2018 Volume 46 Issue 2 Pages 77-83
Human herpesvirus-6 (HHV-6) infection, which is common during infancy and/or early childhood, is a known cause of febrile seizures and may often cause encephalitis or encephalopathy. We treated a patient with HHV-6 encephalopathy who presented with complex febrile seizures without a disturbance of consciousness at the time of admission, but gradually demonstrated behavioral abnormalities and was subsequently diagnosed as having encephalopathy.
A 2-year-old boy without developmental delay presented with complex febrile seizures and was hospitalized for further examination. He was known to have had 5 seizure episodes prior to admission; however, his consciousness was clear in the interim period. His blood tests, computed tomography, and magnetic resonance imaging (MRI) of the head did not reveal any abnormalities. However, an electroencephalogram (EEG) showed a few localized slow waves in the occipital region. Approximately 8 hours after admission, he developed a staring on gaze, oral automatism, and involuntary movements of his arms and legs. A repeat EEG was obtained based on clinical suspicion of a disturbance of consciousness, and this EEG showed slow-wave activity in all areas of the brain, leading to a diagnosis of encephalopathy. We initiated steroid pulse treatment in addition to other management. The patient’s blood samples that had been sent to the Kawasaki City Institute of Public Health showed HHV-6, and the patient was diagnosed as having HHV-6-related encephalopathy. Post-treatment repeat MRI and EEG did not show any abnormalities indicative of nervous system disorders. He was discharged 12 days after onset with no neurological sequelae.
We emphasize the importance of close monitoring even in patients who show clear consciousness during the interictal period. Regular monitoring with EEGs is important to detect encephalopathy.
