Electromyographic findings in patients after recovery from peripheral nerve lesions and poliomyelitis.

Electromyography was performed in 10 patients 14 to 50 years after acute poliomyelitis and in 12 patients 6 to 16 years after a peripheral nerve lesion. All patients had made an almost complete recovery from initially severe paresis. In the poliomyelitis group the main finding was an increased mean action potential duration in all patients. In the patients with peripheral nerve lesions an increased frequency of spontaneous activity could be seen in 8 out of 10 and an increased mean action potential duration in 7 out of 9 patients during the initial phase. Six to 16 years later the main pathological results were a prolonged mean action potential duration (9 out of 12 patients) whilst increased spontaneous activity was detectable only in 3 out of 12 patients. In two patients all EMG findings were normal.