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United States Patent  [in Patent Number: 4,590,949
Pohndorf  Date of Patent: May 27, 1986
U.S. Patent May27,1986 Sheet 1 of2 4,590,949
 NEURAL STIMULATING LEAD WITH
STABILIZING MECHANISM AND METHOD
FOR USING SAME
 Inventor: Peter J. Pohndorf, Miami Shores, Fla.
 Assignee: Cordis Corporation, Miami, Fla.
 Appl. No.: 667,228
 Filed: Nov. 1, 1984
 Int. CI.* A61N 1/04
 U.S. CI 128/785
 Field of Search 128/784, 785, 786
 References Cited
U.S. PATENT DOCUMENTS
2,022,065 11/1935 Wappler 174/89
3,516,412 6/1970 Ackerman 128/418
3,754,555 8/1973 Schmitt 128/785
3,814,104 6/1974 Imich et al 128/418
3,835,864 9/1974 Rasor et al 129/419 P
3,844,292 10/1974 Bolduc 128/418
3,902,501 9/1975 Citron et al 128/418
3,976,082 8/1976 Schmitt 128/418
4,033,357 7/1977 Helland et al 128/418
4,057,067 11/1977 Lajos 128/418
4,217,913 8/1980 Dutcher 128/785
4,236,529 12/1980 Little 128/785
4,257,428 3/1981 Barton et al 128/785
4,269,198 5/1981 Stokes 128/785
4,285,347 8/1981 Hess 128/785
4,374,527 2/1983 Iversen 128/786
4,409,994 10/1983 Doring 128/785
4,414,983 11/1983 Dickhudt et al 128/785
4,419,819 12/1983 Dickhudt et al 128/785
Primary Examiner—William E. Kamm
Attorney, Agent, or Firm—Henry W. Collins; Thomas R.
A neural stimulating lead including a stabilizing mechanism. The stabilizing mechanism comprises two pairs of parallel laterally projecting vanes and an extendible tine adapted to be extended to apply pressure against a dorsal surface of a vertebrum to force and hold an electrode assembly of the neural stimulating lead against a spinal cord. The tine is extendible through a port in the electrode surface from a retracted position within the lead body to an extended position by pulling on an actuating cable which is attached at one end to the tine and which has its other end extending from a connector portion on a proximal end of the lead.
20 Claims, 8 Drawing Figures
NEURAL STIMULATING LEAD WITH STABILIZING MECHANISM AND METHOD FOR USING SAME
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a neural stimulating lead including a stabilizing mechanism. More specifically, tne present invention relates to a stimulating lead incuding a stabilizing mechanism which is adapted for movement within an epidural space of a vertebrum to stabilize the positioning of an electrode of the lead at a desired location along the spinal cord traversing the vertebrae of the spine.
2. Description of the Prior Art
Heretofore, stimulating leads for use in spinal cord stimulation have had a tendency to migrate after placement. The migration has a considerable effect on stimulation no matter how miniscule the migration is. In this 20 - respect, migration of a stimulating lead will lead to poor electrical contact of the electrode with the spinal cord or will lead to stimulation of an improper area of the spinal cord which will negate the effect required, such as stimulation of a precise area to alleviate pain.
To overcome such migration, various solutions have been proposed, such as, for example, button electrodes for S-shaped leads. Examples of some of these proposed solutions are disclosed in the following U.S. Patents:
The Ackerman U.S. Pat. No. 3,516,412 discloses a bipolar electrode which is fed through a needle to a desired point of lodgement and, when the needle is withdrawn, the electrode end bends to an angle of up to 90° C. to provide secure placement of a tip of the electrode against tissue.
The Hess U.S. Pat. No. 4,285,347 discloses a neural electrode lead with stabilizing structure. The stabilizing structure here is in the form of lateral expandable loop elements.
The Dickhudt et al. U.S. Pat. No. 4,414,986 discloses 40 a biomedical stimulation lead which has perpendicularly extending tines located at a tip of a lead body. Further, the lead body, proximal to the electrode, is provided with a helical configuration to add another stabilizing element which stabilizes the electrode during 45 the period immediately after implantation.
The Dickhudt et al. U.S. Pat. No. 4,419,819 discloses a biomedical lead with lobed lead anchor. The anchor comprises a sleeve which is slit in a direction parallel to the axis of the lead body and when the tubing is compressed, the slit portions expand into lobes to stabilize the position of a lead electrode therein.
As will be described in greater detail hereinafter, the lead of the present invention includes a stabilizing mechanism which comprises a tine that is movable from a retracted position to an extended position for securing an electrode against spinal cord tissue. Further, the tine is retractable when it is desired to remove the lead.
an active fixation stabilizng mechanism situated in said distal end portion and comprising stiff, but flexible, laterally projecting, vertebrum engaging means and extendable/retractable, dorsal stabilizing means comprising a stiff, but flexible, elongate member which has a proximal inner end and a distal, free end and which is movable transversely of said vertebrum engaging means through said port between a retracted position and an extended position where said free end bears against a dorsal wall of a vertebrum for anchoring said lead within an epidural space of a vertebrum of a spine, said elongate member being positioned entirely within the hollow lead body in its retracted state, and being extendible outwardly from its position within the hollow lead body through said port.
Further according to the invention there is provided a method of using a neural stimulating lead with an active fixation stabilizing mechanism comprising the steps of: feeding a lead comprising a hollow lead body having a proximal end and a distal end portion which has a side port therein, a distal electrode assembly mounted in said distal end portion and including a sleeve electrode, a stimulator connector mounted at said proximal end of said lead body, a wire conductor connected between said sleeve electrode and said stimulator connector and an active fixation stabilizing mechanism situated in said distal end portion and comprising, stiff but flexible, laterally projecting, vertebrum engaging means and extendable/retractable, dorsal stabilizing means comprising a stiff, but flexible, elongate member which has a proximal inner end and a distal end and which is movable transversely of said vertebrum engaging means through said port between a retracted position and an extended position where said free end bears against a dorsal wall of a vertebrum for anchoring said lead within an epidural space of a vertebrum of a spine, said elongate member being positioned entirely within the hollow lead body in its retracted state, and being extendible outwardly from its position within the hollow lead body through said port, through an incision and into an epidural space of foramen of a vertebrum in such a manner that said laterally extending vertebrum engaging means lie in a horizontal plane when a patient is supine and such that said elongate member can be moved upwardly within the foramen; positioning said sleeve electrode in a proper position; and once said sleeve electrode is positioned, moving said elongate member an appropriate distance upwardly and outwardly of said lead body to place the distal free end of said elongate member at a position where said distal end engages and anchors itself against a dorsal wall of the vertebrum within which is it positioned.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of the lead including stabilizing mechanism of the present invention therein with portions broken away.
FIG. 2 is a side perspective view of the lead shown in FIG. 1 with portions broken away and shows a doral tine of the stabilizing mechanism in an extended position.
FIG. 3 is a radial sectional view of the lead shown in FIG. 2 and is taken along line 3—3 of FIG. 2.
FIG. 4 is an axial cross-sectional view of a distal portion of the lead shown in FIG. 3, is taken along line 4—4 of FIG. 3 and shows the dorsal tine in its extended position.