Frame-based stereotaxy in a frameless era: current capabilities, relative role, and the positive- and negative predictive values of blood through the needle.

INTRODUCTION: In the modern era of frameless stereotaxis (FL), the role of frame-based (FB) stereotactic needle biopsy is evolving. METHODS: Retrospective review of prospective database of 106 lesions in 91 consecutive patients undergoing FB stereotactic needle biopsy with a systematic "geologic core" technique by a single surgeon. Diagnostic accuracy was calculated comparing biopsy diagnosis with final pathology in 11 patients who underwent subsequent surgical resection. All instances of intra-operative bleeding through the needle were prospectively noted and compared with post-biopsy CT scan. Lesions were classified as risky for FL technique if they were (1) infratentorial or pineal, (2) within 10 mm of the circle of Willis or root of the Sylvian fissure, or (3) within 10 mm of deep cerebral veins. RESULTS: Diagnostic yield was 94%. Diagnostic accuracy was 91%. Of 18 lesions involving the corpus callosum, 13 (72.2%) were GBM 2 were anaplastic astrocytoma, and 1 each were found to be anaplastic oligodendroglioma, primary central nervous system lymphoma (PCNSL) and tumescent MS. Of 25 multifocal lesions, malignant primary brain tumor was diagnosed in 17 (68%) (11 GBM, 3 PCNSL, 2 anaplastic ologodendroglioma, and 1 anaplastic astrocytoma). Mortality was 0%. Three patients developed temporary neurologic deficits and one had permanent deficit. Absence of persistent blood through the biopsy needle had a negative predicative value of 98.8% for subsequent neuroimaging blood >5 mm diameter. According to our criteria, 80% of patients would have been candidates for FL biopsy. CONCLUSIONS: Stereotactic biopsy is an effective, safe and important technique for histologic diagnosis of brain lesions, particularly for multifocal and corpus callosum lesions. Post-biopsy CT can be safely reserved for patients who demonstrate persistent bleeding through the biopsy needle. FB stereotaxy remains an important technique for the 20% with small or deep seated lesions or when it is advantageous to avoid an incision, a burr hole or general anesthesia.

Blister Aneurysms of the Internal Carotid Artery: Microsurgical Results and Management Strategy.

Background: Blister aneurysms of the supraclinoid internal carotid artery (ICA) are challenging lesions with high intraoperative rupture rates and significant morbidity. An optimal treatment strategy for these aneurysms has not been established. Objective: To analyze treatment strategy, operative techniques, and outcomes in a consecutive 17-year series of ICA blister aneurysms treated microsurgically. Methods: Seventeen patients underwent blister aneurysm treatment with direct clipping, bypass and trapping, or clip-reinforced wrapping Results: Twelve aneurysms (71%) were treated with direct surgical clipping. Three patients required bypass: 1 superficial temporal artery to middle cerebral artery bypass, 1 external carotid artery to middle cerebral artery bypass, and 1 ICA to middle cerebral artery bypass. One patient was treated with clip-reinforced wrapping. Initial treatment strategy was enacted 71% of the time. Intraoperative rupture occurred in 7 patients (41%), doubling the rate of a poor outcome (57% vs 30% for patients with and without intraoperative rupture, respectively). Severe vasospasm developed in 9 of 16 patients (56%). Twelve patients (65%) were improved or unchanged after treatment, and 10 patients (59%) had good outcomes (modified Rankin Scale scores of 1 or 2). Conclusion: ICA blister aneurysms can be cautiously explored and treated with direct clipping as the first-line technique in the majority of cases. Complete trapping of the parent artery with temporary clips and placing permanent clip blades along normal arterial walls enables clipping that avoids intraoperative aneurysm rupture. Trapping/bypass is used as the second-line treatment, maintaining a low threshold for bypass with extensive or friable pathology of the carotid wall and in patients with incomplete circles of Willis.

Upfront boost Gamma Knife "leading-edge" radiosurgery to FLAIR MRI-defined tumor migration pathways in 174 patients with glioblastoma multiforme: a 15-year assessment of a novel therapy.

OBJECTIVE Glioblastoma multiforme (GBM) is composed of cells that migrate through the brain along predictable white matter pathways. Targeting white matter pathways adjacent to, and leading away from, the original contrast-enhancing tumor site (termed leading-edge radiosurgery [LERS]) with single-fraction stereotactic radiosurgery as a boost to standard therapy could limit the spread of glioma cells and improve clinical outcomes. METHODS Between December 2000 and May 2016, after an initial diagnosis of GBM and prior to or during standard radiation therapy and carmustine or temozolomide chemotherapy, 174 patients treated with radiosurgery to the leading edge (LE) of tumor cell migration were reviewed. The LE was defined as a region outside the contrast-enhancing tumor nidus, defined by FLAIR MRI. The median age of patients was 59 years (range 22-87 years). Patients underwent LERS a median of 18 days from original diagnosis. The median target volume of 48.5 cm3 (range 2.5-220.0 cm3) of LE tissue was targeted using a median dose of 8 Gy (range 6-14 Gy) at the 50% isodose line. RESULTS The median overall survival was 23 months (mean 43 months) from diagnosis. The 2-, 3-, 5-, 7-, and 10-year actual overall survival rates after LERS were 39%, 26%, 16%, 10%, and 4%, respectively. Nine percent of patients developed treatment-related imaging-documented changes due to LERS. Nineteen percent of patients were hospitalized for management of edema, 22% for resection of a tumor cyst or new tumor bulk, and 2% for shunting to treat hydrocephalus throughout the course of their disease. Of the patients still alive, Karnofsky Performance Scale scores remained stable in 90% of patients and decreased by 1-3 grades in 10% due to symptomatic treatment-related imaging changes. CONCLUSIONS LERS is a safe and effective upfront adjunctive therapy for patients with newly diagnosed GBM. Limitations of this study include a single-center experience and single-institution determination of the LE tumor target. Use of a leading-edge calculation algorithm will be described to achieve a consistent approach to defining the LE target for general use. A multicenter trial will further elucidate its value in the treatment of GBM.

Early optical detection of cerebral edema in vivo.

OBJECT: Cerebral edema is a significant cause of morbidity and mortality in diverse disease states. Currently, the means to detect progressive cerebral edema in vivo includes the use of intracranial pressure (ICP) monitors and/or serial radiological studies. However, ICP measurements exhibit a high degree of variability, and ICP monitors detect edema only after it becomes sufficient to significantly raise ICP. The authors report the development of 2 distinct minimally invasive fiberoptic near-infrared (NIR) techniques able to directly detect early cerebral edema. METHODS: Cytotoxic brain edema was induced in adult CD1 mice via water intoxication by intraperitoneal water administration (30% body weight intraperitoneally). An implantable dual-fiberoptic probe was stereotactically placed into the cerebral cortex and connected to optical source and detector hardware. Optical sources consisted of either broadband halogen illumination or a single-wavelength NIR laser diode, and the detector was a sensitive NIR spectrometer or optical power meter. In one subset of animals, a left-sided craniectomy was performed to obtain cortical biopsies for water-content determination to verify cerebral edema. In another subset of animals, an ICP transducer was placed on the contralateral cortex, which was synchronized to a computer and time stamped. RESULTS: Using either broadband illumination with NIR spectroscopy or single-wavelength laser diode illumination with optical power meter detection, the authors detected a reduction in NIR optical reflectance during early cerebral edema. The time intervals between water injection (Time Point 0), optical trigger (defined as a 2-SD change in optical reflectance from baseline), and defined threshold ICP values of 10, 15 and 20 mm Hg were calculated. Reduction in NIR reflectance occurred significantly earlier than any of the ICP thresholds (p < 0.001). Saline-injected control mice exhibited a steady baseline optical signal. There was a significant correlation between reflectance change and tissue specific gravity of the cortical biopsies, further validating the dual-fiberoptic probe as a direct measure of cerebral edema. CONCLUSIONS: Compared with traditional ICP monitoring, the aforementioned minimally invasive NIR techniques allow for the significantly earlier detection of cerebral edema, which may be of clinical utility in the identification and thus early treatment of cerebral edema.

Hippocampus minor, calcar avis, and the Huxley-Owen debate.

On the bicentennial of Darwin's birth, we describe the origin of the calcar avis and summarize the debate around this structure, which played a central role in the evolution debate in the mid-19th century. We performed a comprehensive review of relevant neuroanatomic literature, bibliographic sources, and 19th century primary sources. Once known as the hippocampus minor, the structure now known as the calcar avis is an involution of the ventricular wall produced by the calcarine fissure. A heated debate raged between 2 prominent scientific theorists, Sir Richard Owen and Thomas Henry Huxley, over the presence of the hippocampus minor in apes versus humans. Owen put forward the lack of an identifiable hippocampus minor in humans as part of an attempt to debunk evolution. A bitter personal and academic rivalry ensued, as Huxley conducted his own dissections to refute Owen's claims. Huxley ultimately dismantled Owen's premises, securing the epithet "Darwin's bulldog" for his defense of the theory of evolution. Thus, this relatively obscure neuroanatomic landmark served as a pivotal point of contention in the most popularized and acrimonious evolutionary debate of the 19th century.

Isolated amygdala neurocysticercosis in a patient presenting with déjà vu and olfactory auras. Case report.

Neurocysticercosis is the most common parasitic infection in the CNS and a leading cause of epilepsy. Since it is a circumscribed lesional cause of epilepsy, specific locations of neurocysticercal lesions may lead to specific clinical presentations. The authors describe a 17-year-old Hispanic boy who had a single enhancing bilobar mass in the right amygdala. Initially, the patient presented with secondarily generalized tonic-clonic seizures, which resolved with antiepilepsy drug therapy. On further investigation, he was found to have persistent olfactory and déjà vu auras. A right amygdalectomy without hippocampectomy was performed, and both the seizures and auras immediately resolved. Pathological analysis revealed neurocysticercosis. To the authors' knowledge, this case is the first reported instance of 2 distinct mesial temporal aura semiologies associated with localized neurocysticercosis in the amygdala and successfully treated with resection. Uniquely, the case demonstrates that both olfactory and déjà vu auras can emanate from the amygdala.

The madness of Dionysus: a neurosurgical perspective on Friedrich Nietzsche.

OBJECTIVE: To examine the possibility that an intracranial mass may have been the etiology of the headaches and neurological findings of the philosopher Friedrich Nietzsche (1844-1900) and the cause of his ultimate mental collapse in 1889. METHODS: The authors conducted a comprehensive English and German language literature search on the topic of Nietzsche's health and illness, examining Nietzsche's own writings, medical notes from his physicians, contemporary medical literature, biographical texts, and past attempts at pathography. We also examined archived portraits and engravings of the philosopher from 1864 onward. An English language search in the modern literature on the topic of psychiatric presentations of intracranial mass lesions was also conducted. RESULTS: From his late 20s onward, Nietzsche experienced severe, generally right-sided headaches. He concurrently suffered a progressive loss of vision in his right eye and developed cranial nerve findings that were documented on neurological examinations in addition to a disconjugate gaze evident in photographs. His neurological findings are consistent with a right-sided frontotemporal mass. In 1889, Nietzsche also developed a new-onset mania which was followed by a dense abulia, also consistent with a large frontal tumor. CONCLUSION: A close examination of Nietzsche's symptomatic progression and neurological signs reveals a clinical course consistent with a large, slow growing, right-sided cranial base lesion, such as a medial sphenoid wing meningioma. Aspects of his presentation seem to directly contradict the diagnosis of syphilis, which has been the standard explanation of Nietzsche's madness. The meningioma hypothesis is difficult, though not impossible, to prove; imaging studies of Nietzsche's remains could reveal the bony sequelae of such a lesion.