Defining encephalopathy in acute disseminated encephalomyelitis.

The International Pediatric Multiple Sclerosis Study Group requires the presence of encephalopathy to diagnose acute disseminated encephalomyelitis. Clinical characteristics of encephalopathy are inadequately delineated in the pediatric demyelinating literature. The authors' purpose was to better define encephalopathy in pediatric acute disseminated encephalomyelitis by describing the details of the mental status change. A retrospective chart review was conducted for 25 children diagnosed with acute disseminated encephalomyelitis according to the International Pediatric Multiple Sclerosis Study Group guidelines. Frequency of encephalopathy-defining features was determined. Clinical characteristics, cerebrospinal fluid findings, and electroencephalography (EEG) findings were compared between patients with different stages of encephalopathy. The authors found irritability (36%), sleepiness (52%), confusion (8%), obtundation (20%), and coma (16%) as encephalopathy-defining features in acute disseminated encephalomyelitis. Twenty-eight percent had seizures, and 65% demonstrated generalized slowing on EEG. Approximately half of the patients in this study were diagnosed with encephalopathy based on the presence of irritability and/or sleepiness only. Such features in young children are often subtle and transient and thus difficult to objectively determine.