Trigeminal sensory neuropathy.

The etiology of trigeminal sensory neuropathy remains obscure. In a recent case, a relationship to herpes simplex virus might be inferred. A woman, aged 63 years, had at least ten episodes of "cold sore," always at the same site on her upper lip. After a typical prodromal burning, she expected a cold sore to appear, but a trigeminal sensory neuropathy began instead, starting at the site where the cold sores had always appeared.