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• Tumor control rate is superior following total resection than following stereotactic radiosurgery

• There is no long term data regarding efficacy of lower radiation doses that may be used during stereotactic radiosurgery

• According to available data, it appears that for tumors less than 4 cm. there is no significant difference between Gamma knife radiosurgery and microsurgery regarding facial nerve preservation and hearing preservation. However, complications involving the trigeminal nerve are significantly lower for patients undergoing microsurgery.

• Mortality rates for surgical therapy are very low and for radiosurgery it is zero. However, there is a higher risk of postradiation secondary tumor development with stereotactic radiosurgery which usually carries a very poor prognosis.

• The most frequent complication of surgery for acoustic neuroma is CSF leakage which can be repaired.

• Approximately 5% of patients undergoing stereotactic radiosurgery for acoustic neuromas require subsequent surgical excision of the tumor. This is very difficult surgery for which hearing preservation is not an option and the level of facial function following this surgery is low on the House-Brackmann scale.

The term "salvage surgery" refers to surgery used to treat a patient who had not responded to other treatments. Salvage surgery after failed stereotactic radiosurgery is technically very difficult. The American Neurotology Society has noted that neurosurgeons who performed salvage surgery approximately 35 months after radiotherapy experienced the following complications:

• Very friable tissue (easily broken into small fragments)
• Anatomical landmarks were difficult to identify
• Tumors tended to adhere to the facial nerve resulting in the majority of patients experiencing postoperative facial palsy.

For more information regarding the opinion of American Neurotology Society, please click on the following link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstract&listuids=10821551&queryhl=1&itool=pubmed_DocSum

Some surgeons recommend that salvage surgery should be delayed at least 6-18 months after the stereotactic radiosurgery which is the period of time for highest risk of post-radiation injury to cranial nerves.