Study design: Retrospective analysis of a prospectively accrued series of 191 consecutive patients who underwent intraoperative neurophysiologic monitoring during scoliosis corrective surgery.
Objectives: To compare the monitoring outcome of idiopathic and neuromuscular scoliosis. To demonstrate the usefulness of the epidural electrode. To report sensitivity and specificity of the monitoring method employed at a single institution.
Summary of background data: Reports in the literature emphasized the difficulty to obtain data in neuromuscular patients. Multimodality spinal cord monitoring has been recommended. Despite their still debated composition, neurogenic motor-evoked potentials have proven their validity in clinical practice.
Methods: Somatosensory and neurogenic evoked potentials were attempted in all patients presenting for scoliosis correction between 1999 and 2005. Study patients were divided into 3 groups: group 1, idiopathic; group 2, neuromuscular; and group 3, miscellaneous origins.
Results: The use of the epidural electrode demonstrated significant usefulness in the ability of monitoring otherwise nonmonitored patients, especially in group 2. Inability to obtain any evoked potentials occurred in 4 cases (2.1%). Five cases were found to be true positives. An adapted and rapid intervention permitted to avoid new postoperative deficit in all cases. There was no instance of false-negative data. The overall method sensitivity was 100%, and specificity was 52.69%.
Conclusions: The use of a single epidural electrode allowing somatosensory evoked potentials recording and spinal cord stimulation alternately is a safe and valid method of intraoperative monitoring.