Perineural spread in Nasopharyngeal carcinoma: detection by CT and MRI

Nasopharyngeal carcinoma is mainly arising from the fossa of Rosenmuller frequently extends to the paranasopharyngeal space, which contains fibrofatty tissue and portions of the third division [V3] of the trigeminal nerve. The aims of this work are to describe the radiological findings of perineural spread in nasopharyngeal carcinoma and to compare the accuracy of MRI and CT in diagnosing perineural metastasis along the cranial nerves. A total of 52 patients diagnosed with nasopharyngeal carcinoma were included in this study. Both computed tomography and magnetic resonance imaging of the head and neck, including the nasopharynx, were performed for all patients. The extent of the trigeminal perineural tumor invasion was evaluated and correlated with neurologic symptoms. All 52 cases of nasopharyngeal carcinoma showed radiologic evidence of perineurai spread. However, clinical signs and symptoms of cranial nerve palsy were only seen in 36.5% [19 of 52] of the patients, leaving 63.5% [33 of 52] of the patients with no signs of nerve paralysis. The most common nerve to be infiltrated is the mandibular nerve in 30.7%. Maxillary nerve [V2], Ophthalmic division [VI] and vidian nerve were involved in 15.4%, 7.7%, 13.5% respectively. Maxillary and mandibular nerves were involved together in 32.7% of the patients. Perineural spread of the cranial nerves especially, trigeminal nerve is one of the most common and important routes in the intracranial extension of nasopharyngeal carcinoma.Clinical and radiologic findings reveal that nasopharyngeal carcinoma has a significant liability for perineural invasion. Neurologic symptoms usually present when the intracranial perineural spread has occurred. MR is the preferred imaging method for the evaluation of nasopharyngeal carcinoma perineural spread