Augmented startle responses in opsoclonus-myoclonus syndrome.

We report a 3-year-old boy with opsoclonus-myoclonus syndrome (OMS) who presented with exaggerated startle responses to unexpected auditory stimuli during an episode of myoclonic status. An augmented blink reflex was also observed clinically and electrophysiologically. Based on the assumption that hyperexcitability in the lower pontine tegmentum may be responsible for the acoustic startle and blink reflex in OMS, we considered that increased excitability of independent but neighboring structures, including the pontine paramedian reticular formation, may cause OMS symptoms.