Novel Transabdominal Motor Action Potential (TaMAP) Neuromonitoring System for Spinal Surgery

Abstract

IntroductionMinimally invasive lateral lumbar interbody fusion (LLIF) approaches to the lumbar spine reduce patient morbidity compared to anterior or posterior alternatives. This approach, however, decreases direct anatomical visualization, creating the need for highly sensitive and specific neurophysiological monitoring. We seek to determine feasibility in 'transabdominal motor action potential (TaMAP)' monitoring as an assessment for the integrity of the neural elements during lateral-approach surgeries to the lumbar spine. MethodsCathode and anode leads were placed on the posterior and anterior surfaces of two porcine subjects. Currents of varying degrees were transmitted across, from front to back. Motor responses were monitored and recorded by needle electrodes in specific distal muscle groups of the lower extremity. Lastly, the cathode and anode were placed anterior and posterior to the chest wall and stimulated to the maximum of 1500 mA to determine any effect on cardiac rhythm.ResultsResponses were seen by measuring vertical height differences between peaks of corresponding evoked potentials. Recruitment began at 200 mA in the lower extremities. Stimulation at 450 mA recruited a reliable and distinguishable electrographic response from most muscle groups. Responses were recorded and reliably measured and increased in proportion to the graduation of transabdominal stimulation current; no responses were seen in the arms or face. 1500 mA across the chest wall failed to stimulate or induce cardiac arrhythmia on repeated stimulation, indicating safety of stimulation.ConclusionTaMAPs seen in the animal model provide a potential alternative to standard transcranial motor evoked potentials done in the lateral approach of LLIFs. TaMAP recordings in most muscle groups were recordable and reliable, though some muscle groups failed to stimulate. Safety of transabdominal motor evoked potentials was confirmed in this porcine study. Future studies should examine TaMAPs reliability in detecting compressive lesions of nerve roots and peripheral nerves.

Transabdominal Motor Action Potential Monitoring of Pedicle Screw Placement During Minimally Invasive Spinal Procedures: A Case Study

“…Additional studies are needed to further corroborate these findings and continue to examine the benefits of this technique. There is currently only one other study to our knowledge discussing TaMAP, as it is a relatively novel tool [17]. Given that the current study involved only a case of a malpositioned screw, future research should involve an experimental follow-up with a larger, more comprehensive set of data points.…”

“…TaMAP recordings can be obtained as a function of stimulus current, offering real-time functional feedback. Studies on porcine models have shown TaMAP to be a beneficial neuromonitoring alternative to the complications and limitations caused by a previously used technique transcranial motor evoked potential (TcMEP) [17][18]. Thus, the current study seeks to validate the use of TaMAP as a safer, more effective alternative to prior methods and is the first to examine this technique in human participants.…”

“…TaMAP is a relatively new form of neurophysiological monitoring that has shown effectiveness in detecting inadvertent iatrogenic nerve damage due to spinal procedures [17]. This intraoperative method monitors the integrity of nerves by electrode stimulation across the abdomen at the T12 level to trigger a response within corresponding muscles, as has been demonstrated in ovine models [17]. TaMAP recordings can be obtained as a function of stimulus current, offering real-time functional feedback.…”