Tumours at the skull base may show perineural infiltration of the mandibular nerve. Subsequent retrograde spread into the cavernous sinus, Gasserian ganglion, the trigeminal nerve and the pons may be seen. The patient, a known and treated case of nasopharyngeal carcinoma (NPC), complained of trigeminal neuralgia and difficulty in chewing. Magnetic resonance imaging (MRI) revealed a Gasserian ganglion and trigeminal infiltration with resultant atrophy of the muscles innervated by the mandibular nerve. Proximal cranial nerve involvement should be suspected in patients with skull base malignancy presenting with trigeminal neuralgia. MRI is the modality of choice in delineating the pathological process.