Tumor shape as a prognostic factor for the growth of intracanalicular vestibular schwannoma: a long-term observational study.

Abstract

To evaluate the predictive factors of tumor growth in patients with vestibular schwannoma (VS) managed with the wait-and-scan approach. The data of 31 patients diagnosed with intracanalicular VS and followed for > 5years were retrospectively analyzed. VS was diagnosed according to MRI findings and tumor growth was monitored. Tumor growth was defined as an increase of 2mm or more in the maximal tumor diameter. The association between the initial tumor size and shape and tumor growth was assessed. Tumor growth was observed in 16 of 31 patients (51.6%) over a mean follow-up duration of 7.3years. The initial tumor size was not statistically correlated with tumor growth. However, fusiform or cylindrical tumors exhibited higher growth rates than oval or round tumors. Additionally, a significant correlation was observed between cerebellopontine angle extension and tumor shape. In this study, 51.6% of the patients with intracanalicular VS who were managed with the wait-and-scan strategy over a follow-up period of > 5years showed tumor growth. Tumor shape, especially fusiform or cylindrical shape, was found to be a significant predictor of tumor growth.