Clinical-radiologic issues in perineural tumor spread of malignant diseases of the extracranial head and neck.

The radiologic and clinical records of 52 patients with radiologically documented perineural tumor were reviewed to assess the spectrum of tumors responsible, the nerves most commonly involved, and the optimal methods for imaging perineural tumor infiltration. Perineural tumor infiltration was most commonly seen with head and neck squamous cell carcinoma, followed by adenoid cystic carcinoma and several others, such as non-Hodgkin lymphoma, malignant schwannoma, minor salivary gland malignancy, and other sarcomas. The second and third divisions of the trigeminal nerve and the facial nerve were most commonly involved with perineural tumor. Both antegrade and retrograde perineural tumor spread were seen, although retrograde spread was significantly more common. Both high-resolution direct coronal computed tomography and magnetic resonance (MR) imaging clearly showed perineural tumor below the skull base. MR imaging best depicted skull base, cisternal, and brain stem perineural tumor infiltration. T1-weighted MR imaging before and after administration of gadopentetate dimeglumine is the study of choice in investigation of perineural tumor.