scope of the invention, as appears from the attached claims .

[0029] The present invention will be better described by some preferred embodiments thereof , provided by way of example and not by way of limitation, with reference to the attached drawings , in which :

[0030] - Figures 1 to 4 show a first embodiment of the device of the present invention;

[0031] - Figures 5 to 8 show the first embodiment of the device of the present invention equipped with bending lugs ;

[0032] - Figures 9 to 12 show a second embodiment of the device of the present invention;

[0033] - Figures 13 to 16 show the second embodiment of the device of the present invention equipped with bending lugs ;

[0034] - Figures 17 to 20 show a third embodiment of the device of the present invention; and

[0035] - Figures 21 to 24 show the third embodiment of the device of the present invention equipped with bending lugs .

[0036] The invention therefore concerns a cranial fixation device for decompressive / augmentative craniectomy comprising a lid and a plurality of brackets ( 3A, 3B, 3C, 3D, 3E , 3F) , the device being designed for the treatment of pathologies that cause herniation of the brain with consequent increase in intracranial pressure , of the type that involves the creation of an opening in the cranial case , by milling along a craniotomy edge , suitable to allow the expansion of the brain and the application of the lid at a certain distance in vertical from the craniotomy edge, with functions of protection and containment of the brain, the lid being connected to the craniotomy edge by the plurality of brackets (3A, 3B, 3C, 3D, 3E, 3F) which are fixed simultaneously to the lid (4) and to the craniotomy edge.

[0037] With reference to the attached figures, three different embodiments (each with or without bending lugs) of the innovative brackets (3A, 3B, 3C, 3D, 3E, 3F) are shown, which constitute the device of the present invention. These brackets (3A, 3B, 3C, 3D, 3E, 3F) are fixed on this edge using screws (not shown) and the cover (not shown) is fixed on said brackets (3A, 3B, 3C, 3D, 3E, 3F) .

[0038] According to a preferred embodiment, these brackets (3A, 3B, 3C, 3D, 3E, 3F) are made of titanium and include:

[0039] - a plane central body (10) ;

[0040] - a first shelf (31) and a second shelf (32) , planar and lying on mutually perpendicular planes, and which have the function of a spacer between the craniotomy edge and the lid, the first shelf (31) being connected and co-planar with the central body (10) , the second shelf (32) being connected to and perpendicular to the central body (10) ;

[0041] - a third shelf (33) and a fourth shelf (35) , respectively equipped with a first opening (34) and a second opening (36) for the passage of the connection screws, the third shelf (33) being connected and perpendicular to the central body (10) , the fourth shelf (35) being connected with and co-planar to the central body (10) , the third shelf (33) being arranged on the opposite side of the central body (10) with respect to the first shelf (32) , the third and fourth shelves (33, 35) fixing the brackets (3A, 3B, 3C, 3D, 3E, 3F) in the anchoring point on the skull and preventing the lid from sinking.

[0042] The central body (10) , in some configurations, can also be equipped with an opening (11) to reduce the weight.

[0043] The embodiments shown include brackets (3A, 3B, 3C, 3D, 3E, 3F) , each equipped with two third shelves (33) and two fourth shelves (35) , but configurations equipped with only one third shelf (33) and only one fourth shelf (35) are obviously possible, as would be evidently obtained by dividing the brackets illustrated in Figures 1 to 24 in half, along their centreline.

[0044] In the embodiments of the brackets (3B, 3D, 3F) respectively shown in Figures 5 to 8, 13 to 16 and 21 to 24, the brackets (3B, 3D, 3F) are equipped with a first bending lead line (20) located on the central body (10) at its connection with the second shelf (32) , and are equipped with a second bending lead line (21) located on the central body (10) at its connection with the first shelf (31) . These first and second bending lead lines (20, 21) facilitate the slight bending of the central body surface (10) during the insertion step of the brackets (3B, 3D, 3F) and during their operation, simplifying installation and improving the operation of the device of the present invention .

[0045] In general, the first shelf (31) of the central body (10) rests on the craniotomy edge, while the second shelf (32) is designed to accommodate the lid. The opening distance between the craniotomy edge and the lid is defined by the length (L) of the central body (10) .

[0046] The brackets (3A, 3B, 3C, 3D, 3E, 3F) are sufficiently resistant to guarantee a seal even in the event of trauma to the head and are suf ficiently malleable to be taken and bent with special pliers ( not illustrated) so as to be able to be adapted when implanting the lid .

[0047] According to another preferred embodiment , the brackets ( 3A, 3B, 3C, 3D, 3E , 3F) are made of thermoplastic material ( for example polyether ether ketone , PEEK) or of composite material with a thermoplastic matrix ( for example carbon fibers impregnated with PEEK or other thermoplastic polymer ) . In this case , to shape the brackets ( 3A, 3B, 3C, 3D, 3E , 3F) it may be necessary to heat them adequately .

[0048] As is clear from the previous description, the fundamental technical problem addressed has been completely solved, as the device according to the invention defines a space for the free herniation of the brain .

Claims

CLAIMS1. Cranial fixation device for decompressive / augmentative craniectomy comprising a lid and a plurality of brackets (3A, 3B, 3C, 3D, 3E, 3F) , said device being designed for treating pathologies that cause herniation of the brain with consequent increase in intracranial pressure, of the type that involves a creation of an opening in a skull, by milling along a craniotomy edge, suitable to allow an expansion of a brain and an application of said lid at a certain vertical distance from said craniotomy edge with functions of protection and containment of the brain, said lid being connected to the craniotomy edge by said plurality of brackets (3A, 3B, 3C, 3D, 3E, 3F) which are fixed simultaneously to the lid and to the craniotomy edge, said brackets (3A, 3B, 3C, 3D, 3E, 3F) including: a flat central body (10) , the opening distance between the craniotomy edge and the lid being defined by a length (L) of the central body (10) ;- a first shelf (31) and a second shelf (32) , planar and lying on mutually perpendicular planes,and which function as a spacer between the craniotomy edge and the lid, the first shelf (31) being connected and co-planar with the central body (10) , the second shelf (32) being connected to and perpendicular to the central body (10) ;- at least one third shelf (33) and at least one fourth shelf (35) , respectively equipped with a first opening (34) and a second opening (36) for passing connection screws, the third shelf (33) being connected and perpendicular to the central body (10) , the fourth shelf (35) being connected with and co-planar to the central body (10) , the third shelf (33) being arranged on the opposite side of the central body (10) with respect to the first shelf (32) , the third and fourth shelves (33, 35) fixing the brackets (3A, 3B, 3C, 3D, 3E, 3F) in an anchoring point on the skull and preventing the lid from sinking, characterized in that the brackets (3A, 3B, 3C, 3D, 3E, 3F) are each equipped with two third shelves (33) and two fourth shelves (35) .

2. Device according to claim 1, characterized in that the central body (10) is equipped with an opening (11) to reduce the weight.

3. Device according to any of the previous claims,characterized in that the brackets (3B, 3D, 3F) are equipped with a first bending lead line (20) placed on the central body (10) in correspondence with its connection with the second shelf (32) , and are equipped with a second bending lead line (21) located on the central body (10) in correspondence with its connection with the first shelf (31) , these first and second bending lead lines (20, 21) facilitating the slight bending of the plane of the central body (10) during the insertion phase of the brackets (3B, 3D, 3F) and during their operation.

4. Device according to any of the previous claims, characterized in that the brackets (3A, 3B, 3C, 3D, 3E, 3F) are made of titanium.

5. Device according to any one of claims 1 to 3, characterized in that the brackets (3A, 3B, 3C, 3D, 3E, 3F) are made of thermoplastic material.

6. Device according to claim 5, characterized in that said thermoplastic material is polyether ether ketone, PEEK, or a composite comprising carbon fibres impregnated with PEEK.

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