Various aspects of the instant disclosure relate to electrodes and electrode delivery tools. In some specific examples, the disclosure concerns intracranial electrodes and delivery systems.
Epilepsy affects large patient populations. One third of epilepsy patients continue to have seizures despite medications. Surgery is the most effective treatment for medically resistant focal epilepsy, and can be a cure if the region generating seizures can be resected. Epilepsy surgery, however, is vastly under-utilized because localizing the focal brain region generating seizures is highly invasive, and associated with significant risk, patient discomfort, and expense. Currently, patients undergo electrode implantation for chronic intracranial EEG (iEEG) monitoring that extends over multiple days in order to capture and pinpoint the origin of seizures.
Epilepsy surgery can deliver a cure if the brain region generating seizures can be localized and removed. Surgical treatment for epilepsy is based on the concept that seizures begin in a focal region, the seizure onset zone (SOZ), and then propagate to susceptible tissue. For seizure freedom the SOZ and surrounding epileptogenic zone (EZ) must be removed. In current practice, early seizure propagation and active inter-ictal spiking determine the EZ. In addition, if the SOZ is accurately localized, electrodes can be implanted permanently for therapeutic electrical brain stimulation.
Intracranial EEG (iEEG) is the gold standard for localizing the SOZ and EZ. Patients have electrodes implanted via a large craniotomy. The evaluation requires multiple days of iEEG to capture spontaneous seizures, and define the SOZ and surrounding EZ. The long duration of iEEG monitoring is driven by the need to record seizures (unpredictable events requiring days to capture). Patients are hospitalized in the Neuro ICU at considerable cost. They experience significant discomfort and risk of morbidities.
There remains a continuing need for improved electrodes, including but not limited to intracranial EEG electrodes, delivery tools and associated methods. In particular, there is a need for such electrodes, tools and methods that can improve outcomes. Technologies of these types that can efficiently decrease invasiveness and morbidity would be especially desirable.
In various embodiments, a cortical access system for delivery of one or more electrodes into an epidural and/or subdural space and onto a patient's brain tissue through a cranium opening comprises: a turret including a proximal end portion, a distal end portion, and a first channel extending from an entrance opening to an exit opening, the first channel configured to guide the one or more electrodes from the entrance opening to the exit opening for positioning on the patient's brain tissue.
In some examples, the distal end portion includes a periphery; and the exit opening of the first channel is on the periphery of the distal end portion, and the channel is configured to guide the one or more electrodes onto the patient's brain tissue below the cranium.
In some examples, the turret further comprises a second channel configured for the one or more electrodes to be released from the turret.
In some examples, the second channel is narrower than the first channel such that only a portion of each of the one or more electrodes is releasable via the second channel.
In some examples, the first channel is curved or sloped to form a ramp for guiding the one or more electrodes out of the exit opening generally horizontally between the patient's brain tissue and cranium.
In some examples, the turret comprises a turret frame and a turret insert removably mated to the turret frame, and wherein the turret insert defines the first channel.
In some examples, the cortical access system further comprises a mounting plate configured to be secured to the patient's cranium at the cranial opening via securing elements and to rotatably receive the turret.
In some examples, the cortical access system further comprises a retaining ring configured to be coupled to the mounting plate such that the turret is rotatable while translational motion of the turret is limited.
In some examples, the turret is adjustable for different skull thicknesses.
In some examples, the turret further comprises an endoscope channel configured to receive an endoscope for imaging of an electrode being delivered by the system.
In some examples, the turret further comprises a force sensor configured to monitor a force exerted onto the patient's brain tissue.
In some embodiments, an electrode comprises: a head having a proximal end portion and a distal end portion wider than the proximal end portion; a tail extending from the proximal end portion of the head; and one or more electrode contacts disposed on the head; wherein the electrode is flexible and configured to be inserted through a cortical access system to access a patient's brain tissue.
In some examples, the electrode further comprises a bumper at the distal end portion of the head.
In some examples, the bumper is radiopaque.
In some examples, the bumper is configured to releasably receive a guiding tool.
In some examples, manipulation of the guiding tool causes movement of the electrode.
In some examples, the tail is configured to be releasably coupled to the guiding tool via a clamp.
In some examples, the electrode further comprises a tab at a proximal end of the tail.
In some examples, the electrode comprises a biocompatible dielectric substrate, a conductive layer coupled to the substrate, and a biocompatible dielectric top layer coupled to the conductive layer.
In some examples, the biocompatible dielectric substrate and/or the biocompatible dielectric top layer comprises at least one of polyimide, Parylene-C, and silicone.
In some examples, the conductive layer comprises at least one of platinum, titanium-platinum, gold, copper, and tin.
In some examples, the head is configured to be movable through a first channel of the cortical access system and not movable through a second channel of the cortical access system.
In some examples, the tail is configured to be movable through the second channel of the cortical access system.
In some examples, the tail is configured to be manipulated such that the electrode is releasable from a turret of the cortical access system to allow another electrode to be inserted through the cortical access system.
In some examples, the body is generally wedge-shaped such that a plurality of the electrodes is circumferentially distributable on the patient's brain tissue.
In some examples, the electrode further comprises one or more fluid chambers disposed at least at the head.
In some examples, each fluid chamber is fluidically connected to a fill tube at a proximal end of the electrode.
In some examples, the fill tube is configured to transport fluid in and out of each fluid chamber to change fluid quantities in the fluid chamber.
In some examples, the one or more fluid chambers are configured to transition the electrode between an initial state and a positive state in response to a change in fluid quantity in the one or more fluid chambers.
In some examples, the electrode has a variable stiffness corresponding to a fluid quantity in the one or more fluid chambers.
In some examples, the electrode is configured to move in response to a sequential change in fluid quantities in the one or more chambers.
In some examples, the electrode is configured to transition between a delivery state at which the electrode has a first width, and a deployed state at which the electrode has a second width greater than the first width, in response to change in fluid quantities in the one or more chambers.
In some embodiments, a method for deploying one or more electrodes of an intracranial apparatus including a cortical access system having a turret with a first channel includes: deploying the cortical access system at a patient's cranial opening; inserting an electrode through the patient's cranial opening via the first channel to access the patient's brain tissue; and releasing the electrode from the turret such that the turret is rotatable independently of the released electrode.
In some examples, the cortical access system further includes a mounting plate and a retaining ring, wherein deploying the cortical access system comprises: coupling the mounting plate to a patient's cranium at the cranial opening via securing elements; coupling the turret to the mounting plate; and coupling the retaining ring to the mounting plate such that the turret is rotatable.
In some examples, the turret includes a turret frame and a turret insert, and wherein coupling the turret to the mounting plate includes: coupling the turret frame to the mounting plate; and coupling the turret insert to the turret frame.
In some examples, inserting the electrode comprises guiding the electrode's head out of the first channel to a location between the patient's cranium and brain tissue.
In some examples, guiding the electrode's head comprises: coupling a guiding tool to the electrode head; and manipulating the guiding tool to guide the electrode.
In some examples, coupling the guiding tool comprising coupling the guiding tool to a bumper on the electrode's head.
In some examples, guiding the electrode's head further comprises verifying the placement of the electrode via visualizing the location of the bumper.
In some examples, guiding the electrode's head further comprising coupling the electrode and the guiding tool via a clip.
In some examples, inserting the electrode comprises advancing the electrode such that the clip comes into contact with the turret.
In some examples, releasing the electrode comprises removing the clip such that the electrode's tail is manipulatable independently from the guiding tool.
In some examples, releasing the electrode comprises removing the guiding tool from the electrode.
In some examples, the electrode is configured to be released such that the turret is rotatable independently from the electrode.
In some examples, the method for deploying one or more electrodes of an intracranial apparatus further comprises: rotating the turret such that another of the one or more electrodes can be inserted; and inserting another of the one or more electrodes.
In some examples, the method for deploying one or more electrodes of an intracranial apparatus further comprises: repeating rotating the turret and inserting another of the one or more electrodes such that the one or more electrodes are deployed circumferentially.
In some examples, the one or more electrodes are deployed circumferentially to cover a substantial area within a circle.
In some examples, the method for deploying one or more electrodes of an intracranial apparatus further comprises: inserting an endoscope through the patient's cranial opening via the cortical access system and using the endoscope to visualize the electrode.
In some examples, releasing the electrode from the turret comprises releasing the electrode through a second channel in the turret that is connected to the first channel.
In some embodiments, a cortical access system for delivering a medical tool into an epidural and/or subdural space and onto a patient's brain tissue through a cranium opening comprises: a turret including a proximal end portion, a distal end portion, and a first channel extending from an entrance opening to an exit opening, the first channel configured to guide the medical tool from the entrance opening to the exit opening for positioning on the patient's brain tissue.
In some examples, the distal end portion includes a periphery; and the exit opening of the first channel is on the periphery of the distal end portion, and the channel is configured to guide the medical tool onto the patient's brain tissue below the cranium.
In some examples, the first channel is curved or sloped to form a ramp for guiding the medical tool out of the exit opening generally horizontally between the patient's brain tissue and cranium.
In some examples, the turret comprises a turret frame and a turret guide removably mated to the turret frame, and wherein the turret guide defines the first channel.
In some examples, the cortical access system further comprises a turret base configured to be secured to the patient's cranium at the cranial opening via a securing means and to rotatably receive the turret.
In some examples, the cortical access system further comprises a turret lock configured to be coupled to the turret base such that the turret is rotatable while translational motion of the turret is limited.
In some examples, the cortical access system further comprises a guide clamp configured to be coupled to the turret to help secure the medical tool received in the first channel.
In some examples, the cortical access system further comprises a clamp lock configured to secure the guide clamp to the turret guide.
In some examples, the medical tool is an electrode or an endoscope.
While the disclosure is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The disclosure, however, is not limited to the particular embodiments described. On the contrary, the disclosure is intended to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure as defined by the appended claims.
As shown, the turret insert 40 has a proximal end 72 or an upper portion having a periphery, a distal end 76 or a lower portion including a periphery, and a first surface 80 (e.g., a curved surface) configured to be coupled or mated with the turret frame 36. The turret insert 40 may further include a second surface 84 (e.g., an oblique surface) configured to be coupled or mated with the turret frame 36. One or both of the surfaces 80, 84 may help position the turret insert 40 in the turret frame 36 in a target orientation (e.g., an orientation where an electrode 28 (see
The turret insert 40 further has or defines a delivery or first channel 88 extending from an entrance opening 92 at the proximal end 72 to a side exit or exit opening 96 near the distal end 76 (e.g., on the periphery of the lower portion). The exit opening 96 may be at least partially directed horizontally (e.g., parallelly to the base 128 of the turret frame 36). The first channel 88 may be configured to guide or direct an electrode 28 (see
As shown, the turret frame 36 has a proximal end 108 or an upper portion having a periphery, a distal end 112 or a lower portion having a periphery, and a retaining structure 116 (e.g., a rim, a ring, and/or a groove) configured to be coupled to, such as rotatably coupled to the mounting plate 32 and/or retaining ring 44. The turret frame 36 further has an insert opening 118 configured to receive the turret insert 40 and a first surface 120 (e.g., a curved surface) configured to be coupled to the turret insert 40 (e.g., to the first surface 80). The turret frame 36 may further have a second surface 124 (e.g., an oblique surface) configured to be coupled with the turret insert 40 (e.g., to the second surface 84). One or both of the surfaces 120, 124 may help position the turret insert 40 in the turret frame 36 in a target orientation (e.g., an orientation where an electrode 28 (see
The turret frame 36 further defines or has a first side opening 132 configured to be aligned to or adjacent the exit opening 96 of the turret insert 40 such that an electrode 28 (see
The turret frame 36 may further include a tool channel (e.g., an endoscope channel 140) connecting a tool entrance opening (e.g., an endoscope entrance opening 144) and a tool exit opening (e.g., an endoscope exit opening 148). The tool channel or endoscope channel 140 may be curved or slanted (see
As shown, the mounting plate 32 may have or define one or more securement openings 156 configured to receive the securing elements 48 (e.g., screws or pins) to secure the mounting plate to the patient's skull. The mounting plate 32 further includes an opening 160 (e.g., a central opening) configured to receive, such as rotatably receive the turret frame 36 and/or the turret insert 40. For example, the mounting plate 32 may include one or more retaining structures 164 (e.g., stepped supports) configured to be coupled, such as rotatably coupled with the retaining structure 116 of the turret frame 36. The mounting plate 32 may further include one or more coupling members 168 (e.g., clips, magnets, snap-fit connectors, and/or tight-fit connectors) configured to cooperate with the coupling members 60 of the retaining ring 44 to limit translational motion but allow rotational motion of the turret frame 36 and/or turret insert 40 relative to the mounting plate.
As shown, when the cortical access system 24 is deployed, the proximal end 52 may be extracranial and the distal end may be intracranial such that a user may manipulate tools and/or components in a patient's skull (e.g., electrodes 28 of
The delivery tool attachment structure may include a distal attachment structure on the distal end portion of the body portion. The delivery tool distal attachment structure may include a radiused member (e.g., a tubular bumper 192 having a channel 200) configured for the delivery tool (e.g., the guide wire) to extend through. The bumper 192 may provide rigidity along the distal (i.e., leading) edge and side edges of an electrode (e.g., electrode 28) such that force exerted (e.g., by a user) to the delivery tool may allow force to be transferred to the distal edge while inhibiting folding, creasing, and/or damaging of the electrode. The delivery tool attachment structure may include a side attachment structure on one or both of the first or second side portions of the body portion. The delivery tool side attachment structure may include a tubular member. The delivery tool may be configured for attachment to the delivery tool side attachment structure and include a wire configured to extend through the tubular member of the side attachment structure. An electrode (e.g., electrode 28) may generally be deployed by applying a force to its distal end such that the electrode is not urged to buckle.
The electrode 28 may further include a tab 204 at the proximal end 172 and configured to be manipulated by a user, for example, for bending the tail portion 184 of the electrode (see
The electrode 28 may be a flexible thin film laminate including a biocompatible dielectric substrate (e.g., polyimide, Parylene-C, and/or silicone), a conductive layer coupled to the substrate and forming electrical connections between the one or more electrode contacts 188, and a dielectric top layer having openings at the contacts and the connection pad. The conductive layer may include conductive material such as platinum, titanium-platinum, gold, copper, and/or tin. The dielectric top layer also includes biocompatible material such as polyimide, Parylene-C, and/or silicone. Additionally or alternatively, the electrode contacts 188 may be formed via electroplating, physical vapor deposition, chemical vapor deposition, photolithography, soft lithography, and/or ink-based printing. The electrode 28 may be 5-100 microns thick.
As shown, the one or more electrodes 212 may be deployed to be substantially near each other, such as having a gap of less than 10 mm, such as less than 5 mm, such as less than 1 mm. The body portion or the head portion (e.g., head portion 180) of each of the one or more electrodes 212 (e.g., electrode 28) may be generally wedge-shaped such that the one or more electrodes 212 may be circumferentially distributed to cover a substantial area within a circle, such as more than 75%, such as more than 85%, such as more than 95% of the area within the circle. The circle may be generally outlined by the distal ends (e.g., distal end 56) and/or the distal bumpers (e.g., bumper 192). Each of the one or more electrodes 212 may be generally wedge-shaped to cover an angle, such as an angle being a fraction of a full circle (i.e. 360°). For example, each of the wedge-shaped electrodes 212 may cover 180° (i.e., with 2 electrodes), 90° (i.e., with 4 electrodes), 60° (i.e., with 6 electrodes), 30° (i.e., with 12 electrodes), 15° (i.e. with 24 electrodes), 10° (i.e. with 36 electrodes), 5° (i.e., with 72 electrodes), or 1° (i.e., with 360 electrodes).
In various examples, the cortical access system 424 is configured to guide a medical tool (e.g., the electrode 28 or the endoscope 152) into a patient's skull (e.g., through the cranial opening 806, for example, as shown in
In some embodiments, the turret base 432 is configured to be mounted to the patient's skull, such as to be secured to the patient's skull via securing elements 448 (e.g., screws, bolts, clips, and/or O-rings). In various examples, the turret base 432 is configured to receive and/or secure the turret 434, such as to receive and/or secure the turret frame 436. For example, the turret base 432 is configured to receive and secure the turret frame 436 such that the turret 434 can or is able to limit translational motion but allow rotational motion of the turret frame 436 with respect to the turret base 432.
In certain embodiments, the turret frame 436 is configured to receive and/or secure the turret guide 440. For example, the turret frame 436 defines a guide receptacle 518 configured to receive the turret guide 440. In various examples, the turret frame 436 and the turret guide 440, when coupled and/or secured (e.g., via a guide clamp 624 and/or a clamp lock 628), are configured to rotate together.
In various examples, the turret guide 440 defines a guide channel or guide ramp 488 extending from a guide entrance opening 492 to a guide exit opening 496. In certain embodiments, the guide ramp 488 is configured to guide or direct a medical tool (e.g., the electrode 28 or the endoscope 152) or any other tools (e.g., a stereotactic pointer, a suction device, or a biopsy device) or components from outside of the skull to a subdural space inside of the skull (e.g., by entering from the guide entrance opening 492 and extending out from the guide exit opening 496). In some examples, the guide ramp 488 is curved or slanted, such as extending from a top to a side of the cortical access system 424.
In various embodiments, the turret lock 444 is configured to be coupled to the turret base 432 to limit translational motion but allow rotational motion of the turret frame 436 and/or the turret guide 440 (e.g., when coupled to the turret frame 436) with respect to the turret base 432. In certain examples, the turret lock 444 is a cam lock configured to rotate between an open position and a secure position. In various examples, the turret lock 444 is configured to be actuated to a position that prevents rotation of the turret frame 436 with respect to the turret base 432.
In some examples, the guide clamp 624 is configured to be coupled to the turret guide 440 to help secure the turret guide 440 to the turret frame 436, such as via the clamp lock 628. In various examples, the guide clamp 624 is configured to help secure the medical tool (e.g., the electrode 28 or the endoscope 152) to the turret guide 440, such as to the guide ramp 488 of the turret guide 440. In some examples, the clamp lock 628 is configured similarly as the turret lock 444, such as a cam lock configured to rotate between an open position and a secure position.
The use example demonstrates the use of a minimally invasive endoscopic assisted device (e.g., intracranial apparatus 20, cortical access system 24, and/or cortical access system 424) for subdural electrode implantation in Epilepsy. The use example is pertinent to subdural grids and strip electrodes which provide wide coverage of the cerebral cortex, precise delineation of the extent of the seizure onset zone, and improved spatial sampling to perform functional mapping for eloquent cortex. The use example describes a novel device which allows for a minimally invasive approach to implantation of subdural grid and strip electrodes.
In the use case, a skull mounted device is configured to allow for implantation of subdural electrodes through a keyhole craniotomy with direct visualization using the aid of a flexible neurovideoscope. The initial studies in preparation for grid development performed on cadaveric skulls were analyzed to determine the size of craniotomy required for deployment, maximal distance of strip electrode deployment from center of craniotomy, and visual inspection of the cortex was performed for any underlying damage.
The device allowed for the placement of subdural electrodes through a 40 mm craniotomy. Subdural electrodes were deployed in multiple directions to a distance of a 70 mm radius from the center of the craniotomy. There was no visual damage to the underlying cortex after the procedures were completed.
Large craniotomies are typically desired to provide direct visualization of the implantation of subdural electrodes, but can increase the risk of subdural hemorrhages and infections. This use case describes a novel minimally invasive endoscopically assisted device for the implantation of subdural strip electrodes under direct visualization. The use case shows this device is capable for limiting the size of the craniotomy, avoiding incision through the temporalis muscle, and implanting subdural electrodes with visualization of the cortex.
The device combines the benefits of open surgery with those of an endoscopic approach for grid placement. In response, an electrode surgical delivery device was devised capable of enabling endoscopic operative imaging and improved electrode delivery. The device provides the ability to insert an endoscope into the subdural space to visualize navigation along the surface of the cerebral cortex. In addition, similar size electrode arrays as used for open surgery can be delivered through the device. With this platform, the device can be configured for deployable cortical coverage. The application of this device greatly reduced craniotomy size compared to the traditional approach and has the potential to access the majority of the cortical convexity. Given the limitations of current surgical procedure, embodiments of the invention provide a novel minimally invasive endoscopic assisted device for the placement of subdural electrodes in subdural grid electroencephalography (sdEEG).
The device includes a mounting plate, a turret, an electrode holder, and a retaining ring. The mounting plate is used to affix the delivery device to the skull. The turret is used to retain the endoscope and the electrode array. The retaining ring is used to hold the turret in place with the appropriate force and provide the ability to rotate the delivery device within the mounting plate to change imaging and electrode delivery direction.
This device was tested on three cadaveric heads, bilaterally, for a total of six trials of the device. After fixation in a head-holder, a linear incision was made, being careful to avoid the termporalis muscle. The dura was then opened in a cruciate manner and tacked back with sutures. Following this, the cranial plate was mounted and the turret was locked in place with the locking ring. Once this was completed, a Storz flexible videoneuroscope was introduced through the scope channel and the subdural space was navigated. Following this a standard four contact sdEEG strip electrode was deployed using the working channel of the turret. The turret was then removed and the underlying cortex was visually examined. Measured variables included the size of craniotomy required for deployment, maximal distance of electrode deployment from center of craniotomy, and the quality of the underlying cortex once the electrode deployment had been completed.
In embodiments, the device comprises a turret with a separate channel for a flexible endoscope, a locking ring, and a cranial mounting plate. The overall width of the device when mounted to the skull is 61 mm. The opening in the mounting plate for the turret is 45 mm. When the turret is depressed into the mounting plate the plunge depth is 22.23 mm below the outer cortex of the skull. The average bone thickness in the frontal area ranges from 6-8 mm; the device extends 1.4-1.6 cm below the inner table however this can be adjusted. The diameter of the turret itself is 38 mm, which requires a 40 mm craniotomy for adequate placement. A standard 4-contact (1 cm spacing) sdEEG strip electrode can be deployed to approximately 8 cm from the turret to the distal contact with endoscopic visualization. With the turret removed, the cortex was visually inspected for any injury from the device, and no obvious injury was noted. The device did not leave an impression on the cortex.
In this use study, the device is configured to allow hybrid electrophysiologic recordings with both sdEEG and stereoencephalography (sEEG). After implantation of sEEG depth electrodes, a linear incision would be created in an area devoid of sEEG electrodes. A small craniotomy would then be fashioned, and subdural strip electrodes would be placed on cortical areas of interest under direct visualization. One significant benefit of this approach would be the direct visualization of bridging veins and the potential ability to either avoid them or control them using instruments through the endoscope. Additionally, as the turret can rotate 360 degrees, the device can be used with a circular subdural strip electrode array that covers a wide area of cortex, as we can place electrodes approximately 7 cm from the device.
This use case describes a concept study describing a novel minimally invasive surgical approach introducing an endoscopically assisted device for the implantation of subdural strip electrodes under direct visualization. Embodiments involve creating the device using biocompatible materials that would allow for sterilization and reprocessing, and using this device in a population of patients undergoing intracranial electroencephalography (iEEG) for epilepsy.
Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present disclosure. For example, while the embodiments described above refer to particular features, the scope of this disclosure also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present disclosure is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof.
This application claims the benefit of U.S. Provisional Application 62/664,978, filed May 1, 2018, which is incorporated herein by reference in its entirety for all purposes.
Filing Document | Filing Date | Country | Kind |
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PCT/US2019/030224 | 5/1/2019 | WO | 00 |
Number | Date | Country | |
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62664978 | May 2018 | US |