[Contribution of somatosensory evoked potentials in the surveillance of the spinal cord during spinal surgery].

This study shows the results obtained in 51 patients, children and adolescents by monitoring somatosensory evoked potentials during spinal surgery: Cotrel-Dubousset instrumentation, surgical anterior correction by plating, spondylolisthesis and hemivertebra surgery. The recordings were made in preoperative, peroperative and postoperative periods; the electro-physiological and anaesthetic conditions allowed us to obtain reliable recordings. Analysis of the peroperative somatosensory evoked potentials showed significant differences in latencies, but also in amplitudes and morphology during distraction in scoliosis or spondylolisthesis. These impairments gradually improved and recovered their normal values at the end of the operation. The impairments were, with equal correction, 4 times more important in Cotrel-Dubousset instrumentation than in surgical anterior correction by plating. In 3 cases, the modifications observed during instrumentation led the surgeon to change his operative behavior avoiding certainly a postoperative neurological disorder. The correlation between the neurological troubles and the impairments of the potentials allowed us to define alarm criteria, and if they persist the wake-test becomes necessary.