MedifocusHealth

• The tumor is not removed
• Higher tumor recurrence rate than after conventional surgery
• Higher incidence of trigeminal nerve injury with higher dose stereotactic radiosurgery than following conventional surgery
• The incidence of post-radiation tumors (secondary malignancy) is unknown in the long term but it could be a potentially life threatening problem. This is a consideration which is especially important for young people who are considering stereotactic radiosurgery vs. conventional surgery
• Higher incidence of post-treatment disabling vestibular dysfunction compared to conventional acoustic neuroma surgery
• Hydrocephalus (an accumulation of cerebrospinal fluid in the skull) may occur in up to 5% of patients who undergo stereotactic radiosurgery
• Surgery to remove residual tumor following stereotactic radiosurgery is very difficult
• Long-term ramifications of using low-dose radiation is not yet known

While some authors feel that stereotactic radiosurgery will eventually become the first- line treatment for acoustic neuromas, others believe that the higher rate of tumor recurrence and increased chance for secondary malignances related to radiation will limit its role to that of a second-line treatment modality.

Fractionated Stereotactic Radiosurgery

Fractionated stereotactic radiosurgery (FSR) involves short, multi-dose treatments in which smaller doses of radiation are delivered but the tissue included in the area which is targeted is larger than for standard stereotactic radiosurgery. Treatment continues daily for several weeks. Fractionated stereotactic radiosurgery was developed in an attempt to minimize cranial nerve complications following the delivery of radiation. It may be performed on an outpatient basis at special centers or in the radiology department of a hospital. Currently, there is limited data regarding the long term effects of fractionated stereotactic radiation and whether it has any advantage for treatment outcome over single-dose stereotactic radiosurgery.

Researchers from Heidelberg, Germany reported results for 106 patients with acoustic neuromas who underwent fractionated stereotactic radiosurgery. With a median follow up period of 4 years, they reported the following findings:

• Treatment was well tolerated by all patients
• Local tumor control at 5 years was 93%
• Hearing preservation was achieved in 94% of patients at 5 years and was 98% overall.
• Rates of successful hearing preservation were significantly reduced in the presence of neurofibromatosis
• Rate of facial nerve complications was 2.3%
• Rate of trigeminal nerve complications was 3.4%

To read more about this study, click on the following link: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&listuids=16111574&queryhl=4&itool=pubmed_DocSum

Microsurgery vs. Stereotactic Surgery

The 1991 NIH Consensus Statement recommended that first-line treatment for acoustic neuromas should be microsurgery for most patients and that radiotherapy should be considered only for a subset of patients who are unable or unwilling to undergo surgery. The statement also noted the delayed occurrence of complications following stereotactic radiosurgery and the limited available long-term data regarding other aspects of this treatment.

Information regarding the comparative advantages for each treatment modality may be summarized as follows:

• Though the goals of each treatment are different regarding tumor control, many surgical studies report close to 100% tumor removal and the latest results of tumor control hover at approximately 97%. There is no tumor removal with stereotactic radiosurgery, only tumor reduction.