Patent Description:
During cranioplasty procedures, diseased or damaged portions of the skull (craniectomy defects) are safely removed and replaced, while the brain is exposed underneath without injury. However, a similar operation could also be done in areas of normal, healthy cranial bone - in instances where a neuromodulation device is needed for implantation but the contour and appearance is challenging (and normal skull bone is removed and left off permanently in exchange for a cranial implant), such as in non-bearing scalp areas such as frontal or temporal regions. Following resection of diseased cranial bone (or normal bone in cosmetically-sensitive areas), such craniectomy defects are often reconstructed with custom craniofacial implants (CCIs) - as opposed to using generic, "off-the-shelf" materials.

Historically, however, cranioplasty patients requesting custom craniofacial implant-based reconstruction for an ideal appearance have been limited to "second-stage" operations in instances of pre-existing skull defects so that the exact fit and design could be obtained. However, recent modifications to the approach have allowed a few isolated surgical teams to perform "single-stage cranioplasties" - by which a clinician, such as a surgeon, manually reshapes/resizes a previously-ordered, custom implant (with oversized dimensions) to fit perfectly into the skull defect - as opposed to using "off-the shelf" materials. Either way, for single-stage methods involving skull tumors or second-stage cranioplasties for pre-defined skull defects, the advent of computer-aided design/manufacturing (CAD/CAM), has provided surgeons with perfectly-shaped custom craniofacial implants designed and manufactured based in part on fine cut preoperative computed tomography (CT) scans and three-dimensional reconstruction (with or without stereolithographic models).

In fact, recent reports suggest that the use of custom craniofacial implants can improve cosmesis, decrease operative times, prevent scalp-related wound complications, and enhance patient satisfaction - and therefore, they serve as an ideal medium for reconstructing neurosurgery patients. Similarly, all custom craniofacial implants up until now have been used to replace abnormal bone having some form of disease, either of benign or malignant etiology. These customized skull implants may be termed "static custom craniofacial implants" - mainly because their main constant (i.e., unchanged purpose with respect to time) purpose encompasses strictly two benefits following placement - "brain protection" and "enhanced appearance".

Meanwhile, there are other "off-the-shelf" neurological implants that have functionality, such as delivering electrical impulses to interrupt seizure activity, but aren't customizable or designed to protect the brain. Most of these so-called functional neurological implants fall into two categories: Deep Brain Stimulators (DBS) and Cortical Brain Stimulators (CBS). Modern day neurologic devices are confronted and challenged with high extrusion and infection risk (i.e., current flaws in modern day devices lead to high incidence of extrusion through skin thereby requiring premature explantation) approaching <NUM>%. Similarly, battery-powered, low-profile devices for intercranial placement currently do not exist on the market. As such, the field of neurosurgery has been hampered and limited in many areas including examples like battery-powered neuromodulation cortical stimulation and delivery of neurological medicines.

But with increasing experience and surgical complication rates exceedingly low, the custom craniofacial implants can also be modified in real-time for scenarios where more or less skull bone is removed and the skull defect dimensions do NOT match up perfectly to the pre-fabricated custom craniofacial implant (versus as originally envisioned, for example, as designed in a planning stage). Or in a scenario where normal bone is to be removed simply to assure proper contour with neuromodulation implantation, one could use a pre-fabricated cutting guide for custom cranial implant placement.

Due to the recent reductions for time needed to design, fabricate and implant custom craniofacial implants, more cranioplasty procedures with alloplastic implants are being performed around the world than ever before. Accordingly, these recent developments in custom craniofacial implant sterility, shape design, and streamline production - together provide an opportunity that extends custom craniofacial implant-based cranioplasty beyond only patients who require replacement of pre-existing craniectomy defects.

<CIT> can be considered as the closest prior art and describes an implantable device including an electronic circuit to be implanted in the head. A casing of an implantable device configured to be implanted in a human head has an outer convexity surface matching an external shape of a resected skull related to at least a craniotomy site of the artificial bone designed in accordance with a skull shape of each person in order to fill the craniotomy site. The electronic circuit and the casing are assembled by means of e.g. screws or plates but do not interdigitate.

<CIT> describes intracranial ferrules, systems, and methods for sensing and stimulating neural tissues. The ferrules are generally designed to include a holding area for retaining an implantable device. In some variations, the ferrule itself may perform the sensing and stimulating functions. In other variations, the ferrule may function to sense data from neural tissues and the implantable device may function to stimulate neural tissues. In yet other variations, the ferrule may function to stimulate, and the implantable device may function to sense data from, the neural tissues. The sensing and stimulating functions may be used to detect and/or treat various neurological conditions.

<CIT> describes a custom implantable medical device (IMD) formed based on an image of a structure of a patient, such as the head of the patient.

<CIT> describes a ferrule for removably retaining a self-contained implantable device within a cranial opening of a patient.

<CIT> describes a totally implantable cochlear implant system forming a single implantable unit.

<CIT> describes a medical implant which is suitable for implantation in an artificial bone bed surgically made on the outer surface of the mastoid region of the skull, having a hermetically sealed housing in which electronic components and other components or modules are accommodated.

<CIT> describes medical electrical lead systems and related methods.

Embodiments not falling with the scope of the claims are exemplary only. The present invention advances the possibilities associated with custom craniofacial implants by providing pre-fabricated, customized, patient-specific implantable devices with low-profiles (i.e., to avoid unnecessary contour irregularities, scalp-related complications, and high extrusion risk leading to premature explantation). The present invention also provides methods of making and implanting such implant devices, including methods using computer-assisted surgical procedures, such as computer-assisted cranioplasty (see <CIT>, based upon <CIT>, entitled "COMPUTER ASSISTED CRANIOPLASTY") and/or robot-assisted implant modification (see <CIT>, based upon <CIT>, entitled "A CUTTING MACHINE FOR RESIZING RAW IMPLANTS DURING SURGERY").

Still further, the present invention optimizes the relationship between custom craniofacial implants and functional neurological implants in synergy - making it possible to integrate these "normally asymmetric" components within a low-profile intercranial device for provision of enhanced treatment to patients. Such improvements exploit the benefits of direct access to the brain and ideal anatomical location/proximity provided by these novel custom craniofacial implants placed directly on top and just a few millimeters away from the brain to deliver life-changing interventions providing an unprecedented method to deliver locally, for example, Neurologic Deep Brain stimulations, or neurologic medicines, that are otherwise prevented from diffusing through the blood-brain barrier via common delivery methods (i.e., oral, intravenous) and battery-powered functions via various encased components including neuromodulation devices, imaging devices, radiation therapy devices, and remote sensing/ monitoring devices.

It is, therefore, an object of the present invention to provide a low-profile intercranial device including a low-profile static cranial implant and a functional neurosurgical implant, wherein the low-profile static cranial implant and the functional neurosurgical implant are designed and interdigitated prior to physical assembly of the low-profile intercranial device.

It is also an object of the present invention to provide a method for manufacturing a low-profile intercranial device including virtual design and interdigitating of distinct cranial implants prior to physical manufacture of the low-profile intercranial device. The method includes creating a static cranial implant, creating a functional neurosurgical implant shaped and dimensioned to interdigitate with the static cranial implant, and integrating the functional neurosurgical implant with the static cranial implant. For illustrative purposes only and not forming part of the present invention, it is further disclosed a method for the implantation of a low-profile intercranial device including a static cranial implant and a functional neurosurgical implant positioned within a cavity of the static cranial implant. The method includes diagnosing a need for implantation of the low profile intercranial device as a replacement for a specific portion of a cranium of a patient, creating the static cranial implant, creating the functional neurosurgical implant, integrating the functional neurosurgical implant with the static cranial implant, and implanting the low-profile intercranial device within the intercranial space.

Other objects and advantages of the present invention will become apparent from the following detailed description when viewed in conjunction with the accompanying drawings, which set forth certain embodiments of the invention.

The detailed embodiments of the present invention are disclosed herein. It should be understood, however, that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, the details disclosed herein are not to be interpreted as limiting, but merely as a basis for teaching one skilled in the art how to make and/or use the invention. For example, while the disclosure is preferably directed to a low-profile intercranial device that includes a customized cranial implant, it is within the scope of the disclosure that the cranial implant could be fabricated and provided as a standardized shape or size implant configured to receive a standard size and shape functional implant, rather than a patient-specific customized implant designed to conform to the skull opening. This is especially the case where skull resection is not determined, for example, by the shape of a resected tumor and may be created in a standardized manner specifically to accommodate the low-profile intercranial device of the present disclosure.

As used within this disclosure, the term "intercranial" means situated or occurring within the cranium itself such that such devices are positioned within the space existing between the inner surface of the scalp and the outer surface of the dura. As such, intercranial devices are those devices intended for positioning within the cranium itself as opposed to devices that may be positioned on or adjacent to the cranium or positioned along the interior of the cranium, for example, between the cerebral cortex and the interior surface of the cranium. With this in mind, intercranial devices such as those discussed below replace resected portions of the cranium due to abnormalities in the cranium, damage to the cranium, or other medically sufficient reasons for resecting positions of the cranium.

With reference to the various figures, a low-profile intercranial device <NUM> and a method for manufacturing the low-profile intercranial device <NUM> are disclosed. In addition to the actual manufacture of the low-profile intercranial device <NUM>, the present method includes the virtual design and maximal interdigitating of distinct cranial implants (that is, a low-profile customized static cranial implant <NUM> and a functional neurosurgical implant <NUM> in accordance with a preferred embodiment of the present invention) prior to the physical manufacture of the low-profile intercranial device <NUM>. The term "interdigitating" is meant to refer to the interlocking of two distinct elements (that is, the low-profile customized static cranial implant <NUM> and a functional neurosurgical implant <NUM>) such that the two distinct elements mesh together to ultimately define a single product. It is appreciated that while the various embodiments disclosed herein only show a single functional neurosurgical implant in conjunction with a low-profile customized static cranial implant, multiple functional neurosurgical implants may be used in a single low-profile intercranial device in accordance with the present invention.

As mentioned above, the low-profile intercranial device <NUM> is generally composed of a customized static cranial implant <NUM> and an interdigitating functional neurosurgical implant <NUM>. This combination of elements results in the present low-profile intercranial device <NUM> that improves and optimizes the spatial arrangement between the customized static cranial implant <NUM> and the functional neurosurgical implant <NUM> when placed within the confines of one's skull (as opposed to the current methods where functional neurosurgical implants are positioned "above" or "below" the skull). The low-profile intercranial device <NUM> is particularly adapted for ideal functional and aesthetic benefits, thereby minimizing unnecessary spaces, inter-implant gaps, and sharp irregular angles. This helps to minimize risk of scalp pain, visible deformity, and implant micromotion - all of which often leads to treatment failure and surgical explantation (that is, premature removal of the implant).

More specifically, the low-profile intercranial device <NUM> of the present invention employs a CT (Computed Tomography) scan-based, virtual design session performed pre-operatively based on the brain-specific geographical location (as opposed to the standard method of using the skull-specific geographic location). As a result, and for the first time, the methodology employed in accordance with the present invention accommodates both brain and skull pathology in three-dimensional space, in all three axes, prior to surgery unlike ever before.

With this information, as well as knowledge regarding the dimensions of the functional neurosurgical implant <NUM>, the customized static cranial implant <NUM> is produced. The customized static cranial implant <NUM> is augmented, reduced and/or modified to include a hollowed-out center cavity <NUM> (it is appreciated multiple cavities may be employed where the functional neurosurgical implant(s) being used dictates and that the cavity need not be directly in the center of the customized static cranial implant <NUM> but may be offset as dictated by the procedure being performed), as well as other structural elements <NUM> (for example, wire tunnel(s), pocket(s), etc.), shaped and dimensioned for optimal anatomical placement of the functional neurosurgical implant <NUM> that is ultimately positioned within the confines of the center cavity <NUM> (and other structural elements <NUM>) of the customized static cranial implant <NUM> (i.e., like an empty shell case but with exact negative and positive enhancements to optimize anatomical positioning of both the customized static cranial implant <NUM> and the functional neurosurgical implant <NUM>). Depending upon the specifics of the functional neurosurgical implant <NUM> positioned within the center cavity <NUM> of the of customized static cranial implant <NUM>, various mechanical coupling mechanisms, for example, screws, plates, etc. (not shown), are used to ensure that the functional neurosurgical implant <NUM> is securely held in place. As will be explained below in greater detail, the manufacture of the low-profile intercranial device <NUM> utilizes computer-based designs of both the customized static cranial implant <NUM> and the functional neurosurgical implant <NUM>.

The computer-based designs of the customized static cranial implant <NUM> and the functional neurosurgical implant <NUM> are optimized during virtual design sessions incorporating neurosurgeon, plastic-reconstructive, or other surgeon input. The optimization process takes into account the three-dimensional, spatial relationship between the customized static cranial implant <NUM> and the functional neurosurgical implant <NUM> (amongst one another if there is more than one functional neurosurgical implant), as well as the underlying topographical relationship of the customized static cranial implant <NUM>/functional neurosurgical implant <NUM> with the brain-skull anatomy and physiology of the specific patient for whom the low-profile intercranial device <NUM> is being customized and manufactured. Modification of a digitally rendered base static cranial implant 112a with a final shape and contour before sterilization and surgical implantation in accordance with the present invention (to produce the final customized static cranial implant <NUM>) results in the present low-profile intercranial device <NUM>. Through this process the spatial arrangement between the low-profile customized static cranial implant <NUM> and the functional neurosurgical implant <NUM> is improved when placed within the confines of one's skull. This represents a major advancement in the field of neurosurgery and plastic-reconstructive surgery versus current methods, which involve placing the functional neurosurgical implant either "above" or "below" the skull, are not patient-specific, and are not using a cranial implant as a protective covering.

The term "static" is used in the description of the present invention because the customized static cranial implant <NUM>, has no encapsulated inner working (i.e., "functional") parts, batteries, wires, or computers, and is essentially an improved "empty-shell" which optimizes the inter-implant positioning within the confines of the skull and the neighboring functional neurosurgical implant <NUM>.

Briefly, and as will be appreciated based upon the following disclosure, the customized static cranial implant <NUM> of the present invention is a modified version of a low-profile cranial implant commonly used and known by those skilled in the art of cranial surgical procedures. Such implants may take a variety of forms and are most commonly shaped and dimensioned for integration into the structure of a patient's skull; that is, the customized cranial implant has a geometry that substantially conforms with a resected portion of the patient's anatomy to which the implant is to be secured. Briefly, the customized static cranial implant <NUM> of the present invention includes an outer (commonly convex) first surface 12o, an inner (commonly concave) second surface 12i, and a peripheral edge 12p extending between the outer first surface 12o and the inner second surface 12i. The customized static cranial implant <NUM> is shaped and dimensioned for engagement with the skull of the patient upon implantation in a manner well known to those skilled in the field of neurosurgical procedures. The outer first surface 12o and inner second surface 12i of the customized static cranial implant <NUM> are preferably curved in a superior to inferior direction, a posterior to anterior direction, and a medial to lateral direction. In addition, and as noted in the examples discussed with reference to <FIG>, <FIG>, and <FIG>, the peripheral edge 12p has a substantial taper for resting upon a matching taper formed along the skull. It is, however, appreciated that this taper may vary (or not exist at all, that is, the peripheral edge may be substantially perpendicular relative to the outer first surface and the inner second surface) depending upon the specific needs of the procedure. In accordance with a preferred example, the customized static cranial implant will have a preselected thickness not exceeding the space between the inner surface of the scalp and the outer surface of the dura, for example, in the range of around <NUM> millimeter to <NUM> millimeters (with areas of strategic bulking and/or thinning) and depending upon the strength of the materials used in the construction of the customized static cranial implant <NUM>. Preferably, the customized static cranial implant <NUM> will have a thickness of <NUM> millimeter to <NUM> millimeters.

As mentioned above, the customized static cranial implant <NUM> also includes a cavity <NUM> (for example, formed along the inner surface) and optional structural elements <NUM>, for example, channels, pockets, access holes, and/or other structural elements, designed to accommodate various features of the functional neurosurgical implant <NUM>. In the disclosed embodiment, structural elements in the form of channels <NUM> are provided. The channels <NUM> have a first end in communication with the center cavity <NUM> and a second end extending to the inner second surface 12i (or top surface 12t) of the customized static cranial implant <NUM> for the passage of electrodes 14e of the functional neurosurgical implant <NUM> for applying stimulation to the brain. As many functional neurosurgical implants <NUM> such as disclosed in <FIG>, <FIG> and <FIG> interact with a control device (not shown) via wireless mechanisms, access between the outer first surface 12o (or top surface 12t) and the center cavity <NUM> may not be required, although it is appreciated channels or other structural elements could certainly be provided for external contact as needed and as shown in the embodiment disclosed with reference to the deep brain stimulation device <NUM> shown in <FIG>.

In accordance with a preferred example, the customized cranial implant <NUM> is fabricated from a wide array of commonly-available biomaterials including, but not limited to, clear and/or opaque PMMA (Poly(methyl methacrylate)), PEEK (Polyether ether ketone), PEKK (Polyetherketoneketone), porous polyethylene, titanium alloy, allograft, autograft, xenograft, and/or various other tissue-engineered constructs. In accordance with one example, the customized static cranial implant <NUM> is ideally made of clear PMMA since it's fully lucent and transparent. This allows for novel inspection of the interdigitated functional neurosurgical implant <NUM> and neighboring components. As will be explained below in greater detail, it also allows for the critical transmission of vital imaging with minimal distortion, such as ultrasound waves for brain pathology detection, and wireless signal communication (i.e., electroencephalography or ECOG) - essential for various neuromodulation devices such as NeuroPace®, for example. Another clear material that may be readily used in accordance with the present invention is cubic zirconium. While clear material is disclosed in accordance with a preferred embodiment, it is appreciated the underlying concepts of the present invention may be achieved through the utilization of an opaque customized static cranial implant <NUM> as shown with reference to <FIG>.

The optical clarity of the customized static cranial implant <NUM> is important in expanding the potential uses of the low-profile intercranial device <NUM> and in expanding the potential functional neurosurgical implants <NUM> that may be used in conjunction with the present invention. For example, the provision of high optical clarity allows for wireless optical links between the functional neurosurgical implants <NUM> and remote devices or between functional devices on the interior of the cranium and the exterior of the low-profile intercranial device <NUM> (for example, transmitting between the cortex and the other side of the low-profile intercranial device <NUM>). Enhanced optical clarity similarly allows for power transmission and/or receipt between the functional neurosurgical implants <NUM> and devices outside of the customized static cranial implant <NUM>. Potential operations that may be achieved through the utilization of optical links through a high clarity customized static cranial implant <NUM> include, but are not limited to, device start-up, device calibration, and device operational control.

Still further, the customized static cranial implant <NUM> is constructed of a material allowing for imaging of the brain through the customized static cranial implant <NUM>, for example, via ultra-sound. It is known that clear PMMA will provide the ability to permit ultra-sound imaging of the brain therethrough so long as it is manufactured without additives that might function to block the radio waves of the imaging device. In addition, and with reference to <FIG>, the customized static cranial implant <NUM> may include an embedded antibiotic (shown as little dots <NUM>), which is mixed with the polymer from which the customized static cranial implant <NUM> is made, to help reduce the risk of acute or chronic infections from occurring.

With reference to <FIG>, the customized static cranial implant <NUM> may also be provided with an embedded serial number (or implant identifier) <NUM> that is viewable via CT or MRI (Magnetic Resonance Imaging) scan. In accordance with a preferred embodiment, such embedded serial numbers <NUM> will be positioned along the inner second surface 12i of the customized static cranial implant <NUM>. The embedded serial number <NUM> is preferably in the form of a QR (Quick Response) Code, that is, a two dimensional barcode offering enhanced patient privacy, ready readability, and vast versatility. The embedded serial number <NUM> is achieved by integrating various materials that are viewable via CT or MRI scan into the base material of the customized static cranial implant <NUM>. For example, the materials may be barium sulfate or zirconium dioxide integrated into the customized static cranial implant so as to function as a serial number that may be viewed after implant.

As shown with reference to <FIG>, the customized static cranial implant <NUM> is also preferably constructed with alignment markings <NUM>, <NUM>. In accordance with a preferred embodiment, the alignment markings <NUM>, <NUM> run fully across the customized static cranial implant <NUM> and are formed in the shape of a cross. As such, the alignment markings <NUM>, <NUM> include a first alignment marking <NUM> formed upon the customized static cranial implant <NUM> to identify the superior to the inferior direction of the low-profile intercranial device <NUM> when properly implanted, and a second alignment marking <NUM> formed upon the customized static cranial implant <NUM> necessary to identify the posterior to anterior direction of the low-profile intercranial device <NUM> when properly implanted. These alignment markings <NUM>, <NUM> are preferably formed via laser etching of the customized static cranial implant as the customized static cranial implant is fabricated for use in accordance with the present invention. The laser etching may be combined with CNC (Computer Numerically Controlled) techniques to optimize the accuracy of markings or other known marking techniques may be employed were they offer sufficient accuracy to warrant use in accordance with the present invention.

The customized static cranial implant <NUM> of the present invention may be provided with relief recesses <NUM> (see <FIG>) for the creation of a perfectly smooth surface when titanium plates are utilized in conjunction with the low-profile intercranial device <NUM> for securing the low-profile intercranial device <NUM> in a desired position. In accordance with such an embodiment, the relief recesses <NUM> are <NUM> in depth as titanium plates are known to be very thin.

Still further, and with reference to <FIG>, the customize static cranial implant <NUM> may be provided with laser cut lines <NUM> identifying cuts for various other devices that may be utilized in conjunction with the low-profile intercranial device <NUM>. For example, the laser cut lines <NUM> might identify the location of a NeuroPace® neurostimulator device positioned adjacent to the low-profile intercranial device <NUM>. Still further, the laser cut lines <NUM> may be utilized for providing insight into the desired location of the low-profile intercranial device <NUM>.

In addition to laser cut lines <NUM>, laser markings <NUM> maybe made along the outer first surface 12o or inner second surface 12i of the customized static cranial implant <NUM> to provide an indication of critical anatomy relating to the installation of the low-profile intercranial device <NUM> in accordance with the present invention. For example, such laser markings <NUM> might be useful in identifying critical neuro anatomy relating to the functional neurosurgical implant <NUM> of the low-profile intercranial device <NUM>.

While a preferred customized static cranial implant <NUM> is disclosed in accordance with the present invention, the customized static cranial implant <NUM> used in conjunction with the present invention may take a variety of forms so long as the customized static cranial implant <NUM> includes a center cavity <NUM> (and, optionally, other structural elements <NUM>) configured to conform to the exact requirements of the functional neurosurgical implant <NUM> in accordance with the present invention.

While a one-piece construction for the customized static cranial implant <NUM> is disclosed above, multiple-piece constructions are contemplated in accordance with the present invention. With reference to <FIG>, <FIG>, the customized static cranial implant <NUM> has a two-piece construction allowing for ready access to the functional neurosurgical implant <NUM> without the need for complete removal of the low-profile intercranial device <NUM>. As with the embodiment described above, the two-piece customized static cranial implant <NUM> has no encapsulated inner working parts, batteries, wires, or computers, and is essentially an improved "empty-shell.

The two-piece customized static cranial implant <NUM> in accordance with this embodiment includes a base cranial implant member <NUM> and a cover cranial implant member <NUM>. The base cranial implant member <NUM> has a geometry that substantially conforms with a resected portion of the patient's anatomy to which the low-profile intercranial device <NUM> is to be secured. The base cranial implant member <NUM> includes an outer (commonly convex) first surface 214o, an inner (commonly concave) second surface 214i, and a peripheral edge 214p extending between the outer first surface 214o and the inner second surface 214i. The customized static cranial implant <NUM> is shaped and dimensioned for engagement with the skull of the patient upon implantation in a manner well known to those skilled in the field of neurosurgical procedures. The outer first surface 214o and inner second surface 214i of the base cranial implant member <NUM> are preferably curved in a superior to inferior direction, a posterior to anterior direction, and a medial to lateral direction.

The base cranial implant member <NUM> also includes a center recess <NUM> formed along the outer first surface 214o and optional structural elements <NUM>, for example, channels, pockets, access holes, and/or other structural elements, designed to accommodate various features of the functional neurosurgical implant <NUM>. As with the prior embodiment, multiple recesses may be employed where the functional neurosurgical implant(s) being used dictates and that the recess need not be directly in the center of the base cranial implant member but may be offset as dictated by the procedure being performed.

In accordance with a preferred embodiment, the base cranial implant member <NUM> is fabricated from a wide array of commonly-available biomaterials including, but not limited to, clear and/or opaque PMMA (Poly(methyl methacrylate)), PEEK (Polyether ether ketone), PEKK (Polyetherketoneketone), porous polyethylene, titanium alloy, and/or various other tissue-engineered constructs. In accordance with one embodiment, the base cranial implant member <NUM> is ideally made of a clear PMMA since it's completely transparent and fully lucent. This allows for novel inspection of the interdigitated functional neurosurgical implant <NUM> and neighboring components.

In addition to the base cranial implant member <NUM>, the two-piece customized static cranial implant <NUM> includes a cover cranial implant member <NUM>. The cover cranial implant member <NUM> is shaped and dimensioned for positioning over the center recess <NUM> along the outer first surface 214o of the base cranial implant member <NUM>. In accordance with a preferred embodiment, the cover cranial implant member <NUM> is secured to the base cranial implant member <NUM> by screw fixation <NUM>. The cover cranial implant member <NUM> includes an outer (commonly convex) first surface 215o, an inner (commonly concave) second surface 215i, and a peripheral edge 215p shaped and dimensioned for engagement with the outer first surface 214o of the base cranial implant member <NUM> along the periphery of the center recess <NUM>. As with the base cranial implant member <NUM>, the outer first surface 215o and inner second surface 215i of the cover cranial implant member <NUM> are preferably curved in a superior to inferior direction, a posterior to anterior direction, and a medial to lateral direction.

The base cranial implant member <NUM> and the cover cranial implant member <NUM> have a total thickness similar to that of the embodiment described above, that is, and depending on the strength characteristics of the materials used, the base cranial implant member <NUM> and the cover cranial implant member <NUM> will have a thickness (with areas of strategic bulking and/or thinning) of around <NUM> millimeter to <NUM> millimeters, preferably, <NUM> millimeter to <NUM> millimeters.

As mentioned above, the cover cranial implant member <NUM> fits over the center recess <NUM> along the outer first surface 214o of the base cranial implant member <NUM>. In this way, the inner second surface 215i of the cover cranial implant member <NUM> and the outer first surface 214o of the base cranial implant member <NUM>, along the center recess <NUM>, define a center cavity <NUM> configured to conform to the exact requirements of the functional neurosurgical implant <NUM> in accordance with the present invention. With this in mind, the inner second surface 215i of the cover cranial implant member <NUM> is shaped and/or contoured to enhance the positioning of the functional neurosurgical implant <NUM> within the center cavity <NUM>.

The functional neurosurgical implant <NUM> of the present invention is selected from a variety of FDA-approved and experimental options for electrical, optical, mechanical, medicinal and other treatment/monitoring devices designed for long term invasive treatment and/or disease-monitoring of patients requiring such attention. These functional neurosurgical implants <NUM> are known devices manufactured by various vendors within the neurosurgical industry and have known, unmodifiable dimensions that may be used in the modification of the customized static cranial implant <NUM> to optimize surgical results by minimizing abnormal shapes, visible contours, and/or craniofacial deformities.

Based upon the functional neurosurgical implant <NUM> used in conjunction with the present invention, the functional neurosurgical implant <NUM> may be useful in the treatment of various patient conditions such as epilepsy, movement disorders, chronic pain, spasticity, cerebral palsy, multiple sclerosis, spinal cord injury, traumatic brain injury, attention-deficit/hyperactivity disorder, autism, etc. - and the potential to obtain supra-normal levels of brain function in both military and civilian situations. Furthermore, incorporation of imaging devices within cranial implants could help to provide ongoing tumor bed monitoring for early detection of disease recurrence.

By way of example, one potential functional neurosurgical implant <NUM> that may be employed in accordance with the present invention is a battery-powered functional neurosurgical implant known as the NeuroPace® device, that is, a device for responsive neurostimulation for epilepsy, which has a design flaw in that it limits the visible aesthetic result due to its irregular shape(s), requires placement of battery(ies) within the chest with wires going along the neck, and suffers from high rates of implant micromotion thereby leading to common device infection and bone flap osteomyelitis (See, <NPL>. ) These deficiencies are overcome in accordance with the present invention by optimizing the customized static cranial implant <NUM> for receipt of the NeuroPace® device.

Further, the present invention allows the possibility of combining the benefits of the ideal contour customized static cranial implant <NUM> with the efficacy of neuromodulation potentially reducing the complication rates of repetitive nerve stimulation (RNS) to the complication rates of cranial reconstruction (<NUM>% to <NUM>-<NUM>%) and giving surgeons an option when the existing bone is resorbing.

The present invention also allows the possibility of combining the benefits of the present low-pressure intercranial device <NUM> with the ability to monitor cranial pressure mitigating the needs for excessive imaging, offering patients and surgeons the ability to capture spikes or drops in pressure related to hydrocephalous, hematoma, stroke, etc..

The present invention also allows the possibility of combining the benefits of the present low-pressure intercranial device <NUM> with the ability to control hydrocephalous or overactive ventricles possibly preventing a second surgical sight for shunt placement and at least eliminate the irregular contour and work time of post fabrication modification of cranial reconstruction implant.

The present invention also allows the possibility of reducing or eliminating the need for post-operative imaging, saving money for insurance companies, providing peace of mind for patients, and allowing on-demand assessment for surgeons.

The present invention also allows the possibility of combining the benefits of the present customized static cranial implant with the ability to deliver pharmaceuticals past the blood brain barrier. The proximity to the ventricles or excised tumor beds reduces the clinical challenges of tunneling catheters great distances from other anatomies.

Another functional neurosurgical implant <NUM> that may be used in conjunction with the customized static low-pressure intercranial device <NUM> is a remote video unit <NUM> (see <FIG>). Considering the fact the customized static cranial implant <NUM> is clear, a remote video unit <NUM> may be deployed for viewing the brain and in particular the healing of the brain in the area adjacent to the low-profile intercranial device <NUM>. Where the two-piece customized static cranial implant <NUM> is employed, the remote video unit <NUM> could be selectively removed and deployed by simply accessing the cover cranial implant member <NUM> and removing the same allowing for access to or deployment of the remote video unit <NUM>. In addition to batteries, lenses and other components commonly employed in conjunction with digital cameras, the remote video unit <NUM> includes a Bluetooth transmitter <NUM> allowing for the transmission of images to a remote display where the images may be viewed or stored for later viewing. Still further, and with reference to <FIG>, functional neurosurgical implants <NUM> that may be used in conjunction with the low-profile intercranial device <NUM> include a deep brain stimulation device <NUM> (<FIG>), a shunt device <NUM> (<FIG>) and a brain mapping device <NUM> (<FIG>).

With the foregoing in mind, additional functional neurosurgical implants <NUM> that may be used in conjunction with the present invention include, but are not limited to the following: Deep Brain Stimulators (DBS); Cortical Brain Stimulators (CBS); neurologic medicines that are otherwise prevented from diffusing through the blood-brain barrier via common delivery methods; battery/passively/kinetically/or otherwise-powered functional devices including neuromodulation devices, imaging devices, radiation therapy devices, and remote sensing/monitoring devices; monitoring devices for abnormal levels of intracranial pressure (ICP) or brain activity (i.e., seizures), such as an electrical array for motor/vision cortex control, battery/passively/kinetically/or otherwise -based stimulation hardware for epilepsy management (grids/batteries/wires); low-profile remote imaging devices (e.g., optical coherence tomography (OCT), duplex ultrasound); delivery/sensing devices for electrical impulses; neurological and physiological systems required for deep space/sleep functionalities enhancing the monitoring and/or maintenance of bodily vital signs, nutrition, cognition, etc.; convection enhanced delivery systems effectively delivering therapeutics to substantial volumes of brain and brain tumor; and remote neuro-imaging devices (i.e., electroencephalogram (EEG).

The functional neurosurgical implants <NUM> of the present invention may also incorporate high-precision and fully implantable next-generation neural interface systems taking advantage of microelectronics and photonics along with advances in scalable neural encoding and processing algorithms to demonstrate the transformation of high-definition sensory stimuli to and from sensory cortex areas, bridging physiological and electronic neural activity representations.

With this in mind, the term "functional neurosurgical implant" is meant to reference any therapeutic hardware or compositions including, but not limited to, medicines to treat any patient-specific illness, or electronic, mechanical, imaging modality and/or electro-mechanical device to remotely monitor (e.g., via Wi-Fi connectivity) or intervene any specific neurologic illness, including imaging, monitoring, electrostimulation, radiation therapy, polarized light/laser neuronal modulation devices. The term "functional" denotes the fact that these implants provide the low-profile intercranial device <NUM> with the ability to function as more than a safe custom-shaped skull replacement by providing various functionalities, for example, local drug delivery, monitoring (such as brain monitoring), or local electric stimulation to the patient.

The following describes the steps employed in the manufacture and installation of the low-profile intercranial device <NUM> of the present invention. While the procedure is described for manufacture and installation of the one-piece customized static cranial implant, the two-piece customized static cranial implant is processed in the same manner. After the patient is diagnosed as requiring the implantation of a low profile intercranial device <NUM> as a replacement for a specific portion of the cranium (either to reconstruct a portion of the cranium or to replace a surgeon created defect) in accordance with the claimed invention, the patient first undergoes a high-definition, protocol CT scan of his or her head prior to surgery (which is customary for all neurosurgical patients in need of cranial implants) (see <FIG>) and the CT scan is then converted to an STL (STereoLithography) file (or other digital data format useful in computer-assisted design/computer-assisted manufacture (CAD/CAM) manufacture procedures) (see <FIG>).

With the STL file of the CT scan completed, the digital image of the patient (for those patients either with or without an existing skull defect) is used by a design engineer to create a digitally rendered base static cranial implant 112a using conventional computer-assisted design (CAD)/computer-assisted modeling (CAM) techniques (See <FIG> and <FIG>). Feedback from a surgeon(s) pre-operatively helps to reveal any unexpected surgical details and aids one in confirming an ideal, planned location of functional neurosurgery and relevant topographical brain anatomy underneath the planned low-profile intercranial device <NUM>. It is appreciated the CAD/CAM techniques, as well as other automated elements of the present methodology are accomplished using conventional computer and technology equipment <NUM> well known to those skilled in the art. The digitally rendered base static cranial implant 112a exhibits a shape exact to the size, thickness, and contour of the patient's unique cranium. The digitally rendered base static cranial implant 112a is then stored as an STL file (or other digital data format useful in computer-assisted design manufacture procedures).

Simultaneously, before or after the creation of the digital design of the cranial implant, a digital rendering of the functional neurosurgical implant ("digitally rendered functional neurosurgical implant 114a") to be used with the customized static cranial implant <NUM> is created (or obtained from the third party vendor responsible for the manufacture of the functional neurosurgical implant (See <FIG>). As with the digitally rendered base static cranial implant 112a, the digitally rendered functional neurosurgical implant 114a is stored as an STL file (or other digital data format useful in computer-assisted design manufacture procedures) commonly used by design engineers using (CAD)/(CAM) techniques and, as explained below, the exact dimensions of the functional neurosurgical implant are incorporated into the final low-profile intercranial device <NUM> of the present invention.

The digitally rendered functional neurosurgical implant 114a is then superimposed on the digitally rendered base static cranial implant 112a to produce a hybrid rendering 120a including both the digitally rendered functional neurosurgical implant 114a and the digitally rendered base static cranial implant 112a (see <FIG>). It is appreciated multiple digital renderings of functional neurosurgical implants will be created and superimposed where the planned low-profile intercranial device <NUM> includes multiple functional neurosurgical implants. With the digitally rendered functional neurosurgical implant 114a superimposed on the digitally rendered base static cranial implant 112a as a single superimposed digital drawing (that is, the hybrid rendering 120a), the functional neurosurgical implant and the cranial implant (that is, the digitally rendered versions of both) may be optimized with patient-specific independent width/height/length dimensions to optimize anatomical harmony amongst the functional neurosurgical implant <NUM> and the customized static cranial implant <NUM> prior to surgery and allow virtual planning for the seamless integration of the functional neurosurgical implant <NUM> and the customized static cranial implant <NUM>. This optimization process results in the optimized hybrid rendering 120b, composed of an optimized digitally rendered functional neurosurgical implant 114b and the optimized digitally rendered customized static cranial implant 112b as shown in <FIG>.

In particular, and with the digitally rendered functional neurosurgical implant 114a superimposed on the digitally rendered base static cranial implant 112a, the center cavity, that is, the digitally rendered center cavity 116b (as well as linear channels for wires to tunnel through, pockets to pack excess wire length, access holes for battery replacement, etc. - referenced as structural element 117b) of the customized static cranial implant <NUM> are designed and integrated into the optimized hybrid rendering 120b. The digitally rendered center cavity 116b (and other structural elements 117b) is designed virtually as to the best-case scenario location. In addition to the inclusion of the digitally rendered center cavity 116b, optimization may include changes to the dimensions of the digitally rendered base static cranial implant 112a and changes with regard to positioning of the functional neurosurgical implant 114a relative to the digitally rendered base static cranial implant 112a. The goal is to design a low-profile intercranial device <NUM> so that there will be no need for any intra-operative modification of the low-profile intercranial device <NUM>. This offers a valuable advance allowing for up to <NUM>-<NUM> hours of time saving. In addition, and because of the non-changeable and fixed in shape/size/contour of the functional neurosurgical implant <NUM> used in accordance with the present invention, the present low-profile intercranial device <NUM> exhibits all the advantages of pre-operative and intra-operative plasticity related to shape, contour and size by integrating the unmodified functional neurosurgical implant <NUM> into the customized static cranial implant <NUM>.

As shown in <FIG>, The optimized digitally rendered functional neurosurgical implant 114b and the optimized digitally rendered customized static cranial implant 112b are optimized such that the final physical functional neurosurgical implant <NUM> will have a "key-in-lock" type (that is, a closely conforming or high tolerance) fit within the final physical customized static cranial implant <NUM>. This optimization results in the optimized hybrid rendering 120b composed of the optimized digitally rendered functional neurosurgical implant 114b and the optimized digitally rendered customized static cranial implant 112b.

The optimized hybrid rendering 120b offers both pre-operative virtual assessment of the relationship optimized digitally rendered functional neurosurgical implant 114b and an optimized digitally rendered customized static cranial implant 112b, as well as pre-operative optimization of the physical low-profile intercranial device <NUM> via known laser-cutting devices facilitated via surgical robot-assisted technologies (or by hand where such capabilities are not available). Both steps help to strengthen the chances that the relationship of customized static cranial implant <NUM> and the functional neurosurgical implant <NUM> will be optimized down to submillimeter accuracy. Depending upon the needs of the patient, the structure of the optimized digitally rendered customized static cranial implant 112b, and the specifics of the optimized digitally rendered functional neurosurgical implant 114b, the optimized digitally rendered functional neurosurgical implant 114b and the optimized digitally rendered customized static cranial implant 112b (as well as the resulting low-profile intercranial device <NUM> produced as a result of these renderings) will likely have many desired features (for improved safety and aesthetic outcomes relative to the patient appearance), such as, linear channels formed within the customized static cranial implant <NUM> for wires to tunnel through, pockets within the customized static cranial implant <NUM> to pack excess wire length, access holes within the customized static cranial implant <NUM> for battery replacement, etc..

Once the optimized digitally rendered functional neurosurgical implant 114b and the optimized digitally rendered customized static cranial implant 112b are virtually matched, the anatomical aspects will be ideal for patient-specific needs and the optimized hybrid rendering 120b (saved as an STL (or other digital format)) file is then used to manufacture the present low-profile intercranial device <NUM> which may ultimately be assembled with the functional neurosurgical implant <NUM> positioned with center cavity <NUM> of the customized static cranial implant <NUM>.

In particular, with the STL (or other digital format) file of the optimized hybrid rendering 120b of the customized static cranial implant <NUM> and the functional neurosurgical implant <NUM>, conventional manufacturing techniques are used to fabricate and laser cut the customized static cranial implant <NUM> and the functional neurosurgical implant <NUM> with robot-assistance for extreme accuracy (see <CIT>, based upon PCT Application No. <CIT>, entitled "A CUTTING MACHINE FOR RESIZING RAW IMPLANTS DURING SURGERY,"), as compared to commonly-employed, human hand modification. For example, the customized static cranial implant <NUM> can be obtained in "non-sterile form" from any of the dozens of FDA-approved companies in existence nationwide that are capable of producing cranial implants in accordance with the requirement of the optimized digitally rendered customized static cranial implant 112b. A functional neurosurgical implant <NUM> corresponding to the optimized digitally rendered functional neurosurgical implant 114b may be purchased from appropriate vendors with or without FDA approval.

It is also appreciated that the customized static cranial implant <NUM> and/or the functional neurosurgical implant <NUM> may be produced through the use of <NUM>-D digital printing technology <NUM> (see <FIG>). With this in mind, and in addition to distinctly separate functional neurosurgical implants <NUM>, the functional neurosurgical implant or portions thereof may be integrated into the customized static cranial implant through three-dimensional printing. With the use of three-dimensional printing electronic circuitry employed by the functional neurosurgical implant may be created directly on the surfaces of the customized static cranial implant in a manner optimally utilizing the space available for the remaining portions of the functional neurosurgical implant. Similarly, vital nervous system components may be printed into the customized static cranial implant or non-clear bony structures designed to resolve complex disabilities may be printed into the customized static cranial implant. For example, the functional neurosurgical implant or portions thereof may be three-dimensionally printed within the center cavity. Where the two-piece embodiment as described above is employed, the functional neurosurgical implant or portions thereof may be three-dimensionally printed on the center recess of the base cranial implant member or the cover cranial implant member. In another embodiment, the customized cranial implant and the printable components of the functional neurosurgical implant may be printed in a single print process taking advantage of the three-dimensional printing system's ability to print multiple materials during a single print job. Ultimately, the application of three-dimensional printing in accordance with the present invention allows immensely complex systems to be compacted into the space needed in the replacement of cranial bones.

It is also appreciated robot-assisted methodologies for implant modification may be used to optimize accuracy by employing laser-cutting methods as described in <CIT>, based upon PCT Application No. <CIT>, entitled "A CUTTING MACHINE FOR RESIZING RAW IMPLANTS DURING SURGERY". Such optimization of the physical low-profile intercranial device <NUM> may take place pre-operatively via existing laser-cutting devices facilitated via surgical robot-assisted technologies and navigation-based technologies (for example, da Vinci® surgical system, Mako® robotic-arm surgical system, and the Johns Hopkins system described in <CIT>, based upon PCT Application No. <CIT>, entitled "A CUTTING MACHINE FOR RESIZING RAW IMPLANTS DURING SURGERY,"), as well as via future surgical robot-assisted and surgical navigation-based technologies that become available. It is further appreciated optimization of the physical low-profile intercranial device <NUM> may also be achieved intra-operatively as required by making such technologies available within (or adjacent to) the operating room by using a laser-cutting robot in the operating room to perform real-time modifications of the static cranial implant modification for ideal interdigitation with the functional neurologic implant.

By way of example, the customized static cranial implant <NUM> is created by first using a <NUM>-D printed model of the optimized digitally rendered customized static cranial implant 112b, which is then molded with a hard plastic model. With this mold in hand, the customized static cranial implant <NUM> is fabricated with a liquid material, for example a clear PMMA as discussed above. Once cured and solid, processed and sterilized, the customized static cranial implant <NUM> will be complete, but may be pre-operatively modified by robot and/or laser (or manually where such robot controlled lasers are not available) to help optimize its position alongside the functional neurosurgical implant <NUM>.

The customized static cranial implant <NUM> will commonly be in the shape of the resected portion of the patient's original cranium but with a negative space (that is, the center cavity <NUM> (or cavities where required)) exactly the shape of the functional neurosurgical implant <NUM> (or implants) hollowed out. The present low-profile intercranial device <NUM> is the first-ever such medical device to provide a hollowed-out customized static cranial implant <NUM> capable of "accepting" a neighboring functional neurosurgical implant <NUM> with ideal shape and form amongst the two. Essentially, the functional neurosurgical implant <NUM> is the "male" component and the customized static cranial implant <NUM> is the "female" component - and together they are in exact harmony thereby improving surgical outcomes and ultimate patient satisfaction.

By manufacturing the present low-profile intercranial device <NUM> in this manner, the final physical components of the low-profile intercranial device <NUM>, that is, the customized static cranial implant <NUM> and the functional neurosurgical implant <NUM> are virtually matched pre-operatively such that the resulting low-profile intercranial device <NUM> is ideally constructed to drastically minimize the risk of scalp pain, scalp contour irregularities, extrusion of implant through scalp, painful scalp syndrome, visual craniofacial deformity, and infection secondary to micromotion of foreign materials, and/or brain injuries when being placed underneath the skull.

With the low-profile intercranial device <NUM> fully fabricated and assembled, that is, the functional neurosurgical implant <NUM> positioned within the center cavity <NUM> of the customized static cranial implant <NUM>, the low-profile intercranial device <NUM> is positioned within the intercranial space so as to replace the resected portion of the cranium (see <FIG> for the one-piece customized static cranial implant example and <FIG> for the two-piece customized static cranial implant embodiment).

Claim 1:
A low-profile intercranial device, comprising:
a functional neurosurgical implant; and
a low-profile static cranial implant (<NUM>) shaped and dimensioned for placement within an intercranial space as defined by a resected portion of a patient's skull during performance of a cranioplasty, the low-profile static cranial implant including
a base member (<NUM>) with an outer surface (214o), an inner surface (214i), and a peripheral edge (214p) shaped and dimensioned to conform to a resected portion of the patient's skull upon implantation during performance of a cranioplasty so as to provide brain protection and enhanced appearance, the base member defining a recess (<NUM>) formed in the outer surface thereof, the recess being shaped and dimensioned to receive the functional neurosurgical implant; and
a cover cranial implant (<NUM>) shaped and dimensioned to selective placement over the recess along the outer surface of the base member to define a cavity (<NUM>) formed in the static cranial implant, the cavity being shaped and dimensioned to receive and interdigitate with the functional neurosurgical implant (<NUM>) to interlock the low-profile static cranial implant and the functional neurosurgical implant such that the low-profile static cranial implant and the functional neurosurgical implant mesh together.