Natural History of Residual Vestibular Schwannoma After Incomplete Microsurgical Resection: Delayed Progression During Long-Term Surveillance.

BACKGROUND

Deliberate incomplete resection of vestibular schwannoma (VS) is increasingly accepted to preserve cranial nerve function, but the long-term behaviour of remnants remains uncertain. We describe the natural history of residual VS during extended radiological surveillance.

METHODS

Of 194 patients who underwent VS microsurgery at a single centre between 2013 and 2019, 68 had complete pre- and postoperative MRI and formed the study cohort; 22 (32%) had a residual tumour on baseline MRI and constituted the analysis population. Progression was defined as a ≥2-mm increase in maximum linear diameter. Progression-free survival (PFS) was estimated with the Kaplan-Meier method; residual size (<10 mm vs. ≥10 mm) was explored with log-rank tests and Cox regression.

RESULTS

Median age was 56 years (range, 25-72), 13 patients (59%) were female, and median follow-up was 84 months (range, 37-144). Twelve patients (55%) showed progression, 5 of them (42%) more than 5 years after surgery; 3 remnants regressed. Median PFS was 81 months (95% CI, 35-127); PFS was 77% at 3 years and 68% at 5 years. Residual size was not significantly associated with progression (log-rank p = 0.48; hazard ratio for ≥10 mm, 1.71; 95% CI, 0.38-7.79). Six patients (27%) received secondary treatment (surgery, n = 4; radiosurgery, n = 2).

CONCLUSIONS

In this small cohort, more than half of residual VS progressed, often beyond 5 years. These data support the feasibility of MRI surveillance extending beyond 5 years after incomplete resection but do not establish its comparative safety or effectiveness.