Upper plexus lesions affect mostly C5 and, less frequently, C6. They are usually due to trauma, for example falling on the shoulder, or traction on the arm at birth - in which case the name Erb Duchenne paralysis is given.
The arm hangs at the side with the elbow extended and the forearm pronated; the so-called waiter's tip or Erb's palsy.
On examination, there is loss of:
- shoulder abduction - deltoid, supraspinatus
- external rotation - infraspinatus
- elbow flexion - biceps, brachialis
There may be a slight loss of shoulder adduction.
Treatment is by placing the arm in an abduction splint with a movable joint at the elbow. The prognosis is better for lesions in the neonate than the adult.