T138. Neurophysiologic Intraoperative Monitoring (NIOM) in pediatric patients with polyneuropathy

Abstract

Introduction Pediatric patients may develop scoliosis, often during periods of increased growth, and those with polyneuropathy are at higher risk. For cases that warrant surgical intervention, neurophysiologic intraoperative monitoring (NIOM) routinely is performed for all pediatric patients undergoing surgery for scoliosis treatment. An NIOM monitoring plan including sensory evoked potentials (SEP), motor evoked potentials (MEP), free-run electromyography (EMG) and triggered EMG recording during pedicle screw stimulation is consistent regardless of etiology of scoliosis. However, individuals with polyneuropathies have pre-existing neurophysiologic abnormalities, and there is limited literature as to how this may complicate acquisition of baseline and intraoperative recordings. Methods For this case series, we identified 6 patients with a diagnosis of polyneuropathy who had undergone spine surgery for scoliosis between 2010 and 2017. We reviewed these patients’ medical records for further clinical information and examined their monitoring reports and data for whether baseline recordings were obtained and whether modified parameters had been applied. Results The etiologies for polyneuropathy included conditions such as Charcot-Marie-Tooth disease, ataxia telangiectasia, giant axonal neuropathy and Friedreich’s ataxia. A spectrum of baseline findings was present: some had absent waveforms while others had reliable waveforms with prolonged latencies. For some patients with no recorded SEP data, MEPs were present; no patients with absent MEPs had SEPs present. Modifications to the typical recording parameters for NIOM scoliosis cases included: slowing the stimulation rate for SEP acquisition; placement of needle electrodes rather than surface electrodes for SEPs; changing the train parameters for MEP acquisition; and increasing the sweep speed for SEP, MEP and triggered EMG recordings. Some patients with poorly reliable baseline data were monitored only through the time of pedicle screw stimulation after which time monitoring was discontinued. Conclusion This sample of previously monitored scoliosis cases in children with polyneuropathy allowed us to investigate patterns of commonly seen findings and common troubleshooting attempts to optimize the data monitored. Awareness of pertinent medical history such as peripheral polyneuropathy should prepare the NIOM team to make changes to the typical recording parameters based on the known underlying neurophysiologic process. A multimodality approach seemed most likely to provide useful information as several of these cases would have been unmonitorable with the use of SEPs alone. The awareness of the difficulties in monitoring patients with polyneuropathy also prepares the NIOM team for monitoring a patient with presumed idiopathic scoliosis who has an unrecognized polyneuropathy as this may contribute to further clinical or laboratory investigation into the diagnosis postoperatively.