Twenty children (12 female; age range, 1.3-15 years) with encephalitis lethargica were studied over 9 years by researchers at University of Sydney, Westmead, Australia; and John Radcliffe Hospital, Oxford, UK. Encephalitis lethargica is characterized by psychiatric features (catatonia, agitation, compulsive behaviors), extrapyramidal movement disorders (hyperkinetic, chorea, oculogyric crises, dystonia, hemiballism, or akinetic, Parkinsonism), and sleep disturbance (insomnia or hypersomnolence). Seizures, autonomic dysfunction, encephalopathy, and cognitive dysfunction are less common. Ten sera (from 2 males and 8 females) and 6 cerebrospinal fluid samples, taken during the first 3 weeks of the illness before immunotherapy, were positive for N-methyl-d-aspartate receptor autoantibodies. Of 10 NMDAR-Ab-positive patients, 4 were <5 years of age, and only 2 had preceding infection. Presentation was often dramatic with agitation, catatonia, dyskinesias and seizures, and Parkinsonism and somnolence were prominent only in 4 patients. Unusual dyskinesias included cycling, stereotyped flailing, and orolingual “rabbit” movements. At follow-up, 4 patients were completely recovered, and 6 were impaired. None had identified ovarian tumor. Of 10 NMDAR-Ab-negative patients, none was <5 years of age; 7 were postinfectious. Parkinsonism was the dominant movement disorder. Seven had persistent symptoms at follow-up. Immunotherapies included IV methyl-prednisolone followed by oral prednisolone (n=13) or IV immunoglobulin (n=2). [1]

COMMENT. NMDAR-Ab encephalitis is a dyskinetic form of encephalitis lethargica that may affect very young children and is rarely preceded by infection. Detectable ovarian tumors are uncommon in female patients under the age of 20 years. Outcome is poor, and early immunotherapy is considered warranted. The detection of specific antibodies is important in children with symptoms of encephalitis. The authors previously reported 20 cases of encephalitis lethargica with evidence of basal ganglia autoimmunity, mainly in children, and the condition is not rare. (Ped Neur Briefs Jan 2004;18:1-2) [2]