The Shoulder

Spinal Accessory Nerve Lesion

The spinal accessory nerve is the sole motor nerve of the trapezius. A direct forceful blow to the neck can cause a crush injury to the nerve. The lesion is sometimes iatrogenic, resulting grom cervical lymph node biopsy or other surgical procedures. Sometimes no proper cause for the neuritis can be detected.

Clinical Presentation:

Severe and continuous unilateral scapular pain for about three weeks. The patient then starts to complain of weakness of the arm.
The functional examination of the shoulder shows a painless limitation of the active elevation of the arm; the passive movements are fully normal and the resisted movements strong and painless.

The accessory test shows a painless weakness of the trapezius muscle.

Evolution :

The pain disappears spontaneously, usually after a few weeks. A non-traumatic neuritis recovers completely with a full restoration of the motor function after 8 months to one year. The prognosis is worse in traumatic or iatrogenic lesions.