Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical energy applicator
Reexamination Certificate
1999-07-15
2001-10-23
Layno, Carl (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical energy applicator
C607S116000
Reexamination Certificate
active
06308105
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to medical electrical stimulation, and particularly to a system to provide medical electrical stimulation to nervous tissue.
BACKGROUND OF THE INVENTION
Medical electrical stimulation is currently used for a variety of reasons. Among the fastest growing indications for medical electrical stimulation is the treatment or suppression of pain.
Medical electrical stimulation typically treats pain through the application of electrical pulses to a nerve or nerve fibers. Generally speaking, one of the difficulties with providing electrical stimulation to nerve fibers is to provide an adequate, simple and reliable coupling of the treatment electrodes with the nerve fibers.
One nerve which may be in need of electrical stimulation to treat pain is the trigeminal nerve. The trigeminal nerve is the largest of the facial nerves.
Trigeminal neuralgia is a malfunction of this nerve which causes (usually) spasmodic pain. Any of the three branches can be affected. The pain can be caused by one or more of several causes.
Pressure of a blood vessel on the root of the nerve.
Demyelinization of the nerve (i.e. the destruction of the myelin sheath that protects the nerve fiber).
Physical damage, such as failed dental procedures or infections.
Unknown. Not all cases seem to have a clear cause.
Only one side of the face is usually affected, but trigeminal neuralgia of both sides is also known to exist. In “classical” trigeminal neuralgia, the pain is extremely sharp and seizure-like. It is often triggered by certain stimuli such as touching the face, eating, talking, shaving, etc. These triggers vary from person to person.
When a blood vessel is suspected to be pressing on the root entry zone, an operation, aimed at removing the source of the compression, requires a craniotomy at the base of the skull. This bony opening is often very small, referred to as “key hole” surgery.
Symptom relief is usually obtained through microvascular compression where offending blood vessel is physically moved away from the root entry zone. On occasion, a more radical approach is required such as partial or complete cutting of the nerve. This procedure is very effective and long lasting, particularly if an artery is found compressing the nerve as it enters the brainstem.
Common complications from rhizotomy procedures include facial or eye numbness, change in bite and TMJ problems. Serious complications such as strole, paralysis, blindness or death are rare. The typical complications of microsurgical vascular decompression are facial or eye numbness, deafness, coordination problems, change in bite, TMJ problems and wound healing problems.
One of the typical features of trigeminal neuralgia is that it is rarely typical. In addition to the stabbing neuralgic pain, many victims experience various kinds of pain that may be described as burning, crushing, pulsating, etc. These “typical” forms of pain are often very difficult to treat.
Trigeminal neuralgia is a very rare condition. Statistics vary, but the relevance is probably about 150 cases per million people per year. There are some relatively effective treatments for trigeminal neuralgia. Unfortunately, although some of the treatments are becoming standard, there is no single treatment that is effective for all victims.
In a so-called “key-hole” surgical operation the neurosurgeon approaches the point where the trigeminal nerve enters the brain (the root entry zone) directly, using an operating microscope, through a small opening behind the car at the affected side. The surgeon searches for, and nearly always finds, a blood vessel (usually an artery, but it could be a vein) close against the nerve, kinking the nerve. It is presumed that the physical kinking of the nerve by the offending blood vessel has a part to play in causing trigeminal neuralgia. The vessel is carefully separated from the nerve thus unkinking or decompressing the nerve. It is important to be sure that the separation of the vessel and nerve is maintained so as to reduce the chance of the condition recurring. For this purpose teflon cotton pads are placed in between the vessel and the nerve. Often, however, separation of the nerve and vessel is not sufficient and electrical stimulation is desired to suppress pain.
SUMMARY OF THE INVENTION
Thus, there exists a need for a medical electrical lead configured for implant around a trigeminal nerve.
There exists a further need for such a lead which is suitable for implant through the so-called “key-hole” surgical approach.
These and other needs are met by the present invention, which provides a system for providing electrical stimulation to the trigeminal nerve through a novel lead. The lead features a lead body, a coupling for connecting a lead into a medical stimulator and a distal electrode assembly.
The electrode assembly features a pair of oppositely disposed curved semi-circular cuffs disposed to conform a lumen therethrough. The ends of each cuff are mounted into a resilient hinge disposed upon the distal end of the lead body. The hinge biases the cuffs towards one another in such a manner that the lumen is maintained patent such that the nerve will remain therein. The hinge is further designed so as to be easily opened so as to spread the cuffs apart. Hinge opening is accomplished through a specialized implant tool, the implant tool being a generally cylindrical tube designed to meet about the lead body. A divergence in the lead body near the hinge permits the implant tool to engage the lead body in that section and thus forces the cuffs apart. In such a manner the cuffs may be opened so as to be implanted around the lead merely through manipulation of the proximal end of the lead body. Thus, this design permits the leads to be implanted using the so-called “key-hole” surgical approach. Additional embodiments of the lead are also disclosed.
REFERENCES:
patent: 4920979 (1990-05-01), Bullara
patent: 5095905 (1992-03-01), Klepinski
patent: 5215089 (1993-06-01), Baker, Jr.
patent: 5375594 (1994-12-01), Cueva
patent: WO 91/17791-A1 (1991-11-01), None
Adams Paulus G.
Duysens Victor P.J.
Gubbels Paulus A. A.
Kretzers Leo
van Venrooij Paulus
Berry Tom G.
Jaro Michael J.
Layno Carl
Medtronic Inc.
Woods Thomas F.
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