Treatment of acute demyelinating encephalomyelitis associated with recent rickettsial infection.

Acute disseminated encephalomyelitis (ADEM) is a rare, immune-mediated demyelinating disorder of the central nervous system that typically follows viral or bacterial infections. There are only two known case reports that describe an association with ADEM post rickettsial infection. A female in her 80s presented with progressive neurological decline, including dysarthria, dysphagia and hemiparesis, following recent treatment in Hong Kong for rickettsial infection. Initial CT brain imaging showed a right subcortical infarct. She deteriorated with encephalopathy and respiratory failure, requiring intubation. MRI revealed extensive brain and spinal demyelination. Infectious, autoimmune and paraneoplastic investigations were negative, while serology revealed markedly elevated spotted fever group antibodies. Treatment with high-dose corticosteroids and plasma exchange therapy resulted in significant neurological recovery. She was discharged after rehabilitation with a good recovery at 70%-80% of pre-morbid function. This case supports a possible post-infectious immune-mediated mechanism linking rickettsia and ADEM and underscores the importance of early recognition and treatment of ADEM.