Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical therapeutic systems
Reexamination Certificate
1999-10-12
2003-05-06
Schaetzle, Kennedy (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical therapeutic systems
C600S544000, C600S553000, C600S036000
Reexamination Certificate
active
06560486
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the field of neuroscience and, more particularly without limitation, to a subfield of neuroprostheses for housing devices in close proximity to the brain.
2. Glossary of Terms and Useful Definitions
The term “electroencephalogram” (“EEG”) refers to voltage potentials recorded from the scalp and encompasses any recordings obtained from a source outside the dura mater. The term “electrocorticogram” (“ECoG”) refers to voltage potentials recorded intracranially, e.g., directly from the cortex. “EKG” is an abbreviation for the term “electrocardiogram,” “EMG” for the term “electromyogram” which records electrical muscle activity, and “EOG” for the term “electrooculogram” which records eye movements.
The term “real-time” as used herein describes a system with negligible latency between input and output.
As used herein, the term “outer table” refers to the outer bony sheet of the skull in contact with the scalp; the term “inner table” refers to the inner bony sheet of the skull in contact with the outermost brain membrane or “dura”; and the term “diploe” refers to the part of the skull between the outer table and inner table that provides nutrients and minerals necessary for developing and maintaining the skull.
3. Description of the Related Art
Humans and animals have several normal states of behavior, such as wakefulness and sleep, as well as multiple sub-states, such as attentive wakefulness and REM sleep. Abnormal states of behavior in humans and animals include reversible states, such as seizures, and progressive irreversible states, such as dementia.
Recent advances in the field of clinical neurosciences have opened a new era for the use of and need for implantable therapeutic devices. For example, the use of prostheses, for the diagnosis or treatment of neurologic illnesses, is rapidly growing and will continue to expand as new applications are found. As new technological developments take place, so does the opportunity to improve current designs or performance, decrease power requirements or cost, or minimize complications associated with chronic implantation. For instance, a device to electrically stimulate brain regions, via chronically implanted electrodes for Parkinson's disease, has been recently approved for commercial use by the Food and Drug Administration. Implantable devices to detect and control abnormal brain states, such as epileptic seizures, are currently under development (see Osorio et al.,
Epilepsia
39(6):615-627, 1998).
Currently, brain devices, such as the one used for Parkinson's disease, are implanted under the collarbones at a substantial distance from the brain. For example, the use of wires or conductors to carry a signal into or out of the brain, requires a special, time consuming procedure and careful placement of wires and connectors to avoid scalp/skin erosion, a common and serious complication which often requires removal of the device with loss of benefit to the subject. More specifically, such an approach has several significant disadvantages: (i) the long conductors for connecting the device to electrodes implanted in the brain require tunneling under the scalp and skin, thereby requiring prolonged surgical and anesthesia for installation; (ii) the tract along the conductors often becomes infected requiring, in many cases, that the conductors be explanted with consequent cessation of treatment to the subject; (iii) the conductors often erode the overlying scalp, forcing removal of the cables so that healing can take place but, at the same time, removing the means for warning of or treating impending abnormal activities; (iv) the conductors often fracture since they are subjected to torsional and other forces generated by normal head
eck movements with consequent corrective surgery to replace the faulty conductors; and (v) in the case of telemetered signals, closer proximity of the emitter to the receiver would increase fidelity of the transmitted signals and decrease power requirements, hence prolonging battery life and decreasing frequency of surgical replacement procedures.
The placement of prior art brain devices outside the skull, such as in the infraclavicular regions, is due to lack of space between the brain and the skull to position such devices and also to the inability to convert virtual into real spaces without affecting the integrity of the skull. Indeed, while the brain is closely apposed to the inner table of the skull, leaving no usable space to safely house any device, the skull has several properties that enable conversion of virtual into real space for use of the integrated ergonomic placement of devices. These properties, which have not been heretofore exploited, include:
a) sufficient wall thickness to allow housing of access systems/electronic components partially or completely within the confines of the two tables of the skull;
b) high tensile strength; and
c) semi-circular configuration allowing equal distribution of forces over its surface.
In addition, scalp tissue has the elasticity or deformability necessary for accommodation of housing devices.
Accurate and reproducible prediction of behavioral or biologic signal changes associated with abnormal brain activities has not been generally possible as such events typically occur unpredictably. This limitation has been recently overcome, making it possible to accurately predict various types of brain states, such as epileptic seizures, etc., as taught in U.S. Pat. No. 5,995,868.
Thus, what is needed is a cerebral interface system that permits spacing essential mechanisms, which perform these or other tasks in close proximity to a subject's brain.
SUMMARY OF THE INVENTION
The present invention includes improvements for enabling simultaneous accessibility between the brain of a subject and the outside world for direct application of measures to monitor and analyze the brain activity of the subject, to predict or detect changes in such brain activity, and to allow warning, recording, preventing, and/or controlling undesirable changes in such brain activity, such as the activity changes associated with an epileptic seizure, for example.
The present inventive cerebral interface system for sensing and/or controlling normal or abnormal brain activity in a subject includes: a brain access mechanism comprising a housing mechanism configured to be spaced in a cavity formed in the subject's skull; an attaching mechanism configured to attach the housing mechanism to the subject's skull; a sealing mechanism configured to provide a fluid-tight seal between the housing mechanism and the subject's skull; a control mechanism or signal processor, such as a properly programmed microprocessor, spaced within the housing mechanism; a communication mechanism, which may include one or more sensors implanted in the subject's brain, configured to communicatingly connect the subject's brain to the control mechanism; and a power source configured to operatively power the apparatus.
Preferably, the housing mechanism includes an inner wall having an inner surface substantially aligned with the inner table of the subject's skull. The inner wall may include one or more ports such that a connector or connectors of the communication mechanism can extend through the port or ports into the subject's brain. For this arrangement, the sealing mechanism may include a fluid-tight seal between the connector or connectors and the inner wall. The sealing mechanism may include a bio-compatible coating, a layer of resilient bio-compatible materials such as silicon, polyurethane, or plastic encircling the housing mechanism, etc.
The housing mechanism, which is preferably oval shaped, may include an outer wall having an outer surface that is substantially aligned with the outer table of the subject's skull. In that event, the housing mechanism may include a flanged edge configured to be spaced in abutting engagement with an outer surface of the outer table of the subject'
Frei Mark
Osorio Ivan
Schaetzle Kennedy
Schoonover Donald R.
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