Faculty Bibliography

Twelve patients with a median age of 75 years underwent gamma knife thalamotomy for essential tremor (ET) (n = 9) or MS-related tremor (n = 3). All 11 evaluable patients noted improvement in action tremor. Six of eight ET patients had complete tremor arrest, and the violent action tremor in all three patients with MS was improved. One patient developed transient arm weakness. Stereotactic radiosurgery for ET and MS-related tremor is safe and effective for patients who may be poor candidates for other procedures.

OBJECTIVE: To evaluate the role of stereotactic cyst aspiration in the context of multimodality management of cystic glial and metastatic tumors, we retrospectively reviewed our experience with 38 patients during a 10-year interval. METHODS: All 38 patients had one or more computed tomography or magnetic resonance imaging guided stereotactic cyst aspirations. Twenty-seven patients had glial neoplasms and 11 had metastatic brain tumors. Twenty-two patients underwent cyst aspiration as the initial treatment modality while 15 patients had cyst aspiration following previous treatments. RESULTS: In the immediate postoperative period, 19 of the 27 (70%) patients with gliomas and nine of the 11 (82%) patients with metastatic tumors experienced symptomatic improvement. No procedure-related morbidity was encountered. Twelve patients (31.5%) eventually required a catheter-reservoir system. Thirty-seven percent of patients with cystic glial neoplasms and 18% of patients with metastatic tumors had delayed cytoreductive surgery by craniotomy subsequent to stereotactic cyst aspiration. Reduction in tumor volume following aspiration facilitated Gamma knife radiosurgery in seven patients. CONCLUSION: Single stereotactic aspiration is a low risk procedure that provides immediate relief of symptoms in patients with cystic brain tumors. It appears to be valuable together with the use of other therapeutic strategies.

Experiments were carried out in a nude mouse model of human glioblastoma to determine whether gamma-knife radiosurgery combined with herpes simplex virus thymidine kinase (tk) suicide gene therapy and tumor necrosis factor alpha (TNFalpha) gene transfer provided an improved multimodality treatment of this disease. Animals were inoculated intracerebrally with 2 x 10(5) U-87MG human glioblastoma cells to establish brain tumors. At 3 days postinoculation, the tumor region was injected with 2 x 10(6) infectious particles of highly defective herpes simplex viral vectors expressing the viral tk gene with the kinetics of a viral immediate early gene either alone (T.1) or together with TNF alpha (TH:TNF). Subgroups of animals were given daily intraperitoneal injections of ganciclovir (GCV) for 10 days and/or subjected to gamma-knife radiosurgery on the fifth day post tumor-cell implantation. Comparisons of animal survival showed that the TH:TNF vector in combination with radiosurgery and GCV administration provided the most effective therapy; eight of nine animals survived for 75 days compared to four of eight using the next best protocol. These findings suggest that gene therapy in combination with more conventional therapeutic methods may provide an improved strategy for extending the life expectancy of patients afflicted with this ultimately fatal disease.

BACKGROUND: Stereotactic radiosurgery is an alternative to resection or to radiotherapy alone for patients with brain metastases. Outcomes after radiosurgery for patients with brain metastases specifically from breast cancer have not been defined. METHODS: We retrospectively studied survival and tumor control for all patients with brain metastases from breast cancer who underwent gamma knife stereotactic radiosurgery at the University of Pittsburgh. Univariate and multivariate analyses were used to determine which prognostic factors significantly affected survival. RESULTS: Thirty patients underwent radiosurgery between 1990 and 1997. A total of 58 metastases were treated. The median length of survival for all patients was 13 months from radiosurgery and 18 months from diagnosis of brain metastases. The tumor control rate on follow-up imaging was 93%. On multivariate analysis, the only factor that correlated with longer survival was the absence of multiple brain metastases. Age, presence of systemic disease, previous whole brain radiation, location, and total tumor volume did not significantly affect survival. Four patients had tumors with evidence of radiation-induced edema after radiosurgery but did not require resection. Two patients underwent delayed resection for tumor growth after radiosurgery. CONCLUSIONS: Stereotactic radiosurgery is an effective treatment for brain metastases from breast cancer and is associated with a low complication rate.

OBJECT: The goal of this study was to define treatment results of repeated arteriovenous malformation (AVM) radiosurgery, namely AVM obliteration and complications. METHODS: The authors analyzed their experience with repeated AVM radiosurgery performed in 41 patients for whom follow-up review lasted at least 2 years. The median duration of follow up was 34 months (range 7-65 months) after repeated radiosurgery in this group. The residual nidus was located within the area of focus (in field) of the initial radiosurgery in 28 patients (68%). Initial doses to the margin varied from 12.5 to 20 Gy (median 18 Gy). During repeated treatment the dose to the margin varied from 12.5 to 20 Gy (median 17 Gy) and the retreated volumes ranged from 0.4 to 7 cm3 (median 2.1 cm3). Follow-up angiography performed at least 2 years postradiosurgery revealed complete AVM obliteration in 21 (70%) of 30 patients. The estimated overall 2-year obliteration rate, based on findings on magnetic resonance imaging (eight of 11 obliterated) and angiography (29 of 41 obliterated) was 71%. Obliteration rates correlated with margin doses (p = 0.0045) with a trend toward higher rates in cases with in-field nidus persistence (p = 0.0637). The dose-response curve for AVM nidus obliteration was not significantly different from that of the initial radiosurgery. In two patients (5%) intracranial AVM hemorrhage developed within 125.9 risk years after repeated radiosurgery (1.6% per patient year). Persistent symptomatic adverse radiation effects developed in two (5%) of 41 patients following repeated radiosurgery. Postradiosurgical imaging changes were identified in 11 (27%) of 41 patients, which correlated with a 12-Gy volume from repeated surgery (p = 0.019). CONCLUSIONS: When necessary, repeated AVM radiosurgery achieves obliteration with an acceptable risk. Despite the effects of previous irradiation, repeated radiosurgery required similar or slightly higher radiation doses to achieve the same in-field obliteration rates as those needed to obliterate an AVM that had not been treated by radiation previously.

OBJECTIVE: Sellar and suprasellar arachnoid cysts may be asymptomatic or may cause headache, optic nerve compression, endocrine dysfunction, or hydrocephalus. We propose a minimally invasive treatment strategy when intervention is indicated. METHODS: Four patients with sellar and suprasellar arachnoid cysts presented with headache, visual compromise, and endocrine dysfunction. Two of the four patients previously had undergone unsuccessful surgical intervention. The imaging studies of two patients were diagnostic of an arachnoid cyst. RESULTS: All four patients underwent stereotactic intracavitary radiation with cyst regression and symptomatic improvement. In each patient, the optic chiasm was decompressed successfully. There were no complications from the procedure. CONCLUSION: Stereotactic intracavitary irradiation of arachnoid cysts proved to be safe and effective. The procedure obviated the need for open cyst fenestration or shunting.