Abstract
Intraoperative neuromonitoring (IONM) has become a standard of care in spinal deformity surgeries to minimize the incidence of new onset neurological deficit. Stagnara wake up test and ankle clonus test are the oldest techniques described for spinal cord monitoring, but they cannot be solely relied upon as a neuromonitoring modality. Somatosensory evoked potentials monitor only dorsal tracts and give high false positive and negative alerts. Transcranial motor evoked potentials (TcMEPs) monitor the more useful motor pathways. The purpose of our study was to report the safety, efficacy, limitations of TcMEPs in spine deformity surgeries, and the role of a checklist. Retrospective review of all spinal deformity surgeries performed with TcMEPs from 2011 to 2015. All patients were subjected to IONM by TcMEPs during the spinal deformity surgery. Patients were included in the study only if complete operative reports and neuromonitoring data and postoperative neurological data were available for review. An alert was defined as 80% or more decrement in the motor evoked potential amplitude, or increase in threshold of 100 V or more from baseline. The systemic and surgical causes of IONM alerts and the postoperative neurological status were recorded. In total, 61 patients underwent surgery for spinal deformities with TcMEPs. The average age was 12.6 years (6-36 years) and male:female ratio was 1:1.3. Diagnoses included idiopathic scoliosis (n = 35), congenital scoliosis (n = 13), congenital kyphosis (n = 7), congenital kyphoscoliosis (n = 4), post-infectious kyphosis (n = 1), and post-traumatic kyphosis (n = 1). The average kyphosis was 72° (45°-101°) and the average scoliosis was 84° (62°-128°). There were in total 33 alerts in 22 patients (36%). The most common causes were hypotension (n = 7), drug induced (n = 5), deformity correction (n = 5), osteotomies (n = 3), tachycardia (n = 1), screw placement (n = 2), and electrodes disconnection (n = 1). Reversal of the inciting event cause resulted in complete reversal of the alert in 90% of the times. Three patients showed persistent alerts, out of whom one had a positive wake up test and woke up with neurodeficit, which recovered over few weeks, while the other patients showed persistent alerts but woke up without any deficit. Sensitivity and specificity of TcMEP in deformity correction surgery were 100 and 96.6%, respectively, in our study. IONM alerts are frequent during spinal deformity surgery. In our study, more than 50% of the alerts were associated with anesthetic management. IONM with TcMEPs is a safe and effective monitoring technique and wake up test still remains a valuable tool in cases of a persistent alert.
Highlights
Neurological deficit following surgical correction of deformity is a major concern for any spine surgeon [1, 2]
Surgeries performed with Transcranial motor evoked potentials (TcMEPs) monitoring alone are included in our study
All the surgeries were performed under total intravenous anesthesia (TIVA) protocol developed by the institute, and a trained neurophysiologist who monitors Intraoperative neuromonitoring (IONM) with TcMEPs
Summary
Neurological deficit following surgical correction of deformity is a major concern for any spine surgeon [1, 2]. Ankle clonus test [3, 4] and Stagnara wake up test [5] are the earliest tests described for assessing the spinal cord function These tests assess only gross motor deficits and they require emergence from anesthesia (cannot be applied multiple times) and these tests cannot be solely relied upon as a neuromonitoring modality. Role of somatosensory evoked potentials (SSEPs) in spinal cord monitoring was first demonstrated by Tamaki et al [6] there can be a motor deficit without any concomitant sensory change due to vascular injury [7,8,9,10,11,12]. The purpose of this study was to report the safety, efficacy, and limitations of TcMEPs in spine deformity correction surgeries, and to establish the role of a checklist
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.