Apparatus and methods for applying neural stimulation to a patient

Abstract

Systems and methods for neural stimulation may include a stimulus unit; a first electrode assembly having a first set of contacts; and a second set of contacts. The stimulus unit can be an implantable pulse generator including a first terminal that can be biased at a first signal polarity and a second terminal that can be biased at a second signal polarity. The first electrode assembly includes a support member configured to be placed at the stimulation site, the first set of contacts carried by the support member, and a first lead configured to be attached to the first terminal of the implantable pulse generator for biasing the surface contacts at the first polarity. The second set of contacts is detached from the surface electrode assembly. The second set of contacts can be one or more conductive elements fixed to or forming portions of the implantable pulse generator, or a separate electrode array.

1 - 75 . (canceled)  
     
     
         76 . A system for applying electrical stimulation to a cortex of a patient, comprising: 
 an implantable housing having a first portion and a second portion;    a pulse generator carried by the implantable housing;    a plurality of first electrical contacts carried by the first portion of the housing so as to be positioned at a cortical stimulation site of the patient located at least approximately at or below an inner surface of the patient's skull when the housing is implanted, the first electrical contacts being generally fixed laterally relative to the first portion of the housing, and electrically biasable to different levels; and    at least one second electrical contact carried by the second portion of the housing so as to be positioned at least approximately at or above an outer surface of the patient's skull and beneath the patient's scalp when the housing is implanted.    
     
     
         77 . The system of  claim 76  wherein the first and second portions of the housing face in generally opposite directions.  
     
     
         78 . The system of  claim 76  wherein at least one of the first electrical contacts is fixed in a direction generally normal to the first portion of the housing.  
     
     
         79 . The device of  claim 76  wherein at least one of the first electrical contacts is movable in a direction generally normal to the housing to apply a force to adjacent tissue when the housing is implanted.  
     
     
         80 . The device of  claim 76  wherein the housing includes a forcing element to which at least one of the first electrical contacts is coupled, the forcing element being positioned to apply a force to the first electrical contact in a direction generally normal to the housing.  
     
     
         81 . The system of  claim 76  wherein the at least one second electrical contact includes multiple second electrical contacts that have generally fixed lateral positions relative to the housing.  
     
     
         82 . The system of  claim 76  wherein the first portion of the housing includes a first surface and the second portion of the housing includes a second, oppositely facing surface, and wherein the first electrical contacts are accessible from the first surface and the second electrical contacts are accessible from the second surface.  
     
     
         83 . The system of  claim 76 , further comprising an attachment element carried by the housing and attachable to the skull.  
     
     
         84 . The system of  claim 76  wherein the pulse generator is programmed to provide electrical signals at subthreshold levels.  
     
     
         85 . The system of  claim 76  wherein the first electrical contacts project from the housing in a direction generally normal to the housing.  
     
     
         86 . The system of  claim 76 , further comprising a switching circuit having at least one switch coupled to the pulse generator and among the first electrical contacts to apply electrical power to a subset of one or more selected first electrical contacts.  
     
     
         87 . The system of  claim 76  wherein the switching circuit is coupled to the second electrical contact and is changeable between a first configuration in which a pair of the first electrical contacts operate in a bipolar manner, and a second configuration in which the second electrical contact and one of the first electrical contacts operate in a unipolar manner.  
     
     
         88 . The device of  claim 76  wherein at least one of the first electrical contacts has a generally blunt shape and is positioned to bear against at least one of a dura mater and a pia mater of the patient.  
     
     
         89 . A system for applying electrical stimulation to a cortex of a patient, comprising: 
 an implantable housing having a first portion and a second portion;    a pulse generator carried by the implantable housing;    a first electrical contact carried by the first portion of the housing so as to be positioned at a cortical stimulation site of the patient located at least approximately at or below an inner surface of the patient's skull when the housing is implanted, the first electrical contact being generally fixed laterally relative to the first portion of the housing; and    a second electrical contact carried by the second portion of the housing so as to be positioned at least approximately at or above an outer surface of the patient's skull and beneath the patient's scalp when the housing is implanted.    
     
     
         90 . The system of  claim 89  wherein the first and second electrical contacts are electrically biasable to different levels.  
     
     
         91 . The system of  claim 89  wherein the first electrical contact is one of a plurality of first electrical contacts.  
     
     
         92 . The system of  claim 89  wherein the first and second portions of the housing face in generally opposite directions.  
     
     
         93 . The system of  claim 89  wherein at least one of the first electrical contacts is fixed in a direction generally normal to the first portion of the housing.  
     
     
         94 . The system of  claim 89  wherein the second electrical contact is one of multiple second electrical contacts that have generally fixed lateral positions relative to the housing.  
     
     
         95 . The device of  claim 89  wherein the first electrical contact is movable in a direction generally normal to the housing to apply a force to adjacent tissue when the housing is implanted.  
     
     
         96 . The device of  claim 89  wherein the housing includes a forcing element to which at least one of the first electrical contacts is coupled, the forcing element being positioned to apply a force to the first electrical contact in a direction generally normal to the housing.  
     
     
         97 . The system of  claim 89  wherein the first portion of the housing includes a first surface and the second portion of the housing includes a second, oppositely facing surface, and wherein the first electrical contacts are accessible from the first surface and the second electrical contacts are accessible from the second surface.  
     
     
         98 . The system of  claim 89 , further comprising an attachment element carried by the housing and attachable to the skull.  
     
     
         99 . The system of  claim 89  wherein the pulse generator is programmed to provide electrical signals at subthreshold levels.  
     
     
         100 . The system of  claim 89  wherein the first electrical contact projects from the housing in a direction generally normal to the housing.  
     
     
         101 . The system of  claim 89  wherein the first electrical contact is one of a plurality of first electrical contacts, and wherein the system further comprises a switching circuit having a at least one switch coupled to the pulse generator and among the first electrical contacts to apply electrical power to a subset of one or more selected first electrical contacts.  
     
     
         102 . The system of  claim 89  wherein the switching circuit is coupled to the second electrical contact and is changeable between a first configuration in which a pair of the first electrical contacts operate in a bipolar manner, and a second configuration in which the second electrical contact and one of the first electrical contacts operate in a unipolar manner.  
     
     
         103 . The device of  claim 89  wherein at least one of the first electrical contacts has a generally blunt shape and is positioned to bear against at least one of a dura mater and a pia mater of the patient.  
     
     
         104 . A system for applying electrical stimulation to a cortex of a patient, comprising: 
 an implantable housing;    a pulse generator carried by the implantable housing;    a first electrical contact electrically coupled to the pulse generator so as to be positioned at a cortical stimulation site of the patient located at least approximately at or below an inner surface of the patient's skull when the housing is implanted; and    a second electrical contact carried by the housing and having a fixed position relative to the housing so as to be positioned at least approximately at or above an outer surface of the patient's skull and beneath the patient's scalp when the housing is implanted.    
     
     
         105 . The system of  claim 104  wherein the first electrical contact is coupled to a lead and is laterally movable relative to the housing.  
     
     
         106 . The system of  claim 104  wherein the first electrical contact includes a plurality of first electrical contacts that are electrically biasable to different levels.  
     
     
         107 . The system of  claim 104  wherein the first electrical contact is generally fixed laterally relative to the housing.  
     
     
         108 . The system of  claim 104  wherein the first and second electrical contacts are electrically biasable to different levels.  
     
     
         109 . The device of  claim 104  wherein the first electrical contact is movable in a direction generally normal to the housing to apply a force to adjacent tissue when the housing is implanted.  
     
     
         110 . The device of  claim 104  wherein the housing includes a forcing element to which the first electrical contact is coupled, the forcing element being positioned to apply a force to the first electrical contact in a direction generally normal to the housing.  
     
     
         111 . The system of  claim 104  wherein the at least one second electrical contact includes multiple second electrical contacts that have generally fixed lateral positions relative to the housing.  
     
     
         112 . The system of  claim 104 , further comprising an attachment element carried by the housing and attachable to the skull.  
     
     
         113 . The system of  claim 104  wherein the pulse generator is programmed to provide electrical signals at subthreshold levels.  
     
     
         114 . The device of  claim 104  wherein the first electrical contact has a generally blunt shape and is positioned to bear against at least one of a dura mater and a pia mater of the patient.  
     
     
         115 . A method for implanting a cortical stimulation device, comprising: 
 providing an implantable housing carrying a pulse generator, the pulse generator being electrically coupled to a first electrical contact, the housing carrying a second electrical contact;    forming a hole in a patient's skull;    moving the first electrical contact into the hole and positioning the first electrical contact at a cortical stimulation site of the patient located at least approximately at or below an inner surface of the patient's skull; and    placing the implantable housing in the hole so as to position the second electrode at least approximately at or above an outer surface of the patient's skull and beneath the patient's scalp, with the second electrode having a fixed position relative to the housing.    
     
     
         116 . The method of  claim 115  wherein forming a hole in the patient's skull includes forming the hole to extend through the patient's skull.  
     
     
         117 . The method of  claim 115  wherein placing the implantable housing includes placing the implantable housing while the first electrical contact has a laterally fixed position relative to the housing, and wherein moving the first electrical contact into the hole and placing the implantable housing in the hole are performed simultaneously.  
     
     
         118 . The method of  claim 115  wherein moving the first electrical contact includes moving the first electrical contact while the first electrical contact is connected to the housing with a flexible lead.  
     
     
         119 . The method of  claim 115 , further comprising applying a subthreshold stimulation signal to the patient via the first electrical contact.