Description

Herpes simplex virus (HSV) is the most common non-epidemic and sporadic cause of viral meningoencephalitis with an incidence of approximately 1–3 cases per million.1 Ninety five per cent of fatal adult cases are a result of type 1 HSV (HSV-1) and typically follow latent viral reactivation in the trigeminal ganglion in immunocompetent patients.1 MRI is regarded as being the most sensitive radiological investigation, with changes usually visible within 2–3 days of onset of symptoms.1 Traditionally on MRI, Herpes simplex encephalitis (HSE) exhibits bilateral asymmetrical involvement of the limbic system, including the medial temporal lobes, insular cortices and inferolateral frontal lobes and cingulate gyri.1 Sparing of the basal ganglia is a key feature, which also helps in differentiating from middle cerebral artery infarction on diffusion-weighted imaging (DWI). Atypical patterns, if seen, usually affect the younger population with involvement of the cerebral hemispheres and rarely, the midbrain and pons.1

We present serial brain imaging of a 52-year-old woman who presented to the acute medical unit with a week's history of lethargy, intermittent headaches and an episode of syncope prior …