SHOULDER MUSCLES IN TRAUMATIC TETRAPLEGIA

Abstract

Introduction: The patterns of forearm and hand paralysis in traumatic tetraplegia are recognised and classified by an international classification system. Although weakness and wasting are common around the shoulder in tetraplegia, it is harder to discern individual muscle function.

Aim: To determine the activity of shoulder girdle muscles in patients with traumatic tetraplegia and to relate these results to the subjects’ international forearm classifications.

Methods: Twenty-five male tetraplegic subjects (50 upper limbs) were examined. Forearm muscle strengths were recorded according to the international classification system. The strengths of nine shoulder movements were recorded according to the Medical Research Council (MRC) grading system. The presence of wasting and the electromyographic (EMG) activity of nine shoulder muscle regions were noted. Using surface electromyography we noted whether voluntary EMG patterns were present or absent and whether lower motor denervation signs were present or absent.

Results: Absence of voluntary EMG activity was only seen in latissimus dorsi, and only in patients with very high-level lesions (either no MRC grade IV forearm muscles, or brachioradialis only, i.e. international forearm grade I or less). Lower motor neuron signs were observed in latissimus dorsi in most patients without ipsilateral MRC grade IV finger extension (international forearm grade VI or less). Lower motor neuron signs were observed in infraspinatus in most patients without MRC grade IV forearm pronation (international forearm grade IV or less).

Conclusions: Only patients with very high level lesions showed paralysis of any shoulder girdle muscles and, then, only latissimus dorsi. In most cases of traumatic tetraplegia shoulder girdle muscles have the capacity to be strengthened by use and rehabilitation.