Improved fixation device system for measuring neuronal activity

Abstract

The invention relates to a system for measuring the neuronal activity of a living being, comprising: An implantable measuring device (1) having a housing (10) intended to be housed, at least partially, in a cavity formed in the skull (C) of a living being, and comprising a system (11) of neuronal activity measuring electrodes arranged on one face of the housing (10), and electronic signal processing means (12) housed in the housing, to which the electrode system (11) is connected; A device for fixing (2, 3) the housing in said cavity; The fixing device (2, 3) comprising: At least one mechanical retention device for said housing (10) in the cavity; Fixing means for said mechanical retention device, arranged to fix the retention device in the skull (C) on the periphery of the cavity; Means for adjusting the depth position of the housing (10) in the cavity. Figure to be published with the abbreviation: Figure 1A

Description

Title of the invention: Improved fixation device system for measuring neuronal activity Technical field of the invention

[0001] The present invention relates to a system for measuring the neuronal activity of a living being, the system being equipped with an improved fixation device. State of the art

[0002] There are many devices that can be implanted in the brain of a living being, used for reading, recording and / or controlling neural signals.

[0003] The patent documents referenced EP2623025B1, WO2011 / 123150A1, WO2011 / 067297Al and US7747318B2 describe different devices for measuring the neuronal activity of a living being.

[0004] These devices generally comprise a housing that is partially or completely inserted into a cavity (after a craniotomy) made in the skull. It also includes an electrode system for measuring neuronal activity, arranged on one side of the housing, and electronic signal processing means housed within the housing. It also includes at least one antenna coupled to the electronic means for transmitting measured data to a remote terminal.

[0005] In some cases, the device can be perfectly integrated and follow the shape of the skull (as in patent EP2623025B1), or comprise a part housed in the skull and a part protruding from the surface of the skull (as in patent application WO2011 / 123150A1).

[0006] This type of measuring device must meet several constraints: - It must be perfectly positioned and not move in its cavity, regardless of the patient's activity; - It must also be positioned so that its electrode system makes the best possible contact with the brain to optimize measurement. - It must prevent any injury, particularly in the event of a shock;

[0007] The object of the invention is to propose a measurement system that meets the constraints mentioned above. Description of the invention

[0008] This goal is achieved by a system for measuring the neuronal activity of a living being, comprising: - An implantable measuring device with a housing designed to be housed, at least partially, in a cavity formed in the skull of a being living, and comprising a system of electrodes for measuring neuronal activity arranged on one side of the casing, and electronic signal processing means housed within the casing, to which the electrode system is connected, - A device for securing the housing in said cavity,

[0009] The fastening device comprising: - At least one mechanical retention device for said housing within the cavity, - Means for fixing said mechanical restraint device, arranged to fix the restraint device in the cranial cavity (C) around the perimeter of the cavity, - Means for adjusting the depth position of the housing in the cavity.

[0010] According to a first embodiment, the mechanical retaining device comprises at less a clamping element intended to be screwed into the skull by the said fastening means and arranged to bear against a fin of the housing.

[0011] According to one particular feature, the adjustment means comprise a washer intended to be placed between the fin of the housing and a bearing surface located on the periphery of the cavity, the thickness of the washer defining the depth of insertion of the housing into the cavity.

[0012] According to another feature, the clamping element comprises one or more housings, each intended to receive, in a removable manner, at least one permanent magnet.

[0013] According to another feature, the clamping element is made of a non-magnetic and electrically non-conductive material.

[0014] According to a second embodiment, the mechanical retaining device comprises a receiving piece intended to fit into the cavity, fixed around the perimeter of the cavity by said fixing means, said receiving piece carrying said adjustment means.

[0015] According to one particular feature, the adjustment means comprise an internal thread formed on a surface of the receiving part and configured to cooperate with an external thread formed on a surface of the housing.

[0016] According to another feature, the system includes means for locking the housing deep into the receiving room.

[0017] According to another feature, the reception room includes one or more housings, each intended to receive, in a removable manner, at least one permanent magnet.

[0018] According to another feature, the housing and / or the receiving part includes mechanical means for assisting in screwing the housing into the receiving part.

[0019] According to another feature, the receiving part is made of an amagnetic and electrically non-conductive material.

[0020] According to a third embodiment, the mechanical retaining device comprises several clamping elements distributed around the housing of the measuring device, each clamping element comprising a body intended to be fixed in the skull and a plate adjustable in height relative to the body and clamping the housing by its thickness.

[0021] According to one particular feature, the height adjustment means comprise a worm screw cooperating with said plate and with the body of the clamping member. Brief description of the figures

[0022] Other features and advantages will become apparent in the detailed description that follows, given in relation to the accompanying drawings in which: - Figures IA and IB represent a first variant of the system, respectively in top view and in view along a cross section; - Figures 2A and 2B represent a second variant of the system, respectively in top view and in cross-section view; - Figures 3A and 3B represent a third variant of the system, respectively in top view and in view along a partial cross-section;

[0023] Detailed description of at least one embodiment

[0024] According to the invention, the measuring system comprises: - An implantable measuring device 1 with a housing 10 intended to be housed, at least partially, in a cavity (after a craniotomy) formed on the cranial cavity C of a living being, - A fixing device 2, 3, 4 for the housing 10 in said cavity.

[0025] The measuring device 1 comprises a system 11 of neuronal activity measuring electrodes arranged on an underside of the housing 10, intended to be oriented towards the bottom of the cavity when the housing is in place. The electrodes 110 are each intended to come into contact with the tissues 4 whose electrical activity is to be measured.

[0026] It also includes electronic signal processing means 12 (in particular, signal filtering, amplification, and digitization) housed in the casing 10, to which the electrode system 11 is connected. It may also include a data transmission antenna A1, connected to the electronic processing means for transferring the digitized data to a remote external terminal, and a remote power supply antenna A2 used to supply power to the electronic components and / or to charge a battery of the measuring device 1 by inductive coupling. The battery may be housed in the casing of the measuring device.

[0027] The two antennas A1, A2 can be made on a support 13 fixed to said housing or integrated around or within the housing. In particular, the A1 power supply antenna can be placed within the circumference of the housing, especially if it is made of titanium (a material that negatively impacts power supply via inductive coupling, particularly at 13.56 MHz). The A2 antenna can be positioned peripherally within a ring around the housing, arranged on its top surface, or within the housing itself, depending on the telecommunication frequencies and expected performance.

[0028] According to the invention, the fixation device 2, 3, 4 of the system is arranged to hold the housing 10 in the cavity made in the cranial box C and to allow the electrodes 110 to be held in contact with the tissues 4.

[0029] The fastening device 2, 3, 4 includes at least one mechanical retaining device, responsible for holding the housing 10 in its cavity.

[0030] The fixation device 2, 3, 4 also includes fixation means arranged to fix the mechanical retention device in the cranial box C, on the periphery of the cavity, to maintain the housing 10 in the cavity.

[0031] These fixing means may advantageously comprise several self-drilling screws 20, 30, 40 passing through the retaining device at several points and intended to be screwed into the cranial box C.

[0032] According to the invention, the fixation device also includes means for adjusting the depth position of the housing 10 within the cavity. These adjustment means are intended to optimally position the housing 10 so that its electrode system 11 comes into mechanical contact with the tissues 4, for reliable measurement, without exerting excessive stress.

[0033] In a first embodiment illustrated by [Fig. 1A] and [Fig. 1B], the mechanical retention device for the fixation device 2 comprises one or more clamping members 21. In this first embodiment, for example, two clamping members 21a, 21b are used. The two clamping members 21a, 21b are each made in the form of a crescent-shaped piece that screws into the cranial cavity C and bears against one or more lateral fins 14 of the housing 10 of the measuring device. The lateral fins 14 can be replaced by a collar formed all around the housing 10. The fins 14 or the collar are arranged so as to be positioned opposite the surface of the cranial cavity C, which is present around the perimeter of the cavity.

[0034] The means for adjusting the depth position of the housing 10 advantageously comprise a washer 21 or equivalent, positioned at the interface between the fins 14 (or the flange) of the housing 10 and the surface of the cranial cavity C located on the periphery of the cavity. The thickness of the washer 21 allows adjustment of the depth position of the housing 10 within the cavity. The washer 21 can be replaced by any other equivalent solution, such as a seal made of a flexible material such as silicone or poly- Implantable carbonate, or rigid materials such as, but not limited to, Teflon (trademarked), PEEK, PEKK, or dental cement, etc. Naturally, depending on the thickness of washer 21, the screw depth of clamping elements 21a, 21b will be adjusted. The material used for this adjustment layer will, of course, be biocompatible.

[0035] Advantageously, each clamping member 21a, 21b may have a housing in which a permanent magnet 22 is placed removably. This permanent magnet 22 makes it possible to better locate the device once implanted, in particular its tele-powering antenna A2 to power the device or recharge its battery.

[0036] Without limitation, the retaining device formed by each clamping element may be made of titanium. Alternatively, for MRI compatibility, it may also be made of a biocompatible and insulating polymer such as PEEK or PEKK.

[0037] In a second embodiment shown in [Fig. 2A] and [Fig. 2B], the mechanical retention device for the fixation device 3 comprises a receiving piece 31 that fits into the cavity. This receiving piece 31 has lateral wings 32 or a collar that bear against the surface of the cranial cavity C (external table) located on the periphery of the cavity or on a counterbore. The fastening means also consist of self-drilling screws 30 that pass through said wings 32 or the collar and penetrate the cranial cavity C to fix the receiving piece 31. The screws are distributed around the periphery of the receiving piece 31 to obtain stable and uniform fixation of the receiving piece 31.

[0038] The receiving piece 31 is made in the form of a tubular piece open at the top and bottom. It has a cylindrical internal cross-section. On its inner lateral face, the receiving piece has a thread 310 intended to cooperate with a thread 100 formed on a lateral face of the housing 10 of the measuring device. Screwing the housing 10 into the receiving piece 31 allows adjustment of the depth position of the measuring device 1 and thus the level of contact of its electrode system 11 located on its lower face against the tissues 4. The thread angle is preferably adapted to the coefficient of friction of the materials under humid conditions to obtain an irreversible thread.

[0039] In this embodiment, to ensure the angular stability of the implant 10 during the screwing of the receiving piece 31 or, the screwing of the housing 10 while the receiving piece 31 is wedged in the craniotomy and fixed angularly by means of self-drilling screws, various means can be considered: - Notches 101 can be made in the circumference of the housing 10 at the level of the thread ([Fig. 2A] - which may have discontinuities). These notches are preferably peripheral and through-holes to simplify the qualification of implant cleaning and avoid surgical complications related to friction on roughness or edges in case of contact with the skin; - A tab can be glued with a biocompatible silicone adhesive offering low adhesion (without adhesion promoter); - A suction cup can be temporarily applied to the top face of the housing 10 to hold it or to rotate it relative to the receiving part;

[0040] Locking means can be provided to lock the depth position of the housing 10 screwed into the receiving part 31. These locking means can be achieved by different means, for example via a solution employing a notch and a locking bar or by means of a non-return clip positioned in the thread to hinder the movement of the housing.

[0041] The receiving part 31 is made of a biocompatible, easily machinable, non-magnetic, and insulating material such as PEEK or PEKK. The thread 100 formed on the housing 10 of the measuring device can be obtained by molding or by bonding. The recommended material is also biocompatible and non-magnetic.

[0042] Similarly, the reception room 31 may include one or more housings, each intended to receive a permanent magnet 32.

[0043] In a third embodiment illustrated by [Fig.3A] and [Fig.3B], the mechanical retaining device of the fastening device 4 comprises at least three clamping members 41a, 41b, 41c, advantageously identical, separated from each other and distributed around the housing 10 of the measuring device 1. The three clamping members 41 are therefore advantageously arranged at 120° to each other.

[0044] Advantageously, each clamping element 41a, 41b, 41c can be fixed in the skull C via one or more screws 40 (for example, self-drilling screws). Each clamping element 41a, 41b, 41c also includes a height-adjustable plate 410 configured to cooperate with the housing 10 of the device. This plate 410 may have a U-shaped cross-section, enabling it to grip the housing 10 along its thickness. The height adjustment of the plate 410 can be achieved by means of a worm screw 411 inserted into the body of the clamping element. This adjustment solution allows for fine adjustment of the position of the measuring device 1 (along three axes) and for orienting the housing to better accommodate the shape of the tissues 4 with which the electrode system 11 is to come into contact. Advantageously, the interface with the case will be of a point type so as not to constrain the orientation of the surfaces.The orientation of the plane of the electrode system 11 is adjusted by means of the three worm screws 411, like a tripod.

[0045] The solution of the invention has many advantages, including: It allows for reliable retention of the measuring device in its cavity; It allows for deep adjustment of the position of the measuring device housing, ensuring contact of the electrode system against the tissues, without risk of injury; It is adapted to the existing measuring device, such as that described in patent EP2623025B1;

Claims

[Claim 1] Demands A system for measuring the neuronal activity of a living being, comprising: - An implantable measuring device (1) having a housing (10) intended to be housed, at least partially, in a cavity formed in the skull (C) of a living being, and comprising a system (11) of electrodes for measuring neuronal activity arranged on one face of the housing (10), and electronic signal processing means (12) housed in the housing, to which the electrode system (11) is connected, - A device for fixing the housing in said cavity, Characterized in that the fastening device (2, 3) comprises: - At least one mechanical retention device for said housing (10) in the cavity, - Means for fixing said mechanical restraint device, arranged to fix the restraint device in the cranial cavity (C) around the perimeter of the cavity, - Means for adjusting the depth position of the housing (10) in the cavity, - The mechanical retention device comprising several clamping elements distributed around the housing (10) of the measuring device (1), each clamping element comprising a body intended to be fixed in the skull (C) and a plate adjustable in height relative to the body and clamping the housing by its thickness, - The adjustment means comprising a worm screw cooperating with said plate and with the body of the clamping element.

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