Neuropsychiatric Symptoms After HHV-6 Encephalitis in an Immunocompetent Child: A Case Report

BACKGROUND Human herpesvirus 6 (HHV-6) is a common pathogen known to cause roseola infantum in children and encephalitis in immunocompromised individuals. In immunocompetent children, HHV-6 encephalitis is rare and typically self-limiting. Although neurological symptoms such as seizures and altered consciousness have been reported, neuropsychiatric manifestations - particularly catatonia - are extremely uncommon. CASE REPORT A 4-year-old immunocompetent boy presented with sudden behavioral changes 1 week after a viral infection. Cerebrospinal fluid testing showed HHV-6 positivity. His symptoms included anxiety, irritability, compulsive handwashing, unprovoked laughter, reduced responsiveness, insomnia, and stereotypies, consistent with hyperkinetic catatonia. Autoimmune workup findings were negative, and the patient did not meet criteria for seronegative autoimmune encephalitis, resulting in attribution of his symptoms to HHV-6 encephalitis. Magnetic resonance imaging and electroencephalography findings were unremarkable. The patient received ganciclovir and lorazepam, resulting in substantial improvement. At a follow-up visit 1.5 months after discharge, he had returned to baseline except for mild insomnia. Lorazepam was tapered off 2 months after he achieved full recovery. CONCLUSIONS This is the first report of HHV-6 central nervous system infection causing neuropsychiatric manifestations in an immunocompetent child within the pediatric age group. This case highlights HHV-6 encephalitis as a potential cause of acute neuropsychiatric symptoms in immunocompetent children. Neuropsychiatric manifestations, including catatonia, may occur even in the absence of classical signs of encephalitis. Awareness of this rare presentation may facilitate timely diagnosis and treatment.