Epidemic of acute inflammatory myopathy in Karnataka, south India: 30 cases.

Thirty patients of acute inflammatory myopathy were seen over a short period of 11 months (February to December 1986) at NIMHANS, Bangalore, South India. The characteristic features were: short febrile illness followed a few days later by myalgia, edema of extremities, severe motor weakness and involvement of multiple other systems. Their mean age was 32.3 years and M:F ratio was 4:1. CK levels were increased in all. EMG done in 23 patients showed spontaneous activity in 13 and myopathic pattern in all. Nerve conduction studies revealed abnormalities in 12 cases. Muscle biopsy done in 21 patients showed varying degree of myophagocytosis and inflammatory infiltrates. All patients received steroids for only 6-8 weeks. Twenty-two patients recovered, one developed residual disability and 7 patients died during the acute phase. None of the survivors has developed relapse so far. Such cases with monophasic illness in clusters have not been reported earlier.