Acute disseminated encephalomyelitis - A long-term follow-up study of 84 pediatric patients

Background: Acute disseminated encephalomyelitis (ADEM) is an inflammatory demyelinating disease of the CNS. Few pediatric series have been published, with retrospective and short-term follow-up studies. Objectives: To describe a cohort of pediatric patients with ADEM and to determine whether clinical and neuroimaging findings predict outcome. Methods: A prospective study was conducted between March 1988 and July 2000 on 84 consecutive children with ADEM at the National Pediatric Hospital "Dr. J. P. Garrahan." Results: Mean age at onset was 5.3 +/- 3.9 years, with a significant male predominance. Sixty-two patients (74%) had a preceding viral illness or vaccination. Acute hemiparesis (76%), unilateral or bilateral long tract signs (85%), and changes in mental state (69%) were the most prominent presenting features. Four MRI groups were identified: ADEM with small lesions (62%), with large lesions (24%), with additional bithalamic involvement (12%), and acute hemorrhagic encephalomyelitis (2%). Of the 54 children whose CSF samples were analyzed, none showed intrathecal oligoclonal bands. The use of high-dose corticosteroid treatment, particularly IV methylprednisolone, was associated with good recovery and resolution of MRI lesions. After a mean follow-up of 6.6 +/- 3.8 years, 90% of children showed a monophasic course, and 10% a biphasic disease. Eighty-nine percent of patients show at present Expanded Disability Status Scale scores of 0 to 2.5. Eleven percent have disability scores of 3 to 6.5. Conclusions: Childhood acute disseminated encephalomyelitis is a benign condition, affecting boys more frequently. No association was found between MRI groups and disability. Disability was related to optic nerve involvement at presentation. Even in relapsing cases, the distinction between acute disseminated encephalomyelitis and MS was possible on the basis of long-term clinical and neuroimaging follow-up and the absence of oligoclonal bands in CSF.