Perineural spread of cancer along the three trigeminal divisions.

Perineural spread of head and neck cancers is a well-documented phenomenon, but the diagnosis is often delayed due to lack of familiarity with clinical manifestations, anatomy of the head and neck, and imaging signs. We present single cases of perineural spread along each of the 3 divisions of the trigeminal nerve in which the perineural spread was initially overlooked. Although perineural spread is often associated with a poor prognosis, earlier detection may improve outcome.