Surgery: light – thermal – and electrical application – Light – thermal – and electrical application – Electrical energy applicator
Reexamination Certificate
1999-02-23
2001-02-20
Schaetzle, Kennedy (Department: 3762)
Surgery: light, thermal, and electrical application
Light, thermal, and electrical application
Electrical energy applicator
C607S116000
Reexamination Certificate
active
06192279
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and system or apparatus for non-invasively adjusting the position of at least one implanted electrode.
2. Description of the Prior Art
Heretofore, leads designed for electrical stimulation of human tissue generally comprise electrodes at their distal end which are connected to contacts at their proximal end via insulated conductor wires threaded inside a non-conductive sheath. In general, stimulation leads are used to transport electrical pulses from an implanted pulse generator to the target tissue.
In the case of spinal cord stimulation, the target tissue is a secluded nerve fiber(s) within the spinal cord which transport a distinct neurological message to or from the brain. Two examples of a neurological message are (1) a signal to the brain intended to trigger a defensive or protective action, such as pain or (2) a signal from the brain intended to contract a specific muscle, such as the urinary bladder sphincter.
In the first example, electrical stimulation can be used to modify the pain signal in order to induce analgesia by activation of the endogenous opiate pain suppression system in a specific part of the body.
In the second example, electrical stimulation can be used to cause the contraction of the sphincter in the urinary bladder in order to prevent urinary incontinence.
Trying to recruit specific nerve fibers without affecting other nerve fibers can be a very difficult and time consuming medical procedure. When using electrical stimulation for pain control, a trial stimulation is applied to the spinal cord using an external pulse generator, with the goal of positioning the electrode so that a fine, tingling sensation called paresthesia, is felt in the entire area where there is pain. During this trial stimulation, a patient needs to be fully awake in order to report to the physician when optimal localization of the electrode has taken place. Once the optimal electrode position is achieved, the lead is sutured in place, disconnected from the external pulse generator and connected to an implantable, permanent pulse generator which is then programmed to the same stimulation values as the external one.
Some types of neural stimulation are notoriously ineffective, such as lower back stimulation. The spacing between electrodes and the length of each electrode become very critical factors for effective lower back stimulation. For some patients the physician may choose a lead having large spacing between electrodes in order to achieve complete paresthesia coverage, only to find out that such large spacing makes it too difficult if not impossible to recruit the target nerve. A lead having closely spaced electrodes may facilitate recruitment of the target nerve but may not provide complete paresthesia coverage. The main problem here is that manual pushing or pulling of the implanted lead by the physician often results in larger than desired changes in electrode position, making location of the “sweet spot” (parasthesia location) extremely difficult. An electromechanical means for micro-stepping (rotating) the electrode position, such as described hereinafter, will allow the physician to locate the desired location quicker and with less effort, improving the chances for successful therapy.
Furthermore, one of the major obstacles in preventing long term success of spinal cord stimulation for some patients, has been electrode displacement from their originally implanted position relative to the target nerve. Electrode displacement in most cases is due to normal flexing of the spinal column as the patient goes about his/her normal daily activities. What appears to occur is that the lead retracts slightly when the patient bends forward, but does not fully recoil back to its original location upon the patient returning to the up-right position. This results in a decreased or total loss of medical therapy. In this case, if the system of the present invention is used and the patient is provided with an electrode position controller, a physician or a properly trained patient may be able to non-invasively reposition the electrode to the original site and avert an expensive and uncomfortable surgical procedure to manually reposition the electrode.
SUMMARY OF THE INVENTION
It is the objective of the present invention to provide a completely implanted neurological system which is capable of non-invasively changing the location of the stimulating electrodes in relation to the target nerve.
There are three parts to the lead system of the present invention, namely, (1) an Electrode Position Controller used by the physician to non-invasively command implanted spiral electrodes to change their position in relation to the stationary target nerve within the spinal cord, (2) a Lead Extension which connects a Stimulating Lead to the pulse generator, and (3) the Stimulating Lead having one or more skew or spiral electrodes at its distal end.
The Lead Extension comprises at its proximal end, (1) one or more contact rings for making electrical connection to the pulse generator, (2) one or more insulated wires to carry the electrical pulses from the pulse generator to the stimulating lead, and (3) at its distal end, one or more canted coils to make electrical contact with the contact rings in the Stimulating Lead, a micro-motor, a reduction gear, a shaft and controlling circuitry.
The Stimulating Lead comprises at its proximal end, (1) a mandrel which locks into the shaft of the micro-motor in the Lead Extension, and one or more metal rings to make electrical connection with the canted coils in the Lead Extension, (2) one or more insulated wires to carry the electrical pulses from the Lead Extension, and (3) one or more insulated wires to carry the electrical pulses from the Lead Extension, and (4) at its distal end, one or more Spiral Electrodes.
The Electrode Position Controller sends electromagnetic waves which are picked up and rectified into direct current pulses by the electronic circuit within the Lead Extension. These current pulses are applied to the micro-motor which causes its gear shaft to rotate just a few degrees per burst of electromagnetic waves. Since the Stimulating Lead is locked to the gear output shaft, the Stimulating Lead will also rotate when the micro-motor is energized. As the Stimulating Lead is rotated, the skew or spiral electrodes will slide perpendicularly to the target nerve, effectively changing, in very small and controlled steps, the position of the electrodes in relation to the target nerve.
REFERENCES:
patent: 3598128 (1971-08-01), Chardack
patent: 3822708 (1974-07-01), Zilber
patent: 5674274 (1997-10-01), Morgan et al.
patent: 5762599 (1998-06-01), Sohn
patent: 5895416 (1999-04-01), Barreras, Sr. et al.
Barreras, Sr. Francisco Jose
Jimenez Oscar
Medtronic Inc.
Schaetzle Kennedy
Vigil Thomas R.
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