Mechanisms and Risk Factors of Brachial Plexus Injury in the Treatment of Early-Onset Scoliosis with Distraction-Based Growing Implants

Background: Brachial plexus injuries have been reported in association with distraction-based instrumentation for earlyonset scoliosis. The purpose of this study was to describe brachial plexus injuries associated with distraction-based spine instrumentation with rib anchors and the mechanisms and risk factors responsible. Methods: We performed a retrospective single-center review of a consecutive series of forty-one patients with early-onset scoliosis who underwent distraction-based instrumentation with rib anchors from 2000 to 2011. Results: Four (10%) of the forty-one patients experienced an intraoperative brachial plexus injury. Three mechanisms of brachial plexus injuries were identified: (1) injury of the brachial plexus by the first rib being pushed superiorly by ribanchored growing instrumentation, (2) direct injury to the brachial plexus by the superior pole of the retracted scapula, and (3) injury of the brachial plexus when the scapula was moved inferiorly during Sprengel deformity reconstruction. The last two mechanisms are independent of spinal instrumentation. Two patients had neurological symptoms or neuro-monitoring signal changes when the arm was in the adducted position but not when the arm was abducted. All patients had complete neurological recovery. Conclusions: Patients with Sprengel deformity appear to be at increased risk for brachial plexus injury when undergoing distraction-based spine instrumentation with rib anchors. Injury to the brachial plexus can occur with scapular elevation alone, presumably by direct compression of the superior end of the scapula on the brachial plexus. Brachial plexus injuries may be "hidden'' during monitoring of an arm in shoulder abduction but symptomatic with shoulder adduction, as the brachial plexus is draped over the elevated first rib.