Stimulation lead, stimulation system, and method for limiting mri-induced current in a stimulation lead

Abstract

In one embodiment, a stimulation lead for delivering electrical pulses from a pulse generator to tissue of a patient, comprises: a plurality of electrodes; a plurality of terminals; a plurality of conductors electrically coupling the plurality of electrodes with the plurality of terminals; a lead body of insulative material for enclosing the plurality of conductors; and at least one magnetic-field actuated switch for limiting MRI-induced current between the plurality of electrodes and the plurality of terminals, wherein the magnetic-field actuated switch is actuated by magnetostrictive material.

1 . An implantable pulse generator for generating electrical pulses to stimulate tissue of a patient, comprising:
 pulse generating circuitry for generating electrical pulses;   output circuitry for coupling electrical pulses from the pulse generating circuitry to output contacts adapted for electrical coupling to terminal contacts of one or more stimulation leads; and   at least one magnetic-field actuated switch for modifying one or more circuit paths between the pulse generating circuitry and the output contacts to limit MRI-induced current between the pulse generating circuitry and the output contacts, wherein the magnetic-field actuated switch is actuated by magnetostrictive material.   
     
     
         2 . The implantable pulse generator of  claim 1  wherein the magnetic-field actuated switch controls a resistance, inductance, or capacitance within the circuit path. 
     
     
         3 . The implantable pulse generator of  claim 1  wherein the magnetic-field actuated switch creates an open-circuit condition for the circuit path. 
     
     
         4 . The implantable pulse generator of  claim 1  wherein the magnetic-field actuated switch is disposed within a header of the implantable pulse generator and mechanically separates the output contacts electrical coupling with the output circuitry. 
     
     
         5 . The implantable pulse generator of  claim 1  wherein the magnetostrictive material is a terbium, iron, and dysprosium alloy. 
     
     
         6 . The implantable pulse generator of  claim 1  wherein the magnetostrictive material deforms a piezoelectric material to generate a voltage that in turn controls an electronic circuit, and the magnetic-field actuated switch is controlled in response to the voltage from the piezoelectric element. 
     
     
         7 . An implantable extension connector for connecting an implantable stimulation lead to an implantable extension lead, comprising:
 an extension body adapted to receive the stimulation lead and the implantable extension lead;   a first set of electrical contacts within the extension body for electrically coupling to terminals of the stimulation lead;   a second set of electrical contacts within the extension body for electrically coupling to electrodes of the extension lead;   at least one magnetic-field actuated switch for limiting MRI-induced current between the first and second sets of electrical contacts, wherein the magnetic-field actuated switch is actuated by magnetostrictive material.