ABSTRACT
BACKGROUND: Injury to the spinal accessory nerve causes paralysis of the trapezius muscle, which is a painful and disabling condition. Many injuries are iatrogenic. Diagnosis is often made after a long delay, suggesting that current clinical signs are inadequate. METHODS: Accessory nerve palsy is known to be a cause of winging of the scapula. Observation of six patients with accessory nerve palsy has shown that winging of the scapula is most prominent when the patient actively externally rotates the shoulder against resistance. RESULTS: This is in contrast to the other causes of winging of the scapula including long thoracic nerve palsy and muscular dystrophy, where the scapula is most prominent on flexion or abduction of the shoulder. CONCLUSION: We propose that the resisted active external rotation test should be regarded as the key clinical sign for accessory nerve palsy.
