Muscle Atrophy in a Case of Acute Disseminated Encephalomyelitis

A case of acute disseminated encephalomyelitis (ADEM) accompanied by muscle atrophy is reported. A man of 30 was admitted with acute onset of clouded consciousness, fever, paraplegia and sensory loss, following an upper respiratory tract infection. A week later, marked muscle atrophy was noticed in both legs. A biopsy of the quadriceps femoris muscle showed groups of small angular fibres indicating neuropathic change, and also fibres with round contour and varying diameter suggestive of myopathic change. Some fibres contained vacuoles, basophilic material and or eosinophilic mass. Histochemical examinations suggested that the basophilic material contained mitochondria, lipid and glycogen, while the eosinophilic mass was regarded as hyaline degeneration. Cellular infitration was not observed in the interstitium. Electron micrographs showed disarray and loss of myofibrils, abundant mitochondria and glycogen granules, myelin figures and honeycomb structures. The cause of the muscle changes is uncertain. However, as conceivable causal mechanisms, the possibility of polymyositis is discussed as well as the effect of immobilization and probable involvement of the nerve roots and peripheral nerves.