Denervation due to lesions of the central nervous system. An EMG study in cases of cerebral contusion and cerebrovascular accidents

Abstract

Electromyographic examination of 10 patients with severe cerebral contusion revealed profuse fibrillation potentials and positive sharp waves in many muscles, proximal as well as distal, sometimes also in the paraspinal musculature. In some cases complete denervation of a muscle was found. It appeared that these findings were not due to plexus lesions or spinal root avulsions, but that they were caused by the lesion of the central nervous system. In 10 patients with slight concussion no spontaneous activity was found. Fibrillation potentials and positive sharp waves occurred in the paretic limbs in 20 out of 21 patients with hemisyndromes due to cerebrovascular accidents. The spontaneous activity appeared after 2-3 weeks (as in peripheral nerve lesions) and disappeared or diminished considerably within 6 months. The denervation caused by the central lesion was attended by normal motor and sensory nerve conduction (apart from disturbed motor conduction to totally denervated and subsequently reinnervated muscles). It is concluded that lesions of the central nervous system may cause a dysfunction of anterior horn cells which leads to axonal degeneration, probably in the form of a dying-back process. Apparently in the majority of the anterior horn cells this dysfunction is temporary, so that axonal regeneration and reinnervation soon take place.