Method and apparatus for directed propagation of neural stimulation

Abstract

A neural stimulation system delivers neural stimulation to a target nerve with control of direction of propagation of evoked neural signals in one or more fiber types of the target nerve using electrode configuration, thereby providing effective therapy while minimizing unintended effects. In various embodiments, mechanical parameters of a multi-polar electrode are determined to provide directed propagation of the neural stimulation by effecting neural conduction block in or near the stimulation site. In various embodiments, the electrode includes a cathode for evoking action potentials and a plurality of anodes for blocking the propagation of the evoked action potentials in specified direction(s) and fiber type(s) while minimizing the formation of virtual cathodes.

1 . A method for delivering stimulation pulses to a nerve using an electrode having multiple conductive contacts, the method comprising:
 directing an electrical current of the stimulation pulses to the electrode such that the multiple conductive contacts operate as at least a cathode, a first anode, and a second anode, the cathode positioned to allow the stimulation pulses to evoke action potentials in the nerve, the first anode positioned adjacent to the cathode, the second anode including an array of contacts of the multiple conductive contacts and positioned adjacent to the first anode such that the first anode is positioned between the cathode and the second anode.   
     
     
         2 . The method of  claim 1 , further comprising using sizes of the first anode and the second anode to control a distribution of the electrical current in the first anode and the second anode. 
     
     
         3 . The method of  claim 2 , further comprising determining the sizes of the first anode and the second anode to result in uni-directional blocking of propagation of the evoked action potentials in the nerve using the first anode and minimization of formation of a virtual cathode using the second anode. 
     
     
         4 . The method of  claim 3 , wherein delivering the electrical current to the electrode comprises directing the electrical current to the electrode such that the multiple conductive contacts operate as the cathode, the first anode, the second anode, and a third anode, the third anode positioned adjacent to the second anode such that the second anode is between the first anode and the third anode and including another array of contacts of the multiple conductive contacts. 
     
     
         5 . The method of  claim 1 , further comprising providing a nerve cuff electrode as the electrode with the multiple conductive contacts each including a ring electrode configured to encircle the nerve. 
     
     
         6 . A method for delivering stimulation pulses to a nerve using an electrode having multiple conductive contacts, the method comprising:
 configuring and positioning a first conductive contact of the multiple conductive contacts for operating as a cathode for allowing the stimulation pulses to evoke action potentials in the nerve;   configuring and positioning a second conductive contact of the multiple conductive contacts for operating as a first anode;   configuring and positioning a third conductive contact of the multiple conductive contacts for operating as a second anode such that the first anode is positioned between the cathode and the second anode, the second anode configured to include an array of contacts; and   delivering the stimulation pulses to the nerve using the cathode, the first anode, and the second anode.   
     
     
         7 . The method of  claim 6 , further comprising determining mechanical parameters of the electrode, including determining sizes of the first anode and the second anode to control a distribution of a current in the first anode and the second anode to result in uni-directional blocking of propagation of the evoked action potentials in the nerve using the first anode and minimization of formation of a virtual cathode using the second anode. 
     
     
         8 . The method of  claim 7 , wherein determining the mechanical parameters of the electrode comprises:
 providing an initial amount of blocking current to the first anode, the blocking current flowing from the cathode to the first anode;   providing an initial amount of flanking current to the second anode, the flanking current flowing from the cathode to the first anode; and   adjusting geometrical parameters of the cathode, the first anode, and the second anode in response to the neural conduction block not being effected.   
     
     
         9 . The method of  claim 8 , further comprising forming the first anode and the second anode using a single conductor. 
     
     
         10 . The method of  claim 6 , further comprising configuring and positioning a fourth conductive contact of the multiple conductive contacts for operating as a third anode such that such that the second anode is positioned between the first anode and the third anode, the third anode configured to include another array of contacts and positioned between the first conductive contact and the third conductive contact, the third anode configured to include another array of contacts. 
     
     
         11 . The method of  claim 10 , further comprising determining mechanical parameters of the electrode, including determining sizes of the first anode, the second anode, and the third anode to control a distribution of a current in the first anode, the second anode, and the third anode to result in uni-directional blocking of propagation of the evoked action potentials in the nerve using the first anode and minimization of formation of a virtual cathode using the second anode and the third anode. 
     
     
         12 . The method of  claim 11 , further comprising forming the first anode, the second anode, and the third using a single conductor. 
     
     
         13 . The method of  claim 6 , further comprising providing a nerve cuff electrode as the electrode, and configuring each of the multiple conductive contacts to be a ring electrode encircling the nerve. 
     
     
         14 . The method of  claim 13 , further comprising forming the first anode and the second anode, including:
 providing a cuff substrate including a self-curling sheet configured to be wrapped around a portion of the nerve;   providing a conductive sheet on a portion of the cuff substrate; and   providing an insulation sheet over the conductive sheet, the insulation sheet including openings exposing portions of the conductive sheets to form the first anode and the second anode, the openings including an array of openings to form the second anode including the array of contacts.   
     
     
         15 . A system for delivering stimulation pulses from one or more output channels of a stimulator to a nerve at a stimulation site, comprising:
 an electrode configured to allow pulses of the stimulation pulses from a channel of the one or more channels to be delivered to the nerve and to control a distribution of an electrical current in the nerve resulting from the delivered pulses, the electrode including:
 a first conductive contact configured for operating as a cathode for allowing the electrical stimulation pulses to evoke action potentials in the nerve; 
 a second conductive contact positioned adjacent to the first conductive contact and configured for operating as a first anode; and 
 a third conductive contact positioned adjacent to the second conductive contact such that the second conductive contact is positioned between the first conductive contact and the third conductive contact, the third conductive contact configured for operating as a second anode and including an array of contacts. 
   
     
     
         16 . The system of  claim 15 , wherein the first anode and the second have sizes determined for minimizing of formation of a virtual cathode. 
     
     
         17 . The system of  claim 15 , wherein the first anode and the second anode have sizes each determined to control a distribution of the electrical current in the first anode and the second anode to result in uni-directional blocking of propagation of the evoked action potentials in the nerve using the first anode and minimization of formation of a virtual cathode using the second anode. 
     
     
         18 . The system of  claim 17 , wherein the first anode and the second anode are formed using a single conductor. 
     
     
         19 . The system of  claim 18 , wherein the electrode further comprises a fourth conductive contact positioned adjacent to the third conductive contact such that the third conductive contact is positioned between the second conductive contact and the fourth conductive contact, the fourth conductive contact configured for operating as a third anode and including another array of contacts, the first anode, the second anode, and the third anode are formed using the single conductor. 
     
     
         20 . The system of  claim 15 , wherein the electrode comprises a nerve cuff electrode including:
 a cuff substrate including a self-curling sheet configured to be wrapped around a portion of the nerve;   the cathode, the first anode, and the second anode each formed on the cuff substrate and including a ring electrode configured to encircle the nerve.