Unveiling Sunderland Zero Injury in a Patient with Brachial Plexus Trauma

Peripheral nerve injuries can profoundly impact patients' functionality and quality of life. Classification systems such as those proposed by Seddon and Sunderland have provided valuable frameworks for understanding the nature and severity of nerve injuries. However, recent emerging evidence has shed light on an underrecognized category of nerve injury. This article provides a review of nerve injury classification systems and presents information on the Sunderland zero injury, a milder category of nerve injury characterized by immediate recovery upon decompression. We present a focused Sunderland zero literature review and a case report of a 26-year-old with a brachial plexus injury who developed secondary proximal median nerve compression. Intraoperative somatosensory-evoked potentials and motor-evoked potentials were obtained immediately before and after surgical decompression to dynamically assess nerve function. Preoperatively, the patient demonstrated median nerve motor deficits despite interval recovery from the brachial plexus injury. Immediately following decompression at the level of the lacertus fibrosus, increased motor-evoked potential amplitude and improved somatosensory-evoked potential waveform quality were demonstrated. Early postoperative examination confirmed functional improvement without the expected temporal profile of axonal regeneration. Sunderland zero represents a reversible ischemic conduction block without demyelination or axonal loss. Recognition of this nerve injury category is critical, as timely intervention may result in immediate clinical improvement and meaningful functional recovery and improved patient outcomes. Further research is needed to refine diagnostic and therapeutic strategies to identify Sunderland zero injuries.