GB2505174A - Inflatable cranial cavity sealing device - Google Patents

Abstract

A cranial cavity sealing device insertable and removable through the nasal cavity, the device comprising at least one inflatable layer 20, which at least one inflatable layer 20 is arranged to be inflated by a fluid, and a valve (20a, Figure 10) arranged to allow the at least inflatable layer 20 to be inflated with fluid. An integral bearing surface e.g. control ring adapted to enable control of expansion of the first inflatable flexible layer, thereby facilitating sealing engagement between a surface of the inflatable flexible layer with the cranial cavity. The device may comprise second and third inflatable layers 10,30. The third layer 10 may comprise a flexible structure 12 made from collagen regeneration matrix material. The device can repair an opening and stop or reduce cerebrospinal (CSF) leakage.

Description

lnflatableseaiinqelernenment The present invention relates to an inflatable seal [or blocking an opening formed as a result of extended endoscopic endonasal surgery procedures. In particular, but riot exclusively, the present invention relates to a plug for sealing an orifice created to perform transsphenoidal endoscopic surgery.

During the past 20 years, endoscopic sinus surgery has developed significantly because superior technological equipment, for example, cameras and powered instruments, has become more widely available. As a result! new surgical techniques which allow a surgeon to access parts of the central nervous system through the nose have also been developed during this time. The nose provides a naturally occurring orifice, which can be used as an access point to reach and treat, for exampie, the base of the skull, the central portion of the brain and the top of the spine.

These surgical techniques are typically referred to as extended endoscopic endonasal approaches (hereinafter EEEA) and are primarily used to remove brain tumours and lesions through the nose. While performing EEEA, surgeons reach tumours and lesions ol the base of the skull and top of the spine directly by operating through the nasal cavity and the sinuses; typically, the sphenoid sinuses.

The sphenoid sinuses are a pair of air-filled cavities located behind the sphenoid bone, a somewhat butterfly-shaped bone, at the base of the skuil. The sphenoid bone comprises a saddle-shaped depression referred to as sella turcica, which saddle-shaped depression includes a seat" called hypophyseal fossa. The pituitary gland (or hypophysis), a pea-sized structure, is located at the bottom of the hypothalamus at the base of the brain and rests in the pituitary or hypophyseal fossa.

The brain, pituitary and other structures of the central nervous system are enveloped by the meninges, a system of membranes consisting of three layers which line the cranial cavity to protect the contents thereof. These three layers are from the centre to the outermost: the pia mater, the arachnoid mater and the dura mater. This membranous system also includes a space between the pia mater and the arachnoid mate which known as subarachrioid space. Cerebrospinal fluid (CSF) is a clear, colourless, bodily fluid produced by the choroid plexus. CSF flows with!n and around the brain (ventricles and subarachnoid space) and spinal cord to help cushion the brain from injury. Further, CSF provides mechanical and mmunologcal protection to the brain and serves a vital function in cerebral self-regulation of cerebral blood flow.

CSF is continuously being absorbed and replenished in a closed pressurised system *which is protected by the dura mater. Thus, lesions affecting the meninges lead to significant health problems.

The functions of the pituitary gland include secreting hormones; controlling hormone function and other hormone secreting glands. Anatomically, the pituitary gland is divided into two lobes, an anterior lobe (also called adenohypophysis), which is hormone-producing, and a posterior lobe (or neurohypophysis). Any lesions or tumours which affect the pituitary gland have serious endocrine consequences.

Further, lesions of the brain and upper spinal cord can obviously cause major health issues as they may prevent the brain from performing its activity or receiving electrochemical impulses transferred via the spinal cord.

Examples of conditions which can be treated by performing EEEA include for example: lesions of the pituitary (such as micro and macroadenomas), lesions in the anterior skull base (such as meningiomas and olfactory neuroblastonias), benign lesions of the central portion of the brain (such as craniopharyngiomas, chondromas and chondrosarcomas) and lesions in the top the spine (such as clival chordomas) amongst others.

Some of the well-known advantages of EEEA over craniotomy include: procedure is minimally invasive, large incisions are unnecessary, indsions or disfigurement to the patient's skull or face are avoided, the recovery time is much shorter (typically being days rather than weeks or months), chemotherapy or radiation treatment can be started sooner after surgery because there is no need to wait for incisions to heal, the hospital stay is much shorter (typically patients can be discharged within one or two days); risk of neurological damage is reduced because the brain does not have to be manipulated thus it is easier to preserve important nerves, side effects are fewer.

Although EEEA results in a decrease in side effects, complications can and do arise..

These are classified into three categories: Nasal complications ncludng: adhesion formafion, ancsmia, hyposmia and nasolacrimal duct damage.

Orbital compUcations including: orbital haemorrhage, abscess and optic nerve damage.

Intracranial complications including: cerebrospinal fluid leak, meningitis, brain abscess and intracranial haemorrhage.

The most dangerous complications from the ones listed above are intracranial complications because they are typicafly life-threatening and are associated with the highest levels of morbidity. As a result, surgeons are equally concerned with post-operative management to avoid intracranial and other compPcations as they are with the surgical technique considered appropriate for each case.

The most common difficulty within the group of intracranial complications is CSF leak. CSF overall flow is the result of two separate processes: bulk flow, that is circulation of CSF from its formation sites to its absorption sites, and pulsatile flow, which is an oscillatory cycle related to the cardiac cycle, respiratory cycle and changes in blood volume caused by arterial expansion. These two processes occur in different tirnescales, the former happens over minutes while the latter has a timescale ci milliseconds. Normally, a delicate balance is maintained between the amount of CSF that is absorbed and the amount that is produced. An imbalance is dangerous because, for example, accumulation leads to hydrocephalus, i.e. an abnormal accumulation of CSF in the ventricles, which may cause an increase in brain pressure and a number of symptoms which may result in death. Leakage on the other hand may lead to a brain pressure drop and is also associated with a multitude of symptoms. When EEEA surgery is performed, the dura mater is generally punctured to access the relevant lesion; thus, the pressurised system is interrupted and CSF drains into the nose. As CSF equilibrium is necessary, it is essential that the leak is minimised during surgery and the opening into the nose repaired once the relevant lesion has been removed.

Further, the passage created between the nasal cavity and the cranal cavity and subsequent CSF leakage may result in additional complications, such as, bacterial infections which can cause meningitis or brain abscesses. Moreover, opening of the dura matter may cause pneumocephalus (i.e. presence of air or gas within the cranial cavty). The aforemenUoned complications have significantly negative consequences for a patient.

Accordingly, CSF rhinorrhoea or eak and closure of the passage between the nasal cavity and the cranial cavity are Important factors to consider before, during and after EEEA surgery.

Various techniques of seflar reconstruction and closure have been described; for example, a bone or synthetic graft secured with biologic glue can be used. Existing techniques which achieve closure of skull base detects and leaks created as a result of EEEA surgery typicafly combine autologous materials, for example: abdominal fat, muscle, deep fascia of the thigh, pedicled or non-pedicied nasal mucosal grafts, and non-autologous materials, such as: Gelfoam (TRM), coflagen fleece,4, Vicryl (RTM) patches, polyester-silicone dural substitute and different types of tissue adhesive.

Examples of commerciafly available tissue adhesive are DuraGen (RTM), Duraseal (RTM) and Tisseel (RTM). In the aforementioned techniques, the outer layer of the repair includes nasal mucosal tissue which is placed around the passage; this type of tissue should, ideally, heal and be amalgamated into the adjoining mucosal lining of the nasal cavity. The passage area is then packed with absorbable materials which provide additional support and seal. Known techniques are, however, prone to seal failure because the pumping action of CSF inside the cranial cavity generates pressure on the graft and packing materials leading to displacement thereof. Further, gravity tends to pull the graft out of the cranial cavity and once the seal has been displaced as a result of CSF pumping, CSF leakage ensues.

As apparent from the foregoing, sealing the passage is difficult and requires supreme skill to ensure closure is permanent and does not leak. Thus, if the surgeon is less experienced, the CSF leakage rates are much higher. The reason is that although conceptually the sealing process is simple, in practice brain pulsations and CSF in the area tend to displace the graft leaving exposed openings which will allow CSF to leak after the operation. Further, during an EEEA procedure, the cranial cavity is accessed from below whereas the subsequent sealing procedure will typically involve placing the graft on top of the ephenoid bone or other bones which form the base of the skull; thus, once the operation is completed and the patient is conscious, gravity may displace [he graft or aggravate movement caused by pumping of CSF in the brain. Moreover, once the opening area has been sealed, the graft cannot be inspected to check for leakages or displacements because the absorbable materials prevent access.

US 2011/0087232 describes an alternative method which seeks to overcome the problems faced by traditional sealing techniques described above. In the method described therein, bone cement, for example hydroxyapatite cement (HAC), is used to seal a disc of biocompatible maLerial. such as sihcone or a tissue graft, within the cranial cavity. The disc is supported by a central stalk or rod structure and constraint strings which are sealed in the cranial cavity with cement. Although this method provides a more effective impermeable seal, the cement permanently seals the cranial cavity and thus makes the cranial cavity completely inaccessible so that any complications, for example further operations, require a new opening and/or drilling of the cement and graft seal. Accordingly, removal of subsequent tumours or an operation to relieve hydrocephalus would be much more complex and dangerous if this sealing technique has been used.

It is therefore clear that known sealing options do not provide reliable prevention of cerebrospinal fluid leakage from the brain into the sinus and or nasal cavity. Further, the alternative technique provided by US 2011/0081232 is completely permanent and therefore suffers from additional problems; in addition, the use of cement in the cranial cavity may deter patients from consenting to the use oF this technique.

Thus, repairing an opening which allows CSF to leak, whether the opening in was intentionally or unintentionally created, is imperative. The present invention therefore seeks to provide a suitable alternative to known sealing methods arid to prevent CSF leakage. At the same time, is also easily and readily removable in case a complication or the need for further surgery in the future arises.

According to the present invention there is provided a sealing device insertable and removable through the nasal cavity, the device comprising: at least one inflatable flexible layer, which at least one inflatable flexible layer is arranged to be inflated with a fluid; a valve arranged to allow the at least one inflatable flexible layer to be inflated with fluid; and a support arranged to bear the at least one inflatable flexible layer.

The present invention provides a more suitable sealing system because it reduces CSF pressure in the sealed area thereby reducing risk of displacement, is impermeable and provides support for the mucosal graft. Accordingly, brain pulsations of CSF are less likely to lead to displacement and CSF leakage.

Although autologous grafting is commonly used, it requires a separate incision, prolongs operative time and causes additional discomfort to the patient; whereas if synthetic materials are used, these may cause an immune reaction or provide a site for bacterial infection. Further, the use of metals or alloys is not possible as the metal would interfere with imaging techniques. In the present invention, the amount of synthetic material used is limited to the inflatable ayers as the internal volume contains a non-reactive fluid. Consequently, immune reactions are less likely and in the event they do occur, the seal may be removed easily and replaced with different materials in cases of extreme immune response. Moreover, metals or alloys are not used, thus, enable MRI and other types of imaging are not affected by the seal.

More advantageously, the support comprises a flexible structure made from collagen regeneration matrix material. As a result, the present invention provides a seal in which the graft is provided with underlay support which is easily removable and discernible, As a result, additional graft obtaining procedures are minimised as only a single mucosal layer is necessary and therefore incisions, operative time and patient discomfort are reduced. Further, as the outer layer or the second layer and, if applicable, the collagen matrix provide ample structural support; the present invention prevents the use of absorbable materials for packing and therefore the seal can be easily checked and or removed in an emergency, for example if the patient suspected to suffer from other complications.

Preferably, the device further comprises a second inflatable layer between the first inflatable flexible layer and the support, which second inflatable layer includes the valve and a docking point. More preferably, the support is inflatable. These features have the advantage of allowing the device to be manufactured in the same material and using the same process, for example injection moulding. Another advantage of the device of the present invention is that one or a few sizes of sealing device can be used to close all types of defect, whether regular or irregular in shape because the seal will expand to fit around or into the walls of the opening and will thereby be customised to each specific defect. This results in manufacturing and cost savings because it allows surgery to be carried out with one size or a minimum of sizes of sealing devices provided instead of having to provide multiple size seats with diameters which increase by I mm. However, bone cement is not used and therefore the defect will remain sealed in a semi-permanent way despite being customised to the defect.

Even more preferably, the second inflatable layer provides a connective surface arranged to cooperate with walls of an opening or defect. Ideally, the second inflatable layer forms a pair of opposing lips, which opposing lips clamp the connective surface to walls of an opening and provide an addftional seal over each side of the opening. These features allow the seal to be particularly effective because: it minimises the effect of CSF pulsations and pressure over the surface immediately above (i.e. within the cranial cavity) the opening, It provides an additional sealing surface below the opening (i.e. within the nasal cavity) and it constantly maintains the connective surface clamped to the walls of the opening.

Advantageously, the valve is a non-return valve and the device further comprises a deflating mechanism. This allows the device to retain fluid effectively and, at the same time, to be removed in an emergency.

Furthermore, additional complications such as: meningitis, brain abscesses and pneumocephaius as a consequence of CSF leakage are avoided because CSF leakage prevented effectively.

Exemplary embodiments of the present invention win now be described in detail with reference to figures in which: FIgure 1 is an inflatable element according to a first embodiment of the present invention, Figure 2 Is a diagrammatic representation of an assembled inflatable eiement according to a first embodiment of the present invention, Figure 3 is a diagrammatic representation of the inflatable element of Figure 2 in use, Figure 4 shows a measuring disc used to measure a defect, Figure 5 shows an assembled inflatable element having a docking point according to a first embodiment of the present invention, Figure 6 is an exploded view of the inflatable element of Figure 5, Figure 7 is a diagrammatic representation of the distal end of an inflating tube, Figure 8 shows the proximal end of an inflating tube, Figure 9 is a diagrammatic representation of a release mechanism, Figure 10 is a three-dimensional representation of the sealing device, Figure 11 is a diagrammatic representation of an assembled inflatable element according to a first embodiment of the present invention during installation, Figure 12 shows an inflatable element according to a second embodiment of the present invention, in which the inflatable chambers are deflated, Figure 13 is a side view of the inflatable element of Figure 12, wherein the posterior inflatable element is inflated, Figure 14 is a side view of the inflatable element of Figure 12, in which the anterior and posterior inflatable elements are inflated, Figure 15 is a schematic representation of a third embodiment of the present invention, and Figure 16 is a schematic representation of the device of Figure 15 in use.

Referring now to Figures 1 to 3, an inflatable device 1 according to a first embodiment of the present invention has a multi-layered structure comprising a pliable inner sealing inflatable layer 30, a mid-layer 20 having a valve and a docking point, which mid-layer provides an expansible connective surface. An outer inflatable layer or support 10 having a collagen regeneration matrix material (shown and described in more detail with reference to Figure 6) loosely attached thereto is the final layer. Figure 1 depicts the layers separately; each layer 10, 20, 30 comprises a moderately flat circular body made from a polymeric material, such as polyethylene terephthalate (PET) or comparable polymer material, arranged to cooperate with one another to form a sandwich-like construction with three chambers, each chamber being formed by ts respectve layer 10, 20, 30; this type of construction is easily assembled and manufactured.

Figure 2 shows the ayers 10, 20, 30 assembled into the sandwich-Uke device 1, the mid-layer 20 acting as a connective surface between the outer 10 and inner 30 ayers. (see Figure 4 b&ow) in the mid-layer 20 sUows the device 1 to be positioned within th.e opening created during the EEEA procedure so that the inflatable ayers 10, 20, 30 may then expand proporfionaDy into different directions to seal the opening. In use, the device I expands to fill the defect in a three-stage procedure described in detail with reference to Figures 4 and 5 below. As seen in Figure 3, the inner layer 30 is inflated during the first stage so that it expands to cooperate with an opening. Because the in situ mass of the device can be modified by increasing or decreasing the amount of fluid within the inflatable layers 10, 20, 30, there are only a small number standard sizes or simply one standard size. The collagen matrix material acts as an underlay to the mucosal graft and thus provides structural support to the sealing device 1. In addition, each inflatable external layer 10, 30 allows the device I to seal the opening on opposite edges so that the defect is sealed from both sides. The deflated device I is conveniently compact and can therefore be inserted through the nasal cavity with case. Once the device 1 has been inserted, the inflatable layers 10, 20, 30 are deployed.

Referring now to Figure 4, when the procedure reaches a stage in which it is necessary to repair the skull base defect, the surgeon will need to follow the steps below. Firstly, the size of the defect will probably need to be measured; this can be achieved by inserting a reference disc 80 into the nasal cavity. The reference disc 80 is made from a substantially translucent flexible and non-reactive material, such as a silastic sheet which can easily be inserted through a nostril even if the disc itself 80 has a diameter larger than that of the nostril. Once the disc 80 is inside the nasal cavity, it can be extended to its actual size so that the surface of the disc is visible through an endoscope or to the surgeon's naked eye. The disc surface 81 is perforated and bears concentric markings 85 to allow the defect to be measured.

The disc shown 80 has a central cylindrical portion 82 which protrudes vertically from the disc surface. This cylindrical portion 82 can be introduced into a hollow portion of a malleable sucker (not shown) available on a surgical kit for EEEA surgery. When the cylindrical portion 82 of the disk 80 is coupled to the malleable sucker, the sucker can be used to introduce, move and position the disc into and within the nasal cavity through direct endoscopic view. Simultaneously, the negative pressure power of the suctioning machine provides stabihty. Further, as the disc is perforated, fluids (Le.

blood and or CSF) do not accumulate below the disc and therefore do not significantly hinder endoscopic vision. The size of the defect is measured by comparing the edges thereof with the concentric markings 85 on the disc. Once the size is determined, the disc 80 is removed from the nasal cavity by disconnecting the suction apparatus. In the event the disc 80 is detached from the hollow portion, it can be retrieved and removed easily by using standard grasping forceps, such as Blakesley forceps. Although the measurement procedure has been described with reference to this first embodiment, it should be clear that it the same procedure applies to the second and third embodiments described below.

After the size of the defect has been determined, it is necessary to choose the size and or volume of the appropriate sealing device. As the components of the sealing device are expandable, a small number of sizes conform or adapt to a multitude of defect sizes. The sealing device may be supplemented with an information leaflet or printed table for allowing a user to determine the maximum volume and size a device of a specific initial or deflated size will reach so that the user can choose the most appropriate sealing device from the small selection of sizes. Further, to increase accuracy, the leaflet or table may include a detailed correlation between the volume of fluid irected and the resulting diameter of the inflatable ayers 10,20 and 30.

Referring now to Figures 5 to 9, when the size of the defect has been determined and the appropriate sealing device chosen, the docking point is used as a stabilising point for the device when the user connects the docking point to a semi rigid or malleable inflating tube and then inserts the device through a nostril. The device 1 is conveniently compact and can therelore be inserted into the nasal cavity with ease.

Referring specifically to Figures 5 and 6, the inner 30 and an outer 10 inflatable sealing layers are configurable to fit the bone opening when inflated. In this particular embodiment, the mid-layer 20 is a disc-shaped element while the inner 30 and outer 10 layers are concentric rings adapted to cooperate with the mid-layer 20.

The valve 22 and docking point 24 are centrally arranged on the layer 20 so that the device 1 can be placed generally in the centre of the opening or defect and can also be held in place with the inflating tube while the external layers 10, 30 are deployed.

As mentioned above in relation to Figure 2, in this embodiment, the device I has a three-phase deployment: the inner layer 30 is inflated or deployed first; the connective mid-layer 20 is then expanded and thereby expands the inner seal 30 and subsequently, the outer seal 10 is filled with fluid and deployed. Once inflated, the layers 10, 20, 30 form a cylinder or disc with a larger circumference than, that of the mid-layer 20 alone; moreover, the valve 22 and docking point 24 remain centrafly located and accessible.

As shown in Figures 7 and 8, the inflating tube 50 comprises a maUeable hoflow body of plastic materials and has a number of inner tubes 51, 52, 53 which corresponds to the number of inflatable chambers or ayers 10! 20, 30 of the device, in this case three. The tubes 51, 52, 53 run from a proximal end of the body 55a to a distal end 55b having a locking mechanism which allows the docking point 24 to be connected securely to the inflating tube 50 when necessary and at least one projecting port 58; in this particular case, the distal 55b end has three projecting ports 58a, 58b, 58c, one for each valve 22a, 22b, 22c in the device. As shown in Figure 9, the proximal end 55a has a trigger release mechanism 60 which releases the connection between the inflating tube 50 and the docking point 24 as required. The proximal end 55a further comprises a number of ports (not shown), each port having a Luer lock connector for enabling connection to a barrel-type syringe which can be used to individually and manually inflate an inflatable layer 10, 20, 30. The number of inflating tubes 51, 52, 53 in the hollow body 55 and the number of connecting ports in the proximal end of the hollow body 55 will be such as to match the number of inflatable layers 10, 20, 30 of the specific embodiment of the seahng device being used. Although the inflating tube 50 has been described in relation to the first embodiment, it should be clear that it can also be used with the second and third embodiments described below.

As the inflation tube 50 is held by the user's hand, the inflatable device 1 is stahilised at the required location. The connection between the device I and the tube offers 50 the stabilisation required for allowing the device 1 to be manoeuvred and positioned inside the nasal cavity before it is secured at the appropriate location. Subsequently, the device I will be placed over the area of the defect and layer 30 will be inflated with a predetermined amount of fluid. As layer 30 is smaller than the diameter of the defect in this three-layered embodiment, this first deployment phase will not seal the defect. Accordingly, the user inflates layer 20 so that the size of layer 30 is increased and regulated because both layers 20, 30 are connected and expandable. As mentioned above, the volume of liquid necessary to inflate each layer 10, 20, 30, and in particular, layer 20 is determined by using a correlation between the size of the defect and the size and elastic properties of the device I so that the user can simply inject a predetermined volume of fluid to inflate the device to a specific size.

Endoscopic observation allows the user to confirm expansion and to decide when to stop deployment of layer 20. Deployment ideally stops as soon as layer 30 assumes a size slightly larger than the size of the defect.

Finally the user Inflates or deploys layer 10 in order to cover the anterior edge of the defect Applying pressure from both sides of the defect will effectively stabilize device I over the area of the CSF leak. As each layer expands 10, 20, 30, it adapts to the specific shape and size of the EEEA opening. Further, each external layer 10, seals the opening from a different side. The valve 22 allows fluId to be pumped into the inflatable layers 10, 20, 30 and maintains the pressure within the device I so that the seal provided is adequate. Valves 22a, 22b and 22c are used in this embodiment to prevent fluid from escaping from each one the inflatable layers 10, 20, 30 respectIvely. Each valve is located in a port connector and allows fluid to be inserted into the respective layer when the relevant projecting port is connected. In the event access to the device is necessary after Installation, a user can re-establish the connection between the docking point and the inflating tube so that the projecting ports 58a, 58b, 58c on the distal end 55b allow fluid within the Inflatable chambers to be regulated by opening or unlocking the valves 22a, 22b, 22c.

Figure 9 shows an exemplary trigger release mechanism 60 having a frontal connector with a number of Luer lock connectors arranged to couple with the Luer lock connectors in the ports on the proximal end of the hollow body', as the number of connectors on the release mechanism matches that on the hollow body 50, there are three connectors in this exemplary release mechanism. The posterior end of the release mechanism shown 61 comprIses at least one inflating source to supply inflating material (not shown) into the tubes 51, 52, 53 within the hollow body 55. As mentioned above the valves 22a, 22b, 22c are kept open by the distal projecting ports 58a, 58b, 56c the release mechanist disengages the docking point from the inflatable tube and therefore when the distal projecting ports are disengaged from the valves 22a, 22b, 22c fluid is prevented from escaping the chambers formed by each layer 10, 20, 30.

Once the device is installed and the docking point has been disengaged from the Inflating tube by using the release trigger, the inflating tube can be removed from the insIde of the nose. The plugged area can then be covered with mucosa and sealed circumferentially with an adhesive, such as TISSEEL (RIM).

As shown in Figure 10, the inflated device 1 has a generally cyUndricai shape having a narrower mid-section or mid-layer 20 and two ring sections or external ayers 10, arranged to enclose and cooperate with the mid-layer 20 so that the upper and lower portions of the cyhnder are wider than the mid-section. The docking point 24 is located in the centre of the mid layer 20. Further, a valve 22a which allows a fluid to enter the mid-layer 20 is included in the docking point 24. Two addiUonal valves 22a, 22b are integrated into the mid-layer; each valve 22b, 22c being arranged to control ingress of a fluid to the layers 10 and 30 respectively. As the valves 22a, 22b, 22c are posiUoned in the mid-layer 20, the inflating tube can be connected to the docking point 24 so that each inner tube can be coupled to a valve 22a, 22b, 22c.

Referring now to Figure 11, the device 1 is placed in such way that the EEEA opening is generally equidistant to the inner 30 and outer 10 layers and approximately in the middle plane of the mid-connective layer 20 so that the mid-layer 20 is compressed around the abutment 25 and a lip 25a, 25b created on each side. The outer layer 10 is inflated to a size wider than the opening and thus provides a seal on the nasal cavity side of the opening. The inner layer 30 is also inflated to a size wider that the opening so it provides a seal on the cranial cavity side of the opening. The collagen matrix 12 is loosely attached to the cuter layer 10 and forms a loose sac over the mid 20 and inner 30 layer of the device 1 and thereby acts as a protective bubble over these layers 20, 30 so that CSF is prevented from leaking into the nasal cavity regardless of gravity. Typically, the collagen matrix material 12 is pliable and, in addition, it is soft and malleable. Further, this material 12 is well-tolerated (i.e. not likely to induce an immune response) and shows minimal adhesion to the pia mater and or arachnoid mater. An example of suitable collagen matrix material is DURAGEN (RTM) or any other equivalent collagen matrix material. As mentioned above, the device I is deployed in a three-stage procedure in which the seal is positioned and stabilised over the opening, the inner layer 30 is filled and deployed, the mid-layer 20 is inflated and thereby expands of the inner layer 30 and secures the posterior edge of the device over the opening, the outer layer 10 is then filled and deployed and the positioning and inflating or deployment tube is removed so that the outer layer 10 can be covered with mucosa and sealed circumferentially with an adhesive.

Figures 12 to 14 illustrate a second embodiment of a device 2 according to the present invention. In this embodiment, the device 2 comprises of two inflatable layers instead of three: a first pliable inner sealing inflatable layer 30 for sealing posterior end of the opening, and a second pHable inner seahng inflatable layer 10 for seafing the anterior end of the opening. First 10 and second ayers 30 are permanenfly attached to a semi-rigid support 40; specificafly the posterior wall of layer 30 is firmly connected to the back wall of the concave surface of the semi-rigid support 40. As a result, layer 30 cannot expand posteriorly and, in addWon, expansion of ayer 30 wiu conform to a circumferential fashion. Layers 10 and 30 are kept deflated for storage and fitting (as shown in Figure 8), and deployed when the device 2 has been p;aced in the defect. In use, the device 2 is ntroduced through the nasal cavity and located within the EEEA opening by connecting it with an inflating tube or by using forceps. The inflating tube used in this embodiment has two inner tubes instead of three and can be used for stabilisation, positioning and expansion of the device 2 by connecting it to a docking point on the semi-rigid support 40. Once the device 2 is placed on the opening, it is secured by deploying and inflating the first layer 30 and then by deploying and inflating the layer 10. In this embodiment 2, the layers 10, 30 form a circular pair of opposing lips 30a, iOa which allow the walls of the opening to be secured between the layers 10, 30; CSF leakage is thus prevented. Layer 10 is then covered with mucosal tissue and sealed circumferentially with an adhesive as described in relation to the first embodiment.

Figures 15 and 16 show a third embodiment 3 of the present invention; in this embodiment the seaflng device 3 comprises a single pliable inner sealing inflatable layer 30 of material having an anterior wall 31 and a posterior wall 32 thicker than those of the previous embodiments. These thicker walls 31, 32 control anterior and posterior expansion of the single layer 30. The anterior and posterior walls 31, 32 of the device 3 are joined by a mid-portion 33. The device 3 further comprises a control ring 35 arranged to prevent expansion of the mid-portion 33 of the device over a certain predetermined volume. The control ring mechanism 35 comprises a pair of projections 36, 37 arranged to allow tightening and loosening of the control ring and a thread which is pulled or released by the pair of projections. The midline of the mid-portion 33 has a threaded design which allows the thread to be positioned over the portion symmetrically so that the control ring 35 splits the device into two portions 30a, 30b when in use. As mentioned above in relation to the first embodiment, a user ideally measures the diameter of the defect before installing the sealing device.

Once the measurement is performed the control ring is adjusted to allow the mid-portion 33 to have a diameter marginally smaller than that of the defect so that CSF is prevented from leaking. The control ring 35 is then secured along the midline; as a result, further expansion of the mid-portion 33 along the midline is prevented.

However, the lateral wafls 34. 39 that lie circumferential to the ring 35 can continue to expand so that a surface 38 which covers the defect is created on each side thereof.

Although the device has been described in relation to three specific embodiments, it shotdd be dear to those skiHed in the art that sonic modifications and alternatives are possible. For example, in the first embodiment, the coHagen matrix could be omitted or replaced with a similar material and the three ayers could be made integrafly by injection moulding or other suitable processes. Further, the separate deflation mechanism can be omitted.

Further, the inflating tube described in relation to the first embodiment could be used in the second and third embodiments by simply reducing the number of inner tubes.

Equally an inflating tube having a single inner tube and an adaptor could be used in devices with a different number of inflatable components of the seal.

In addition, a connector other than a Luer-Lock could be used in relation to any embodiment. It should also be clear that a connector may be used with the second and third embodiments.

Although a barrel-type syringe has been given as an example of a manually inflating means, it should be dear to a skilled person that different manually inflating means may be used.

It should also be apparent that the number of ports on release mechanism may be varied and that the inflating source may be connected directly to the hollow body or through a different part of the release mechanism.

Additionally, the collagen matrix sac described in relation to the first embodiment could be loosely attached to the semi-rigid support or second layer described in relation to the second embodiment to provide additional support by forming a protective bubble over the inflatable layer, Similarly, a collagen matrix sac may be loosely attached to the single layer of the third embodiment to function in an identical manner.

Claims (8)

1. Claims 1. A cranial cavity sealing device insertabie and removable through the nasal cavity, the device comprising: at least one inflatable flexible layer, which at east one inflatable flexible layer is arranged to be inflated with a fluid; a valve arranged to allow the at east one inflatable flexible layer to be inflated with fluid; and an integral bearing surface adapted to enable control of expansion of the first inflatable flexible layer, thereby facilitating sealing engagement between a surface of the inflatable flexible layer with the cranial cavity.
2. 2. A device according to claim 1, wherein the integral bearing surface is a control ring.
3. 3. A device according to claim 2, wherein the control ring is positioned in a mid portion of the inflatable flexible layer.
4. 4. A device according to claim 1, wherein the integral bearing surface is a second inflatable layer, the at least one inflatable flexible layer bearing on the secondinflatable layer.
5. 5. A device according to claim 3, further comprising a third layer between the first inflatable flexible layer and the second inflatable layer, the valve and a docking point being located on the third layer
6. 6. A device according to claim 4, wherein the third layer is inflatable.
7. 7. A device according to claim 3, 4 or 5. wherein either the second flexible layer or the third layer comprises a flexible structure made from collagen regeneration matrix material.
8. 8. A device according to any one of claims 3 to 6, wherein the second inflatable layer provides a connective surface arranged to cooperate with walls of an opening.a, A tics aoPwthflg hciair Z;' whetS itt second Sa*abte *r forms a páS aasthgó, wh'lchopposiflg hØs'clnip the conneothesutface to wtt of' an opsnbtgtfld prOVIdO an addItbflat seal oversach sideof'teopSng4 10. A device according to any preceding claim, wherein the device further comprises a deflating mechanism.11. A device according to claim 9, whereIn the valve is a non-return valve.12. A sealing device substantially as described herein with reference to. and as illustrated In, the accompanying drawings.