[Case of non-convulsive status epilepticus after influenza virus B infection]

A 24-year-old woman was referred to our hospital because of impaired consciousness after influenza virus B infection. Neurological examination revealed mild disturbance of consciousness without other neurological abnormalities. Laboratory tests showed elevated serum CRP, IL-6 and TNF-α levels. The level of IL-6 in the cerebrospinal fluid was also slightly elevated. Electroencephalography (EEG) disclosed almost continuous generalized spike and wave complexes and multiple spikes and wave complexes at 1.5-3 Hz. Brain MRI was normal. She was diagnosed as having influenza encephalopathy presenting non-convulsive status epilepticus (NCSE), and commenced methylprednisolone pulse therapy followed by prednisolone with gradual tapering. She was also treated with intravenous phenytoin and oral sodium valproate for NCSE. The next day, her consciousness level had improved. Although she became alert, epileptic discharges on EEG were still observed on the seventh hospital day, and levetiracetam was added. Then, her epileptic discharges almost completely disappeared on the twelfth hospital day. She was discharged without any neurological deficit. We consider this patient to be a case of transient NCSE due to influenza encephalopathy; alternatively, she may have epileptic traits and her NCSE may have been provoked by influenza virus infection.