Abstract

Brachial plexus lesions frequently lead to significant physical disability, psychologic distress, and socioeconomic hardship. Adult brachial plexus injuries can be caused by various mechanisms, including penetrating injuries, falls, and motor vehicle trauma. Often the diagnosis is delayed or ignored as the practitioner waits for some recovery. Expedient diagnosis and testing is the best means of maximizing functional return. Evaluators must remember that muscles will begin to undergo atrophy and lose motor end plates as soon as the proximal injury occurs [1]. The vast majority of brachial plexus injuries involve denervation of the shoulder’s supporting musculature. A weak shoulder girdle allows subluxation of the glenohumeral joint. The shoulder joint is inherently unstable, although the capsule and ligaments play a supporting role in joint stability, the majority of support is provided through active contraction of the supraspinatus muscle. Therefore, significant weakening of the supraspinatus leads to shoulder subluxation [2]. However, electromyography (EMG) study is required for muscle weakness by nerve damage. The study of muscle function through EMG is an established method for quantifying muscle activity through electrical activity [3].