Faculty Bibliography

PURPOSE: To assess the relationships of smoking and other cardiovascular disease risk factors (hypertension, diabetes, hypercholesterolemia, and gender) to rates of radiosurgery-induced obliteration of arteriovenous malformations (AVM). METHODS AND MATERIALS: We evaluated follow-up imaging and clinical data in 329 AVM patients who received gamma knife radiosurgery at the University of Pittsburgh between 1987 and 1994. There were 113 smokers, 29 hypertensives, 5 diabetics, 4 hypercholesterolemics, 159 male patients, and 170 female patients. All patients had regular clinical or imaging follow-up for a minimum of 3 years after radiosurgery. RESULTS: Multivariate analysis showed that smoking had no effect on AVM obliteration (p > 0.43). Hypertension, diabetes, and hypercholesterolemia had no discernible effect on AVM obliteration in this study (p > 0.78). However, females aged 12-49 had a statistically significant lower in-field obliteration rate than males (78% vs. 89%, p = 0.0102). CONCLUSION: Smoking has no effect on AVM obliteration. Hypertension, diabetes, and hypercholesterolemia had no discernible effect in this study. Further study is needed to establish whether estrogen has a vascular protective effect that could partially limit radiosurgical AVM obliteration, as suggested by this study.

The purpose of this report was to review the results of stereotactic radiosurgery in the management of patients with residual neurocytomas after initial resection or biopsy procedures. Four patients underwent stereotactic radiosurgery for histologically proven neurocytoma. Clinical and imaging studies were performed to evaluate the response to treatment. Radiosurgery was performed to deliver doses to the tumor margin of 14, 15, 16, and 20 Gy, depending on tumor volume and proximity to critical adjacent structures. More than 3 years later, imaging studies revealed significant reductions in tumor size. No new neurological deficits were identified at 53, 50, 42, and 38 months of follow up. The authors' initial experience shows that stereotactic radiosurgery appears to be an effective treatment for neurocytoma.

AVM radiosurgery has been in practice for over 30 years and is now a common method to manage properly selected patients with brain AVMs. The techniques have been refined along with our understanding of the expected response. It is this understanding of expected outcomes that should allow a rational discussion of the pertinent issues for management of patients with AVMs. Some patients will require multimodality approaches. All AVM patients should seek to understand whether stereotactic radiosurgery is an appropriate option for their problem.

We are confident that neurodegenerative diseases will be managed by an array of pharmacologic and cellular therapies. These may involve oral or intravenous preparations, surgical cell deliveries, or infusion through cerebral delivery systems. Achievements in neuroscience over the past three decades have redefined some of the rules for basic and clinical research in neurotransplantation. Restorative neurosurgical procedures will develop from different directions, and it is likely that a combination of approaches will be necessary to maximize patient outcomes.

PURPOSE: To test the hypothesis that increasing the nerve length within the treatment volume for trigeminal neuralgia radiosurgery would improve pain relief. METHODS AND MATERIALS: Eighty-seven patients with typical trigeminal neuralgia were randomized to undergo retrogasserian gamma knife radiosurgery (75 Gy maximal dose with 4-mm diameter collimators) using either one (n = 44) or two (n = 43) isocenters. The median follow-up was 26 months (range 1-36). RESULTS: Pain relief was complete in 57 patients (45 without medication and 12 with low-dose medication), partial in 15, and minimal in another 15 patients. The actuarial rate of obtaining complete pain relief (with or without medication) was 67.7% +/- 5.1%. The pain relief was identical for one- and two-isocenter radiosurgery. Pain relapsed in 30 of 72 responding patients. Facial numbness and mild and severe paresthesias developed in 8, 5, and 1 two-isocenter patients vs. 3, 4, and 0 one-isocenter patients, respectively (p = 0.23). Improved pain relief correlated with younger age (p = 0.025) and fewer prior procedures (p = 0.039) and complications (numbness or paresthesias) correlated with the nerve length irradiated (p = 0.018). CONCLUSIONS: Increasing the treatment volume to include a longer nerve length for trigeminal neuralgia radiosurgery does not significantly improve pain relief but may increase complications.

OBJECTIVE: There is no known effective treatment for chronic stroke. In this report, we used positron emission tomography (PET) with [18F]fluorodeoxyglucose (FDG) to map the metabolic brain response to neuronal cell implantation in the first human neuroimplantation trial for stroke. METHODS: Twelve patients (nine men, three women; mean age +/- standard deviation, 60.8+/-8.3 yr) with chronic basal ganglia infarction and persistent motor deficit underwent FDG PET within 1 week before and 6 and 12 months after stereotactic implantation of human neuronal cells. Serial neurological evaluations during a 52-week postoperative period included the National Institutes of Health stroke scale and the European stroke scale. RESULTS: Alterations in glucose metabolic activity in the stroke and surrounding tissue at 6 and 12 months after implantation correlated positively with motor performance measures. CONCLUSION: FDG PET performed as part of an initial open-label human trial of implanted LBS-Neurons (Layton BioScience, Sunnyvale, CA) for chronic stroke demonstrates a relationship between relative regional metabolic changes and clinical performance measures. These preliminary findings suggest improved local cellular function or engraftment of implanted cells in some patients.

This study evaluated the role of stereotactic radiosurgery in the multimodality management of craniopharyngioma patients whose prior therapies failed. Ten consecutive patients (3 males and 7 females) had radiosurgery for craniopharyngioma during a 10-year interval. Their ages ranged from 9 to 64 years (median, 14.5 years). The median interval between diagnosis and radiosurgery was 46.5 months. In total, 12 stereotactic radiosurgical procedures were performed to control the solid component of the tumor (2 intrasellar and 10 suprasellar tumors). The median tumor volume was 1.35 cm3. One to 9 isocenters with different beam diameters were used; the median marginal dose was 16.4 Gy; and the dose to the optic apparatus was limited to less than 8 Gy. Clinical and imaging follow-up data were obtained at a median of 63 months (range, 13-150 months) from radiosurgery. Overall, 7 of 12 tumors became smaller or vanished within a median of 8.5 months. Prior visual defects objectively improved in 6 patients. One patient with prior visual defect deteriorated further and lost vision 9 months after radiosurgery. Multimodality therapy is often necessary for patients with refractory solid and cystic craniopharyngiomas. Stereotactic radiosurgery is a reasonable option in select patients with small recurrent or residual craniopharyngioma.