Herpes simplex virus encephalitis – an unexpected relapse with choreoathetosis

Background: The early diagnosis of herpes simplex virus (HSV) encephalitis and the immediate beginning of an antiviral medication with Aciclovir is essential for the prognosis. We report about an unexpected unfavorable course of HSV encephalitis.

Case Report: We report the case of an 11-month-old boy, whom we diagnosed with an HSV encephalitis on the basis of febrile focal status epilepticus. Aciclovir was used early in the course of the disease and he was admitted more than 21 days. Initially, his health state was critical, but within 3 weeks, he recovered completely.

Three days after the discharge from hospital his state worsened. He developed a general muscular hypotonia, showed no visual contact, and had an impressive choreoathetotic movement disorder, which primarily was thought to be epileptic (video demonstration). A reactivation of an HSV encephalitis was not found in liquor examination. The serious movement disorder was resistant to several therapeutic approaches including plasmapheresis and remained for several weeks. As a result of the disease, the boy had a severe cognitive impairment with a revoked sleep-wake cycle and an impulsive behavioral disorder.

Conclusion: From the literature we know that 11 to 26% of patients with HSV encephalitis have a relapse, which is either due to a virus reactivation or an autoimmunological reaction. An early reactivation manifests within 2 to 4 weeks after the primary disease with a potential lethal outcome (13% of cases). Children younger than 2 years seem to be affected the most.

This study urges restraint of prognosis for the course of an HSV encephalitis. Although the virostatic therapy was admitted early and initially a restitutio ad integrum was achieved, a secondary relapse with a severe neurological residual syndrome resulted.