Herpes virus type 6 encephalitis in an immunocompetent patient

Abstract

Introduction: herpes virus type 6 (HHV-6) encephalitis is an infection mainly described in immunosuppressed patients. However, there are some reports of infections in immunocompetent patients.

Clinical case: a 28-year-old male patient with no significant medical history was admitted to the emergency room due to a one-week history of right-sided headache, associated with episodes of psychomotor agitation and disorientation. On the admitting exam he had no motor focalization signs or meningeal signs. Initial brain magnetic resonance imaging and magnetic resonance angiography indicated cortical hyperintensity in the frontal and right insular FLAIR sequences. His state of consciousness deteriorated progressively, and therefore a follow-up cranial computed tomography scan was done, showing acute hydrocephaly. A lumbar puncture had an opening pressure of 36 cmH20, with an inflammatory cytology report showing low cerebrospinal fluid (CSF) glucose, lymphocytic pleocytosis, 9.5 ADA and a multiplex PCR positive for herpes type 6. Given these findings, with the suspicion of possible meningeal tuberculosis, four-drug treatment was started along with antiviral treatment with ganciclovir for 14 days, due to HHV-6 isolation.

Discussion: Our patient’s clinical presentation was marked by behavioral changes, confusion and delirium, in the absence of immunosuppression. These symptoms are compatible with a viral encephalitis profile, which was also corroborated by a positive CSF PCR. However, the findings of acute hydrocephalus with severely low CSF glucose, which are not reported in the literature on herpes encephalitis, raise the suspicion of a differential diagnosis, such as concomitant meningeal TB infection.