Systems and methods for reversibly blocking nerve activity

Abstract

Systems and methods for blocking nerve impulses use an implanted electrode located on or around a nerve. A specific waveform is used that causes the nerve membrane to become incapable of transmitting an action potential. The membrane is only affected underneath the electrode, and the effect is immediately and completely reversible. The waveform has a low amplitude and can be charge balanced, with a high likelihood of being safe to the nerve for chronic conditions. It is possible to selectively block larger (motor) nerve fibers within a mixed nerve, while allowing sensory information to travel through unaffected nerve fibers.

The invention claimed is: 
     
       1. A method for selectively blocking activity of a nerve in an animal by application of an electric current, said method comprising: generating an electrical waveform having a first phase with a first polarity, a first duration, and a first amplitude, that produces subthreshold depolarization of the nerve membrane and a second phase after the first phase that has a second polarity, a second duration, and a second amplitude; and applying the waveform to a targeted nerve region, wherein the phases of said waveform are delivered at a rate of at least 5 kilohertz (kHz), and the ratio of the amplitude of the second phase to the amplitude of the first phase is about 1:1 to about 1:5. 
     
     
       2. The method as set forth in  claim 1 , wherein said first and second phases are charge balanced. 
     
     
       3. The method as set forth in  claim 1 , wherein said pulses of said waveform are delivered at a rate of between about 5 kilohertz (kHz) and 10 kilohertz (kHz) inclusive. 
     
     
       4. The method as set forth in  claim 1 , wherein said second amplitude is greater than said first amplitude. 
     
     
       5. The method as set forth in  claim 1 , wherein said second duration is less than said first duration. 
     
     
       6. The method as set forth in  claim 1 , wherein at least one of said first and second amplitude are increased over time to block conduction of said action potential in progressively smaller nerve fibers. 
     
     
       7. The method as set forth in  claim 1 , wherein the first amplitude is about 0 to 1 milliamps. 
     
     
       8. A method for selectively blocking conduction of an action potential in a nerve of an animal such as a human, said method comprising: delivering an electrical waveform to a nerve, said waveform comprising a series of bi-phasic pulses that, when applied to said nerve, block conduction of an action potential by said nerve, wherein said nerve comprises h gates and m gates and wherein said bi-phasic pulses of said waveform close said h gates and said m gates sufficiently to block said nerve from conducting said action potential, wherein each pulse of said electrical waveform comprises: a first phase having a first polarity, a first duration and a first amplitude, said first amplitude less than an activation threshold of said nerve; and, a second phase having a second polarity, a second duration and a second amplitude, wherein the pulses of said waveform are delivered at a rate of at least 5 kilohertz (kHz), and the ratio of the amplitude of the second phase to the amplitude of the first phase is about 1:1 to about 1:5. 
     
     
       9. The method as set forth in  claim 8 , wherein said second amplitude is greater than said first amplitude. 
     
     
       10. The method as set forth in  claim 8 , wherein said second duration is less than said first duration. 
     
     
       11. The method as set forth in  claim 8 , wherein said pulses of said waveform are delivered at a rate of between about 5 kilohertz (kHz) and 10 kilohertz (kHz) inclusive. 
     
     
       12. The method as set forth in  claim 8 , wherein at least one of said first and second amplitude are increased over time to block conduction of said action potential in progressively smaller nerve fibers. 
     
     
       13. The method as set forth in  claim 8 , further comprising: monitoring at least one of electroneurogram (ENG) activity and electromyogram (EMG) activity of the animal of which said nerve is a part; and, using said at least one of said electroneurogram and electromyogram activity to derive said waveform. 
     
     
       14. The method as set forth in  claim 8 , wherein said first phase is cathodic and the second phase is anodic. 
     
     
       15. A method, comprising:
 generating a steady state electrical waveform,   where the steady state electrical waveform has a first phase having a first polarity, a first duration, and a first amplitude, the first phase being a cathodic, depolarizing phase configured to depolarize a nerve,   where the steady state electrical waveform has a second phase having a second polarity, a second duration, and a second amplitude, the second phase being an anodic, repolarizing phase configured to repolarize the nerve,   where the ratio of the first amplitude to the second amplitude is 1:1 to 1:5,   where each of the first phase and the second phase has a frequency in the range of 5 kiloHertz (KHz) up to 10 KHz, and   applying an electric current to the nerve in an animal according to the steady state waveform, where applying the electric current comprises:   selectively, repetitively, alternately applying the first phase of the steady state electrical waveform to the nerve and then applying the second phase of the steady state electrical waveform to the nerve for a period of time sufficient to arrest signal transmission through the nerve, and   arresting signal transmission in progressively smaller nerve fibers in the nerve by altering, over time, at least one of the first amplitude and the second amplitude.    
     
     
       16. The method of claim 15, where the first amplitude is about 0 milliamps to 1 milliamps.  
     
     
       17. A method, comprising:
 selectively blocking conduction of an action potential in a nerve in an animal by selectively, repetitively delivering a series of bi-phasic pulses to the nerve,   where a member of the series of the bi-phasic pulses has a first phase and a second phase, the first phase having a first polarity, a first duration, and a first amplitude, the first phase being a cathodic, depolarizing phase,   the second phase having a second polarity, a second duration, and a second amplitude, the second phase being an anodic, repolarizing phase,   each of the first phase and the second phase being delivered at a frequency in the range of at least 5 KHz up to 10 KHz,   where the ratio of the first amplitude to the second amplitude is 1:1 to 1:5, and   selectively blocking conduction of action potentials in progressively smaller nerve fibers in the nerve by altering, over a period of time, one or more of the first amplitude and the second amplitude.    
     
     
       18. The method of claim 17, where the first duration is greater than the second duration.  
     
     
       19. The method of claim 17, comprising:
 acquiring, from the animal, one or more of, electroneurogram (ENG) data, and electromyogram (EMG) data; and   configuring the electrical waveform as a function of one or more of, the ENG data, and the EMG data.    
     
     
       20. The method of claim 17, where selectively blocking conduction of the action potential down regulates neural activity in the animal.  
     
     
       21. The method of claim 20, comprising down regulating neural activity in an amount sufficient to treat a disease or condition.  
     
     
       22. The method of claim 21, the disease or condition being one of, neuroma, spasticity, and muscle spasms.  
     
     
       23. A method, comprising:
 selectively blocking conduction of an action potential in a nerve in an animal by selectively, repetitively delivering a series of bi-phasic pulses to the nerve,   where a member of the series of the bi-phasic pulses has a first phase and a second phase, the first phase having a first polarity, a first duration, and a first amplitude, the first phase being a cathodic, depolarizing phase,   the second phase having a second polarity, a second duration, and a second amplitude, the second phase being an anodic, repolarizing phase,   each of the first phase and the second phase being delivered at a frequency in the range of at least 5 KHz up to 10 KHz,   where the ratio of the first amplitude to the second amplitude is 1:1 to 1:5, and   where the first duration is greater than the second duration.