PERONEAL NERVE REPETITIVE NERVE-STIMULATION TEST - ITS VALUE IN DIAGNOSIS OF MYASTHENIA-GRAVIS AND LAMBERT-EATON MYASTHENIC SYNDROME

We have developed a repetitive nerve stimulation (RNS) technique for t he peroneal nerve. Normal limits for the decremental responses for the anterior tibialis and extensor digitorum brevis muscles are 6-21% at the low rate of stimulation and 44-70% at the high rate of stimulation . These values exceed the normal limits for other commonly tested musc les. This may be due to the lower safety factor for neuromuscular tran smission for the anterior tibialis and extensor digitorum brevis muscl es. We present 4 cases in which the peroneal nerve RNS test was crucia l for the diagnosis of the limb-girdle form of MG or LEMS. Thus, we co nclude that, in a small number of patients with neuromuscular transmis sion disorders, the peroneal nerve RNS test is needed for confirmation of disease. (C) 1995 John Wiley and Sons, Inc.