Surgical Treatment of Caudal Cranial Nerves Schwannomas: Literature Review and Analysis of Own Clinical Observations

Introduction: The group of non-vestibular schwannomas includes caudal cranial nerves schwannomas (CCNS). Tumors grow from one of the following cranial nerves: glossopharyngeal, vagus, and accessory nerves. Such tumors make up to 2.9-4.0% of all intracranial schwannomas.

Objective: Analysis of literature data and own clinical observations of CCNS, highlighting clinical features and surgical approaches in this type of neoplasms.

Material and methods: We have analyzed subject-related literature data in English. Three own clinical observations were analyzed. In all cases, 1.5 Tesla T1, T2, Flair, DWI, T1 IV-enhanced MRI and helical CT angiography were performed before the surgery. All patients underwent surgical treatment. Using a standard retrosigmoid approach, medullocerebellar cistern was opened and CSF was evacuated to relax the cerebellum. OPMI VARIO 700 microscope (Carl Zeiss, Oberkochen, Germany) Soring’s ultrasonic tumor aspiration system was used for tumor removal. In a type D tumor patient, endoscopic assistance was used (Karl Storz endoscopy tower and 30-, 45-, and 70-degree endoscopes). Facial nerve function and caudal nerves function were neurophysiologically monitored using Nim Response 3.0 (Medtronic, Minneapolis, USA) at all surgery stages.

Results: In all cases, total resection of intracranial part of the tumor was performed. Bulbar disorders in two patients were temporary and only one patient had persistent bulbar disorders. Intraoperative neuromonitoring of facial nerve and caudal cranial nerves function is an important step in a surgery, which helps to reduce the risk of cranial nerves damage.

Keywords:Non-vestibular schwannomas; Caudal cranial nerves schwannomas; Surgical treatment; Intraoperative neuromonitoring