Surgery – Diagnostic testing – Structure of body-contacting electrode or electrode inserted...
Reexamination Certificate
1998-11-05
2001-11-20
Layno, Carl H. (Department: 3762)
Surgery
Diagnostic testing
Structure of body-contacting electrode or electrode inserted...
C607S116000
Reexamination Certificate
active
06321104
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a cranial lead system and, more particularly, a system and method for affixing a brain lead or catheter which is positioned through a cranial burr hole, so that the lead is secured in position relative to the patient's brain without moving the distal end of the lead.
BACKGROUND OF THE INVENTION
Systems for providing either electrical stimulation of the brain or coupling as fluid to or from the brain are coming into increased use for various purposes. Electrical stimulation of the brain is utilized for relief of chronic pain and treatment of movement disorders. A typical electrical brain stimulation system comprises a pulse generator operatively connected to the brain by a lead. The lead has one or more electrodes at its distal end, designed to be implanted within the patient's brain at a precise location, so that the electrode or electrodes are optimally and safely positioned for the desired stimulation. The lead is connected to the pulse generator at its proximal end, and also needs to be anchored with respect to a burr hole drilled in the patient's skull or cranium, in order to reliably secure the electrodes at the target location. Likewise, in the case of a catheter for providing fluid to the brain or for providing drainage, it is necessary to be able to secure the distal portion of the catheter that passes through the skull and transfers the fluid at a predetermined exact location within the brain. Still further, for a combined catheter and lead member, such secure and reliable anchoring of the member so that the distal end is precisely located within the skull, is very important. As used herein, the term lead, or lead-type member, refers to any such cranial catheter or lead.
Reference is made to U.S. Pat. No. 5,464,446, “Brain Lead Anchoring System,” assigned to Medtronic, Inc., which is incorporated herein by reference. The referenced patent illustrates an effective lead anchoring system, and it discusses the method of providing access through the skull by drilling a burr hole with a cranial drill, inserting a stimulation lead through the burr hole and positioning it so that the electrode or electrodes are at the desired stimulation site. The lead is positioned using a stereotactic instrument, which permits a very precise movement within the brain. Once the lead is positioned and tested to determine that the results of stimulation are satisfactory, it is critical that the lead is not moved, since even a small displacement can result in less than optimal results, and even injury to the brain. Accuracy should be maintained with ±0.5 mm.
The anchoring system of the '446 patent shows a basic anchor for fixing the lead in place with the distal portion extended through the cranial burr hole, and then securing it by bending it into a slit such that it is held by a friction fit. However, the lead must first be removed from the stereotactic instrument, such that this system does not provide a reliable way for accurately securing the lead, or catheter, before it is bent into the fixation position. Thus, such a system does not reliably preclude a small movement of the distal end of the lead at the time of fixating, or securing the lead in place. Rather, it is required that the lead be removed from the stereotactic device before the lead can be fixed to the skull.
In U.S. application Ser. No. 08/705,566, filed Aug. 29, 1996, assigned to the same assignee as this invention, there is shown an apparatus and method wherein a compression screw cap is screwed down onto a compressible seal, the seal being flexible and compressed laterally against the outer wall of the lead. This system provides a substantial improvement over the prior art, and in particular enables securing the lead with respect to the skull before it is stereotactically released. However, it is operative only when the lead is to be positioned in the center of the burr hole. If, however, the target localization procedure indicates that the lead must be inserted off-center, this assembly and the procedure of using it is not adequate; the lead must be bent in order to fix it through the iso-centric burr hole cap, and this bending results in a lead displacement from the stereotactically determined target. There thus remains a need in the art for a reliable system which enables off-center, or eccentric placement of the lead through the burr hole, without requiring stereotactic release of the lead.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a brain treatment system, having a fixation subassembly and procedure for fixing a brain lead off-center, or eccentric from the center axis of the burr hole in the patient's skull. This objective is to be met without stereotactic release of the lead, so that the lead is secured to the patient's brain without displacement of the lead distal end from the stereotactically determined target.
There is provided a system and method for electrical and/or fluid treatment of a patient's brain, having a subsystem for anchoring a lead or a fluid catheter within a cranial burr hole within a patient's skull, wherein the anchoring subsystem has a feed-through burr hole piece, and an adjustable compressive element through which the lead is positioned. The compressible element is movable laterally so that it can be positioned to the required off-center position that has been identified by the target localization procedure. The burr hole feed-through piece contains a radial slit through which the lead passes, the slit further having an upper grooved portion for receiving a compressible O-ring. A compression plate is placed over the O-ring, and pressed down thereupon by a clamping screw, causing compression of the O-ring and radially inward compressive force on the lead outer surface, thereby securing the lead in place with respect to the skull while it is still being stereotactically held. Following fixation by the compressive O-ring, the lead is released from the stereotactic instrument and secured through a burr hole cap, the proximal end of the lead then being connected to an implantable stimulator device or pump.
REFERENCES:
patent: 4328318 (1982-05-01), Ray
patent: 5464446 (1995-11-01), Dreessen et al.
patent: 5843150 (1998-12-01), Dreessen et al.
patent: 5865842 (1999-02-01), Knuth et al.
patent: 5927277 (1999-07-01), Baudino et al.
Medtronic Quad Compact Implant Manual—Model 3887.
Elands W A. J.
Gielen Frans L. H.
Jaro Michael J.
Layno Carl H.
Medtronic Inc.
Patton Harold
Woods Thomas F.
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