Spinal cord stimulator electrode positioning system

Abstract

A Spinal Cord Stimulator (SCS) electrode placement system that includes a stimulator, at least one amplifier, a processing unit, the processing unit programmable with software. The automated system aids surgeons in placing SCS electrodes by determining neurophysiologic position. It does this by adjusting parameters and stimulating the muscles of a patient from the SCS electrode to capturing electrophysiologic signal such as Electromyography (EMG) data from different muscles. This data is then collected at various positions on the SCS electrode and then aggregated to display the location of the SCS electrode. The data is then visually outputted to the surgeon to help make a lateralization decision. All aspects of the system can be manually adjusted by the surgeon.

What is claimed is: 
     
         1 . An electrode positioning system, comprising:
 a pulse generator, the pulse generator configured to generate electrical pulse currents based on a parameter;   a Spinal Cord Stimulator (SCS) electrode, the SCS electrode configured to apply the generated electrical pulse currents at a contact point from a plurality of contact points;   a recording electrode configured to measure electrophysiologic signals triggered by application of the generated electrical pulse currents;   an output device configured to indicate the contact point of the SCS electrode; and   a base unit, the base unit having a processor configured to:
 analyze measured electrophysiologic signals, by:
 performing an electrical stimulation cycle methodology, 
 performing a lateralization based on the electrical stimulation cycle methodology, 
 determining a mid-contact point of the SCS electrode based on the electrical stimulation cycle methodology and the lateralization, 
 identifying a location of a length of the spinal cord based on the determined mid-contact point, and 
 identifying a location of the SCS electrode relative to the location of the length of the spinal cord based on an aggregation of the measured electrophysiologic signal, and 
 
 outputting the location of the length of the spinal cord and the location of the SCS electrode to the output device. 
   
     
     
         2 . The electrode positioning system of  claim 1 , wherein the output device comprises a display, and wherein the processor is further configured to output the location of the length of the spinal cord on the display. 
     
     
         3 . The electrode positioning system of  claim 2 , wherein the processor is further configured to display the location of the SCS electrode relative to the location of the length of the spinal cord based on the measured electrophysiologic signal. 
     
     
         4 . The electrode positioning system of  claim 3 , wherein the processor is further configured to display an overlay of the location of the SCS electrode and the location of the spinal over an image captured by another modality of an area surrounding the SCS electrode. 
     
     
         5 . The electrode positioning system of  claim 1 , wherein the measured electrophysiologic signal is an electromyography (EMG) signal or a Compound Muscle Action Potential (CMAP). 
     
     
         6 . The electrode positioning system of  claim 1 , wherein the measured electrophysiologic signal indicates a level of myotomal activation. 
     
     
         7 . The electrode positioning system of  claim 1 , wherein the base unit further includes an amplifier configured to amplify the measured electrophysiologic signal. 
     
     
         8 . The electrode positioning system of  claim 1 , wherein the electrical stimulation cycle methodology includes:
 generating electrical pulse currents based on the parameter;   applying the generated electrical pulse currents at the contact point;   measuring electrophysiologic signals triggered by the application of the generated electrical pulse currents;   comparing the measured electrophysiologic signals to a reference electrophysiologic signal;   determining a deviation based on the comparison;   adjusting the parameter based on the deviation;   repeating the generation of the electrical pulse currents, the application of the generated electrical pulse currents, the measurement of the electrophysiologic signals, the comparison of the measured electrophysiologic signals, the determination of the deviation, and the adjusting of the parameter until the deviation is minimized;   storing the contact point of the SCS electrode in which the deviation is minimized in a memory as stored data; and   moving the SCS electrode to another contact point of the plurality of contact points and repeating the generation of the electrical pulse currents, the application of the generated electrical pulse currents, the measurement of the electrophysiologic signals, the comparison of the measured electrophysiologic signals, and the determination of the deviation until the plurality of contact points has been exhausted.   
     
     
         9 . The electrode positioning system of  claim 8 , wherein the adjusting the parameter includes incrementally increasing an intensity of the generated electrical pulse currents, changing a pulse width of the generated electrical pulse currents, or changing a pattern of the generated electrical pulse currents. 
     
     
         10 . The electrode positioning system of  claim 8 , wherein the moving of the SCS electrode contact point includes a rostral-to-caudal or a left-to-right directional movement. 
     
     
         11 . The electrode positioning system of  claim 8 , wherein the electrical stimulation cycle methodology further includes determining whether the parameter is within a predetermined threshold after being adjusted. 
     
     
         12 . The electrode positioning system of  claim 8 , wherein performing the lateralization includes:
 determining a Root Mean Square (RMS) value of the stored data;   comparing the RMS value of the stored data corresponding to one of the plurality of contact points to the RMS value of the stored data corresponding to another one of the plurality of contact points;   calculating a ratio between the RMS value of the stored data corresponding to the one of the plurality of contact points and the RMS value of the stored data corresponding to another one of the plurality of contact points;   designating the one of the plurality of contact points as a left contact point, upon the ratio being less than 1;   designating the one of the plurality of contact points as a right contact point, upon the ratio being more than 1;   designating the one of the plurality of contact points as the mid-contact point, upon the ratio being 1, and storing the designated mid-contact point;   repeating the determining, the comparing, the calculating, and the designating for each data of the plurality of contact points; and   collating the plurality of contacting points that are designated as the mid-contact point to form a midline, wherein the midline corresponds to a length of a spinal cord.   
     
     
         13 . An electrode positioning method, the electrode positioning method comprising:
 attaching a recording electrode on a patient;   using the recording electrode, receiving an electrophysiologic signal from muscles of the patient that is triggered by electrical pulse currents applied by a Spinal Cord Stimulator (SCS) electrode of the electrode positioning system of  claim 1 , wherein electrode positioning system is configured to:
 perform an electrical stimulation cycle methodology, 
 perform a lateralization based on the electrical stimulation cycle methodology, 
 determine a mid-contact point of the SCS electrode based on the electrical stimulation cycle methodology and the lateralization, 
 identify a location of a length of the spinal cord based on the determined mid-contact point, and 
 identify a location of the SCS electrode relative to the location of the length of the spinal cord, based on an aggregation of the received electrophysiologic signal; 
   output the location of the length of the spinal cord and the location of the SCS electrode to the output device; and   repositioning the SCS electrode based on the outputted location of the length of the spinal cord and the location of the SCS electrode.   
     
     
         14 . An electrode positioning system having a non-transitory computer readable medium having stored thereon instructions for causing a processing circuitry configured to perform the steps of:
 performing an electrical stimulation cycle methodology;   performing a lateralization based on the electrical stimulation cycle methodology;   determining a mid-contact point of the SCS electrode based on the electrical stimulation cycle methodology and the lateralization;   identifying a location of the spinal cord based on the determined mid-contact point;   identifying the location of the SCS electrode the length of the spinal cord and the location of the SCS electrode and the midpoint signal; and   outputting the location of the length of the spinal cord and the location of the SCS electrode and the midpoint to an output device.