Review on Methodology and Interpretation of Results of Motor Evoked Potentials Induced With Magnetic Field or Electrical Stimuli Recorded Preoperatively or Intraoperatively

Abstract

Introduction The method of motor evoked potentials recordings induced with magnetic field (MEP) (as part of the differential diagnosis of disease in the musculoskeletal system before the introduction of treatment) and motor evoked potentials induced with electrical stimuli (during intraoperative neuromonitoring) is particularly intensively used among clinical neurophysiology studies in the last twenty years. Aim The aim of the study is to review the practical usefulness of MEP in clinical diagnostics and present the most common examples of the application of this method, the possibility of modifications aimed at increasing non-invasiveness, safety and diagnostic precision. Material and methods The results of pilot tests of different variants of MEP recordings are presented preoperatively from muscles and nerves of the lower extremities in healthy volunteers (N = 10) and patients with disc-root conflicts (N = 15). Results Pilot tests show that in healthy people after oververtebral stimulation with the magnetic field at the lumbar level, the MEP amplitude and latency parameters recorded from nerves compared to those recorded from muscles are characterized by lower values (amplitudes by about 50%, latencies with mean at about 3 ms) and the time duration is increased by approximately 20%. The variability of MEP parameters is similar in patients with disc-root conflict in preoperative diagnostics, even though mean amplitude values from muscles were lower in comparison to healthy control group. Conclusions The MEP recording method from nerves vs. muscles after oververtebral stimulation with the magnetic field at the lumbar level in patients with disc-root conflict is diagnostically essential in cases of visible atrophic changes in muscles with symptoms of slight pathology in the transmission of nerve impulses in motor axons. Keywords: motor evoked potentials, neurophysiological diagnostics, neuromonitoring, methodological modifications

Update on the neuromonitoring procedures applied during surgeries of the spine – observational study

“…The parameters of amplitudes and latencies of MEPs recorded from nerves and muscles were output measures. The amplitude was measured from peak to peak of the signal, the latency from the stimulus application marked by the artefact in the recording to the onset of the positive inflection of potential, the duration from the onset of the potential to its end with reference to the isoelectric line [ 13 ].…”

The Usefulness of Motor Potentials Evoked Transvertebrally at Lumbar Levels for the Evaluation of Peroneal Nerve Regeneration after Experimental Repair in Rats

“…Human clinical studies on using MEPs for transvertebral magnetic stimulation show marked differences between normal subjects and subjects with disc–root conflict in preoperative diagnostics. One of the essential advantages of indirect nerve conduction assessment with MEPs is the possibility to conduct the examination non-invasively compared with the direct evaluation of nerve conduction with ENG, which is often performed intraoperatively [ 16 , 18 , 19 ]. When MEPs are recorded in elderly subjects with advanced muscle atrophy caused by axonal pathological changes, especially in those with lumbosacral chronic disc–root conflicts, this method may show limitations because fewer muscle motor units react to the excitation applied with the magnetic stimuli.…”

“…When MEPs are recorded in elderly subjects with advanced muscle atrophy caused by axonal pathological changes, especially in those with lumbosacral chronic disc–root conflicts, this method may show limitations because fewer muscle motor units react to the excitation applied with the magnetic stimuli. Significant neurogenic changes in muscles, with the first visible signs of muscle mass reduction caused by sarcopenia in “healthy subjects” aged 50 years and more, which are usually not the result of degenerative changes in motor axons, have been reported [ 16 ]. This phenomenon may better explain the results of electroneurographic studies than electromyographic recordings for the same patient.…”

“…Transvertebral magnetic stimulation is casuistically described in the literature, and some similar techniques have been proposed [ 12 , 14 , 15 , 16 ]. Kagan et al used a handcrafted solenoid coil to stimulate the sciatic nerve directly.…”

Bilateral Bi-Level Erector Spinae Plane Blocks as a Part of Opioid-Sparing Multimodal Analgesia in Scoliosis Surgery: A Case Series of Six Pediatric Patients

“…Neurophysiological monitoring of spinal integrity of motor evoked potential (MEP) and somatosensory evoked potentials (SSEPs) is essential for the safety of scoliosis surgery [ 28 , 29 ]. Anesthetics, including remifentanil and propofol, decrease the amplitude of transcranial motor evoked potentials in a dose-dependent manner [ 30 ].…”