Field augmented current steering using voltage sources

Abstract

A neurostimulation comprises a plurality of electrical terminals configured for being respectively coupled to an array of electrodes, at least three configurable sources respectively coupled to at least three of the electrical terminals, and control circuitry configured for programming each of the at least three configurable sources to be either a current source or a voltage source. A method of providing neurostimulation therapy to a patient using an array of electrodes implanted adjacent neural tissue of the patient, comprises conveying electrical stimulation energy between a first one the electrodes and a second one of the electrodes, thereby creating an electrical field potential within the neural tissue, regulating a first current flowing through the first electrode, and regulating a first voltage at a third different one of the electrodes, thereby modifying a shape of the electrical field potential within the neural tissue.

1 . (canceled) 
     
     
         2 . A neurostimulation system, comprising:
 at least one lead to provide an array of electrodes;   a plurality of electrical terminals configured to be electrically connected to the array of electrodes via the at least one lead;   independent sources including independent current sources and independent voltage sources; and   control circuitry configured to connect the independent sources to select ones of the plurality of electrodes to both regulate current flow to provide an electric field with a shape and regulate voltage to further shape the electric field.   
     
     
         3 . The neurostimulation system of  claim 2 , wherein each of the independent sources include a current source and a voltage source, and each of the independent sources are capable of being programmed to operate as the current source and being capable of being programmed to operate as the voltage source. 
     
     
         4 . The neurostimulation system of  claim 3 , wherein the control circuitry is configured to program at least one of the independent sources to operate as a current source and to connect the current source to at least one electrode in the array of electrodes to generate a current distribution in neural tissue and program at least one other independent source to operate as a voltage source and to connect the voltage source to at least one other electrode in the array of electrodes to shape the current distribution. 
     
     
         5 . The neurostimulation system of  claim 4 , further comprising monitoring circuitry configured for measuring compliance voltages on electrical terminals to which the positive and negative current sources are coupled, and the control circuitry is configured for assigning a voltage value to the voltage source that is between the compliance voltages on the electrical terminals. 
     
     
         6 . The neurostimulation system of  claim 4 , wherein the control circuitry is further configured for selecting stimulation magnitude values for the current source and the voltage source. 
     
     
         7 . The neurostimulation system of  claim 2 , wherein the control circuitry is configured for programming one of the independent sources as a positive current source, one of the independent sources as a negative current source, and one of the independent sources as a voltage source. 
     
     
         8 . The neurostimulation system of  claim 2 , wherein the independent sources comprise at least four independent sources. 
     
     
         9 . The neurostimulation system of  claim 2 , wherein the independent sources comprise five independent sources, wherein the system is configured to program three of the five independent sources as current sources and to connect them to the plurality of electrodes to provide a current-regulated rostro-caudal anode guarded tripole, and the system is configured to program two of the five independent sources as voltage sources and to connect them to the plurality of electrodes to provide two voltage-regulated media-lateral flanking electrodes. 
     
     
         10 . A neurostimulation system, comprising:
 at least one lead to provide an array of electrodes;   a plurality of electrical terminals configured to be electrically connected to the array of electrodes via the at least one lead;   independent sources including independent current sources and independent voltage sources; and   control circuitry configured to connect the independent sources to select ones of the plurality of electrodes to provide a current-regulated tripole to provide an electric field with a shape and voltage regulated flanking electrodes to further shape the electric field.   
     
     
         11 . The neurostimulation system of  claim 10 , wherein each of the independent sources include a current source and a voltage source, and each of the independent sources are capable of being programmed to operate as the current source and being capable of being programmed to operate as the voltage source. 
     
     
         12 . The neurostimulation system of  claim 11 , wherein the control circuitry is configured to program at least one of the independent sources to operate as a current source and to connect the current source to at least one electrode in the tripole to generate a current distribution in neural tissue and program at least one other independent source to operate as a voltage source and to connect the voltage source to at least one flanking electrode separate from the tripole to shape the current distribution. 
     
     
         13 . The neurostimulation system of  claim 12 , further comprising monitoring circuitry configured for measuring compliance voltages on the at least one flanking electrode separate from the tripole, and wherein the control circuitry is configured to assign a voltage value to the voltage source that is between the compliance voltages on the electrical terminals. 
     
     
         14 . The neurostimulation system of  claim 10 , wherein the control circuitry is configured to provide and shape the field to stimulate targeted spinal cord tissue and avoid non-targeted spinal cord tissue. 
     
     
         15 . A method comprising:
 applying an electric field to stimulate targeted tissue and avoid non-targeted tissue, including creating the electric field with a shape using a current-regulated tripole, and further shaping the electric field using voltage-regulated flanking electrodes.   
     
     
         16 . The method of  claim 15 , further comprising delivering a current from at least one flanking electrode of the tripole to a central electrode of the tripole. 
     
     
         17 . The method of  claim 16 , further comprising applying a voltage to at least one flanking electrode separate from the tripole. 
     
     
         18 . The method of  claim 17 , wherein the voltage applied to at least one flanking electrode separate from the tripole is between compliance voltages on the flanking electrode of the tripole and the central electrode of the tripole. 
     
     
         19 . The method of  claim 15 , further comprising coupling a programmable current source to the at least one flanking electrode of the tripole and the central electrode of the tripole and programming the current source to deliver the current from the at least one flanking electrode of the tripole to the central electrode of the tripole. 
     
     
         20 . The method of  claim 16 , further comprising coupling a programmable voltage source to the at least one flanking electrode separate from the tripole and programming the voltage source to deliver the voltage to the at least one flanking electrode separate from the tripole. 
     
     
         21 . The method of  claim 14 , wherein the targeted tissue includes spinal cord tissue and the non-targeted tissue includes other spinal cord tissue.