Faculty Bibliography

OBJECTIVE: A 10-year prospective clinical and magnetic resonance imaging study was undertaken to determine the natural history of venous malformations. We assessed the hemorrhage rate and morbidity associated with venous malformations of the brain. PATIENTS AND METHODS: From 1986 to 1996, 80 patients with venous malformations were referred to the University of Pittsburgh multidisciplinary vascular malformation study group for evaluation. Observation was recommended for all patients. Follow-up clinical information was obtained from patients or their referring physicians through questionnaire or phone conversation. RESULTS: Twenty-two patients presented with neurological signs or symptoms that were thought to be related to the malformations (nine with headaches, four with seizures, three with sensory symptoms, three with motor deficits, two with trigeminal neuralgia, and one with an extrapyramidal disorder). Twenty-three patients presented with headaches that were not considered to be related to the malformations. The retrospective hemorrhage rate (from birth to study entry) was 0.61% (18 bleeds in 2,949 patient-years). Sixteen patients had sustained previous brain hemorrhage in the region of the venous malformations, two of whom had suffered subsequent hemorrhage. During the prospective follow-up period totaling 298 patient-years of clinical observation, two patients suffered hemorrhage (0.68% per year), but only one had a symptomatic bleed (0.34% per year). This patient had not hemorrhaged previously. One of these patients remained asymptomatic, whereas the second developed temporary worsening of facial paresthesias. No patient died as a result of the venous malformations. CONCLUSION: The hemorrhage rate of a patient with venous malformations is similar to the rates presented in previous reports for patients with cavernous malformations without previous symptomatic hemorrhage. We think that hemorrhage in a patient with venous malformations may be related to an underlying but not yet documented cavernous malformation. Because of the low risk for new neurological events, we advocate conservative management. The risks associated with surgical intervention greatly exceed the low risk of morbidity related to venous malformation hemorrhage.

Radical microsurgical resection is the procedure of choice for tentorial meningiomas. Despite advances in microsurgery, tentorial meningiomas continue to challenge surgeons and patients. To evaluate the response of tentorial meningiomas, we evaluated 41 patients who had Gamma knife stereotactic radiosurgery during a 9 year period. Patient age varied from 32 to 79 years. Headache, trigeminal neuralgia, or facial paraesthesia were the most common presenting symptoms. Sensory deficits in the distribution of the trigeminal nerve were the most common finding. Eighteen patients (44%) had undergone between 1 and 5 (mean, 1.9) resections prior to radiosurgery; 23 had tumors diagnosed by neuroimaging. The average tumor diameter in this series was 20 mm. The maximum tumor dose varied from 24 to 40 Gy (mean, 30.5 Gy), and the tumor margin dose varied from 12 to 20 Gy (mean, 15.3 Gy). During the average follow-up interval of 3 years (range, 1-8 years), 19 patients had clinical improvement, 20 remained stable, and 2 patients deteriorated. Follow-up imaging showed a reduction in tumor size in 18 patients, no further tumor growth in 22, and an increase in tumor size in one (overall tumor control rate of 98%). Stereotactic radiosurgery using the Gamma Knife was a safe and effective primary or adjuvant treatment for patients with tentorial meningiomas.

BACKGROUND: The authors evaluated results after stereotactic radiosurgery (SR) for brain metastases from renal cell carcinoma (RCC) and identified factors associated with improved survival and tumor control. METHODS: The authors reviewed the management results from a total of 52 RCC brain metastases in 35 consecutive patients who underwent stereotactic radiosurgery (SR) during a 9-year interval. Twenty-eight patients also underwent whole brain radiation therapy (WBRT). The mean tumor volume was 2.4 mL (range, 0.1-14.1 mL). The mean dose delivered to the tumor margin was 17 gray (Gy) (range, 13-20 Gy). Univariate and multivariate testing was performed to determine significant prognostic factors. RESULTS: The median survival was 11 months after SR and 14 months after brain tumor diagnosis. Only 2 patients (8%) died of progression of the irradiated tumor. Age < 55 years, lack of active systemic disease, and use of chemotherapy and/or immunotherapy after SR were significant favorable prognostic factors in multivariate testing. Post-SR imaging was evaluated in 26 patients (39 tumors). The local control rate from the 39 treated tumors imaged was 90% (tumor disappearance, 21%; tumor regression, 44%; and stable disease, 26%). Local recurrence developed in 3 patients (4 lesions) and remote brain disease in 12 patients. No patient developed a new focal neurologic deficit due to SR. Patients were classified into two groups: SR with and SR without WBRT. The addition of WBRT to SR did not improve survival. Distant failure occurred similarly in both groups (46% vs. 50%). WBRT combined with SR may contribute to local control, but did not prevent the development of new remote tumors. CONCLUSIONS: SR for brain metastasis from RCC results in brain disease control in the majority of patients and was associated with few complications. Early detection of brain metastases and treatment with SR provides extended quality survival.

Stereotactic radiosurgery is an important treatment option for arteriovenous malformations (AVMs) and hemorrhagic cavernous malformations. Radiosurgery is effective in obliterating AVMs and preventing rebleeding of cavernous malformations with two or more hemorrhagic episodes. Outcome analyses of radiosurgery for these vascular malformations have provided important information to improve the safety and effectiveness of radiosurgical treatment.

OBJECTIVE: To analyze the clinical and angiographic variables that affect the results of arteriovenous malformation (AVM) radiosurgery and to propose a new method of reporting patient outcomes after AVM radiosurgery. This method incorporates both the obliteration status of the AVMs and the postoperative neurological condition of the patient. METHODS: Patient outcomes were defined as excellent (nidus obliteration and no new deficits), good (nidus obliteration with a new minor deficit), fair (nidus obliteration with a new major deficit), unchanged (incomplete nidus obliteration without a new deficit), poor (incomplete nidus obliteration with any new deficit), and dead. Two hundred twenty patients who underwent AVM radiosurgery at our center before 1992 were subjected to a multivariate analysis with patient outcomes as the dependent variable. RESULTS: Multivariate analysis determined four factors associated with successful AVM radiosurgery: smaller AVM volume (P=0.003), number of draining veins (P=0.001), younger patient age (P=0.0003), and hemispheric AVM location (P=0.002). Preradiosurgical embolization was a negative predictor of successful AVM radiosurgery (P=0.02). CONCLUSION: AVM obliteration without new neurological deficits can be achieved in at least 80% of patients with small volume, hemispheric AVMs after single-session AVM radiosurgery. Future studies on AVM radiosurgery should report patient outcomes in a fashion that incorporates all the factors involved in successful AVM radiosurgery.

PURPOSE: Skull base chordomas and chondrosarcomas pose management challenges owing to their critical location, locally aggressive nature, and high recurrence rate despite multimodality treatment. We used stereotactic radiosurgery as primary or adjuvant therapy to achieve safe and effective therapeutic irradiation. METHODS AND MATERIALS: At an average of 4 years (range 1-7), we evaluated 15 patients (nine with chordomas and six with chondrosarcomas) who had gamma-knife radiosurgery as an adjunct (13 patients) or as an alternative to microsurgical resection (two patients). Patient age varied from 7 to 70 years (mean 38). There was a distinct male preponderance (2:1). Thirteen patients had undergone between one and four resections. Using conformal radiosurgical planning, a maximum tumor dose of 24-40 Gy (mean 36) and a tumor margin dose of 12-20 Gy (mean 18) was given to a mean tumor volume of 4.6 ml. RESULTS: Eight patients showed clinical improvement, three remained stable, and four died. Two of the four patients who died had tumor progression remote from the radiosurgery volume; two patients died of unrelated disorders. Among 11 surviving patients, follow-up imaging showed a reduction in tumor size in five, no further tumor growth in five, and an increase in the size of the tumor in one. The patient with further tumor growth after radiosurgery subsequently underwent repeat resection. CONCLUSION: Despite the formidable management challenge posed by these neoplasms, our long-term evaluation has shown that radiosurgery is a safe and effective treatment for patients with small volume tumors.

The increased use of ablative movement disorder surgery, pallidotomy, and thalamotomy must be followed by our better understanding of regional neuroanatomy, use of imaging and physiologic techniques for targeting, and methods of lesion creation. The safety of these techniques has been established; efficacy will require additional studies. Selection of appropriate patients and our understanding of outcomes will assist the surgeon in choosing between ablative surgeries and other forms of management.

OBJECTIVE: To evaluate the role of stereotactic radiosurgery in the management of petroclival meningiomas, we retrospectively reviewed our experience with 62 patients managed at the University of Pittsburgh during an 8-year period. METHODS: All patients had cranial base meningiomas involving the region between the petrous apex and the upper two-thirds of the clivus. Some tumors extended into the cavernous sinus. Each of 39 patients (63%) had previously undergone one or more attempts at surgical resection. Seven patients (11%) had received fractionated external beam radiation therapy. Using the gamma knife, conformal multiple isocenter radiosurgery was performed with tumor margin doses of 11 to 20 Gy. RESULTS: During the median follow-up period of 37 months, neurological statuses improved in 13 patients (21%), remained stable in 41 patients (66%), and eventually worsened in 8 patients (13%). Tumor volumes decreased in 14 patients (23%), remained stable in 42 patients (68%), and increased in 5 patients (8%). Despite the proximity of these tumors to critical neural and vascular structures, complications resulting from radiosurgery were rare. Five patients (8%) developed new cranial nerve deficits within 24 months of radiosurgery, although none had evidence of tumor progression. These deficits resolved completely in two patients within 6 months of onset. CONCLUSION: Although an even longer follow-up period is desirable, we conclude that stereotactic radiosurgery provides a safe and effective management strategy for petroclival meningiomas, both as a primary procedure and as an adjunct to incomplete resection.