Acute disseminated encephalomyelitis: clinical and MRI study from South India.

Clinical and MRI appearances were reviewed in 25 cases of acute disseminated encephalomyelitis (ADEM) seen in a university hospital in South India. Specific viral infections and Semple antirabies vaccination together accounted for 56% of antecedent events. Clinical and MRI features were suggestive of diffuse/multifocal form in 15 patients. Of the 10 patients with clinically site restricted forms, two patients with dorsal myelitis and one patient with polyradiculitis had asymptomatic cerebral white matter lesions. MRI was essentially normal in all the four patients with acute ataxia following varicella infection. Of the 13 patients with multiple white matter lesions, lesions were asymmetrical in size and morphology in nine patients and symmetrical in four patients. Two of them had extensive destructive lesions and one patient had multiple discrete lesions. Lesions occurred at the corticomedullary junctions in seven patients. The distribution was subcortical and/or centrum semiovale in 10 patients. The regions affected include internal capsule(s), thalami, brainstem, cerebellar peduncles and cerebellum. No specific differences were observed in patients with ADEM following specific viral infections, Semple antirabies vaccination, and nonspecific upper respiratory tract infections. There was fairly good correlation between clinical and MRI findings in 81% of patients. Patients with incomplete recovery showed extensive and/or multifocal lesions.