SPINAL ACCESSORY NERVE PALSY
The spinal accessory nerve (C2–6)
supplies the sternomastoid muscle and then runs obliquely across the posterior
triangle of the neck to innervate the upper half of the trapezius. Contrary to
general belief, the nerve appears also to have sensory functions, including pain
sensibility. Because of its superficial course, it is easily injured in stab
wounds and operations in the posterior triangle of the neck (e.g. lymph node biopsy).
It is occasionally injured in whiplash injuries.
Clinical
features
Following an open wound or operation,
the patient complains of severe pain and ‘stiffness’ of the shoulder. Examination
reveals asymmetry or drooping of the shoulder, reduced ability to hitch or
hunch the shoulder and weakness on abduction of the arm; typically there is
mild winging of the scapula on attempting active abduction against resistance;
unlike the deformity in serratus anterior palsy, this disappears on flexion or
forward thrusting of the shoulder. Often the true nature of the problem is not
appreciated and diagnosis is delayed for weeks or months. In late cases there
may be wasting of the trapezius.
Treatment
Stab injuries and surgical injuries
should be explored immediately and the nerve repaired. If the exact cause of
injury is uncertain, it is prudent to wait for about 8 weeks for signs of
recovery. If this does not occur, the nerve should be explored: (a) to confirm
the diagnosis and (b) to repair the lesion by direct suture or grafting. While
waiting for recovery the arm is held in a sling to prevent dragging on the neck
muscles. The results of early nerve repair are generally good but some patients
continue to complain of shoulder fatigue during lifting and overhead
activities.
Reference:
·
Apley’s System
of Orthopaedics and Fractures (Page- 281)
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