Acute disseminated encephalomyelitis  

 05 November 2004

•      Aka post-infectious or post-vaccinal encephalomyelitis

•      incidence is unknown - ? 10-15% of cases of acute encephalitis

•      associated with vaccinia and measles in the past

CLINICAL FEATURES

•      usually a history of an exanthem or non-specific URTI/gastrointestinal disease

•      cerebellum commonly involved but can present with many signs

•      decreased conscious state is associated with severe disease and is a poor prognostic indicator

INVESTIGATIONS

•      CSF reveals mild mononuclear pleocytosis and elevated protein but up to a third can have normal studies

•      EEG reveals diffuse slowing

•      gadolinium enhanced MRI is the most useful test - can differentiate between ADEM and viral encephalitis by the striking enhancement of multifocal white matter lesions

•      imaging abnormalities take many months to resolve (well after there has been clinical recovery)

TREATMENT

•       case reports proposing efficacy of IVIG and prednisolone but small studies have not shown any benefit

•      supportive therapy probably more important

PROGNOSIS

•      usually good

•      obtundation and coma augur a worse prognosis with a mortality of 30% however recovery had been reported even after prolonged periods of profound coma