Presentation
Patient presented to the emergency department with a 1 week history of mild fever, malaise, confusion, and multiple falls.
Patient Data
Asymmetric unilateral FLAIR cortical hyperintensity along the right temporal lobe including the insular region, with questionable asymmetric leptomeningeal enhancement along the right temporal lobe.
Cortical and to a lesser degree subcortical FLAIR hyperintensity and cortical swelling throughout the right temporal lobe, progressed from prior. Additional new FLAIR hyperintensity in the left parieto-occipital lobe.
Case Discussion
This patient presented with nonspecific systemic and neurological symptoms. The patient was not initially evaluated for viral etiology, and the radiologist played a vital role in guiding proper workup and management. Including "viral encephalitis" as a differential in the impression of the radiology report prompted initiation of IV acyclovir and collection of CSF cultures.
Cultures came back positive for herpes simplex virus type 2 (HSV-2). Although the patient was being treated with acyclovir, symptoms progressed over the following days and the patient began experiencing seizures. Repeat MRI showed progression of right temporal lobe FLAIR hyperintensity, with new involvement of the left parieto-occipital lobe.
Main teaching points for this case are as follows:
initial CT is often normal or nonspecific in early stages of herpes simplex encephalitis, so it is necessary to have a high index of suspicion for further workup
imaging findings can progress over time, and involvement is not always isolated to the temporal lobe
it is crucial to include herpes simplex encephalitis in the differential in a patient with altered mental status and abnormal signal changes in the temporal lobe on MRI. Calling this in the radiology report can prompt early treatment with acyclovir.
in an immunocompetent adult, HSV-2 is an exceedingly rare cause of herpes simplex encephalitis compared to infection with herpes simplex virus type 1