Faculty Bibliography

Sphenopalatine neuralgia is a rare craniofacial pain syndrome that is characterized by unilateral pain in the orbit, mouth, nose, and posterior mastoid process. During attacks of pain, vasomotor activity often results in ipsilateral nasal drainage, eye irritation, and lacrimation. The authors present a patient with a 15-year history of sphenopalatine neuralgia who underwent stereotactic radiosurgery targeted at the sphenopalatine ganglion, with initial pain relief, and repeated radiosurgery 17 months later for partial pain recurrence. Two years following radiosurgery, the patient is pain free, no longer suffering from nasal discharge and eye irritation.

OBJECTIVE: Future improvements in the results of stereotactic radiosurgery will be related to better patient selection, dose planning, radiosensitization of the target, and, possibly, protection of the brain surrounding the target. 21-Aminosteroids may provide protection against brain radiation injury by inhibition of lipid peroxidation and a selective action on vascular endothelium. We hypothesized that the 21-aminosteroid U-74389G would reduce radiosurgery-related brain injury without attenuating the target volume response. METHODS: One hundred and forty-five rats were divided into four experimental groups before undergoing radiosurgery: control (n = 47); low-dose U-74389G (5 mg/kg of body weight, n = 30); high-dose U-74389G (15 mg/kg, n = 20); and methylprednisolone (2 mg/kg, n = 48). The drug was administered 1 hour before radiosurgery (4-mm gamma knife collimator) of the normal rat frontal lobe (single-fraction maximum doses of 50, 100, or 150 Gy) was performed. All brains underwent histological examination at 90 or 150 days to evaluate the diameters of necrosis and the findings of radiation-induced vasculopathy, brain edema, and gliosis. RESULTS: None of the animals that received 50-Gy radiation developed histological changes, whereas all of the animals that received 150-Gy radiation developed radiation necrosis without drug-induced protection from vascular changes or edema. In animals receiving 100-Gy radiation, high-dose aminosteroid reduced radiation-induced vasculopathy at 90 days (P = 0.06) and at 150 days (P = 0.02) and prevented regional edema at 90 days (P = 0.01) and at 150 days (P = 0.03). Low-dose aminosteroid and corticosteroid provided no protection. CONCLUSION: The 21-aminosteroid U-74389G provided protection after a single intravenously administered dose of 15 mg/kg against radiation-induced vasculopathy and edema. High-dose 21-aminosteroids seem to have optimal properties for radiosurgery, surrounding brain protection without reducing the therapeutic effect desired within the target volume.

PURPOSE/OBJECTIVE: To assess the relationships of radiosurgery treatment parameters to the development of complications from radiosurgery for arteriovenous malformations (AVM). METHODS AND MATERIALS: We evaluated follow-up imaging and clinical data in 307 AVM patients who received gamma knife radiosurgery at the University of Pittsburgh between 1987 and 1993. All patients had regular clinical or imaging follow up for a minimum of 2 years (range: 24-96 months, median = 44 months). RESULTS: Post-radiosurgical imaging (PRI) changes developed in 30.5% of patients with regular follow-up magnetic resonance imaging, and were symptomatic in 10.7% of all patients at 7 years. PRI changes resolved within 3 years developed significantly less often (p = 0.0274) in patients with symptoms (52.8%) compared to asymptomatic patients (94.8%). The 7-year actuarial rate for developing persistent symptomatic PRI changes was 5.05%. Multivariate logistic regression modeling found that the 12 Gy volume was the only independent variable that correlated significantly with PRI changes (p < 0.0001) while symptomatic PRI changes were correlated with both 12 Gy volume (p = 0.0013) and AVM location (p = 0.0066). CONCLUSION: Complications from AVM radiosurgery can be predicted with a statistical model relating the risks of developing symptomatic post-radiosurgical imaging changes to 12 Gy treatment volume and location.

The authors made a review of a series of patients with hemangioblastomas of the posterior fossa treated between 1973 and 1993. A total of 32 patients were analyzed with 24 patients receiving resection, 8 patients receiving radiosurgery and 2 patients receiving conventional radiotherapy. The mortality in the patients with a resection was considered acceptable with 2 deaths (8%) and with a morbidity of 3 patients (12.5%). A review of the literature suggests that conventional radiotherapy with high doses (45-60 Gy) may have a role in the post-operative control of hemangioblastomas and in some cases could be employed even before the resection in order to facilitate the surgery. The radiosurgical treatment is regarded like adjuvant. Poor results were obtained with radiosurgery in large tumors where low doses (less than 20 Gy) were used. Because of the rarity and complexity of these tumors, mainly when associated with von Hippel-Lindau disease, a multicenter study could be useful with the assessment of the optimal utilization and combination of these treatment modalities.

Intracavitary irradiation is reported as an additional treatment for intracranial arachnoid cysts that do not communicate with the subarachnoid space. A 46-year-old woman with a large suprasellar arachnoid cyst that had enlarged over a 4-year interval presented with new onset headaches. Stereotactic intracavitary irradiation was performed using colloidal phosphorus-32 as an alternative to craniotomy or insertion of a shunt. Total regression of the cyst occurred within one month with resolution of her headaches. After three years of follow-up, imaging studies showed only an empty sella appearance, and no cyst recurrence. No early or delayed morbidity occurred. Intracavitary irradiation may be a useful therapy for arachnoid cysts, in an attempt to alter the biology of the cyst lining.