[A one-year-old male infant with sleep-associated febrile myoclonus].

Febrile myoclonus is a benign neurological symptom induced by fever. The physiological mechanism is unknown. We herein report a 1 year and 7 months old male patient with intermittent jerks of the whole body during a high fever caused by acute otitis media. He experienced more than 50 jerks over a period of 2 days. The jerks appeared only during sleep. He showed no impairment of consciousness and no abnormalities in neurological examination, blood examination, electroencephalogram, or brain MRI findings. We diagnosed him with febrile myoclonus. The myoclonic jerks disappeared as the fever decreased without neurological sequelae. To the best of our knowledge, febrile myoclonus only during sleep has never been reported. To clarify the pathophysiology of febrile myoclonus, we should focus on the relationship between the myoclonus and the sleep/awake states.