Trochlear Nerve Schwannoma: Case Report and Literature Review

Abstract

Schwannomas arise from the Schwann cells of the peripheral and cranial nerves. They represent 8% of the primary cerebral neoplasms. Although schwannomas usually develop in sensory nerves, most often on the vestibular and trigeminal nerves, in very rare cases they can develop in motor nerves. We reported an unusual case of a 29-year-old woman with headache, nausea, vomiting, and blurred vision ongoing for 3 years. Magnetic resonance of the brain showed a solid-cystic expanded injury, heterogeneous, with limits partially defined and epicenter on the pineal gland. The lesion presented hyposignal in T1 and isosignal in T2. An intense enhancement of the solid part was observed after contrast injection. Foci of calcification and absence of diffusion restriction were also observed. The patient underwent microneurosurgery with supracerebellar infratentorial approach in a seated position. Subtotal resection was performed with maintenance of calcified tumor tissue adhered to the right Rosenthal basal vein. In the postoperative phase, the patient remained with diplopia when looking down; however, she reported improvement of headache and nausea.