Systems and Methods for Performing Neurophysiologic Monitoring During Spine Surgery

Abstract

A neuromonitoring system utilizing transcutaneous, trans-abdominal nerve root stimulation to monitor the health and status of the motor neural pathways of the lower extremities during the portions of a surgical procedure in which a tissue retraction assembly is used to maintain an operative corridor.

What is claimed is: 
     
         1 . A method for a spinal surgical procedure comprising:
 transcutaneously and trans-abdominally stimulating a patient using a cathode electrode posteriorly adhered at spinal level L1-L2 of the patient above a surgical target site; and   recording neuromuscular responses from at least one muscle innervated by at least one nerve from the patient's lumbar plexus so as to determine a baseline stimulation threshold intensity and a subsequent stimulation threshold intensity before or after forming a lateral trans-psoas corridor to determine nerve health status during the surgical procedure.   
     
     
         2 . The method of  claim 1 , further comprising:
 stimulating the patient and recording a response using an electrode located on a retractor blade inserted into the lateral trans-psoas corridor to determine neural structures near the retractor blade.   
     
     
         3 . The method of  claim 1 , further comprising:
 adhering a first recording electrode of one or more recording electrodes at a muscle innervated by one or more nerves of the patient's lumbar plexus.   
     
     
         4 . The method of  claim 1 , wherein recording the neuromuscular responses include:
 recording a first neuromuscular response from at least one muscle innervated by at least one nerve from the lumbar plexus so as to determine the baseline stimulation threshold intensity; and   recording a second neuromuscular response from at least one muscle innervated by at least one nerve from the lumbar plexus so as to determine the subsequent stimulation threshold intensity.   
     
     
         5 . The method of  claim 4 ,
 wherein recording the first neuromuscular response occurs before forming the lateral trans-psoas corridor; and   wherein recording the second neuromuscular response occurs after forming the lateral trans-psoas corridor.   
     
     
         6 . The method of  claim 1 , further comprising:
 displaying an indication of the determined nerve health status during the spinal surgical procedure via a display.   
     
     
         7 . The method of  claim 1 , further comprising:
 passing an implant to the surgical target site through the lateral trans-psoas corridor.   
     
     
         8 . A method for a spinal surgical procedure, the method comprising:
 transcutaneously and trans-abdominally stimulating a patient using a posterior electrode of a patient above a surgical target site;   recording a first neuromuscular response to determine a baseline stimulation threshold intensity;   determining a baseline stimulation threshold intensity based on the first neuromuscular response;   recording a second neuromuscular response to determine a baseline stimulation threshold intensity;   determining a subsequent stimulation threshold intensity based on the second neuromuscular response; and   determining a nerve health status based on comparing the baseline stimulation threshold intensity and the subsequent stimulation threshold intensity.   
     
     
         9 . The method of  claim 8 , wherein recording the second neuromuscular response occurs after forming a lateral trans-psoas corridor. 
     
     
         10 . The method of  claim 8 , wherein the posterior electrode is a cathode. 
     
     
         11 . The method of  claim 8 , wherein the posterior electrode is located at spinal level L1-L2. 
     
     
         12 . The method of  claim 8 , wherein the stimulating the patient further uses an anterior electrode on the patient. 
     
     
         13 . The method of  claim 8 , further comprising:
 passing an implant to the surgical target site.   
     
     
         14 . A method for a spinal surgical procedure, the method comprising:
 adhering a first electrode to a posterior location on a patient;   adhering a second electrode to an anterior location of the patient;   adhering a first recording electrode of one or more recording electrodes at a muscle;   delivering, from the first electrode to the second electrode, one or more initial transcutaneous, trans-abdominal stimulation signals to the patient selected to cause muscle activity inferior to a surgical target site detectable by one or more of the one or more recording electrodes;   determining an initial stimulation threshold intensity required to elicit at least one neuromuscular response with at least one of the one or more initial transcutaneous, trans-abdominal stimulation signals, the at least one neuromuscular response detected via the one or more recording electrodes;   after determining the initial stimulation threshold intensity, creating an operative corridor to the surgical target site;   during or after creating the operative corridor:
 delivering, between the first electrode and the second electrode, one or more subsequent transcutaneous, trans-abdominal stimulation signals selected to cause detectable muscle activity inferior to the surgical target site; 
 determining a subsequent stimulation threshold intensity required to elicit at least one neuromuscular response with at least one of the one or more subsequent transcutaneous, trans-abdominal stimulation signals, the at least one neuromuscular response detected via at least one of the one or more recording electrodes; and 
 determining nerve health status during the spinal surgical procedure based on a comparison of the determined initial stimulation threshold intensity and the subsequent stimulation threshold intensity required to elicit at least one neuromuscular response prior to establishment of the operative corridor; and 
   providing one or more instructions to display the determined nerve health status during the spinal surgical procedure via a display.   
     
     
         15 . The method of  claim 14 , wherein delivering the transcutaneous, trans-abdominal stimulation signal to the spine of the patient includes increasing a stimulation current associated with the transcutaneous, trans-abdominal stimulation signal until the at least one neuromuscular response is elicited. 
     
     
         16 . The method of  claim 14 , wherein determining the stimulation threshold intensity includes using one of a linear and a non-linear hunting algorithm. 
     
     
         17 . The method of  claim 14 , wherein the transcutaneous, trans-abdominal stimulation signal is a single pulse signal. 
     
     
         18 . The method of  claim 14 , wherein determining the nerve health status includes determining an effect of intraoperative nerve compression or patient positioning on the nerve health status. 
     
     
         19 . The method of  claim 14 , further comprising:
 passing an implant to the surgical target site.   
     
     
         20 . The method of  claim 14 , further comprising:
 causing the display to present:
 one or more visual indicia indicating that transabdominal nerve root stimulation mode is active; 
 one or more visual indicia indicating spinal levels being monitored; 
 one or more visual indicia indicating a nerve or group of nerves associated with the spinal levels being monitored; 
 waveforms of evoked neuromuscular responses; 
 one or more visual indicia indicating stimulation parameters; 
 one or more visual indicia indicating stimulation intensity required to elicit a response; and 
 one or more visual indicia indicating a stimulation intensity required to elicit a threshold response.