Nerve Stimulator and Method

Abstract

This invention presents a device, and the method it implements, which is an improvement in the design of nerve stimulators. Like conventional stimulators, it uses a percutaneous, insulated needle for the performance of therapeutic interventions targeting nerves. The improvement comprises offering an option for either constant current or constant voltage, offering a choice of waveform parameters, controlling a pulse generator, supplying a second background waveform, measuring the current and voltage applied to the tissue, computing further electrical characteristics, dynamically adjusting circuit components to ensure a desirable waveform applied to the tissue, and displaying measured and computed electrical characteristics of the tissue. The object is improved positioning of a needle tip near a nerve or nerve plexus for regional anesthesia, pain management, and other medical purposes.

1 . A system for nerve stimulation via an insulated needle for the performance of therapeutic interventions targeting nerves within tissue, comprising: 
 a needle electrode with an exterior surface which includes an electrical insulator except near a tip of the needle electrode, wherein the electrical insulator is configured so as to electrically insulate the needle electrode from tissue except at the tip of the needle electrode when the needle electrode is inserted in tissue;    a return electrode;    an electrical sensor coupled to the needle electrode and return electrode, the electrical sensor configured to sense electrical properties of a circuit formed between the needle electrode and return electrode when the needle electrode and return electrode are applied to tissue; and    a processor coupled to the electrical sensor, the processor configured to calculate waveform characteristics from the sensed electrical properties measurements and, based on the calculated waveform characteristics, adjust characteristics of electrical signals applied to the needle electrode and return electrode so as to produce a desired waveform in the circuit formed between the needle electrode and return electrode.    
   
   
       2 . The system according to  claim 1 , further comprising a pulse conditioning circuit electrically coupled to the needle electrode and return electrode, the pulse conditioning circuit configured to adjust electrical characteristics of the circuit formed between the needle electrode and return electrode in response to control signals received from the processor.  
   
   
       3 . The system according to  claim 2 , wherein the pulse conditioning circuit comprises: 
 an adjustable resistor; and    an adjustable capacitor electrically coupled in parallel with the adjustable resistor.    
   
   
       4 . The system according to  claim 2 , further comprising a first pulse generator coupled to the pulse conditioning circuit and to the circuit formed between the needle electrode and return electrode.  
   
   
       5 . The system according to  claim 1 , further comprising: 
 a first pulse generator;    a second pulse generator; and    a switch electrically coupled to the first and second pulse generators, the needle electrode and the return electrode, wherein the switch is configured to complete a circuit formed between the needle electrode and return electrode through either the first pulse generator or the second pulse generator in response to a control signal received from the processor.    
   
   
       6 . The system according to  claim 5 , further comprising a pulse conditioning circuit electrically coupled to the first pulse generator and configured to adjust electrical characteristics of the circuit formed between the needle electrode and return electrode in response to control signals received from the processor.  
   
   
       7 . The system according to  claim 6 , wherein the first pulse generator is configured to receive control signals from the processor and, in response to the control signals, produce pulses with particular waveform characteristics.  
   
   
       8 . The system according to  claim 7 , wherein the second pulse generator is configured to receive control signals from the processor and, in response to the control signals, produce pulses with particular waveform characteristics.  
   
   
       9 . The system according to  claim 8 , wherein the second pulse generator is configured to produce periodic pulses of with particular waveform characteristics.  
   
   
       10 . An apparatus for stimulating nerves within tissue by applying an electrical potential to a needle electrode and a return electrode when the needle electrode and return electrode are applied to tissue, the apparatus comprising: 
 an electrical sensor configured to sense an electrical characteristic of a circuit formed when the needle electrode and return electrode are connected to the apparatus and applied to tissue;    a pulse generator configured to apply an electrical pulse to the circuit formed when the needle electrode and return electrode are connected to the apparatus and applied to tissue; and    a processor electronically coupled to the electrical sensor and configured to receive the sensed electrical characteristic and, based upon the sensed electrical characteristics, control an electrical parameter so as to produce a desired pulse waveform in the circuit formed when the needle electrode and return electrode are connected to the apparatus and applied to tissue.    
   
   
       11 . The apparatus of  claim 10 , further comprising a pulse conditioning circuit electrically coupled to the pulse generator and electronically coupled to the processor, wherein: 
 the processor is configured to send control signals to the pulse conditioning circuit to control the electrical parameter; and    the pulse conditioning circuit is configured to adjust the electrical parameter in response to the control signals received from the processor.    
   
   
       12 . The apparatus of  claim 11 , wherein: 
 the processor is further configured to send control signals to the pulse generator; and    the pulse generator is configured to generate electrical pulses of particular characteristics in response to the control signals received from the pulse generator.    
   
   
       13 . The apparatus of  claim 10 , further comprising: 
 a waveform generator configured to apply an electrical potential having a waveform of particular characteristics to the circuit formed when the needle electrode and return electrode are connected to the apparatus and applied to tissue; and    a switch configured to electrically connect the waveform generator or the pulse generator to the circuit formed when the needle electrode and return electrode are connected to the apparatus and applied to tissue.    
   
   
       14 . The apparatus of  claim 13 , wherein: 
 the switch is further configured to receive control signals from the processor and, in response to the control signals, connect the waveform generator or the pulse generator to the circuit formed when the needle electrode and return electrode are connected to the apparatus and applied to tissue; and    the processor configured to send control signals to the switch so as to control the application and duration of electrical pulses and waveform electrical potential applied to the circuit formed when the needle electrode and return electrode are connected to the apparatus and applied to tissue.    
   
   
       15 . The apparatus of  claim 10 , wherein the processor is a laptop computer.  
   
   
       16 . An apparatus for use with a needle electrode and a return electrode for stimulating nerves within tissue, comprising: 
 means for sensing an electrical characteristic of a circuit formed when the needle electrode and return electrode are connected to the apparatus and applied to tissue;    means for applying an electrical pulse to the circuit formed when the needle electrode and return electrode are connected to the apparatus and applied to tissue; and    means for adjusting an electrical parameter so as to produce a desired waveform in the circuit formed between the needle electrode and return electrode.    
   
   
       17 . The apparatus of  claim 16 , wherein the means for adjusting the electrical parameter comprises: 
 means for receiving the sensed electrical characteristic and generating a control signal for adjusting the electrical parameter; and    means for receiving the control signal and conditioning the electrical pulse in response to the control signal.    
   
   
       18 . The apparatus of  claim 16 , further comprising: 
 means for generating a background waveform signal in the circuit formed when the needle electrode and return electrode are connected to the apparatus and applied to tissue; and    means for selecting whether the background waveform signal or the electrical pulse is applied to the circuit formed when the needle electrode and return electrode are connected to the apparatus and applied to tissue.    
   
   
       19 . The apparatus of  claim 16 , further comprising a means for displaying information regarding the sensed electrical characteristic of the circuit formed when the needle electrode and return electrode are connected to the apparatus and applied to tissue.  
   
   
       20 . An apparatus for use with a needle electrode and a return electrode for stimulating nerves within tissue, comprising means for maintaining a desired waveform of an electrical pulse through a circuit formed when the needle electrode and return electrode are connected to the apparatus and applied to tissue as effective electrical characteristics between the needle electrode and return electrode change.