RESUMO
In spine deformity surgery, iatrogenic neurologic injuries might occur due to the mechanical force applied to the spinal cord from implants, instruments, and bony structures, or due to ischemic changes from vessel ligation during exposure and cord distraction/compression during corrective manoeuvres.Prompt reaction within the reversible phase (reducing of compressive/distractive forces) usually restores functionality of the spinal cord, but if those forces continue to persist, a permanent neurological deficit might be expected.With monitoring of sensory pathways (dorsal column-medial lemniscus) by somatosensory-evoked potentials (SSEPs), such events are detected with a sensitivity of up to 92%, and a specificity of up to 100%.The monitoring of motor pathways by transcranial electric motor-evoked potentials (TceMEPs) has a sensitivity and a specificity of up to 100%, but it requires avoidance of halogenated anaesthetics and neuromuscular blockades.Different modalities of intraoperative neuromonitoring (IONM: SSEP, TceMEP, or combined) can be performed by the neurophysiologist, the technician or the surgeon. Combined SSEP/TceMEP performed by the neurophysiologist in the operating room is the preferable method of IONM, but it might be impractical or unaffordable in many institutions. Still, many spine deformity surgeries worldwide are performed without any type of IONM. Medicolegal aspects of IONM are different worldwide and in many cases some vagueness remains.The type of IONM that a spinal surgeon employs should be reliable, affordable, practical, and recognized by the medicolegal guidelines. Cite this article: EFORT Open Rev 2020;5:9-16. DOI: 10.1302/2058-5241.5.180032.
RESUMO
OBJECTIVE: The aim of this study was to evaluate the differences in transcranial electric motor-evoked potentials - TceMEP on upper limbs and the incidences of postoperative brachial plexopathy between patients with kyphotic and scoliotic trunk shapes. METHODS: In the period of January 2011-January 2017, 61 consecutive patients (mean age: 18.4 years ± 4.4 years (range: 10-32)) with pediatric spinal deformity underwent surgery in our Department. Eight of them had a kyphotic trunk deformity (Scheuermann kyphosis, neurofibromatosis, posterior thoracic hemivertebra), and the rest of the 53 patients had a scoliotic trunk deformity (mostly adolescent idiopathic scoliosis - AIS, lateral hemivertebra). The TceMEP recordings in all four limbs were analyzed every 30 min, or upon the surgeon's command. Upper limb TceMEP recordings were used as a control of systemic and anesthetic related changes, and as the indicator of positioning brachial plexopathy. RESULTS: Four out of 8 patients (50.0%) from the kyphotic group experienced noteworthy decreases in TceMEP amplitude (≥65%) in one or both arms, and only 2 out of 53 patients (3.8%) from the scoliotic group, confirming significant statistical difference (Chi-square 16.75, p < 0.05). Two out of 8 patients with decreases in TceMEP amplitude suffered from transitory postoperative brachial plexopathy, and both of them were from the kyphotic group. CONCLUSION: It seems that kyphotic trunks have a higher risk for positioning-related brachial plexopathy, probably due to distribution of trunk's weight onto only four points (two iliac bones and two shoulders), compared to the scoliotic trunks that have wider weight-bearing areas. We emphasize the importance of proper patient positioning and close intraoperative neuro-monitoring of all four limbs in more than one channel per limb. LEVEL OF EVIDENCE: Level IV Therapeutic Study.