IntroductionMotor evoked potentials (MEPs) are currently considered as a more useful method for neurophysi-ological intraoperative monitoring than somatosensory evoked potentials in cases of surgery applied to patients with adolescent idiopathic scoliosis. The non-invasive approach is preferred to modify MEP recordings, criticizing, in many cases, the fundamentalism for neurophysiological monitoring based only on needle recordings. The aim of the review is to provide our own experience and prac-tical guidelines with reference to neuromonitoring innovations.Material and MethodsRecordings of MEPs with surface electrodes instead of needle electrodes including nerve instead of muscle combinations during neurophysiological monitoring associated with surgical interventions to the spine have become more relevant for pediatric purposes, avoiding the anesthesiology-related influences. Observations on 280 patients with Lenke A–C types of spine curvature are presented before and after the surgical correction.ResultsThe MEPs recorded from nerves do not undergo fluctuations at different stages of scoliosis correc-tions and the anesthesia effect more than MEPs recorded from muscles. The use of non-invasive surface electrodes during neuromonitoring for MEP recordings shortens the total time of the surgical procedure without diminishing the precision of the neural transmission evaluation. The quality of MEP recordings during intraoperative neuromonitoring from muscles can be significantly influ-enced by the depth of anesthesia or administration of muscle relaxants but not those recorded from nerves.ConclusionsThe proposed definition of “real-time” neuromonitoring comprises the immediate warning from a neurophysiologist about the changes in a patient’s neurological status during scoliosis surgery (es-pecially during pedicle screws’ implantation, corrective rods’ implantation, correction, distraction and derotation of the spine curvature) exactly during the successive steps of corrective procedures. This is possible due to the simultaneous observation of MEP recordings and a camera image of the surgical field. This procedure clearly increases safety and limits financial claims resulting from possible complications.

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

Objective: The study aimed to describe properties and to prove diagnostic usefulness of motor evoked potentials (MEPs) recordings from muscles versus nerves of lower extremities when induced at lumbar levels with magnetic field. Methods: Methodologically similar MEPs recordings from muscles and nerves of lower extremities were performed once in healthy volunteers ( N = 43) and patients with disc-root conflicts at lumbar spine levels ( N = 43, proven in MRI studies). Simultaneous electroneurographic (ENG) recordings following stimulation of peroneal nerves verified neural impulses transmission in motor fibers peripherally and at L5 ventral roots. Results: ENG studies in patients proven only moderate axonal type of peroneal nerves injury. The mean values of MEPs amplitudes recorded from nerves were significantly different from those recorded in anatomically related muscles, both in controls (1179.6 ± 451.2 vs 1718.3 ± 481.3) and patients (495.6 ± 275.9 vs 1218.2 ± 465.5) ( p = 0.0009–0.0000012); they are about 30% and 51% smaller, respectively. In both groups of subjects, latencies of MEPs recorded from nerves were shorter at about 3.0 ms and characterized by a slightly longer duration (3.0–5.0 ms) than those recorded from muscles. Results revealed positive correlations between decrease of amplitudes in sEMG and MEPs recordings from lower extremities muscles indicating consequences of pathology in neural transmission from spinal centers. Conclusions: Results of this study point to clear-cut characteristics of MEPs induced oververtebrally with the magnetic field in parameters recorded in healthy subjects and patients with consequences of chronic L4-L5 low back pain, which can be easily implemented in clinical practice. Non-invasive method of MEPs recorded from nerves can be helpful for diagnosing of patients with visible atrophic changes in muscles and simultaneous symptoms of only slight pathology in transmission of nerve impulses peripherally.