Repetitive stimulation of the long thoracic nerve in myasthenia gravis: clinical and electrophysiological correlations.

OBJECTIVE To investigate repetitive stimulation of the long thoracic nerve as a reliable and technically undemanding method for evaluating respiratory muscle function in myasthenia gravis. METHODS 15 patients with myasthenia gravis and positive single fibre electromyography had repetitive stimulation of the long thoracic nerve together with serratus anterior recordings. There were 20 normal controls. RESULTS Eight patients with respiratory symptoms all had abnormal results, with an increased response decrement. These patients required intensive monitoring and supplemental oxygen. The remaining seven cases with no respiratory symptoms all had negative studies. CONCLUSIONS This is a simple well tolerated method that shows good correlation with respiratory symptoms and management requirements in myasthenia gravis. It can alert the physician to serious respiratory complications in this disease.