Abstract
The present study investigated imaging, intraoperative and pathological findings, and surgical indications and timing in 10 patients [5 men, 5 women; mean age, 52.3 years (range, 17-70 years)] with vestibular schwannoma who underwent surgical therapy due to poor radiotherapy-mediated tumor control; these included Gamma Knife (n = 8), X-Knife (n = 1) and proton beam (n = 1) therapies. The mean period from radiotherapy endpoint until surgery was 63.3 months (range, 30-96 months) and patients were classified according to the time elapsed between radiotherapy and surgical therapy [≥ 2 to < 5 years (n = 4); ≥ 5 to < 8 years (n = 4); or ≥ 8 years (n = 2)]. Surgical indications were classified into two groups: exacerbated or additional neurological symptoms caused by solid tumor component enlargement (n = 2); and exacerbated or additional neurological symptoms with extraparenchymal extension of the tumor cyst (n = 8). Imaging findings were classified as large cystic (LC; n = 8), multi-micro cystic (MC; n = 2), or solid component enlargement (SC; n = 0) types. Pathological findings revealed no malignant changes in any patient, and primary pathological conditions comprised radiotherapy-induced exacerbation of vascular occlusion and permeability. MC patients presented marked hemosiderosis and recurrent small hemorrhage was predicted. Intraoperative findings included marked adhesions with peripheral neurons and the cerebellum, as well as arachnoid thickening, rendering complete resection difficult. Decompression surgery was relatively straightforward for LC, which presents little bleeding, but it was challenging for MC due to its hemorrhagic nature. SC cases have been previously reported, but were not found in the present study, which had an inclusion criterion of ≥ 2 years follow-up after radiotherapy. Other than a single case that became malignant, all of the previously reported cases were within 2 years of radiotherapy and transient swelling may have been present.
