Opsoclonus-myoclonus syndrome with abnormal magnetic resonance imaging and brainstem auditory evoked potentials

We describe two patients in encephalitis with opsoclonus-myoclonus syndrome. Cranial magnetic resonance imaging demonstrated an area of hyperintensity on the T2-weighted images in the left tegmentum at the pons level (case 1) and in the left tegmentum and partly basis at the upper pons level (case 2), respectively. On the other hand, brainstem auditory evoked potentials following left monaural stimulation and ipsilateral records revealed a delay of IIIrd wave latency and prolongation of I-III interpeak latencies (case 1). From these findings we suggest that the locus of the lesion of opsoclonus-myoclonus syndrome may partly exist in the brainstem (pontine tegmentum).