Magnetic resonance imaging of perineural spread of head and neck malignancies.

Perineural invasion is a common mechanism of spread of head and neck cancers. Imaging plays an important role in detection of this condition because a large number of patients with perineural spread (PNS) are clinically asymptomatic. Accurate detection of PNS requires an understanding of anatomy of commonly involved neural pathways. High level of suspicion on the part of the radiologist, awareness of common imaging signs of PNS and careful attention to imaging technique can aid in earlier detection of this condition.