Faculty Bibliography

BACKGROUND: Brain metastases are the most common type of intracranial tumor. Until recently, whole brain fractionated radiation therapy (WBRT) was the mainstay of treatment, thereby confining the role of neurosurgeons to resection of an occasional solitary, accessible, and symptomatic brain metastasis. Median survival after surgery and radiation typically ranged from 5 to 11 months. METHODS: We analyzed various demographic incidence reports and our series of brain metastasis patients treated with radiosurgery. During a 15-year interval (1987-2002), radiosurgery was performed on 5,032 patients of whom 1,088 (21.6%) had metastatic brain tumors. RESULTS: In the United States, 266,820 to 533,640 new cases of brain metastases will be diagnosed in the year 2003. Evidence to date demonstrates that radiosurgery provides effective local tumor control for brain metastases. Important prognostic factors affecting patient survival include the absence of active systemic disease, the patient's preoperative performance status, age, and the number of metastases. Survival and local tumor control rates attained with radiosurgery are superior to those of either conventional surgery or WBRT. The morbidity associated with radiosurgery of brain metastasis is very low, and the mortality rate approaches zero. CONCLUSIONS: Compelling evidence indicates that radiosurgery is an effective neurosurgical management strategy for intracranial brain metastases. Quite often, favorable tumor control and survival can be achieved without WBRT. With radiosurgery as a therapeutic option, neurosurgeons now have a vastly expanded armamentarium for treatment of patients with brain metastases. The large number of patients with brain metastases who require care by a neurosurgeon for optimal treatment has significant implications for both the patterns of neurosurgical training and practice in the United States.

OBJECTIVE: Neurotransplantation has focused on disorders that involve subcortical brain targets. We evaluated the concepts of epileptic focus repair and changes in animal behavior through replacement of lost hippocampal neurons. The safety of hippocampal neurotransplantation was assessed in the rat kainic acid (KA) epilepsy model. METHODS: Sixty-three rats were studied and classified into six groups: KA plus 40,000 LBS-Neurons (Layton BioScience, Sunnyvale, CA; n = 13); KA plus 80,000 cells (n = 12); KA plus media (n = 9); no-KA plus 40,000 cells (n = 12); no-KA plus 80,000 cells (n = 12); and no-KA plus media (n = 5). Clinical observation (2 h daily) and electroencephalogram recording (3 h every other week) were performed to check for seizures until Week 11 after KA injection. On Week 12, the Morris water maze test was performed to assess spatial learning and memory. RESULTS: Four rats were excluded because of intracranial hematoma or abscess. In the clinical observation of seizures, the no-KA plus media group had significantly fewer seizures than rats that received KA followed by injection of 40,000 cells, 80,000 cells, or media (P = 0.001, 0.0004, and 0.004, respectively). On electroencephalographic analysis, there was no significant difference between any of the groups. Transplanted rats with KA-induced epilepsy did not have an increased number of seizures. In the Morris water maze test, the hidden platform task showed that the KA plus 80,000 cell group had significantly longer swim latencies than groups with no-KA plus 40,000 cells (P = 0.035) or no-KA plus 80,000 cells (P = 0.015), demonstrating the behavioral deficits caused by KA injection. The probe trial showed no significant difference for the percentage of time in the target quadrant between any of the groups. Histological studies showed that 26 (59%) of 44 transplanted rats had evidence of graft survival. CONCLUSION: The safety of cortical neurotransplantation was demonstrated, even in an animal model predisposed to epilepsy. We did not find evidence for cessation of seizures or improvement in behavior using this model.

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.