Herpes simplex virus encephalitis in pregnancy - A case report and review of reported patients in the literature

Background: Herpes simplex virus (HSV) encephalitis is the most common sporadic cause of encephalitis with significant morbidity and mortality that is drastically reduced by early antiviral treatment. Case presentation: We report a 37 year old woman, 33 weeks pregnant, who presented with seizures due to proven HSV-1 encephalitis, and who had had a previous episode of probable viral encephalitis aged 14 years. She was successfully treated with aciclovir on both occasions and, in the latter, went on to deliver a healthy infant. This case is compared with 17 cases of HSV encephalitis in pregnancy in the literature identifying a predominance in the late 2nd and 3rd trimesters, perhaps in part due to immunological changes in pregnancy. The clinical presentation is also compared with non-pregnant patients with HSV encephalitis in the largest prospective UK and European studies. We also present practical advice on management from recent national guidelines. Conclusion: When pregnant women present with new seizures, headache, impaired consciousness or altered behaviour urgent investigation is required to identify common diagnoses, such as eclampsia, venous sinus thrombosis and metabolic disturbances. Nevertheless, viral encephalitis is a very treatable cause of this presentation with potentially serious complications if missed, and may be more common in latter stages of pregnancy. Encephalitis should not be discounted if the patient is afebrile, has a normal Glasgow coma score, or the cerebrospinal fluid white cell count is only slightly elevated, as these features are well recognised in viral encephalitis.