Kits and methods for securing a burr hole plugs for stimulation systems

A kit or arrangement for securing a burr hole plug that includes a guide base having an upper flange, a lower flange, and a connecting member coupling the upper flange to the lower flange, each of the upper flange and the lower flange defining one or more guide holes, wherein the one or more guide holes of the upper flange are aligned with the one or more guide holes of the lower flange; a drill shank including a cutting element and a main shaft that are configured to pass through any one of the one or more guide holes in the upper flange; and one or more guide collets including a collet shaft and a fastener tube extending from the collet shaft to receive a fastener, where the collet shaft and fastener tube are configured for insertion into any one of the guide holes in the upper flange.

FIELD

The present disclosure is directed to the area of burr hole plugs and kits and methods for securing burr hole plugs. The present disclosure is also directed to implantable electrical stimulation systems including the kits for securing burr hole plugs, as well as methods of making and using the kits, burr hole plugs, and electrical stimulation systems.

BACKGROUND

Implantable electrical stimulation systems have proven therapeutic in a variety of diseases and disorders. For example, stimulation of the brain, such as deep brain stimulation, can be used to treat a variety of diseases or disorders and spinal cord stimulation systems have been used as a therapeutic modality for the treatment of chronic pain syndromes. Peripheral nerve stimulation has been used to treat incontinence, as well as a number of other applications under investigation. Functional electrical stimulation systems have been applied to restore some functionality to paralyzed extremities in spinal cord injury patients.

Stimulators have been developed to provide therapy for a variety of treatments. A stimulator can include a control module (with a pulse generator), one or more leads, and an array of stimulator electrodes on each lead. The stimulator electrodes are in contact with or near the brain, nerves, or other tissue to be stimulated. The pulse generator in the control module generates electrical pulses that are delivered by the electrodes to body tissue.

BRIEF SUMMARY

In some aspects, a kit or arrangement for securing a burr hole plug includes a guide base including an upper flange, a lower flange, and a connecting member coupling the upper flange to the lower flange, each of the upper flange and the lower flange defining one or more guide holes, wherein the one or more guide holes of the upper flange are aligned with the one or more guide holes of the lower flange; a drill shank coupleable to a drill and including a cutting element and a main shaft that are configured to pass through any one of the one or more guide holes in the upper flange of the guide base; and one or more guide collets including a collet shaft and a fastener tube extending from the collet shaft to receive a fastener, where the collet shaft and fastener tube are configured for insertion into any one of the one or more guide holes in the upper flange of the guide base.

In at least some aspects, each of the upper flange and the lower flange defines at least two of the guide holes. In at least some aspects, the shaft of the drill shank has an outer diameter that is greater than an inner diameter of any one of the one or more guide holes in the lower flange of the guide base. In at least some aspects, each of the one or more guide holes in the lower flange has a diameter that decreases toward a bottom of the lower flange, where the shaft of the drill shank has an outer diameter that is greater than an inner diameter of at least a portion of any one of the one or more guide holes in the lower flange of the guide base.

In at least some aspects, the guide collet includes a collet flange disposed on the collet shaft opposite the fastener tube. In at least some aspects, the guide collet has an outer diameter larger than an inner diameter of any one of the one or more guide holes in the upper flange of the guide base.

In at least some aspects, the guide base further includes an alignment arrangement extending from the lower flange to align a base of the burr hole plug with the guide holes of the upper and lower flanges. In at least some aspects, the alignment arrangement includes one or more sections of a ring that fit within an opening of the base of the burr hole plug. In at least some aspects, the one or more sections of the ring form a compression or friction fit with the base of the burr hole plug. In at least some aspects, the alignment arrangement includes one or more pins for engaging the base of the burr hole plug. In at least some aspects, the kit further includes the base of the burr hole plug.

In at least some aspects, the kit further includes one or more fasteners disposed with each fastener disposed in the fastener tube of one of the one or more guide collets. In at least some aspects, the kit further includes the burr hole plug. In at least some aspects, the base defines a gap in at least the lower flange for positioning of a lead extending from a burr hole. In at least some aspects, the base further defines the gap in the upper flange and the connecting member.

In some aspects, a method of securing a burr hole plug to a patient using any of the kits described above includes aligning the guide base with a base of a burr hole plug on a skull of a patient, wherein the one or more guide holes of the upper and lower flanges are aligned with fastener openings in the base of the burr hole plug; drilling one or more pilot holes in the skull using the drill shank inserted into the one or more guide holes of the guide base; inserting the one or more guide collets into the guide holes of the guide base with a fastener in the fastener tube of each of the one or more guide collets; driving the one or more fasteners into the skull using the guide collets and the pilot holes; and removing the guide base leaving the base of the burr hole plug secured to the skull.

In at least some aspects, aligning the guide base includes engaging the base of the burr hole plug with an alignment arrangement extending from the lower flange of the guide base. In at least some aspects, engaging the base includes forming a compression or friction fit between the alignment arrangement of the guide base and the base of the burr hole plug. In at least some aspects, the alignment arrangement includes one or more pins and engaging the base includes engaging the base of the burr hole plug with the pins of the alignment arrangement of the guide base. In at least some aspects, aligning the guide base includes positioning a lead extending from a burr hole in a gap defined in at least the lower flange of the guide base.

DETAILED DESCRIPTION

The present disclosure is directed to the area of burr hole plugs and kits and methods for securing burr hole plugs. The present disclosure is also directed to implantable electrical stimulation systems including the kits for securing burr hole plugs, as well as methods of making and using the kits, burr hole plugs, and electrical stimulation systems.

Suitable implantable electrical stimulation systems include, but are not limited to, a least one lead with one or more electrodes disposed on a distal portion of the lead and one or more terminals disposed on one or more proximal portions of the lead. Leads include, for example, percutaneous leads, paddle leads, cuff leads, or any other arrangement of electrodes on a lead. Examples of electrical stimulation systems with leads are found in, for example, U.S. Pat. Nos. 6,181,969; 6,516,227; 6,609,029; 6,609,032; 6,741,892; 7,244,150; 7,450,997; 7,672,734; 7,761,165; 7,783,359; 7,792,590; 7,809,446; 7,949,395; 7,974,706; 8,175,710; 8,224,450; 8,271,094; 8,295,944; 8,364,278; 8,391,985; and 8,688,235; and U.S. Patent Applications Publication Nos. 2007/0150036; 2009/0187222; 2009/0276021; 2010/0076535; 2010/0268298; 2011/0005069; 2011/0004267; 2011/0078900; 2011/0130817; 2011/0130818; 2011/0238129; 2011/0313500; 2012/0016378; 2012/0046710; 2012/0071949; 2012/0165911; 2012/0197375; 2012/0203316; 2012/0203320; 2012/0203321; 2012/0316615; 2013/0105071; and 2013/0197602, all of which are incorporated by reference. In the discussion below, a percutaneous lead will be exemplified, but it will be understood that the methods and systems described herein are also applicable to paddle leads and other leads.

A percutaneous lead for electrical stimulation (for example, deep brain, spinal cord, peripheral nerve, or cardiac-tissue) includes stimulation electrodes that can be ring electrodes, segmented electrodes that extend only partially around the circumference of the lead, or any other type of electrode, or any combination thereof. The segmented electrodes can be provided in sets of electrodes, with each set having electrodes circumferentially distributed about the lead at a particular longitudinal position. A set of segmented electrodes can include any suitable number of electrodes including, for example, two, three, four, or more electrodes. For illustrative purposes, the leads are described herein relative to use for deep brain stimulation, but it will be understood that such leads can be used for applications other than deep brain stimulation, including spinal cord stimulation, peripheral nerve stimulation, dorsal root ganglion stimulation, sacral nerve stimulation, or stimulation of other nerves, muscles, and tissues.

Turning toFIG. 1, one embodiment of an electrical stimulation system10includes one or more stimulation leads12and an implantable pulse generator (IPG)14. The system10can also include one or more of an external remote control (RC)16, a clinician's programmer (CP)18, an external trial stimulator (ETS)20, or an external charger22.

The IPG14is physically connected, optionally, via one or more lead extensions24, to the stimulation lead(s)12. Each lead carries multiple electrodes26arranged in an array. The IPG14includes pulse generation circuitry that delivers electrical stimulation energy in the form of, for example, a pulsed electrical waveform (i.e., a temporal series of electrical pulses) to the electrode array26in accordance with a set of stimulation parameters. The implantable pulse generator can be implanted into a patient's body, for example, below the patient's clavicle area or within the patient's abdominal cavity. The implantable pulse generator can have eight stimulation channels which may be independently programmable to control the magnitude of the current stimulus from each channel. In some embodiments, the implantable pulse generator can have more or fewer than eight stimulation channels (e.g., 4-, 6-, 16-, 32-, or more stimulation channels). The implantable pulse generator can have one, two, three, four, or more connector ports, for receiving the terminals of the leads and/or lead extensions.

The ETS20may also be physically connected, optionally via the percutaneous lead extensions28and external cable30, to the stimulation leads12. The ETS20, which may have similar pulse generation circuitry as the IPG14, also delivers electrical stimulation energy in the form of, for example, a pulsed electrical waveform to the electrode array26in accordance with a set of stimulation parameters. One difference between the ETS20and the IPG14is that the ETS20is often a non-implantable device that is used on a trial basis after the neurostimulation leads12have been implanted and prior to implantation of the IPG14, to test the responsiveness of the stimulation that is to be provided. Any functions described herein with respect to the IPG14can likewise be performed with respect to the ETS20.

The RC16may be used to telemetrically communicate with or control the IPG14or ETS20via a uni- or bi-directional wireless communications link32. Once the IPG14and neurostimulation leads12are implanted, the RC16may be used to telemetrically communicate with or control the IPG14via a uni- or bi-directional communications link34. Such communication or control allows the IPG14to be turned on or off and to be programmed with different stimulation parameter sets. The IPG14may also be operated to modify the programmed stimulation parameters to actively control the characteristics of the electrical stimulation energy output by the IPG14. The CP18allows a user, such as a clinician, the ability to program stimulation parameters for the IPG14and ETS20in the operating room and in follow-up sessions. Alternately, or additionally, stimulation parameters can be programed via wireless communications (e.g., Bluetooth) between the RC16(or external device such as a hand-held electronic device) and the IPG14.

The CP18may perform this function by indirectly communicating with the IPG14or ETS20, through the RC16, via a wireless communications link36. Alternatively, the CP18may directly communicate with the IPG14or ETS20via a wireless communications link (not shown). The stimulation parameters provided by the CP18are also used to program the RC16, so that the stimulation parameters can be subsequently modified by operation of the RC16in a stand-alone mode (i.e., without the assistance of the CP18).

For purposes of brevity, the details of the RC16, CP18, ETS20, and external charger22will not be further described herein. Details of exemplary embodiments of these devices are disclosed in U.S. Pat. No. 6,895,280, which is expressly incorporated herein by reference. Other examples of electrical stimulation systems can be found at U.S. Pat. Nos. 6,181,969; 6,516,227; 6,609,029; 6,609,032; 6,741,892; 7,949,395; 7,244,150; 7,672,734; and 7,761,165; 7,974,706; 8,175,710; 8,224,450; and 8,364,278; and U.S. Patent Application Publication No. 2007/0150036, as well as the other references cited above, all of which are incorporated by reference.

Turning toFIG. 2, one or more leads are configured for coupling with a control module. The term “control module” is used herein to describe a pulse generator (e.g., the IPG14or the ETS20ofFIG. 1). Stimulation signals generated by the control module are emitted by electrodes of the lead(s) to stimulate patient tissue. The electrodes of the lead(s) are electrically coupled to terminals of the lead(s) that, in turn, are electrically coupleable with the control module. In some embodiments, the lead(s) couple(s) directly with the control module. In other embodiments, one or more intermediary devices (e.g., a lead extension, an adaptor, a splitter, or the like) are disposed between the lead(s) and the control module.

Percutaneous leads are described herein for clarity of illustration. It will be understood that paddle leads and cuff leads can be used in lieu of, or in addition to, percutaneous leads. The leads described herein include 8 electrodes. It will be understood that the leads could include any suitable number of electrodes. The leads can include ring electrodes, a distal-tip electrode, and/or one or more segmented electrodes in lieu of, or in addition to, one or more ring electrodes. Additionally, the term “elongated member” used herein includes leads (e.g., percutaneous, paddle, cuff, or the like), as well as intermediary devices (e.g., lead extensions, adaptors, splitters, or the like).

FIG. 2illustrates one embodiment of a lead100with electrodes125disposed at least partially about a circumference of the lead100along a distal end portion of the lead and terminals135disposed along a proximal end portion of the lead100. The lead100can be implanted near or within the desired portion of the body to be stimulated such as, for example, the brain, spinal cord, or other body organs or tissues. In one example of operation for deep brain stimulation, access to the desired position in the brain can be accomplished by drilling a hole in the patient's skull or cranium with a cranial drill (commonly referred to as a burr), and coagulating and incising the dura mater, or brain covering. The lead100can be inserted into the cranium and brain tissue with the assistance of a stylet (not shown). The lead100can be guided to the target location within the brain using, for example, a stereotactic frame and a microdrive motor system. In some embodiments, the microdrive motor system can be fully or partially automatic. The microdrive motor system may be configured to perform one or more the following actions (alone or in combination): insert the lead100, advance the lead100, retract the lead100, or rotate the lead100.

The lead100for deep brain stimulation can include stimulation electrodes, recording electrodes, or both. In at least some embodiments, the lead100is rotatable so that the stimulation electrodes can be aligned with the target neurons after the neurons have been located using the recording electrodes.

Stimulation electrodes may be disposed on the circumference of the lead100to stimulate the target neurons. Stimulation electrodes may be ring-shaped so that current projects from each electrode equally in every direction from the position of the electrode along a length of the lead100. In the embodiment ofFIG. 2, two of the electrodes125are ring electrodes120. Ring electrodes120typically do not enable stimulus current to be directed from only a limited angular range around of the lead100. Segmented electrodes130, however, can be used to direct stimulus current to a selected angular range around the lead100. When segmented electrodes130are used in conjunction with an implantable pulse generator that delivers constant current stimulus, current steering can be achieved to more precisely deliver the stimulus to a position around an axis of the lead100(i.e., radial positioning around the axis of the lead100). To achieve current steering, segmented electrodes130can be utilized in addition to, or as an alternative to, ring electrodes120.

As described above, the lead100includes a lead body110, terminals135, and one or more ring electrodes120and one or more sets of segmented electrodes130(or any other combination of electrodes). The lead body110can be formed of a biocompatible, non-conducting material such as, for example, a polymeric material. Suitable polymeric materials include, but are not limited to, silicone, polyurethane, polyurea, polyurethane-urea, polyethylene, or the like. Once implanted in the body, the lead100may be in contact with body tissue for extended periods of time. In at least some embodiments, the lead100has a cross-sectional diameter of no more than 1.5 mm and may be in the range of 0.5 to 1.5 mm. In at least some embodiments, the lead100has a length of at least 10 cm and the length of the lead100may be in the range of 10 to 70 cm.

The electrodes125can be made using a metal, alloy, conductive oxide, or any other suitable conductive biocompatible material. Examples of suitable materials include, but are not limited to, platinum, platinum iridium alloy, iridium, titanium, tungsten, palladium, palladium rhodium, or the like. Preferably, the electrodes are made of a material that is biocompatible and does not substantially corrode under expected operating conditions in the operating environment for the expected duration of use.

Each of the electrodes can either be used (ON) or unused (OFF). When the electrode is used, the electrode can be used as an anode or cathode and carry anodic or cathodic current. In some instances, an electrode might be an anode for a period of time and a cathode for a period of time.

As described above, deep brain stimulation leads and other leads may include one or more sets of segmented electrodes. Segmented electrodes may provide for superior current steering than ring electrodes because target structures in deep brain stimulation are not typically symmetric about the axis of the distal electrode array. Instead, a target may be located on one side of a plane running through the axis of the lead. Through the use of a radially segmented electrode array (“RSEA”), current steering can be performed not only along a length of the lead but also around a circumference of the lead. This provides precise three-dimensional targeting and delivery of the current stimulus to neural target tissue, while potentially avoiding stimulation of other tissue. Examples of leads with segmented electrodes include U.S. Pat. Nos. 8,473,061; 8,571,665; and 8,792,993; U.S. Patent Application Publications Nos. 2010/0268298; 2011/0005069; 2011/0130803; 2011/0130816; 2011/0130817; 2011/0130818; 2011/0078900; 2011/0238129; 2012/0016378; 2012/0046710; 2012/0071949; 2012/0165911; 2012/197375; 2012/0203316; 2012/0203320; 2012/0203321; 2013/0197424; 2013/0197602; 2014/0039587; 2014/0353001; 2014/0358208; 2014/0358209; 2014/0358210; 2015/0045864; 2015/0066120; 2015/0018915; 2015/0051681; U.S. patent application Ser. Nos. 14/557,211 and 14/286,797; and U.S. Provisional Patent Application Ser. No. 62/113,291, all of which are incorporated herein by reference. Segmented electrodes can also be used for other stimulation techniques including, but not limited to, spinal cord stimulation, peripheral nerve stimulation, dorsal root ganglion stimulation, or stimulation of other nerves, muscles, and tissues.

FIG. 3is a schematic overview of one embodiment of components of an electrical stimulation system300including an electronic subassembly358disposed within a control module. The electronic subassembly358may include one or more components of the IPG. It will be understood that the electrical stimulation system can include more, fewer, or different components and can have a variety of different configurations including those configurations disclosed in the stimulator references cited herein.

Some of the components (for example, a power source312, one or more antennas318, a receiver302, and a processor304) of the electrical stimulation system can be positioned on one or more circuit boards or similar carriers within a sealed electronics housing of an implantable pulse generator (see e.g.,14inFIG. 1), if desired. Any power source312can be used including, for example, a battery such as a primary battery or a rechargeable battery. Examples of other power sources include super capacitors, nuclear or atomic batteries, mechanical resonators, infrared collectors, thermally-powered energy sources, flexural powered energy sources, bioenergy power sources, fuel cells, bioelectric cells, osmotic pressure pumps, and the like including the power sources described in U.S. Pat. No. 7,437,193, incorporated herein by reference.

As another alternative, power can be supplied by an external power source through inductive coupling via the optional antenna318or a secondary antenna. In at least some embodiments, the antenna318(or the secondary antenna) is implemented using the auxiliary electrically-conductive conductor. The external power source can be in a device that is mounted on the skin of the user or in a unit that is provided near the user on a permanent or periodic basis.

If the power source312is a rechargeable battery, the battery may be recharged using the optional antenna318, if desired. Power can be provided to the battery for recharging by inductively coupling the battery through the antenna to a recharging unit316external to the user. Examples of such arrangements can be found in the references identified above. The electronic subassembly358and, optionally, the power source312can be disposed within a control module (e.g., the IPG14or the ETS20ofFIG. 1).

In one embodiment, electrical stimulation signals are emitted by the electrodes (e.g., electrode array26inFIG. 1) to stimulate nerve fibers, muscle fibers, or other body tissues near the electrical stimulation system. The processor304is generally included to control the timing and electrical characteristics of the electrical stimulation system. For example, the processor304can, if desired, control one or more of the timing, frequency, strength, duration, and waveform of the pulses. In addition, the processor304can select which electrodes can be used to provide stimulation, if desired. In some embodiments, the processor304selects which electrode(s) are cathodes and which electrode(s) are anodes. In some embodiments, the processor304is used to identify which electrodes provide the most useful stimulation of the desired tissue.

Various processors can be used and may be an electronic device that, for example, produces pulses at a regular interval or the processor can be capable of receiving and interpreting instructions from an external programming unit308that, for example, allows modification of pulse characteristics. In the illustrated embodiment, the processor304is coupled to a receiver302which, in turn, is coupled to the optional antenna318. This allows the processor304to receive instructions from an external source to, for example, direct the pulse characteristics and the selection of electrodes, if desired.

In one embodiment, the antenna318is capable of receiving signals (e.g., RF signals) from an external telemetry unit306which is programmed by the programming unit308. The programming unit308can be external to, or part of, the telemetry unit306. The telemetry unit306can be a device that is worn on the skin of the user or can be carried by the user and can have a form similar to a pager, cellular phone, or remote control, if desired. As another alternative, the telemetry unit306may not be worn or carried by the user but may only be available at a home station or at a clinician's office. The programming unit308can be any unit that can provide information to the telemetry unit306for transmission to the electrical stimulation system300. The programming unit308can be part of the telemetry unit306or can provide signals or information to the telemetry unit306via a wireless or wired connection. One example of a suitable programming unit308is a computer operated by the user or clinician to send signals to the telemetry unit306.

The signals sent to the processor304via the antenna318and the receiver302can be used to modify or otherwise direct the operation of the electrical stimulation system. For example, the signals may be used to modify the pulses of the electrical stimulation system such as modifying one or more of pulse duration, pulse frequency, pulse waveform, and pulse strength. The signals may also direct the electrical stimulation system300to cease operation, to start operation, to start charging the battery, or to stop charging the battery. In other embodiments, the stimulation system does not include the antenna318or receiver302and the processor304operates as programmed.

Optionally, the electrical stimulation system300may include a transmitter (not shown) coupled to the processor304and the antenna318for transmitting signals back to the telemetry unit306or another unit capable of receiving the signals. For example, the electrical stimulation system300may transmit signals indicating whether the electrical stimulation system300is operating properly or not or indicating when the battery needs to be charged or the level of charge remaining in the battery. The processor304may also be capable of transmitting information about the pulse characteristics so that a user or clinician can determine or verify the characteristics.

In at least some instances of electrical stimulation of the brain, when a lead is implanted into the brain of a patient, the lead is inserted through a burr hole in the skull of the patient. The lead extends out of the burr hole and is coupled to a control module implanted elsewhere, for example, in the torso of the patient. A burr hole plug is provided in the burr hole to cover the opening through the skull, to protect the lead exiting the skull, and to firmly hold the lead in place to prevent or reduce lead migration within the brain.

At least some current burr hole plug placement methods provide little or no aid in controlling the placement, insertion, and fixation of mounting screws into the skull to hold the burr hole plug in place. The procedure of positioning and assuring secure fixation of the burr hole plug is often difficult due to the small size of the components, the hardness of the skull, and other factors. For example, it may be difficult to align the screws on the skull and insert the screws into the skull at the desired position for proper placement. Moreover, a screw head can be easily stripped, which may create sharp edges in the place of engagement with the screwdriver. This can may result in a future internal hemorrhage or skin erosion.

Accordingly, it is desirable to provide a methodology and tools for reliable placement, securement, and fixation of the burr hole plug to the patient's skull.FIGS. 4A and 4Billustrate one embodiment of a kit450or arrangement for placement, securement, and fixation of a burr hole plug to a patient's skull. The kit450includes a guide base452, a drill shank454, and one or more guide collets456. Other kits may include more or fewer components than kit450illustrated inFIGS. 4A and 4B. Optionally, the kit450may also include a base470(FIG. 6A) for the burr hole plug. In other embodiments, the base470may be obtained from a separate burr hole plug. In yet other embodiments, the kit450may also include the complete burr hole plug arrangement. Examples of burr hole plugs can be found at U.S. Pat. Nos. 7,479,146; 8,043,304; 8,137,362; 8,425,534; 8,731,686; 8,764,767; 8,812,133; 9,043,000; and 9,050,191; and U.S. Patent Application Publications Nos. 2012/0316628 and 2013/0066430, all of which are incorporated herein by reference. It will be understood that other burr hole plugs may also be used with kit450.

The kit450includes the guide base452and the drill shank454for pre-drilling pilot holes for the mounting fasteners of the burr hole plug. The one or more guide collets456, in cooperation with the guide base452, facilitate insertion and securement of the mounting fasteners to the skull.

FIGS. 5A, 5B, and 5Cillustrate three embodiments of the guide base452. The guide base452can be made of metal, rigid plastic, or any other suitable material, or any combination thereof. The guide base452includes an upper flange460, a lower flange462, and a connecting member464coupling the upper and lower flanges. Both the upper and lower flanges460,462define one or more guide holes466a,466bfor guiding the drill shank454and the guide collets456. In the illustrated embodiments, each of the upper and lower flanges460,462of the guide base452has two guide holes466a,466bbecause two fasteners are used to attach the burr hole plug to the skull. The guide holes466aof the upper flange460are aligned with the guide holes466bof the lower flange462. It will be understood that other guide bases may have a different number of guide holes including, but not limited to, one, three, or four guide holes. In at least some embodiments, each of the upper and lower flanges460,462of the guide base452has a number of guide holes466a,466bequal to a number of screws or other fasteners that will be used to secure the burr hole plug to the skull of the patient.

In at least some embodiments, the connecting member464is hollow to provide access or viewing through the burr hole. The guide base452also optionally defines a gap468extending into at least the lower flange462and may also extend into the upper flange460or the connecting member464(or any combination thereof) as shown in the illustrated embodiments. In at least some embodiments, the guide base452is used after implantation of the lead and the portion of the implanted lead which exits the burr hole can be inserted into or through, and remain positioned within, the gap468during use of the guide base452.

In at least some embodiments, the guide base452includes an alignment arrangement for aligning, and optionally attaching or fixing, the guide base to a base of a burr hole plug.FIG. 6Aillustrates one embodiment of a base470of a burr hole plug including one or more fastener receiving opening472, an optional alignment pin opening473, and a burr hole opening474. InFIG. 5A, the alignment arrangement on the guide base452takes the form of one or more sections476(for example, one or more curved walls) of a ring that extend from the lower flange462. The one or more sections476fit into the burr hole opening474of the base470of the burr hole plug to align the base470with the guide base452, as illustrated inFIG. 6B. In at least some embodiments, the sections476form a friction fit or a compression fit with the base to hold the base470on the guide base452. As also illustrated inFIG. 6B, the fastener receiving openings472of the base470of the burr hole plug are aligned with the one or more guide holes466bof the lower flange462of the guide base452.

InFIG. 5B, the alignment arrangement on the guide base452includes the one or more section476of a ring and an alignment pin469. The alignment pin469can be inserted into the alignment opening473(FIG. 6A) on the base470. It will be understood that in other embodiments the alignment pin469can be on the base470and the alignment opening473can be on the guide base452

InFIG. 5C, the alignment arrangement on the guide base452includes multiple pins478that can fit in corresponding holes, slots, or other elements of the base470of the burr hole plug. It will be understood that any other suitable alignment arrangement or combination of alignment arrangements can be used. For example, inFIG. 5C, the guide base452includes pins478and sections476of a ring that fit into the burr hole opening474of the base470of the burr hole plug. In addition, one of the pins478can serve the same function as the alignment pin469ofFIG. 5B.

FIG. 7Aillustrates one embodiment of a drill shank454that includes a cutting element480, a main shaft482, and a drill engagement region484. In at least some embodiments, the main shaft482has a sloping section481that leads to the cutting element480. The drill shank454is typically made of metal but may also include other hard substances to facilitate drilling into the skull of the patient.

The drill engagement region484is configured to fit and lock into a drill486, illustrated inFIG. 7B. The drill engagement region484can have any suitable arrangement and may be dependent on the drill486that is used. Any suitable drill486, including surgical drills, can be used. The drill486may be part of the kit450or may be separate from the kit.

The cutting element480of the drill shank454is sized in diameter to produce pilot holes for the screws (or other fasteners) of the burr hole plug. For example, the outer diameter of the cutting element480may be equal to or smaller than the outer diameter of the fasteners that will be used.

The main shaft482of the drill shank454has an outer diameter483that is smaller than the inner diameter of the guide hole466aof the upper flange460of the guide base452. The main shaft482of the drill shank454can be inserted through the guide hole466aof the upper flange460in order to drill a pilot hole in the skull of the patient. The upper flange460provides a guide for the drill shank454to reliably drill the pilot hole at the desired position on the skull.

The guide hole466bin the lower flange462of the guide base452also provides a guide for the drill shank454. In addition, in at least some embodiments, the guide hole466band lower flange462may act as a stop for the drill shank454to limit the depth of the pilot hole or to prevent or hinder drilling too deeply into the skull of the patient. In at least some embodiments, the guide hole466bof the lower flange462has an inner diameter that is less than the outer diameter483of the main shaft482of the drill shank454so that the main shaft482(or at least the non-sloping portion of the main shaft) is stopped at the lower flange462.

Alternatively, the surface of the guide hole466bmay be sloping so that the inner diameter of the guide hole466bdecreases toward the portion of the guide base452that is positioned closest to the patient's skull. Along that sloping surface of the guide hole466gthe inner diameter of the guide hole466bis smaller than the outer diameter483of the main shaft482(or at least the non-sloping portion of the main shaft) of the drill shank454. In this alternative embodiment, the main shaft482(or the non-sloping portion of the main shaft) is stopped at some position along the guide hole466bof the lower flange462of the guide base452.

FIG. 8illustrates one embodiment of a guide collet456which includes a collet flange488, a hollow collet shaft490, a fastener tube492, and, optionally, a fastener494, such as a screw. In some embodiments, the fastener494is included with the guide collet456and, in other embodiments, the fastener is included with the burr hole plug and inserted into the guide collet456prior to use. There is an opening496through the bottom of the collet shaft490into the fastener tube492and a corresponding opening491(FIG. 4B) in the collet flange488. The collet flange488and collet shaft490can be made of metal or rigid plastic. The fastener tube492can be made of flexible or rigid plastic or metal.

The collet flange488has an outer diameter that is greater than the outer diameter of the guide hole466aof the upper flange460. The collet shaft490has an outer diameter that is less than the outer diameter of the guide hole466aof the upper flange460. When the collet shaft490of the guide collet456is inserted into the guide hole466a, the collet flange488rests on the upper flange460. In some embodiments, the guide hole466aof the upper flange460may be countersunk to enable the collet flange488to fit fully or partially within an upper portion of the guide hole466a.

Preferably, the length of the collet shaft490and fastener tube492are selected so that the distal portion of the fastener tube492is disposed within the guide hole466bof the lower flange462when the guide collet456is inserted into the guide base452. The fastener tube492and openings in the collet flange488and collet shaft490are selected so that a tool such as a screwdriver (preferably, a torque limiting screwdriver) or other appropriate tool can be inserted through the collet flange, collet shaft, and fastener tube and engage the fastener to drive the fastener into the skull and secure the base470of the burr hole plug.

FIGS. 9A-9Cillustrate the use of the components of the kit. InFIG. 9A, the guide base452and the base470(FIG. 9C) of the burr hole plug are placed over the burr hole formed in the skull498of a patient. The drill shank454is attached to a drill (not shown) and then sequentially inserted into each of the guide holes466aof the guide base452to drill a pilot hole in the skull. InFIG. 9B, the guide collets456, with associated fasteners494(FIG. 9C), are inserted into the guide holes466aof the guide base452and the fasteners are then driven into the skull using the drilled pilot holes. InFIG. 9C, the guide base452is removed leaving the base470of the burr hole plug attached to the skull498with the fasteners494.