Faculty Bibliography

Patients who have an acoustic neuroma (vestibular schwannoma) can be managed with observation, open surgical resection, stereotactic radiosurgery, or fractionated radiotherapy. Increasing numbers of patients are choosing radiosurgery over resection for their tumor. In this report we discuss the history of stereotactic radiosurgery, and the evolution in technique that has led to current results with this approach. We discuss the indications for and expectations with the different treatments. The literature on radiosurgery and radiotherapy is reviewed. It is expected that clinical and basic studies will further improve results.

Stereotactic fractionated radiotherapy has been proposed as a strategy to improve upon the results of single-fraction radiosurgery. The rationale for the strategy is that fractionation will allow complciations to be reduced while maintaining the same degree of long-term tumor control. This paper reviews the radiobiological arguements for fractionating radiation treatment of acoustic neuromas and examines claims for improvement in outcome.

OBJECTIVE: The efficacy of stereotactic intracavitary irradiation with phosphorus-32 ((32)P) for patients with cystic craniopharyngiomas was assessed on the basis of patient survival, tumor control, and visual and endocrinological function before and after treatment. Limited data are available regarding long-term outcomes. METHODS: Forty-nine patients were treated with stereotactic (32)P intracavitary irradiation. Of these, 25 had had no prior treatment as the primary treatment, and 24 were treated for residual or recurrent tumor cysts. At the time of (32)P intracavitary irradiation, 34 of the patients were adults, and 15 were children younger than 16 years of age. The mean cyst volume was 13 ml. The radiation dose varied from 189 to 250 Gy to the cyst wall during five half-lives of the isotope (mean, 224 Gy). The mean follow-up periods were 7 years after diagnosis and 4 years after (32)P treatment. RESULTS: The actuarial survival rates were 90% at 5 years after the diagnosis and 80% at 10 years. The actuarial tumor cyst control rates were 76% at 5 years and 70% at 10 years after the diagnosis. After treatment, 9 (23%) of 40 patients who underwent preoperative and postoperative visual testing were found to have delayed worsening in visual function, 6 as a result of tumor progression and 3 attributed to irradiation. Nineteen patients (48%) had improved visual function. Of 17 patients who had normal preoperative pituitary function or stalk effect, 12 (71%) had preserved and 5 (29%) had worsened visual function. No complications other than visual or endocrinological deterioration occurred in these patients. CONCLUSION: For patients with cystic craniopharyngiomas, (32)P intracavitary irradiation proved effective, with a low risk of complications, for the control of tumor cysts but not of solid tumor components.