MRI follow-up and clinical analysis for postradiosurgical acoustic neuromas / 中华放射学杂志

ABSTRACT

Objective To assess the effect of the gamma knife radiosurgery (GKS) for acoustic neuromas, and to analyze the MRI features of the tumors after GKS. Methods GKS was performed in 309 patients with acoustic neuromas from December 1994 to December 2002 at our center. The Leksell Gamma Knife models B and C were used. 249 cases with 256 tumors were followed up with MRI, which included 107 males and 142 females. The median age of the patients was 48.7?14.2 years (10-77 years). GKS was applied as primary treatment for 189 cases (75.9%), and was an adjunctive management approach for 60 cases (24.1%). The median clinical follow-up period and radiological follow-up period was (26.4?21.3) months (6-101 months) and (22.4?19.0) months (6-93 months), respectively. Results Of the 256 tumors, 79 tumors (30.8%) regressed, 165 tumors (64.5%) remained stable, 12 tumors (4.7%) enlarged, and the overall tumor control rate was 95.3%. Among 30 tumors of NF-Ⅱ , 8 tumors (26.6%) regressed, 19 tumors (63.4) remained stable, and 3 tumors (10.0%) enlarged, and tumor control rate was 90%. The rate of hearing deterioration was 22.7%, the rate of permanent facial paralysis was 0%, the rate of transient facial paralysis was 5.9%, and the incidence of transient trigeminal neuropathies was 19.9%. On the image of follow-up MRI, 79 tumors (30.0%) showed loss of contrast enhancement (LOE). LOE was the imaging property of neuromas on follow-up MRI, which symbolized a chronic decrease in the vascularity of neuromas. The histological findings of LOE demonstrated radiation-induced tumor necrosis. The transient swelling of tumors could not be confounded with the growth of tumors. Conclusion GKS is confirmed to be an effective treatment for acoustic neuromas and plays an important role in the control of NF―Ⅱ, and GKS can prevent cranial nerve from injury to a great extent.