Discussion: The decreased facial and corneal sensation as well as head muscle atrophy are indicative of dysfunction of all branches of the trigeminal nerve. The mandibular branch serves motor to the muscles of mastication, the ophthalmic branch sensation to the cornea, and the maxillary branch sensation to the face. Neoplasia and granulomatous disease would be primary rule outs with nerve sheath tumor most likely. A retrobulbar mass or olfactory lobe tumor would be located too far rostrally to affect all major branches of the trigeminal nerve.

More images from the MRI (Click to enlarge):


Question: What part of the brain is being affected by this contrast enhancing lesion?