Aim: To study the clinical syndromes, antecedent events, evoked potential abnormalities and magnetic resonance image (MRI) findings in patients with acute disseminated encephalomyelitis (ADEM) and also to find differences if any when compared to ADEM reported from the Western countries.
Methods: Case records of 64 patients with ADEM seen over a period of 10 year were reviewed.
Results: Specific viral infections and Semple antirabies vaccination together accounted for 56% of antecedent events. Diffuse or multifocal form of ADEM was the clinical syndrome in 56.5% of patients with specific infections. Myeloradiculopathy formed 61% of neuroparalytic complications following Semple antirabies vaccination. Acute cerebellar ataxia made up 67% of post varicella encephalitis. Abnormalities observed on multimodality evoked potential studies corresponded to the clinical localisation of the lesion. White matter lesions observed on MR imaging were similar to the lesions observed in multiple sclerosis. However distribution was subcortical and/or centrum semiovale in 11 patients and thalamic in three patients. No signal alterations in the white matter were seen in all the four patients with acute cerebellar ataxia following varicella infections. Significant disability was seen in 23.5% of cases with diffuse or multifocal form of ADEM. Specific viral infection was the antecedent event in all of them.
Conclusions: Specific viral infections and Semple antirabies vaccination still form important antecedenent events for ADEM in India. The type of clinical syndrome to some extent depends on the type of antecedent event.