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Opsoclonus-myoclonus syndrome is a well recognised disease in children. The aetiology, except for neuroblastoma accounting for a few patients, remains unknown.1 Viral infection is one of the presumed physiopathological mechanisms. We report a case of opsoclonus-myoclonus syndrome due to enterovirus infection with spontaneous remission, no recurrence, and full recovery after 36 months follow up.
A two year old girl, with a previously normal development, exhibited acute ataxia after a two day history of fever and vomiting. One day later, she developed myoclonic jerks and opsoclonus. Initially, she was febrile (39°C), irritable, and unable to sit or to stand because of truncal ataxia. There was resistance to neck flexion. Rapid irregular and oscillatory eye movements were seen with continual myoclonus of the neck and limbs. Enterovirus RNA was detected in CSF at day 3 by polymerase chain reaction (PCR).2 The CSF, on day 3, contained 113 leucocytes/mm3 (98% lymphocytes and 2% polymorphonuclear leucocytes), 25 mg/dl protein, and normal glucose concentrations. The interferon-α titre in CSF was raised (3 U/Ml). At day 15, the CSF contained 20 leucocytes/mm3. The interferon-α titre was normal in both CSF and blood. EEG and brain MRI were normal. A chest radiograph, abdominal ultrasound examination, and urine titres of homovanillic acid and vanillylmandelic acid were normal. Viral culture from CSF was negative. Treatment with clobazam (1mg/kg/day) led to resolution of the myoclonus over 15 days. Developmental and neurological examinations were normal 36 months later (Denver developmental screening test).
We report a child with opsoclonus-myoclonus syndrome associated with enterovirus infection. Enterovirus infection associated with this syndrome has been rarely reported but could be underestimated.3 In fact, a diagnostic method with a high sensitivity was only recently provided by PCR, whereas the previous diagnostic test—namely, viral culture and serological assay, had a low diagnosis yield. Development of enterovirus RNA detection by PCR in blood and CSF should be more systematically performed in opsoclonus-myoclonus syndrome to better define the place of this infection as a cause of this syndrome.The relation between enterovirus infection and opsoclonus myoclonus syndrome could have some therapeutic implications. Interestingly, this patient and the two other similar cases reported in the literature had a spontaneous recovery in less than 15 days.3 Despite the lack of a well designed therapeutic trial, corticosteroid treatment is commonly used in patients with opsoclonus-myoclonus syndrome whatever the aetiology. Most of the patients given this treatment have shown a resolution of ataxic and myoclonic symptoms. However, long term follow up shows nearly constant mental sequelae and a high rate of myoclonic relapse.1 There is clear experimental evidence that corticosteroids potentiate coxsackie virus infection leading some authors to recommend avoidance of this treatment in enterovirus related disease.4 Thus in our opinion corticosteroid treatment should be considered cautiously before the results of virological investigations and avoided during acute enterovirus infection associated with opsoclonus-myoclonus syndrome.