A 9-year-old girl under treatment for Mycoplasma infection developed a fever, began vomiting, and exhibited abnormal behavior The number of cells in the cerebrospinal fluid were increased, and high-amplitude δ waves were found on the electroencephalogram. Diffusion-weighted magnetic resonance imaging images of her head showed an abnormally high signal in the cerebral cortex. After 2 treatments with steroid pulse therapy, intravenous γ immunoglobulin, antibiotics therapy, and antiviral therapy as treatment for encephalitis, her consciousness improved and her ability to perform activities of daily living level had not decreased at the time of discharge. PCR testing of her cerebrospinal fluid revealed type 3 parechovirus, and blood and cerebral spinal fluid tests showed elevation of GluN2B-NT2, GluN2B-CT, GluN1-NT, and GluD2-NT antibodies. Human parechovirus is common as a virus causing sepsis and encephalitis in neonates and infants. There is no case report of parechovirus encephalitis in school-aged children. Careful follow-up is necessary because glutamate receptors can be deeply involved in memory and learning.

We present a difficult-to-diagnose case of hypertrophic pachymeningitis with the absence of characteristic symptoms. A 32-year-old woman was diagnosed as having lupus erythematosus profundus in 2007. In August 2013, she was prescribed oral prednisolone at 20.0 mg/day for her condition, and cyclosporine 100 mg/day was added in July 2016. From October, she experienced headache daily. In November, the prednisolone dosage was reduced to 17.5 mg/day because her lupus erythematosus profundus showed good improvement. About two weeks after the dosage reduction, she complained of fever of over 37 °C, general malaise, and vomiting, in addition to her headache; thus, she was closely examined by her previous doctor, but no organic disease was found. Her symptoms did not improve even when the cyclosporine was stopped. She was diagnosed as having tension-type headache and was prescribed alprazolam and loxoprofen sodium as needed. However, her symptoms barely improved. On her first visit to us, she presented with medium-severity continuous headache occurring every day, but no clearly associated neurological abnormalities were found. Blood test results showed an enhanced inflammatory response and positivity for myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA). Brain magnetic resonance imaging (MRI) indicated enlargement of the pachymeninx on the right side of her head, bilateral fornices, and bilateral cerebellar tentoriums, and she was diagnosed as having hypertrophic pachymeningitis. Her symptoms rapidly improved after the administration of a corticosteroid and did not exacerbated even with the combined use of azathioprine. The diagnosis in this patient was difficult because no characteristic symptoms of hypertrophic pachymeningitis except for headache were observed. The enhanced brain MRI was helpful in determining the underlying cause of headache in the absence of any other clear neurological abnormalities and in making the final diagnosis of hypertrophic pachymeningitis.

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.