RESUMEN
Unilateral brachial plexus injury is a rare complication of thoracoscopic sympathectomy, which is generally considered to be a simple and safe procedure. We report on a 20-year-old female patient who developed persistent pain and weakness of the left arm after thoracoscopic sympathectomy for hyperhidrosis. An electromyographic study revealed evidence of denervation at the C5-C7 level, and a nerve conduction study on the left brachial plexus showed decreased amplitude of the compound muscle action potential of the left musculocutaneous and axillary nerves. The above findings are compatible with left brachial plexopathy, with predominant involvement of the lateral and posterior cord. We suggest that this complication was caused by stretch and/or compression of the left brachial plexus when the arm was hyperabuducted upwards during the operation. Careful attention to positioning by the surgeon and anesthesiologist is needed to prevent this debilitating injury.