WO2022256436A1

WO2022256436A1 - Systems, methods, and apparatus for closing an opening in the dura mater

Info

Publication number: WO2022256436A1
Application number: PCT/US2022/031817
Authority: WO
Inventors: Michael Y. OH; Elliot H. CHOI; Alvin Y. CHAN; Nolan J. BROWN
Original assignee: The Regents Of The University Of California
Priority date: 2021-06-01
Filing date: 2022-06-01
Publication date: 2022-12-08

Abstract

A system for closing an opening in the dura mater, the system comprising: a dural patch having an outer surface, an interior space, and an external port in fluid communication with the interior space; a fluid delivery apparatus configured to deliver fluid through the port and into the interior space; and surgical clips configured to secure the patch to the dura.

Description

SYSTEMS, METHODS, AND APPARATUS FOR CLOSING AN OPENING IN THE DURA MATER Cross-Reference to Related Application

This application claims priority to co-pending U.S. Provisional Application Serial Number 63/195,583, filed June 1 , 2021 , which is hereby incorporated by reference herein in its entirety. Background

Incidental durotomies, in which an unintended tear or puncture of the dura mater occurs, are a common complication of spine and brain surgery. When the dura mater, or simply “dura,” is perforated, the opening must be repaired immediately to avoid complications, such as cerebrospinal fluid (CSF) leakage. A variety of dural repair techniques have been developed to close the dura when an incidental durotomy occurs. Such techniques range from simply suturing the opening closed to applying sealants or patches to the opening. Unfortunately, each of these techniques have their own drawbacks. While suturing can be effective for small, simple tears, using primary sutures as a means for closure poses a risk of CSF leakage through suture tracts.

Although there are various commercially available surgical sealants that could be applied to a dural tear or puncture, such sealants are limited by their poor performance in aqueous environments and their weak adhesion to wet tissues. It is for these reasons that several studies have demonstrated that using a sealant as an adjunct to primary sutures does not reduce the CSF leakage rate.

Multiple patches have been developed for use in covering, and therefore closing, a dural tear or puncture. For example, patches made from tissues such as muscle, fat, or fascia have been produced that are intended to function as a dural substitute. Unfortunately, such patches typically require the creation of an additional operative site as well as extensive suturing.

From the above discussion, it can be appreciated that it would be desirable to have an alternative means for performing dural repair that is quick, easy, and effective.

Brief Description of the Drawings

The present disclosure may be better understood with reference to the following figures. Matching reference numerals designate corresponding parts throughout the figures, which are not necessarily drawn to scale.

Fig. 1A is a cross-sectional side view of an embodiment of an expandable patch that can be used to close an opening in the dura.

Fig. 1 B is a top view of the patch of Fig. 1 A.

Fig. 2 is a cross-sectional side view of an embodiment of a port of the patch of

Fig. 1.

Fig. 3 is a further cross-sectional side view of the patch of Fig. 1 shown with a tube attached to the port of the patch.

Fig. 4 is a side view of an embodiment of a syringe that can be used to expand the patch of Fig. 1.

Fig. 5 is a top view of an embodiment of a surgical clip that can be used to secure the patch of Fig. 1 to the dura.

Figs. 6A-6E are sequential views illustrating an embodiment of a method for repairing an opening in the dura that uses the patch of Fig. 1 .

Detailed Description

As described above, it would be desirable to have a means for performing dural repair that is quick, easy, and effective. Disclosed herein are a system, a method, and an apparatus for closing openings in the dura mater, or “dura,” whether the opening is the result of an accidental tear or puncture, or was intentionally created to perform a particular surgical procedure, such as removing a tumor. As described below, an expandable dural patch can be passed through a dural opening and into the subarachnoid space while in a collapsed orientation and can then be expanded by filling it with a fluid. As the patch expands, it plugs the opening and then can be secured to the dura, for example, using surgical clips. After the patch has been secured, it can be collapsed and sealant can be applied to the patch, the clips, and the surrounding dura to form an impermeable seal. Because the patch is introduced in a collapsed form, it can be passed through small incisions of the type typically used in minimally invasive procedures. When clips are used to secure the patch instead of sutures, the patch can be secured more quickly and easily than with current techniques and no holes are formed through which cerebrospinal fluid (CSF) can leak. In the following disclosure, various specific embodiments are described. It is to be understood that those embodiments are example implementations of the disclosed inventions and that alternative embodiments are possible. Such alternative embodiments include hybrid embodiments that include features from different disclosed embodiments. All such embodiments are intended to fall within the scope of this disclosure.

Figs. 1A and 1 B illustrate an example embodiment of an expandable dural patch 10. In these figures, the patch 10 is shown in an at least partially expanded orientation for purposes of clarity. The size of the patch 10 can depend upon the size of the opening within the dura that is to be closed. In most cases, however, the patch 10 has width and length dimensions in the range of approximately 10 to 20 mm. In the example of Fig. 1 B, the patch 10 is illustrated as being generally elliptical. It is noted, however, that the shape of the patch is not critical. All that is required is that the patch 10 have a size and shape that is adequate to close the dural opening.

As shown most clearly in the cross-section of Fig. 1A, the dural patch 10 is formed from at least one layer 12 of material. In the illustrated embodiment, the patch 10 is formed from a single, continuous layer 12. In other embodiments, however, the patch 10 can be formed from multiple layers of material 12. For example, the patch 10 can comprise two similarly sized and shaped layers 12 of material that are secured to each other around their edges. In either case, the layer 12 forms an exterior surface 13 and a sealed interior space 14 that can be filled with a fluid when the patch 10 is to be expanded.

The material used to construct the layer 12 or layers that define the dural patch 10 can be a collagen material. For example, one or more of the layers can comprise type I and/or type III collagen. Although the molecular characteristics of those two collagen types are different, both can form fibrils in the extracellular matrix and, therefore, can mimic the dura. Type I collagen can play a significant role in regeneration of the damaged dura and may promote the aggregation of platelets. Such platelets may act as a bridge between the patch 10 and the perforated dura and release clotting factors so as to form an impermeable seal between the patch and the dura. In addition, type I collagen is chemotactic to dural fibroblasts and may enhance dural regeneration by promoting the proliferation of dural fibroblasts.

With further reference to Figs. 1A and 1 B, the dural patch 10 also includes an external port 16 that can be used to expand and collapse the patch. More particularly, the port 16 can be used to inflate and deflate the patch 10 using a suitable fluid, such as air. Fig. 2 illustrates the port 16 in greater detail. As shown in that figure, the port 16 comprises a port body 18 that is attached to an outer surface of the layer 12. Extending through the body 18 is a passage 20, such as a cylindrical passage, through which the fluid can flow. The passage 20 extends through an opening 22 formed through the layer 12 so that the fluid passing through the passage can flow into (and possibly out of) the sealed interior space 14.

Referring next to Fig. 3, the passage 20 of the port 16 is configured to receive a small tube 26 that can be used to deliver fluid to or remove fluid from the dural patch 10. In some embodiments, the tube 26 is a flexible polymeric tube that includes a locking element 28, such as a Luer lock connector, on its proximal end that is configured to secure the tube to a fluid delivery/removal device, such as a syringe. An example of such a syringe is described below with reference to Fig. 4.

With reference back to Fig. 2, a sealing element 24 can be provided within the passage 20 of the patch’s port 16. In some embodiments, the sealing element 24 comprises a self-sealing opening 29 that both prevents fluid from entering and exiting the dural patch 10 through the passage 20. In such a case, the patch 10 can be expanded or collapsed by passing the tip of the tube 26 through the opening 29 of the sealing element 24. In other embodiments, the sealing element 24 comprises a one-way valve that enables fluid delivered by the tube 26 to enter the sealed interior space 14 of the patch 10 but prevents the fluid from exiting the space.

As noted above, Fig. 4 illustrates an example syringe 30 can be used to deliver and/or remove fluid from the sealed interior space 14 of the dural patch 10. In this embodiment, the syringe 30 includes a cylindrical body 32 that defines an interior space 34 that can contain fluid. Loaded within the interior space 34 is a piston 36 that is mounted to the distal end of a plunger 38. In addition, a spring 40 is provided within the body 32 that resists movement of the plunger into the body. The provision of the spring 40 is believed to increase the precision with which fluid is ejected by the syringe 30 and, therefore, supplied to the patch 10. A stop 42 is also provided within the body 32 that limits movement of the piston 36 during fluid ejection. When the interior space 34 is filled with fluid and the plunger 38 is pushed into the body 32, fluid is ejected from a nozzle 44 at the distal end of the body, which can incorporate a further locking element, such as a Luer lock connector, that is configured to releasably connect to the locking element 28 of the tube 26 (Fig. 3).

Figs. 6A-6E are sequential views that illustrate an example method for closing an opening in the dura. Specifically, illustrated is an example dural repair procedure within the spine using the dural patch 10. Each figure shows the same step in the procedure from both the top (image on the left) and the side (image on the right).

Beginning with Fig. 6A, an opening, such as a tear, has been made in the dura and must be closed. In preparation for such closure, the tube 26 can be attached to the port 16 of the dural patch 10 in the manner illustrated in Fig. 3. Unlike as shown in Fig. 3, however, the patch 10 is in a collapsed state so that it is in its smallest orientation. The patch 10, with the tube 26 connected to the port 16, can then be delivered to site of the tear, as shown in Fig. 6B, using an appropriate surgical instrument, such as surgical forceps. In some embodiments, the patch 10 is passed through the tear so that it is positioned within the subarachnoid space directly adjacent to the tear and the inner surface of the dura.

Once the patch 10 is in place, it can be expanded. As noted above, such expansion can be effected via inflation of the patch with a fluid, such as air. This is illustrated in Fig. 6C. As can be seen in that figure, when the patch 10 is expanded, a portion of the patch remains within the subarachnoid space and a portion of the patch extends through the opening and outside of the subarachnoid space. In such a case, the patch 10 acts like a three-dimensional plug (as opposed to a two- dimensional patch) that seals the opening. As shown in Fig. 6D, clips can be used to secure the patch 10 to the outer surface of the dura.

Fig. 5 shows an example clip 50 that is suitable for such securing. The clip 50 is made of a biocompatible metal, such as titanium or stainless steel, and includes opposed sharp tips 52. In such a case, one of the tips 52 can embed within the material of a layer 12 of the patch 10 and the other tip 52 can embed within the dura. Irrespective of their specific configuration, the clips 50 do not completely penetrate the patch 10 or the dura and, therefore, do not contact any neural tissues or form any further openings through which CSF can leak, as is the case when sutures are used.

After the patch 10 has been secured to the dura, it can be collapsed (e.g., deflated). How this is achieved can depend upon the nature of the patch’s port 16. For example, if the port 16 includes a self-sealing opening, the fluid that was injected into the patch 10 can be withdrawn using the tube 26 and a syringe. If the port 16 includes a one-way valve, however, the port can be cut out of the patch 10 enabling the fluid it contained to escape.

Finally, referring to Fig. 6E, a resorbable sealant, such as fibrin or polyethylene glycol, can be applied to the secured patch 10, the clips, and the portion of the dura surrounding the opening to ensure that CSF cannot escape through the opening.

The disclosed systems, methods, and apparatus are advantageous for several reasons. While existing patches are designed to seal the dura opening on the outside of the dura, the disclosed dural patch is designed to be inserted within the subarachnoid space and expanded (e.g., inflated) to fill the opening like a three- dimensional plug that seals the opening closed. As the patch is positioned within the subarachnoid space, the patch is urged into contact with the dura by the hydrostatic pressure of the CSF circulating within the subarachnoid space. Accordingly, the hydrostatic pressure helps the patch seal the opening whereas that pressure makes it more difficult for conventional patches secured to the outside of the dura to maintain such a seal.

As noted above, sealants do not do well in aqueous environments and, therefore, are not effective in closing dural openings in the presence of CSF. When the disclosed patch is used, however, the opening is closed and the CSF is contained within the subarachnoid space, thereby providing a dry surface upon which such sealants are more effective.

Finally, as suturing is not needed, the patch can be secured more quickly and easily, without forming multiple holes through which CSF could leak.

It is noted that, while a spinal dura repair was illustrated in Fig. 6, there are several procedures in which the dural patch can be used. For example, the patch can be used when performing pituitary tumor removal, microvascular decompression (MVD), and the Chiari malformation procedure (decompression).

Claims

CLAIMS Claimed are:

1. A system for closing an opening in the dura mater, the system comprising: a dural patch having an outer surface, an interior space, and an external port in fluid communication with the interior space; a fluid delivery apparatus configured to deliver fluid through the port and into the interior space; and surgical clips configured to secure the patch to the dura.

2. The system of claim 1 , wherein the patch is made of a collagen material.

3. The system of claim 1 , wherein the patch is made or one or more layers of collagen material.

4. The system of claim 1 , wherein the port includes a sealing element that prevents fluid from passing through the port in at least one direction.

5. The system of claim 4, wherein the sealing element comprises a self sealing opening through which fluid can enter or exit the space.

6. The system of claim 4, wherein the sealing element comprises a one way valve that only enables fluid to flow into the interior space.

7. The system of claim 1 , wherein the fluid delivery apparatus includes a tube having a first end configured to connect to the external port.

8. The system of claim 7, wherein the fluid delivery apparatus further includes a syringe and wherein the tube has a second end configured to connect to the syringe.

9. A dural patch comprising: at least one layer of material; a sealed internal space defined by the at least one layer of material; and a port mounted to the at least one layer of material, the port being in fluid communication with the internal space.

10. The patch of claim 9, wherein the at least one layer of material is made of a collagen material.

11. The patch of claim 10, wherein the collagen material includes one or both of type I collagen and type III collagen.

12. The patch of claim 9, wherein the port includes a sealing element that prevents fluid from passing through the port in at least one direction.

13. The patch of claim 12, wherein the sealing element comprises a self sealing opening through which fluid can enter or exit the space.

14. The patch of claim 12, wherein the sealing element comprises a one way valve that only enables fluid to flow into the interior space.

15. A method for closing an opening in the dura mater, the method comprising: passing a dural patch through an opening in the dura mater and positioning the patch directly adjacent to the opening and an inner surface of the dura mater; expanding the dural patch so that a portion of the patch extends through the opening and seals it closed; and securing the portion of the dural patch to the dura mater using biocompatible clips.

16. The method of claim 15, wherein the dural patch is made of a collagen material.

17. The method of claim 15, wherein expanding the dural patch comprises inflating the patch with a fluid.

18. The method of claim 15, wherein expanding the dural patch comprises inflating the patch with air.

19. The method of claim 15, wherein securing the portion of the dural patch to the dura mater using biocompatible clips does not comprise puncturing the expanded dural patch or the dura mater.

20. The method of claim 15, further comprising applying sealant to the patch, clips, and the portion of the dura mater that surrounds the patch.