Changes in Vestibular Schwannoma extension over time through the KOOS classification: A multi-center cohort study

Monday, October 13, 2025

9:42 AM - 9:48 AM EDT

Location: 244

Disclosure(s):

Shravan V. Gowrishankar, MD:

faculty for this accredited education activity has no relationship(s) with ineligible companies to disclose.

Introduction: In this multi-center study, we outline changes in tumor extension of vestibular schwannomas (VS) according to the KOOS classification over time.

Methods: An observational cohort study capturing adult patients diagnosed with VS from 2007 to 2024 was conducted from 25 skull base centers in the UK. Extra-meatal extension and brainstem compression was categorized for tumors according to the KOOS classification at the start of the observation period and the end of the observation period. Only tumors managed with observation were included to ascertain course of progression.

Results: At the start of the observation period, there were 4788 KOOS Class I, 5862 Class II, 548 Class III, and 118 Class IV tumors. At the end of the observation period, 73% of Class I tumors remained Class I (n=3513); 14% progressed to Class II (n=658); 8% progressed to Class III (n=386); and 5% progressed to Class IV (n=231). 85% of Class II tumors remained Class II (n=4969); 9% progressed to Class III (n=541); and 6% progressed to Class IV (n=352). 85% of Class III tumors remained Class III (n=467), and 15% progressed to Class IV (n=81).

Conclusions: The majority of tumors did not progress from their initial KOOS classification across the observation period. However, a sizeable minority exhibit extension, highlighting the importance of watchful surveillance scanning.

Presenting Author(s)

SG

Shravan V. Gowrishankar, MD

Research Fellow
Vanderbilt University Medical Center
High Wycombe, England, United Kingdom

Disclosure(s):
faculty for this accredited education activity has no relationship(s) with ineligible companies to disclose.

Co-Author(s)

NC

Nathan Creber, MD, PhD

Cambridge University Hospitals, United States

Disclosure information not submitted.
SO

Stephen O'Leary, MD

Cambridge University Hospitals, United States

Disclosure information not submitted.

Senior Author(s)

DB

Daniele Borsetto, MD

Cambridge University Hospitals, United States

Disclosure information not submitted.