HHV-6-induced status epilepticus in an immunocompetent adult
A new case report from Baylor College of Medicine describes a case of HHV-6 encephalitis presenting as status epilepticus (SE) in an immunocompetent patient. Although the reactivation of HHV-6 is frequently reported in immunosuppressed or immunocompromised patients, the reactivation of HHV-6 with associated disease in immunocompetent patients is rarely reported, in part because HHV-6 testing is not routine for immunocompetent patients presenting with encephalitis.
The report describes a 65-year-old woman who was brought to the emergency room after presenting with a right temporal headache followed by an acute episode of confusion in which she was disoriented in time and space. The patient also displayed left-sided weakness with a muscle twitch in the left arm. The EEG revealed right hemisphere dysfunction with electrographic seizure in the posterior head region. In addition, the MRI displayed multifocal areas of hyperintensities on the T2-weighted image.
Examination for HHV-6 revealed 148,387 copies/mL of HHV-6B DNA in the serum and 16,189 copies/mL of HHV-6B DNA in the CSF. The patient was initially treated with foscarnet, and later switched to ganciclovir for 21 days. The patient also received antiepileptic medications, and has been seizure-free for 1 year.
HHV-6 is a common cause of febrile status epilepticus in infants. In their NIH multi-site FEBSTAT study, Epstein and colleagues found that primary and reactivated HHV-6B infection was the cause of febrile SE in one-third of 167 patients studied (Epstein 2012). These subjects were children between 1 month and 5 years of age. In the Epstein study, 70% of the infants had a primary infection, but in 30% the HHV-6 infection was a reactivation of a previous infection, suggesting that these infants may have experienced difficulty controlling the virus. Infants with febrile status epilepticus are not routinely monitored for HHV-6 infection or immune defects.