Neuromyotonia, peripheral neuropathy and myasthenia gravis.

A patient with neuromyotonia, peripheral neuropathy and myasthenia gravis (MG) is described. Neurophysiological studies, at rest, showed continuous muscle discharges of motor unit action potentials (MUAPs) in duplets and triplets. Motor (MNCV) and sensory (SNCV) nerve conduction studies revealed mild axonal and demyelinating peripheral neuropathy. Plasma exchange was followed by disappearance of clinical and electrophysiological signs of neuromyotonia and MG, as well as peripheral neuropathy.