Rare Cranial Nerve Schwannomas: A Retrospective Review of Nontrigeminal, Nonvestibular Cranial Nerve Schwannomas

Abstract

Introduction:Intracranial schwannomas arising from non-trigeminal and non-vestibular sources are extremely rare constituting <0.8% of all schwannomas. In this article, we have analyzed our experience in the management of these rare tumors over a 10-year period.Material and Methods:There were a total of 16 cases, with 11 of them undergoing microsurgical resection and 5 undergoing stereotactic radiosurgery (SRS).Results:There were no fresh neurological deficit in any of these patients and two patients underwent postoperative SRS for residual tumor. One patient died due to postoperative septicemia.Conclusion:Knowledge of these lesions along with their clinicoradiological profile is essential to maintain a high index of suspicion and understand the nuances of treatment.

Oculomotor schwannoma causing a progressive complete third-nerve palsy

“…These vascular lesions may be identified via flow-void hypointense regions on T1-weighted and T2-weighted MRA. However, the symptomatology and initial MR scans in the present case were not consistent with a lesion of vascular origin 5…”

“…Intracranial schwannomas tend to have an isointense-to-hypointense appearance on T1-weighted sequences, with more heterogeneous intensity on T2-weighted scans 5. Importantly, they demonstrate intense contrast enhancement with gadolinium on T1-weighted images (figure 1b).…”

Expert Commentary on Rare (Nonvestibular, Nontrigenimal) Cranial Nerve Schwannomas

“…Intracranial schwannomas arising from the origins other than vestibular or trigeminal nerves are very rare and constituting <0.8% of all schwannomas. In the paper of Dr. Harsh Deora et al .,[ 3 ] they report on 16 such cases including seven facial nerve, four olfactory groove, three sixth-nerve and two third-nerve schwannomas. Eleven patients had undergone microsurgical resection and five had been sent to stereotactic radiosurgery.…”

“…Dr. et al . [ 3 ] also share their experiences on four cases with olfactory groove schwannomas in their paper. The schwannomas present with either loss of function of originated cranial nerve or symptoms due to their mass effect.…”

“…In accordance, the patients in the case series of Dr. et al . [ 3 ] also have a wide spectrum of signs due to compression of adjacent brain structures or neighbor cranial nerves beside the varying signs owing to originated cranial nerve. For example, most of their patients with facial nerve schwannomas presenting with sudden facial weakness have also hearing loss or dizziness and unsteadiness of gait with cerebellar signs.…”