Trigeminal Neuropathy Ascribed to a Probable Intrinsic Brainstem Schwannoma of the Pons: A Case Report.

Brainstem schwannomas are very rare, only 11 cases have been reported in the literature so far. We report a small intraparenchymal brainstem schwannoma of the pons, in a 37-year-old female patient who presented with a four-day history of numbness at the mandibular division of the trigeminal nerve on the left side of her face. Trigeminal neuralgia was diagnosed, and magnetic resonance imaging (MRI) showed a small intraparenchymal lesion at the level of the nuclei of the left trigeminal nerve present at the junction between the pons and left brachium pontis. A biopsy wasn't feasible in this small lesion. We discuss the keen radiological features that helped in the presumptive diagnosis of an intrinsic brainstem schwannoma, with both intra- and extra-axial components. Our case had the earliest presentation and the smallest probable brainstem schwannoma reported so far, as well as its unique symptomatology of trigeminal neuralgia related to both the nucleus and the nerve of the fifth cranial nerve (CN V).