Fulminant course in a case of diffuse myelinoclastic encephalitis-- a case report

We report on a 10-year old previously healthy boy who exhibited a fulminant and nearly monophasic clinical course of demyelinating encephalitis with relapsing intracranial hypertension syndrome. Histologic examination of a diagnostic brain biopsy revealed an inflammatory demyelinating process with perivascular T lymphocytic infiltration and axonal damage reminiscent of multiple sclerosis-like lesions. In the brain, the DNA of human Herpes virus 6 (HHV6) was detectable. Eleven months after the initial symptoms and on maintainance with oral steroids, MRI showed demyelination of both hemispheres as well as demyelination of the brain stem and Wallerian degeneration. The boy exhibited a severe neurologic defect syndrome. The clinical and radiological course is unusual because of the asymmetric progression of the encephalitis and the extensive confluent lesions without demarcated border or enhancement of the rim after injection of gadolinium. The clinical course showed no definite steroid response. The pathogenetic relevance of HHV6 remains elusive. Although single patients with HHV6-associated encephalomyelitis have been reported, HHV6 DNA is occasionally detected in brains of healthy individuals.