Treating back pain and other conditions by electrically stimulating the spinal cord using an electrode array positioned inside the dura

Abstract

This invention provides an device for electrical stimulation of the spinal cord. The device has an electrode assembly with a sufficiently thin profile to be implanted between the pial surface of the spinal cord and the dura mater, and secured to the dura. Electrodes on the electrode assembly are directed towards the surface of the spinal cord, and connected through the dura to a signal generator located outside the dura. Following implantation, the subject is treated by transmitting electrical signals from the signal generator through the leads to the electrodes, stimulating the subject's spinal cord.

The invention claimed is: 
     
         1 . A method for applying an electrical stimulus to a subject in need thereof, comprising:
 implanting a medical device that comprises a plurality of electrodes into the spinal cord of the subject such that the electrodes are positioned between the pial surface of the spinal cord and the dura mater that surrounds the spinal cord,   wherein the device has a sufficiently thin profile such that the electrodes are implanted at said position without obstructing flow of cerebrospinal fluid (CSF) around the spinal cord;   securing the medical device to the dura mater so as to maintain the electrodes at said position;   implanting a signal generator into the subject outside the dura mater;   electrically connecting the signal generator implanted outside the dura with the electrodes of the device positioned inside the dura; and then   applying to the spinal cord of the subject by way of the electrodes in the device said electrical stimulus.   
     
     
         2 . The method of  claim 1 , wherein the implanting includes securing the medical device to the dura mater of the spinal cord by a water-tight dura-traversing lead fitting. 
     
     
         3 . The method of  claim 1 , wherein the implanting includes securing the medical device wherefrom the electrodes are maintained in direct contact with a region of the spinal cord unaffected by movement of the subject. 
     
     
         4 . The method of  claim 1 , wherein the medical device comprises at least 10 electrodes arrayed on a pliable backing. 
     
     
         5 . The method of  claim 1 , wherein the electrical stimulus alternates at a frequency between 2,000 and 20,000 Hz. 
     
     
         6 . A method for preparing a subject in need thereof for electrical stimulation of their spinal cord, the method comprising implanting the subject with the following components:
 (1) an medical device comprising a plurality of electrodes, implanted such that the electrodes are positioned between the pial surface and the dura mater of the spinal cord, wherein the device is secured to the dura mater without tethering the spinal cord to the dura mater;   (2) a signal generator, implanted outside the dura mater; and   (3) a means for electrically connecting the signal generator through the dura mater to the electrodes of the medical device;   wherein the components are configured and implanted such that the signal generator can be activated to transmit an electrical stimulus through the connecting means to the electrodes of the device, thereby electrically stimulating the subject's spinal cord.   
     
     
         7 . A method of electrically stimulating the spinal cord of a subject in need thereof, the method comprising activating the signal generator of a subject implanted with components according to the method of  claim 6 , thereby causing the signal generator to transmit an electrical stimulus through the connecting means to the electrodes of the medical device, thereby electrically stimulating the subject's spinal cord. 
     
     
         8 . The method of  claim 7 , wherein the electrical stimulus alternates at a frequency that causes stochastic depolarization of the spinal cord, thereby inhibiting transmission of synchronous action potentials initiated within the spinal cord. 
     
     
         9 . The method of  claim 6 , wherein the frequency of the electrical stimulus that is applied to the spinal cord of the subject is adjustable. 
     
     
         10 . The method of  claim 7 , further comprising adjusting the frequency of the electrical stimulus that is being applied to the spinal cord of the subject. 
     
     
         11 . The method of  claim 7 , wherein the electrical stimulus alternates at a frequency at or above 500 Hz. 
     
     
         12 . The method of  claim 7 , wherein of the electrical stimulus alternates at a frequency between 2,000 and 20,000 Hz. 
     
     
         13 . The method of  claim 7 , wherein the electrical stimulus varies in a non-uniform pattern or at stochastic intervals. 
     
     
         14 . The method of  claim 6 , wherein the medical device comprises at least 10 electrodes arrayed on a pliable backing. 
     
     
         15 . The method of  claim 6 , wherein prior to the implantation, deleterious nerve signals in the subject's spinal cord cause the subject to experience back pain. 
     
     
         16 . The method of  claim 7 , wherein the electrical stimulus relieves back pain in the subject. 
     
     
         17 . The method of  claim 6 , wherein prior to the implantation, deleterious nerve signals in the subject's spinal cord cause the subject to experience leg pain. 
     
     
         18 . The method of  claim 7 , wherein the electrical stimulus relieves leg pain in the subject. 
     
     
         19 . The method of  claim 6 , wherein prior to the implantation, the subject experiences pain due to Parkinson's disease, spinal cord injury, failed back surgery syndrome, or arthritic degeneration. 
     
     
         20 . The method of  claim 1 , wherein prior to applying the electrical stimulus, the subject experiences back pain due to disc rupture, congestive heart failure, or osteoarthritis.