Prevention of positional brachial plexopathy during surgical correction ofscoliosis

Continuous intraoperative monitoring of spinal cord function using somatose nsory evoked potentials (SSEP) has gained nearly universal acceptance as a reliable and sensitive method for detecting and possibly preventing neurolo gic injury during surgical correction of spinal deformities. In several rep orts, spinal cord injury was identified successfully based on changes in SS EP response characteristics, specifically amplitude and latency. Less well documented and used, however, is monitoring of peripheral nerve function wi th SSEPs to identify and prevent the neurologic sequelae of prolonged prone positioning on a spinal frame. The authors describe a patient who underwen t surgical removal of spinal instrumentation but was not monitored. A brach ial plexopathy developed in this patient from pressure on the axilla exerte d by a Relton-Hall positioning frame during spinal surgery. In addition, da ta are presented from 15 of 500 consecutive pediatric patients who underwen t surgical correction of scoliosis between 1993 and 1997 with whom intermit tent monitoring of ulnar nerve SSEPs was used successfully to identify impe nding brachial plexopathy, a complication of prone positioning. A statistic ally significant reduction in ulnar nerve SSEP amplitude was observed in 18 limbs of the 500 patients (3.6%) reviewed. Repositioning the arm(s) or sho ulders resulted in nearly immediate improvement of SSEP amplitude, and all awoke without signs of brachial plexopathy. This complication can be avoide d by monitoring SSEPs to ulnar nerve stimulation for patients placed in the prone position during spinal surgery.