EP4648708A1

EP4648708A1 - Burr hole device

Info

Publication number: EP4648708A1
Application number: EP24705307.7A
Authority: EP
Inventors: Andre Machado; Paresh M. VASANDANI; James P. HOPE; Kimberly A. LEON; Michael A. Kamm
Original assignee: Cleveland Clinic Foundation
Current assignee: Cleveland Clinic Foundation
Priority date: 2023-01-09
Filing date: 2024-01-09
Publication date: 2025-11-19
Also published as: WO2024151581A1

Abstract

A burr hole device includes a base defining an opening, wherein the base is fixable to a skull of a subject such that the opening is aligned with a burr hole in the skull. The burr hole device further includes a fluid retainer that is removably coupled to the base and defines a cavity in fluid communication with the opening of the base.

Description

BURR HOLE DEVICE

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. provisional patent application no. 63/437,795 filed January 9, 2023, the contents of which are incorporated by reference.

TECHNICAL FIELD

[0002] The present disclosure relates to a burr hole device and more particularly, a burr hole device that is useful for stereotactic surgery.

BACKGROUND

[0003] Stereotactic surgery is a technique that allows neurosurgeons to approach a target area in the brain with submillimetric accuracy. Stereotaxy is broadly used in neurosurgery for many purposes, including brain biopsy, oncological surgery, surgery for movement disorders, and behavioral neurosurgery. The idea behind stereotaxy is to map a specific patient's brain structures using coordinates in three axes and then use these coordinates to reach the selected target during surgery. In particular, a metal frame is affixed to the surface of the patient's skull, and then computed tomography (CT) or magnetic resonance imaging (MRI) scans are taken with the frame fixed in the patient's head. Any anatomical region within this patient's brain can then be mapped and related to coordinates in the three axes. Then, a burr hole can be cut be formed in the skull, and the target region can be accessed using its known coordinates.

[0004] Stereotactic technique is used in several brain procedures to provide accurate and precise navigation of surgical instruments (cannulas, electrodes, catheters, etc.) to the desired brain region, avoiding functional and eloquent brain areas, vessels, and other vascular structures. For example, stereotactic surgery can be used for the placement of electrodes within the brain for deep brain stimulation (DBS) or stereoencephalography. Stereotactic procedures can be used to treat disorders such as Parkinson's disease, dystonia, essential tremor, seizure disorders, obesity, depression, restoration of motor control, and other debilitating diseases via electrical stimulation via stimulation of one or more target sites, including the ventrolateral thalamus, internal segment of globus pallidus, substantia nigra pars reticulate, subthalamic nucleus (STN), or external segment of globus pallidus. [0005] The placement of surgical instruments during stereotactic procedures can be impeded by intraoperative brain shift (i.e., brain dislocation inside the skull), which reduces the accuracy of the stereotactic mapping. One potential cause of brain shift can be the loss of cerebrospinal fluid (CSF) since the opening of dura mater. More specifically, if CSF escapes the dura mater of the brain and is replaced with air from the external environment, this can alter the co-registration between the brain parenchyma and the fiducial-based stereo-image. That leads to error in the delivery of the stereotactic instrument. Surgeons resort to several strategies to minimize brain shift, including changing the position of the patient and/or surgical apparatus and the utilization of glue or adhesives around the entry point into the dura mater or inside a burr hole. Yet, brain shift continues to be a concern in stereotactic surgery.

BRIEF SUMMARY OF THE INVENTION

[0006] According to a first aspect, a burr hole device includes a base defining an opening, wherein the base is fixable to a skull of a subject such that the opening is aligned with a burr hole in the skull. The burr hole device further includes a fluid retainer that is removably coupled to the base and defines a cavity in fluid communication with the opening of the base.

[0007] According to a second aspect, a method of treating a subject includes providing a burr hole in a skull of the subject, and providing a pool of fluid above the burr hole such that the pool of fluid inhibits air from entering the burr hole.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a perspective view of an example burr hole device fixed to a skull of an animal subject;

[0009] FIG. 2 is a cross-section view of the burr hole device in FIG. 1;

[0010] FIG. 3 is an upper perspective view of a flow retainer of the burr hole device;

[0011] FIG. 4 is a lower perspective view of the flow retainer;

[0012] FIG. 5 is an exploded view of the flow retainer;

[0013] FIG. 6 is a cross-section view of a break junction of the burr hole device; and [0014] FIG. 7 is a perspective view of the burr hole device after the flow retainer has been removed from a base of the burr hole device. DETAILED DESCRIPTION

[0015] Turning to FIGS. 1 and 2, an example burr hole device 10 for stereotactic surgery will now be described. In particular, the burr hole device 10 can be used for a procedure in which a burr hole 14 (see FIG. 2) is cut through the skull 18 of an animal (e.g., human) subject, and then one or more leads 22 are introduced through the burr hole 14 and delivered to a target site in the subject’s brain using a stereotactic targeting apparatus. For the purpose of this disclosure, the term “lead” encompasses electrical stimulation leads, drug infusion catheters, cannulas, or any other elongated medical device to be introduced through the burr hole 14 of the subject. For instance, the leads 22 in the present example are electrical stimulation leads that can be utilized for DBS.

[0016] The burr hole device 10 includes an annular base 30 that defines a circular opening 32 having a central axis X (it is to be appreciated the central axis X of the base 30 defines the axial and radial directions of the device 10). Before the leads 22 are introduced through the burr hole 14, the base 30 of the device 10 can be fixed to the skull 18 such that its opening 32 is aligned (e.g., coaxial) with the burr hole 14. In particular, the base 30 defines a plurality of fastener holes 36, and can be fixed to the skull 18 using fasteners (e.g., screws) 38 that pass through the holes 36 and are screwed into the skull 18. However, the base 30 may be fixed to the skull 18 using other means such as, for example, adhesive.

[0017] The base 30 can comprise a variety of rigid or semi-rigid materials such as polyaryletheretherketone (PEEK), silicone, steel, titanium alloy, nickel-cobalt alloy, titanium, polycarbonate. In one specific example, the base 30 can comprise biocompatible silicone having a Shore A hardness of 60, which can help the base 30 conform to the skull 18 and establish a seal therebetween. Moreover, the shape and configuration of the base 30 can vary by embodiment. Broadly speaking, the base 30 can be any rigid or semi-rigid body that defines an opening for the leads 22 and can be fixed to the skull 18 such that the opening is aligned with the burr hole 14. [0018] The device 10 further includes a fluid retainer 40 that is removably attached to the base 30 and is configured to retain fluid as it exits the burr hole 14 through the base 30. In particular, the fluid retainer 40 comprises a tubular housing 42 that defines an interior cavity 44, a lower opening 46 at a lower end of the cavity 44, and an upper opening 48 at an upper end of the cavity. The fluid retainer 40 further comprises a lid 52 that is movably (e.g., pivotally) coupled to an upper end of the housing 42, and is operable between an open position (see FIGS. 1 and 2) and a closed position (see FIG. 3) to selectively open and close the upper opening 48.

[0019] The housing 42 (including its interior cavity 44 and lower and upper openings 46, 48) is coaxial with the central axis X of the base 30. Moreover, the interior cavity 44 is in fluid communication with the opening 32 of the base 30 (and the burr hole 14 there- below) via the lower opening 46 of the housing 42. In this manner, the leads 22 can be delivered to the burr hole 14 by inserting each lead 22 through the housing 42 and base 40 into the burr hole 14.

[0020] Preferably, the housing 42 is a flexible body that can be manipulated as desired to adjust its internal volume and/or alter the path therethrough for the leads 22. For example, the housing 42 in the present embodiment is a flexible body comprising a plurality of pleats 58 that extend circumferentially about the housing 42 and are axially aligned. The pleats 58 enable the housing 42 to expand or contract in the axial direction, and also enable the housing 42 to flex in directions that are skewed relative to the central axis X. For example, the pleats 58 can enable one side of the housing 42 (e.g., the right side in FIG. 2) to axially contract while the other side of the housing 42 (e.g., the left side in FIG. 2) axially expands, such that the upper opening 48 and its central axis become tilted relative to the central axis X of the base 30.

[0021] The pleats 58 thus enable the housing 42 to axially expand or contract to respectively increase or decrease its internal volume. Moreover, the pleats 58 enable the upper opening 48 to be coaxial with or skewed relative to the central axis X of the base 30. Such adjustability of the upper opening 48 may be desirable for the purposes of observing the burr hole 14 at different angles, adjusting the position or angle of the upper opening 48, and/or adjusting the path in which the leads 22 are delivered or extracted through the housing 42. However, the housing 42 may comprise other non-pleated configurations that are similarly flexible without departing from the scope of the disclosure. Moreover, the housing 42 may be a rigid body in some examples.

[0022] As shown best in FIGS. 4 and 5, the housing 42 comprises a seal portion 64, a first main body portion 66, and a second main body portion 68 that form at least a portion of the housing 42 and its features above. The seal portion 64 is an annular body comprising a cylindrical sleeve 72 that defines the lower opening 46, and a flange 74 that extends radially from an upper end of the sleeve 72. Meanwhile, the main body portions 66, 68 are semi-cylindrical portions that define the upper opening 48. However, it is to be appreciated that the housing portions 64, 66, 68 may have other shapes and configurations without departing from the scope of the disclosure. [0023] Preferably, the main body portions 66, 68 are removably attached to each other at their lateral ends, and are removably attached to the seal portion 64 at their lower ends. For example, the housing 42 in the present embodiment includes first and second break junctions 80, 82 that extend between and removably couple lateral ends of the main body portions 66, 68. The housing 42 also includes a third break junction 84 between the seal portion 64 and main body portions 66, 68, which extends circumferentially about the perimeter of the flange 74.

[0024] For the purposes of this disclosure, a “break junction” between two housing portions corresponds to a structure (or combination of structures) that removably couples the two housing portions and has a mechanical tensile strength that is lower than the adjacent housing portions, such that the break junction will fail first and release its coupling of the housing portions when sufficient tension is applied across the break junction and housing portions. Such a relationship can be achieved in various ways without departing from the scope of the disclosure. For example, the first and second break junctions 80, 82 in the present embodiment each comprise a strip of material that extends between the main body portions 66, 68. Moreover, as shown best in FIG. 6, each break junction 80, 82 has a pair of projections 86 on its lateral ends that engage associated recesses 88 in its adjacent main body portions 66, 68 to form a snap-fit connection. Meanwhile, the third break junction 84 is formed by a projection 90 (see FIG. 5) on the seal portion 64 that engages associated recesses (not shown) in the main body portions 66, 68 to form a snap-fit connection. If sufficient tension is applied across the break junctions 80, 82, 84, their associated projections 86, 90 will withdraw from their respective recesses, thereby decoupling the housing portions 64, 66, 68.

[0025] However, the break junctions 80, 82, 84 can comprise other configurations without departing from the scope of the disclosure. For example, each break junction 80, 82, 84, may comprise a portion of material that is integrally formed with its adjacent housing portions but is perforated or scribed, such that applying sufficient tension across the break junction causes it to tear. As yet another example, each break junction 80, 82, 84 may comprise a weld or adhesive that couples its adjacent housing portions and has a joining strength that is lower than the tensile strengths of its adjacent housing portions.

[0026] As discussed further below, the break junctions 80, 84, 88 of the housing 42 can facilitate removal of the fluid retainer 40 from the base 30 at the end of a stereotactic procedure. However, it is to be appreciated that the housing 42 may comprise additional or fewer break junctions without departing from the scope of the disclosure. Moreover, in some examples, the housing 42 may not include any break junctions between its housing portions 64, 66, 68.

[0027] The housing 42 can further include one or more fluid ports that enable a fluid delivery system to be fluidly coupled to its interior cavity 44. For example, the housing 42 in the present embodiment comprises first and second fluid ports 92, 94 that each define a respective channel in fluid communication with the interior cavity 44. First and second delivery tubes 96, 98 (see FIG. 1) can be inserted into the channels of the respective ports 92, 94, and a fluid (e.g., saline, artificial cerebrospinal fluid, etc.) can be delivered through the tubes 96, 98 and respective ports 92, 94 into the cavity 44. In other examples, each port 92, 94 can comprise a cylindrical tube fitting, which can be inserted into its associated tube 96, 98 to fluidly couple the tube 96, 98 to the cavity 44. Each port 92, 94 can comprise any configuration that is fluidly couplable to a fluid delivery system to place the system in fluid communication with the cavity 44.

[0028] The delivery tubes 96, 98 thus enable fluid to be delivered into the cavity 44. As discussed further below, retaining fluid within the cavity 44 during a stereotactic procedure can help inhibit brain shift. In some examples, the cavity 44 may be completely filled with fluid while the lid 52 is closed. In such embodiments, the lid 52 can be configured to be releasably secured in the closed position, such that the lid 52 remains closed as fluid pressure builds in the cavity 44 but opens once the fluid pressure reaches or exceeds a predetermined threshold (e.g., 15 mmHg). For example, the lid 52 and housing 42 may form an interference fit in the closed position that can withstand fluid pressure under the threshold, but releases once the fluid pressure reaches or exceeds the threshold. The lid 52 can thus function as a fail-safe feature that prevent s excessive pressure from building within the cavity 44.

[0029] As discussed above, the base 30 of the device 10 can be fixed to the skull 18 such that its opening 32 is aligned (e.g., coaxial) with the burr hole 14. Moreover, while the lid 52 is in its open position (see FIGS. 1 and 2), the leads 22 can be delivered to the burr hole 14 by inserting each lead 22 through the upper opening 48 of the housing 42 and into the burr hole 14. However, it may be desirable to keep the lid 52 in its closed position while the leads 22 are delivered to (or already reside within) the burr hole 14. Accordingly, the fluid retainer 40 can include one or more access ports that can provide access to its cavity 44 for the leads 22 and/or other devices. [0030] For example, as shown in FIG. 3, the fluid retainer 40 in the present embodiment includes first and second access ports 102, 104 for providing selective access to the cavity 44 while this lid 52 is in the closed position. Each access port 102, 104 comprises a pair of flexible portions 106a, 108a provided by (e.g., integrally formed with) the housing 42, and a pair of flexible portions 106b, 108b provided by the lid 52. Each flexible portion 106a, 106b, 108a, 108b is cantilevered such that a distal end of the flexible portion 106a, 106b, 108a, 108b is flexible relative to its base.

[0031] Moreover, a slit is defined between each pair of adjacent flexible portions 106a, 106b, 108a, 108b while the lid 52 is in its closed position. More specifically, for each access port 102, 104, a first slit 114a is defined between the pair of flexible portions 106a, 108a on the housing 42, and a second slit 114b is defined between the pair of flexible portions 106b, 108b on the lid 52. Moreover, when the lid 52 is in its closed position, additional slits 114c, 114d will be respectively defined between the flexible portions 106a, 106b and the flexible portions 108a, 108b. The flexible portions 106a, 106b, 108a, 108b are self-sealing and elastically biased to engage each other so they form seals along the slits 114a-d when the lid 52 is in the closed position.

[0032] In this manner, the leads 22 can pass through the slits 114a-d of the respective access ports 102, 104, and the flexible portions 106a, 106b, 108a, 108b can flex to increase the size of the slits 114a-d and accommodate the leads 22. Moreover, the flexible portions 106a, 106b, 108a, 108b can engage the leads 22 so the access ports 102, 104 are still sealed when the leads 22 extend therethrough. Still further, the lid 52 can be adjusted between its open and closed positions such that each time the lid 52 assumes its closed position the leads 22 will pass through their respective access ports 102, 104.

[0033] However, it is to be appreciated that the configuration of each port 102, 104 and its flexible portions 106a, 106b, 108a, 108b can vary in different embodiments. For example, each portion 102, 104 may simply comprise two flexible portions (on the lid 52 or housing 42) that define a slit therebetween for accommodating a lead 22 therethrough.

[0034] As discussed above, the fluid retainer 40 is removably attached to the base 30 such that its interior cavity 44 is in fluid communication with the opening 32 of the base 30 (see FIG. 2). In particular, the seal portion 64 includes a plurality of projections 120 (see FIG. 4) that extend radially from its sleeve 72 and can mate with associated recesses 122 (see FIG. 7) formed in the base 30 to form a releasable snap-fit connection between the base 30 and fluid retainer 40. Moreover, as shown in FIG. 2, the seal portion 64 will engage the base 30 when connected thereto such that a seal is formed between the seal portion 64 and the base 30. However, it is to be appreciated that the fluid retainer 40 may be removably attached to the base 30 in other manners without departing from the scope of the disclosure. As one example, the housing 42 may be joined to the base 30 with a break junction enables the housing 42 to be torn from the base 30.

[0035] The housing 42 of the device 10 described above comprises various portions that can be flexible and/or capable of forming a seal with adjacent components. The housing 42 and its components preferably comprise a material that provide them with suitable flexibility and/or sealing properties. For instance, suitable materials for the housing 42 and its individual components can include, for example, biocompatible silicone, thermoplastic polyurethane, and thermoplastic elastomer. Such materials may also be useful for the flexible portions 106b, 108b on the lid 52. However, it is to be appreciated that other materials may be used for the housing 42 and lid 52, including rigid materials. Moreover, different materials may be utilized for different portions of the housing 42 and lid 52.

[0036] A method of using the device 10 will now be described in further detail. Initially, a fiducial-based stereo-image of the subject’s brain can be generated to determine a target site for implementation of the leads 22. Then, as shown in FIGS. 1 and 2, the burr hole 14 can be cut through the skull 18 of the subject, and the device 10 can be fixed to the skull 18 such that its opening 32 is aligned (e.g., coaxial) with the burr hole 14. Moreover, the first and second delivery tubes 96, 98 can be inserted into the channels of the respective ports 92, 94, and an irrigation fluid (e.g., saline, artificial cerebrospinal fluid, etc.) can be delivered through the tubes 96, 98 and respective ports 92, 94 into the cavity 44. This will create a pool of irrigation fluid that fills the burr hole 14 and at least a portion of the cavity 44. In some examples, the irrigation fluid may fill the entire cavity 44.

[0037] Next, the dura mater below the burr hole 14 can be opened to provide access to the target site of the brain. Because the CSF contained by the dura mater is pressurized as compared to the exterior atmosphere, opening the dura mater may cause some CSF to egress through the burr hole 14 and possibly into the cavity 44 of the device 10. However, because a pool of irrigation fluid is formed above the burr hole 14 and retained within the cavity 44 of the fluid retainer 40, the interior space of the dura mater will remain completely filled with fluid. That is, the pool of irrigation fluid will inhibit air from entering the burr hole 14 and the dura mater below, thereby preventing brain shift. Moreover, the pool of irrigation fluid can be maintained for subsequent steps in the procedure to ensure co-registration between the brain parenchyma and the fiducial-based stereo-image.

[0038] Once the dura mater is opened, the leads 22 can be fed through the device 10 and burr hole 14 to the target site. In particular, for each lead 22, a respective cannula (not shown) can be inserted into the fluid retainer 40 via its upper opening 48 (or an access port 102, 104). Using the fiducial -based stereo-image, the cannula can be fed through the device 10, burr hole 14, and brain parenchyma until its distal end reaches the target site. The lead 22 can then be fed through the cannula and implanted at the target site, after which the cannula can be retracted.

[0039] Once the leads 22 are implanted, they will extend from the target site through the bunhole 14 and device 10 as shown in FIGS. 1 and 2. Moreover, irrigation to the device 10 can be discontinued, and the fluid retainer 40 can be removed from the base 30. For example, the snap- fit connection between the base 30 and fluid retainer 40 can be released, and the housing 42 can be tom along its break junctions 80, 82 84, (see FIG. 5) to separate the housing portions 64, 66, 68 and lid 52. The main body portions 64, 66, and lid 58 can thus be easily removed without disturbing the leads 22. Moreover, the seal portion 68 can be removed from the leads 22 by either sliding it past their proximal ends or simply cutting the seal portion 68.

[0040] The dura mater can then be closed around the leads 22 with sutures. Moreover, the leads 22 can be fixed to the base 30 with one or more locking features. For example, as shown in FIG. 7, the base 30 can include first and second channels 130, 132 that are in communication with the opening 32 and can receive the respective leads 22 therein. Moreover, the device 10 can include a lid 134 having a plurality of projections 136 that can mate with the recesses 122 in the base 30 to form a releasable snap-fit connection between the base 30 and the lid 134. It is to be appreciated that the lid 134 may be the lid 52 of the fluid retainer 40, or it may be a separate lid. Moreover, once connected, the lid 134 can retain the leads 22 within their respective channels 130, 132, and can also provide a sealed closure of the burr hole 14.

[0041] Notably, the channels 130, 132 are in communication with the opening 32 of the base 30 once the fluid retainer 40 is removed, allowing the leads 22 to extend through the opening 32 and their respective channels 130, 132. However, when the fluid retainer 40 is connected to the base 30 as shown in FIG. 2, its seal portion 64 can establish a seal between the opening 32 and channels 130, 132 that prevents irrigation fluid (or CSF) from egressing through the channels 130, 132.

[0042] The device 10 as described above can thus be useful for maintaining a pool of irrigation fluid above the dura mater and burr hole 14 during a stereotactic procedure, thereby preventing brain shift and a deviation of the brain parenchyma from the fiducial-based stereo-image. Maintaining a pool of irrigation fluid above the dura matter and burr hole 14 can also be helpful to prevent pneumocephalus, which the presence of air in the epidural, subdural, or subarachnoid space within the brain parenchyma or ventricular cavities.

[0043] It is preferable that the device 10 retains a sufficient volume of irrigation fluid above the dura mater and burr hole 14 to ensure that the interior space of the dura mater remains completely filled with fluid. To this end, it is preferable that the volume of the cavity 44 within the device 10 is large enough to accommodate an acceptable amount of fluid within the housing 42 that keeps the burr hole 14 covered and applies a sufficient amount of fluid pressure over the burr hole 14. For example, for applications in which the burr hole 14 is about 14 mm (a common diameter for DBS procedures), the volume of the cavity 44 may be at least 2 cm³. However, other volumes are possible without departing from the scope of the disclosure. Moreover, a flow regulator (e.g., valve, variable pump, etc.) can be fluidly coupled to the delivery tubes 96, 98 and can be operated to regulate (e.g., maintain, increase, decrease, cease) the flow of irrigation fluid through the tubes 96, 98 to help maintain a substantially constant volume of fluid within the cavity 44.

[0044] The invention has been described with reference to the example embodiments described above. Modifications and alterations will occur to others upon a reading and understanding of this specification. Example embodiments incorporating one or more aspects of the invention are intended to include all such modifications and alterations insofar as they come within the scope of the appended claims.

Claims

What is claimed is:

1. A burr hole device comprising: a base defining an opening, wherein the base is fixable to a skull of a subject such that the opening is aligned with a burr hole in the skull, and a fluid retainer that is removably coupled to the base and defines a cavity in fluid communication with the opening of the base.

2. The burr hole device according to claim 1, wherein the fluid retainer comprises a housing that defines the cavity, a lower opening at a lower end of the cavity, and an upper opening at an upper end of the cavity, wherein the cavity is in fluid communication with the opening of the base via the lower opening.

3. The burr hole device according to claim 2, wherein the housing is tubular.

4. The burr hole device according to claim 2, wherein the housing is flexible.

5. The burr hole device according to claim 4, wherein the housing comprises a plurality of pleats.

6. The burr hole device according to claim 2, wherein a volume of the cavity is at least 2 cm³.

7. The burr hole device according to claim 2, wherein the housing comprises a first housing portion, a second housing portion, and a first break junction that extends between the first housing portion and second housing portion.

8. The burr hole device according to claim 7, wherein: the first housing portion and the second housing portion are each semi-cylindrical, and the first break junction extends between and along first lateral ends of the first housing portion and the second housing portion.

9. The burr hole device according to claim 8, wherein the housing further comprises a second break junction that extends between and along second lateral ends of the first housing portion and the second housing portion.

10. The burr hole device according to claim 7, wherein the housing further comprises: a third housing portion, and a second break junction that extends between the third housing portion and the first housing portion and the second housing portion, wherein the second break j unction extends about a perimeter of the third housing portion.

11. The burr hole device according to claim 2, wherein the fluid retainer further comprises a lid that is movably coupled to the housing, wherein the lid is operable between an open position and a closed position to respectively open and close the upper opening.

12. The burr hole device according to claim 11, wherein the fluid retainer comprises an access port for providing selective access to the cavity while the lid is in the closed position.

13. The burr hole device according to claim 12, wherein the access port comprises a first flexible portion, a second flexible portion, and a slit that is defined between the first portion and the second flexible portion while the lid is in the closed position.

14. The burr hole device according to claim 13, wherein the first flexible portion is provided by the housing, and the second flexible portion is provided by the lid.

15. The burr hole device according to claim 2, wherein the housing includes a fluid port that is in fluid communication with the cavity and can be fluidly coupled to a fluid delivery tube.

16. The burr hole device according to claim 1, wherein the fluid retainer is removably connected to the base via a snap-fit connection.

17. The burr hole device according to claim 1 , wherein the base defines a channel for receiving a lead therein.

18. The burr hole device according to claim 1, wherein the burr hole device comprises a lid that is couplable to the base to close the opening of the base when the fluid retainer is removed therefrom.

19. A method of treating a subject, the method comprising: providing a burr hole in a skull of the subject, and providing a pool of fluid above the burr hole such that the pool of fluid inhibits air from entering the burr hole.

20. The method according to claim 19, wherein the method comprises providing a burr hole device that includes: a base defining an opening, wherein the base is fixed to the skull of the subject such that the opening is aligned with the burr hole, and a fluid retainer that is removably coupled to the base and defines a cavity in fluid communication with the opening of the base, wherein the pool of fluid is retained by the fluid retainer.