Postoperative Imaging of Vestibular Schwannomas

Introduction: There is a paucity of data regarding the relevancy to perform postoperative serial imaging of vestibular schwannomas. The objectives are to identify the occurrence of acute complications in the postoperative week and the factors that predict tumor relapse at up to ten years of follow-up.

Methods: Retrospective case study of patients from the University of Montreal Hospital Center (CHUM) otolaryngology clinic and operated for vestibular Schwannoma by microsurgical excision from 2003 to 2021 (n = 272). Electronic medical charts are reviewed to obtain the following independent variables: first symptoms that lead to the diagnosis, surgical approaches, partial or complete tumor resection, preoperative dimensions, tumor size according to the Hannover classification, intra-tumoral cysts, bone erosion, diagnosis of neurofibromatosis. Radiology protocols of CT scans completed at postoperative day five were assessed to evaluate the frequency of acute complications. Regrowth is defined as more than 2 mm per year, and the occurrence of a second intervention is identified (microsurgery or radiotherapy).

Results: The most frequent acute post-operative complication is minimal hematoma (intraventricular or at the surgical site) (n = 10.66%), followed by pneumoencephalus (n = 8.46%), venous sinus thrombosis (n = 3.31%), and important hematoma (n = 2.57%). The posterior fossa approach and the presence of cysts are correlated to the occurrence of any acute complication, respectively: X2 (2, n = 60) = 7.135, p = 0.029; X2 (1, n = 60) = 5.000, p = 0.039. Kaplan Meier curve with Log Rank analysis shows increased regrowth in partial resections, compared to complete resections: X2 (1, n = 60) = 13.952, p < 0.001. No regrowth probability is of about 45% at 40 months postoperatively in partial resections, compared to 95% in complete resections.

Conclusions: Acute complications with serious clinical implications are rare, and CT scans should not be completed in the postoperative week in the absence of neurologic clinical signs or symptoms. Most completely resected vestibular Schwannomas do not show recurrence after many years of follow up.