Cavernous Malformation of the Trigeminal Nerve Manifesting as Facial Hypoesthesia: A Case Report and Literature Review.

Cavernous malformations are relatively common vascular lesions of the central nervous system. These lesions can occur along the entire neuroaxis; however, they are very rare in cranial nerves. Trigeminal cavernous malformations can be classified into four types, according to their location: type G (Gasserian ganglion), type C (between the cisternal and intra-axial portions), type P (intra-axial trigeminal nerve root in the pons), and type S (spinal tract of the trigeminal nerve root below the medulla oblongata). In our review, we found a total of 27 cases of cavernomas affecting the trigeminal nerve. Most cases presented with pain as the main symptom. We present the case of a 23-year-old man with facial hypoesthesia over the left V2 region that had started three days before, with progressive intensity. No headache or facial pain was noted. His magnetic resonance imaging (MRI) scans showed a vascular lesion in the left pons involving the fibers of the trigeminal nerve. Since the patient was young and symptomatic and the lesion was surgically accessible, a retrosigmoid craniotomy was devised for resection, with the aid of neurophysiological monitoring. Histology revealed a cavernous malformation. The patient had an uneventful recovery, without new neurological deficits, and post-op MRI confirmed complete resection.