Continued Observation of Growing Vestibular Schwannomas

Objective: To investigate the natural history of continual observation of vestibular schwannomas (VS) that have demonstrated volumetric expansion with continued observation with serial MRI.

Study Design: Single institutional retrospective chart review.

Setting: Tertiary referral center.

Subjects and Methods: All adult patients with VS diagnosed between 2010 and 2020 who demonstrated volumetric expansion (defined as a ≥20% increase in volume) and underwent continued observation with at least one additional MRI ≥6 months after the MRI demonstrating expansion. Patients who had any prior treatment of their VS were excluded. The primary outcome measure was volumetric expansion relative to tumor volume at diagnosis of initial expansion. Tumor volume was calculated using the Brainlab automatic segmentation software package.

Results: Fifty six patients were identified with a median age of 60.7 years (range, 21.4–89.4 years) and 57.1% of patients were female. Median presenting tumor diameter and tumor volume were 8.2 mm (1.9–28.6 mm) and 0.17 cm³ (0.02–5.8 cm³), respectively. Patients demonstrated initial ≥20% volumetric expansion at a median interval of 11.9 months (3.1–59.4 months) following discovery of VS, with a median tumor expansion of 34.1% (20–300%). Patients continued observation or were lost to follow-up for a median interval of 28.6 months (6.7–101.8 months). Only 5 patients (8.9%) demonstrated linear expansion (increase in the greatest linear axial diameter ≥2 mm) at the time of volumetric expansion. After initial expansions, 20 patients (35.7%) had further volumetric expansion of at least 20% over a median of 24 months (10–94 months), while 11 patients (20%) had greater than 2 mm of expansion in greatest diameter over 30.6 months (12–74.4). Three patients (5%) ultimately had surgical resection (2 translabyrinthine resection, 1 middle fossa craniotomy), occurring a median of 26.8 months after the initial expansion (18.8–31.4 months). No patients underwent radiotherapy. There was no statistically significant association between age, gender, initial tumor diameter, initial tumor volume, or degree of initial linear or volumetric expansion with further volumetric or linear tumor expansion on Cox Regression analysis.

Conclusion: In this sample of patients with VS that demonstrated volumetric expansion managed with observation, only 35.7 and 20% of patients demonstrated further volumetric and linear expansion, respectively; and only 5% underwent surgery or radiotherapy.

Publication History

Article published online:
12 February 2021