Faculty Bibliography

INTRODUCTION: Cerebral metastases are a common problem and pose complex treatment decisions, with reference to local control of treated lesions, prevention of new brain metastases, and toxicity of available treatments. At the 2007 Congress of Neurological Surgeons (CNS) Annual Meeting, a novel active learning process, called Integrated Medical Learning(SM), was used to better understand contemporary practice patterns and to monitor the success of education about these critical treatment decisions. METHODS: CNS members received an electronically distributed premeeting survey and educational materials about single and multiple cerebral metastasis treatment; practice patterns were elicited. At the Annual Meeting, 496 surgeons were polled using handheld devices before and after surgical and radiation oncology expert presentations. Surgeons who had answered premeeting surveys received a second, postmeeting questionnaire. RESULTS: In the premeeting questionnaire (N = 214), higher current volume of practice, Tumor Section membership, and academic practice predicted more correct answers (P < 0.05 for all). Fifty five percent favored routine whole brain radiotherapy (WBRT) after metastasis resection. Thirty four percent "most often" used radiosurgery to the resection bed; these respondents cited "cognitive changes" in justifying WBRT omission. At the meeting, expert presentations were followed by audience shifts toward adjuvant WBRT after resection (P = 0.01) or radiosurgery (P < 0.001)-topics for which class I evidence was discussed. There was no shift in preference for surgery or radiosurgery (P = 0.24) or multiple metastasis treatment (P = 0.8)-topics for which clear class I evidence was not presented. Postmeeting questionnaires showed retained knowledge among meeting attendees. CONCLUSIONS: Using IML, we were able to study baseline knowledge and practice patterns for an important neuro-oncological treatment decision. Evidence suggested expert presentations were effective in changing audience opinion when relevant class I evidence was presented, and that knowledge was retained postmeeting.

In a drive toward improved quality and safety in medicine, educators have emphasized the importance of lifelong learning and improved pedagogical models to effective continuing education. Scholarly understanding of disciplinary knowledge and expert thought has progressed rapidly in the past 40 years. Lessons from adult learning theory can and should be systematically applied to the design of effective, learner- centered, collaborative, and conceptually driven continuing education for physicians and surgeons. One example of this pedagogical approach is Integrated Medical Learning (IML), an instructional theory that is based on dynamic interaction between each element of the learning process, is learner centered, incorporates self-assessment, uses various formats and media to facilitate learning, and seeks to apply scientific method to educational process development. This article discusses advances in learning, instructional theory, and practice relevant to medical continuing education and outlines the conceptual basis for IML. The first iteration of IML, which took place in part at the General Scientific Sessions of the 2007 Annual Meeting of the Congress of Neurological Surgeons, will be described elsewhere. In addition to advancing goals related to educational effectiveness, IML produces novel and otherwise not easily obtainable data about current clinical knowledge, attitudes, and actual practice patterns that are relevant to clinical equipoise, study design, and medical evidence.

A new model of Leksell Gamma Knife(R) (LGK), known as Perfexion (LGK PFX), was introduced by Elekta Instrument, AB, Sweden, in 2006. This model has a radically different design from the earlier models U, B, C and 4C. Dosimetric characteristics of LGK PFX, technical differences between LGK PFX and LGK 4C, experience gained with acceptance testing and commissioning of the LGK PFX, and comparison between LGK PFX and LGK 4C are presented in this study. Excellent agreement is found between the manufacturers recommended values of absorbed dose rate, relative output factors for 4 and 8 mm collimators, coincidence of mechanical and dosimetric isocenter, FWHM for beam profiles for various collimators and those reported in the present study. Excellent agreement is also found between the dosimetric characteristics of LGK PFX and LGK 4C for the 4 and 8 mm collimators. Examples of clinical cases treated with LGK PFX and impact of LGK PFX on workflow and dosimetric conformity of treatment planning is also given. The set up and treatment of patients on the LGK PFX is much more efficient since it is a fully automated system. The system also provides more options to generate plan with high dosimetric conformity.

OBJECTIVE: Hemangiomas are rare but highly vascular tumors that may develop in the cavernous sinus or orbit. These tumors pose diagnostic as well as therapeutic challenges to neurosurgeons during attempted removal. We analyzed our increasing experience using stereotactic radiosurgery (SRS). METHODS: Eight symptomatic patients with hemangiomas underwent SRS between 1988 and 2007. The presenting symptoms included headache, orbital pain, diplopia, ptosis, proptosis and impaired visual acuity. The hemangiomas were located in either the cavernous sinus (7 patients) or the orbit (1 patient). Four patients underwent SRS as primary treatment modality based on clinical and imaging criteria. Four patients had previous microsurgical partial excision or biopsy. The median target volume was 6.8 mL (range, 2.5-18 mL). The median prescription dose delivered to the margin was 14.5 Gy (range, 12.5-19 Gy). The dose to the optic nerve in all patients was less than 9 Gy (range, 4.5-9 Gy). RESULTS: The median follow-up period after SRS was 80 months (range, 40-127 months). Six patients had symptomatic improvement; 2 patients reported persistent diplopia. Follow-up imaging revealed tumor regression in 7 patients and no change in tumor volume in 1 patient. All the patients improved after SRS. CONCLUSION: Our extended experience confirms that SRS is an effective management strategy for symptomatic intracavernous and intraorbital hemangiomas. Our study is the first long-term report on the safety and efficacy of SRS.

BACKGROUND: Surgical options for multiple sclerosis (MS) related to trigeminal neuralgia (TN), a severe and disabling pain disorder, include percutaneous rhizotomy, stereotactic radiosurgery, or microsurgical nerve section. Our goal was to evaluate clinical outcomes after gamma knife radiosurgery (GKRS) in patients with MS with TN. METHODS: We evaluated clinical outcomes in 37 patients with TN managed over a 12-year period. The maximum TN target dose varied between 70 and 90 Gy. Seventy-eight percent of patients had failed prior surgery. In 9, GKRS was the first procedure. Median follow-up was 56.7 months (range, 6-174). Pain relief was assessed in each patient by physicians who did not participate in the surgery. RESULTS: Eventual complete pain relief (BNI grade I) after GKRS and reasonable pain control (BNI grade I-IIIb) after GKRS were noted in 23 patients (62.1%) and 36 patients (97.3%) at some point in their course. Reasonable pain control (BNI grade I-IIIb) after GKRS was maintained in 82.6%, 73.9%, and 54.0% of patients after 1, 3, and 5 years. Fourteen patients (37.8%) underwent a second or a subsequent procedure for residual or recurrent pain. Eight patients underwent a second GKRS, 5 underwent percutaneous glycerol rhizotomy, and 1 underwent balloon microcompression. The complication rate after GKRS was 5.4% (new onset of nondisabling paresthesias). No patient developed dysesthesias. CONCLUSIONS: Gamma knife radiosurgery is the most minimally invasive surgical technique for multiple sclerosis-related trigeminal neuralgia and has low morbidity. For this reason, gamma knife radiosurgery proved to be a satisfactory management strategy for multiple sclerosis-related trigeminal neuralgia.

OBJECTIVE: Management options for patients with vestibular schwannoma include observation, surgical resection, stereotactic radiosurgery (SRS), and stereotactic radiation therapy. In younger patients, resection is often advocated because of concern regarding the long-term effects of radiation. We studied tumor response and clinical outcomes after SRS in such patients. METHODS: We reviewed long-term outcomes in 55 patients with vestibular schwannomas. Patients were 40 years of age or younger, underwent gamma knife (GK) SRS between 1987 and 2003, and were followed up for a minimum of 4 years. The median patient age was 35 years (range, 13-40 years). Forty-one patients had Gardner-Robertson class 1 to 4 hearing. Thirteen patients (24%) had undergone surgical removal. The median tumor volume was 1.7 mm. The median tumor margin dose was 13.0 Gy (range, 11-20 Gy). RESULTS: At a median of 5.3 years, (range, 4-20 years), 2 of 55 patients underwent GK SRS for a second time; 1 of these patients had had a recurrence after initial resection. The 5-year rate of freedom from additional management was 96%. Hearing preservation rates (i.e., remaining within the same Gardner-Robertson hearing class) were 93%, 87%, and 87% at 3, 5, and 10 years, respectively. In patients with serviceable hearing before SRS, it was maintained in 100%, 93%, and 93% of patients at 3, 5, and 10 years, respectively. Hearing preservation was related to a margin dose lower than 13 Gy (P = 0.017). At the last assessment, facial and trigeminal nerve function was preserved in 98.2% and 96.4% of patients, respectively; the only facial deficit (House-Brackmann grade III) occurred in a patient who received a tumor dose of 20 Gy early in our experience (1988). None of the patients treated with doses lower than 13 Gy experienced facial or trigeminal neuropathy. All patients continued their previous level of activity or employment after GK SRS. No patient developed a secondary radiation-related tumor. CONCLUSION: Our experience indicates that GK SRS is an effective management strategy for younger patients with vestibular schwannoma, most of whom have no additional cranial nerve dysfunction.

A consortium of translational stem cell and stroke experts from multiple academic institutes and biotechnology companies, under the guidance of the government (FDA/NIH), is missing. Here, we build a case for the establishment of this consortium if cell therapy for stroke is to advance from the laboratory to the clinic.