Pitfalls associated with the diagnosis of herpes simplex encephalitis

Abstract

Herpes simplex encephalitis (HSE) still remains a serious illness with high morbidity and mortality. The characteristic presentation of HSE usually consists of fever, headache, and altered mental function. We present three patients with atypical features of HSE. First, a 48-year-old man with symptomatic posttraumatic epilepsy, who developed a gastrointestinal infection, seizures, and fever. After significant clinical improvement, the patient had fever again and developed a status epilepticus, which led to the diagnosis of HSE. Second, an 84-year-old woman with hyperactive delirium after levofloxacin intake. Cranial computed tomography (CCT) revealed hypodense temporal changes, prompting lumbar puncture and diagnosis of HSE. Third, a 51-year-old diabetic woman presented with fever and acute confusion. As CCT and cell count of cerebrospinal fluid (CSF) were normal, infection and hyperglycemia as initial diagnoses were postulated. Due to aphasic symptoms, the differential diagnosis of a stroke was taken into account. Thus a second lumbar puncture led to the correct diagnosis of HSE. These atypical presentations need a high grade of suspicion and a high willingness to reconsider the initial working diagnosis, in order to prevent a diagnostic delay.

Keywords: Acyclovir; atypical course of disease; cerebrospinal fluid; consciousness disturbance; herpes simplex encephalitis; herpes simplex virus.

Figure 1

48-year-old man at time of convulsive state and temperature of 40°C. (a) Unenhanced axial CT scan shows right mesiotemporal hypodensity and swelling. (b) 10 days later, axial T2-weighted MR image shows increased signal intensity in the right temporal and frontal lobe

Figure 2

85-year-old woman with delirium and myoclonic jerks. (a) Unenhanced axial CT scan shows hypodensity of the right temporal lobe. (b) 4 days later axial T2-weighted MR image shows increased signal intensity in the right temporal lobe and additional movement artefacts

Figure 3

51-year-old diabetic woman with fever and confusion. (a) Unenhanced axial CT scan shows no significant changes in the left temporal lobe. (b) 2 days later unenhanced axial CT scan is still unremarkable. (c) 14 days later, unenhanced axial CT scan shows marked hypodensity in the left temporal lobe