Faculty Bibliography

BACKGROUND: In this article, we report on the technique of placing fat in between a sellar or parasellar neoplasm and the optic chiasm to possibly protect the optic chiasm from sequelae of radiation. METHODS: A review was performed on three patients, each of whom had planned subtotal resection with fat placed near their optic chiasm to facilitate future radiosurgery. RESULTS: Follow-up on our three patients varied from 6 months to 3 years post-stereotactic radiosurgery. The fat remained stable and in place. The tumors either remained stable or reduced in size. No infections, postoperative marker dependent neurological complications or unusual symptoms were encountered. CONCLUSIONS: Placement of fat between a parasellar neoplasm and the optic chiasm appears to be a safe approach to help define the tumor chiasm space, helping to facilitate radiosurgery. Future experience is warranted to determine the efficacy of this technique.

Object The aim of this study was to evaluate the imaging response of brain metastases after radiosurgery and to correlate the response with tumor type and patient survival. Methods The authors conducted a retrospective review of patients who had undergone Gamma Knife radiosurgery for brain metastases from non-small cell lung cancer (NSCLC), breast cancer, or melanoma. The imaging volumetric response by tumor type was plotted at 3-month intervals and classified as a sustained decrease in tumor volume (Type A), a transient decrease followed by a delayed increase in tumor volume (Type B), or a sustained increase in tumor volume (Type C). These imaging responses were then compared with patient survival and tumor type. Results Two hundred thirty-three patients with metastases from NSCLC (96 patients), breast cancer (98 patients), and melanoma (39 patients) were eligible for inclusion in this study. The patients with NSCLC were most likely to exhibit a Type A response; those with breast cancer, a Type B response; and those with melanoma, a Type C response. Among patients with NSCLC, the median overall survival was 11.2 months for those with a Type A response (76 patients), 8.6 months for those with a Type B response (6 patients), and 10.5 months for those with a Type C response (14 patients). Among patients with breast cancer, the median overall survival was 16.6 months in those with a Type A response (65 patients), 18.1 months in those with a Type B response (20 patients), and 7.5 months in those with a Type C response (13 patients). For patients with melanoma, the median overall survival was 5.2 months in those with a Type A response (26 patients) and 6.7 months in those with a Type C response (13 patients). None of the patients with melanoma had a Type B response. The imaging response was significantly associated with survival only in patients with breast cancer. Conclusions The various types of imaging responses of metastatic brain tumors after stereotactic radiosurgery depend in part on tumor type. However, the type of response only correlates with survival in patients with breast cancer.

INTRODUCTION: Essential tremor can be treated by thalamic stimulation or ablation of the ventral intermediate nucleus (VIM) with good outcomes [1]. Routine magnetic resonance imaging (MRI) cannot distinguish between thalamic nuclei so targeting is based on anatomic atlas-based coordinates. Diffusion MRI-based track density imaging (TDI) can better depict internal thalamic structure [2], but previously has required high-field MRI or long acquisitions that are not clinically practical. We applied multiband diffusion MRI [3] to enable 3-Tesla (3-T) MRI TDI in patients with essential tremor. METHODS: Six patients with essential tremor underwent standard preoperative MRI with an additional multiband diffusion sequence that used 3-slice acceleration factor, 3-mm isotropic image resolution, whole-brain coverage (45 slices) and 256 diffusion gradient directions (b = 2500 s/mm) acquired in 11 minutes. TDI data post-processing generated track density and direction-encoded color maps at 500-micron isotropic super-resolution [2]. RESULTS: Combining TDI and multiband diffusion acquisitions resulted in high-quality images of the human thalamus in typical elderly essential tremor patients using 3-T MRI and clinically feasible scan times. Results also were consistent for repeat imaging in the 3 volunteers. TDI with or without direction-encoding demonstrated some of the internal anatomy of the thalamus, but fiber-orientation maps derived from these data (Fig. 1) were preferred by the 2 participating functional neurosurgeons. CONCLUSION: Multiband diffusion acquisition makes TDI-based parcellation of the thalamus feasible in elderly patients with essential tremor using 3-T MRI. This approach provides at least equivalent data to previous diffusion tractography or TDI approaches for thalamus parcellation, but without long scan times or a 7-Tesla MRI system [4-6]. While planning for gamma knife ablation of VIM for these initial 6 patients still relied on conventional methods, future efforts will focus on validation and careful introduction of TDI-derived thalamic maps to actual surgical planning.

INTRODUCTION: It is known that physicians sometimes recommend treatment that, in a similar clinical scenario, they might not choose for themselves. We sought to understand this dynamic across cerebrovascular practice and examine how neurosurgeons value the procedures they offer. METHODS: We conducted an online survey sent to a large cohort of neurosurgeons in May 2013. Respondents were randomised to answer either as the surgeon or as the patient. The questions involved patients presenting with 1) an epidural hematoma (control), 2) un-ruptured anterior communicating artery aneurysm, 3) incidentally found right temporal AVM, 4) spontaneous intracranial and intraventricular haemorrhage in deep structure. Data on practice parameters and experience levels was also collected. RESULTS: We obtained 534 survey responses, 279 responding as the "neurosurgeon", and 255 as the "patient," with a response rate of 19.7%. Demographics amongst the two groups of survey takers was similar. There was no difference in the management of an epidural hematoma, as expected. For the unruptured aneurysm, the rates of opting for treatment was similar amongst respondees. However within the treatment group there was a trend for survey takers to more often chose coiling for themselves and clipping for patients (p = 0.056). Surgeons, however, with a greater than 30% open-cerebrovascular practice had less of a tendency to do so. For arteriovenous malformation management, there was no statistical difference between choosing treatment or conservative management. However, amongst the respondees who chose treatment, more respondees chose resection/embolization for their patient but radiosurgery for self (p = 0.001). In a case of a large spontaneous intracranial and intraventricular haemorrhage neurosurgeons were more likely to place a ventricular drain in a patient than himself or herself. Neurosurgeons in practice more than 10 years since residency were more likely to recommend against interventions for aneurysms, AVMs or intracranial haemorrhage. CONCLUSIONS: In the majority of cases altering the role of the surgeon did not change the decision to pursue treatment or conservative treatment. In certain clinical scenarios, however, neurosurgeons choose treatment options for themselves that are different than what they would choose for their patients. For the management of an arteriovenous malformations, intracranial aneurysms, and hypertensive haemorrhage, responses favored less invasive interventions when the surgeon was the patient. These findings are likely a result of cognitive biases, previous training, experience, areas of expertise, and personal values. DISCLOSURES: O. Tanweer: None. T. Wilson: None. S. Kalhorn: None. J. Golfinos: None. P. Huang: None. D. Kondziolka: None.

: There are many elements to the science that drives the clinical care of patients with brain metastases. Although part of an understanding that continues to evolve, a number of key historical misconceptions remain that commonly drive physicians' and researchers' attitudes and approaches. By understanding how these relate to current practice, we can better comprehend our available science to provide both better research and care. These past misconceptions include: Misconception 1: Once a primary cancer spreads to the brain, the histology of that primary tumor does not have much impact on response to chemotherapy, sensitivity to radiation, risk of further brain relapse, development of additional metastatic lesions, or survival. All tumor primary histologies are the same once they spread to the brain. They are the same in terms of the number of tumors, radiosensitivity, chemoresponsiveness, risk of further brain relapse, and survival. Misconception 2: The number of brain metastases matters. This number matters in terms of subsequent brain relapse, survival, and cognitive dysfunction; the precise number of metastases can also be used as a limit in determining which patients might be eligible for a particular treatment option. Misconception 3: Cancer in the brain is always a diffuse problem due to the presence of micrometastases. Misconception 4: Whole-brain radiation therapy invariably causes disabling cognitive dysfunction if a patient lives long enough. Misconception 5: Most brain metastases are symptomatic. Thus, it is not worth screening patients for brain metastases, especially because the impact on survival is minimal. The conduct and findings of past clinical research have led to conceptions that affect clinical care yet appear limiting. ABBREVIATIONS: CI, confidence intervalHVLT, Hopkins Verbal Learning TestSRS, stereotactic radiosurgeryWBRT, whole-brain radiotherapy.