The developmental outcome of 11 patients with opsoclonus-myoclonus, 8 having occult neuroblastoma, is reported from the Division of Pediatric Neurology, Children’s Memorial Hospital, Chicago. Nine were treated with ACTH and 3 received prednisone. Symptoms recurred in 9 when ACTH was withdrawn. The response to predisone was minimal. Symptoms were not improved by removal of a neuroblastoma. The median age at presentation was 17 months. Follow-up ranged from 12 to 115 months. Delayed development with motor incoordination and speech delay occurred in 8 children and 3 had behavioral problems. IQs ranged from 56 to 75 in 7 children and one had a borderline IQ. Development was normal in 2 of 3 patients without neuroblastoma and in only 1 of 8 whose opsoclonus-myoclonus was associated with neuroblastoma. 
COMMENT. Other terms for this syndrome include myoclonic encephalopathy of infancy (MEI), dancing eyes syndrome, and infantile polymyoclonia. The majority of children with opsoclonus-myoclonus in this study were found to have significant developmental delay. Others report that about 50% are left with intellectual deficits . The criteria for diagnosis were 1) marked motor incapacity from myoclonic jerking and/or cerebellar ataxia, 2) opsoclonus, 3) acute or subacute onset, and 4) absence of central nervous system infection. All 3 children with MEI without neuroblastoma had a viral illness 1-2 weeks before symptoms began. The pathogenesis is multiple and is usually viral in origin, notably poliovirus, Coxsackie virus B3, and St Louis encephalitis virus. An autoimmune mechanism and DDT intoxication have also been invoked . In treatment, some advocate ACTH for the acute stage followed by predisone for several months, (see Progress in Pediatric Neurology I, 1991, Chicago, PNB Publishers, p 486).