Incrementing Responses in Myasthenia Gravis

Twenty-two patients with myasthenia gravis were studied using the technique of repetitive electrical nerve stimulation. A decrementing response, characteristic of myasthenia gravis, could be elicited at some time in all patients with generalized symptoms. In eight patients, an incrementing response was observed on one or more occasions. Seven of these patients were becoming progressively weaker, two of them in association with steroid therapy. These results suggest that in this phase of the disease there is a presynaptic disorder of acetylcholine release. High dose steroid therapy may give rise to a similar defect in transmitter release. If carefully performed, this technique can be of assistance in the diagnosis and management of disorders of neuromuscular transmission.