Extra temporal involvement in herpes simplex encephalitis

Temporal lobe abnormalities on brain imaging have been described as strong evidence for herpes simplex encephalitis (HSE) in appropriate clinical settings. Extra temporal abnormalities are less well described in these patients. We retrospectively reviewed 20 patients of HSE and found extra temporal involvement in 11 (55%) patients. Three patients (15%) had pure extra temporal abnormalities. Twelve patients (60%) had temporal lobe involvement, four patients (20%) had pure temporal lobe involvement and five patients (25%) had normal CT/MRI scans. Our study suggests that extra temporal involvement on brain imaging is common in HSE and in a significant minority of the patients this can even be the sole abnormality.