Horiuchi et al.
Status epilepticus caused by tick-borne encephalitis: A case report. Intern Med. 2025; [In press]. doi:10.2169/internalmedicine.4773-24
A rare case of tick-borne encephalitis (TBE) has been reported in Japan, involving a 78-year-old patient who developed refractory status epilepticus. Shortly after hospital admission, the patient’s condition progressed rapidly from left hemiplegia to impaired consciousness within a few hours, followed by respiratory failure requiring intubation. The clinical course was described in detail. On day 21 after admission, cerebrospinal fluid and serum samples tested positive for TBE-specific IgM and IgG. By day 30, seizure frequency had decreased, and status epilepticus had resolved. Two months after admission, the patient was transferred to another hospital in critical condition.
The incidence of epilepsy in TBE is low, estimated between 0.3% and 3.3%. This case represents the first documented instance of recurrent status epilepticus caused by TBE in Japan. Awareness of TBE among clinicians, especially outside Hokkaido—where only five cases have been previously reported—remains limited, potentially leading to underdiagnosis. TBE should be considered in patients presenting with status epilepticus of unknown origin.