Acute disseminated encephalomyelitis in children. A descriptive study in Tehran, Iran

OBJECTIVE: To determine the frequency, etiology (viral infection or vaccination), presenting signs and symptoms, response to therapy, complication and course of acute disseminated encephalomyelitis (ADEM) in our hospitals.

METHODS: A 2-year retrospective, descriptive, chart review of children with final diagnosis of ADEM in 2 hospitals (Hazrat Rasool and Mofid in Tehran, Iran during 2000-2002) were carried out. The diagnosis is based upon clinical presentation, physical examination and ruling out of other disease (imaging, laboratories and so forth) of expert pediatric neurologists. Acute disseminated encephalomyelitis was documented in all cases by characteristics MRI changes included inflammation and demyelination in subcortical or periventricular regions.

RESULTS: Acute disseminated encephalomyelitis were diagnosed in 15 patients. More than half of patients were between 9-14 years old. It was rare in 1-5 years old children. It had an abrupt onset, preceding infection/vaccination with no gender differences. Approximately 46.4% of cases had a recent upper respiratory tract illness. Varicella zoster virus infection, urinary tract infection, and mycoplasma pneumoniae were observed. Presentation signs included ataxia, decreased consciousness, fever plus nausea/vomiting, cranial nerve involvement, dysarthric speech, convulsion, hemiparesis, paresthesia, meningismus, and headache. We identified inflammation and demyelination in subcortical than periventricular lesions by magnetic resonance imaging. Prognosis was excellent with low mortality rate (6.6%).

CONCLUSION: Acute disseminated encephalomyelitis is common in our children, possibly because of the high prevalence of causative infections. Due to advances in control of traditional exanthematous diseases such as measle, rubella and so forth, most cases of ADEM in this study followed non-specific upper respiratory infections. Differentiation of ADEM from a single episode of multiple sclerosis is difficult. Diagnosis of multiple sclerosis should be carried out if new symptoms and signs or imaging abnormalities appear, more than 3 months after the onset of clinical symptoms in ADEM cases.