Apoptosis following Gamma Knife Radiosurgery in a Case of Acoustic Schwannoma

Abstract

A 25-year-old woman with a large acoustic schwannoma underwent surgical excision 18 months after Gamma Knife radiosurgery because of transient expansion of the tumor causing ataxia. Histopathologial investigation by the TUNEL method revealed the presence of some apoptotic cells. The findings were compared with findings from a control group of 7 operated cases where radiosurgery had not been used. There was no apoptosis found in any of these cases. In addition, another case which resulted in a regrowing tumor following Gamma Knife treatment also showed no apoptosis. These findings suggest apoptosis may be a possible mechanism in reducing tumor size following Gamma Knife radiosurgery.

Association of proliferative activity and size in acoustic neuroma: implications for timing of surgery

“…These results confirm those of a previous analysis of apoptosis in acoustic neuromas. 4 These authors studied the differences in surgical specimens obtained from patients with recurrent tumors after radiosurgery and from those without prior treatment. They found some apoptotic cells in tumor sections after radiosurgery, but none in acoustic neuromas that had not been irradiated.…”

Different responses of benign and atypical meningiomas to gamma-knife radiosurgery: report of two cases with immunohistochemical analysis

“…Fukuoka et al reported the presence of apoptotic cells, as well as necrosis and intratumoral vessel obliteration; in vestibular schwannoma treated with gamma-knife radiosurgery. 7 Recent advances in microsurgical techniques have facilitated more aggressive attempts to remove skull-base meningiomas, while still maintaining acceptable rates of morbidity and mortality. The application of gamma-knife radiosurgery to treat such meningiomas is a relatively recent development.…”

Controversies in building a management algorithm for vestibular schwannomas

“…Secondarily, radiation-induced necrosis may or may not occur. To this effect, evidence of radiation-induced vestibular schwannoma apoptosis has been reported [45]. Apoptosis may be associated with tumor shrinkage; indeed, in the majority of cases, the vestibular schwannoma displays size reduction over time [46 ,47 ].…”