Herpes zoster ophthalmicus progressing to encephalitis: beware pain preceding the rash.

We present a challenging case in which the dermatomal pain associated with herpes zoster ophthalmicus preceded the cutaneous rash by several days. It thus highlights the need to consider this diagnosis among the differentials for severe unilateral headache in the elderly. The patient unfortunately progressed to develop encephalitis, an uncommon but serious complication of zoster reactivation and a reminder that this remains an important cause of morbidity and mortality in the elderly population.