Technical note: the use of frameless stereotactic guidance in the treatment of peripheral intracranial aneurysms.

Frameless stereotactic guidance (FSG) has previously been reported to have advantages over intraoperative computed tomography (CT) and frame-based imaging guidance methods in the targeting of intracranial lesions. We report our experience using FSG to minimize brain dissection during microsurgical repair of peripheral aneurysms. We used FSG as a surgical adjunct in the management of 91 peripheral aneurysms. It was used to localise and avoid larger bridging veins, enabling us to minimise unnecessary brain dissection by coming directly down on the aneurysm dome in unruptured lesions or targeting the parent artery just proximal to the aneurysm in ruptured cases. We treated 72 aneurysms located on the distal ACA (79%), 7 on the PCA (7.7%), 6 on the MCA distal to the MCA bifurcation (6.6%), and 6 on the SCA (6.6%). There were no complications related to FSG use. However, we noted a tendency to create an overly limited corridor to the aneurysm, which did not allow sufficient proximal or distal control of the parent artery. In these cases, we had to widen our exposure by further opening the interhemispheric fissure to obtain more proximal control once the aneurysm was reached. Subsequently, we learned to avoid this problem by creating a slightly wider corridor during the initial exposure. Using FSG as a surgical adjunct for peripheral intracranial aneurysms allowed us to safely limit craniotomy size and brain dissection while more confidently exposing these unusually situated lesions, facilitating aneurysm clipping in our series.

Non-islet cell tumor-induced hypoglycemia in the setting of metastatic intracranial hemangiopericytoma: case report and review of the literature.

Intracranial hemangiopericytoma, particularly in the setting of extracranial metastatic disease, can cause severe hypoglycemia; but there is limited description of this phenomenon in the neurosurgical literature. We report the case of a male patient with recurrent meningeal hemangiopericytoma that had metastasized to multiple extracranial locations, who presented with severe, symptomatic hypoglycemia and abnormal levels of insulin, pro-insulin, insulin-like growth factors I and II, and C-peptide. This case highlights the association between hemangiopericytoma and abnormal levels of peptide hormones involved in glucose homeostasis, which may serve as a warning sign for hemangiopericytoma and/or metastatic disease.

Case report and literature review of BRAF-V600 inhibitors for treatment of papillary craniopharyngiomas: A potential treatment paradigm shift.

WHAT IS KNOWN AND OBJECTIVE: The BRAF-V600E genetic mutation offers a potential targeted therapy for the treatment of papillary craniopharyngiomas. CASE SUMMARY: A 35-year-old man underwent a craniotomy and subtotal resection of a large BRAF-V600E-positive papillary craniopharyngioma before referral to our institution. Our treatment included the BRAF-V600 inhibitor dabrafenib mesylate (75 mg, twice/day) and trametinib dimethyl sulfoxide (2 mg/day). The residual tumour decreased in size by 95% over 21 months without negative side effects. WHAT IS NEW AND CONCLUSION: We reviewed the literature on BRAF-V600E inhibition as a non-invasive method of treating papillary craniopharyngiomas harbouring the BRAF-V600E mutation.

Procedural complications in patients undergoing microsurgical treatment of unruptured intracranial aneurysms: a single-center experience with 1923 aneurysms.

BACKGROUND: With the growing use of endovascular therapy (EVT) to manage unruptured intracranial aneurysms (IAs), detailed information regarding periprocedural complication rates of microsurgical clipping and EVT becomes increasingly important in determining the optimal treatment for individual cases. We report the complication rates associated with open microsurgery in a large series of unruptured IAs and highlight the importance of maintaining surgical skill in the EVT era. METHODS: We reviewed all cases of unruptured IAs treated with open microsurgery by a single neurosurgeon between July 1997 and June 2019. We analyzed surgical complications, deaths, and patient-reported outcomes. RESULTS: A total of 1923 unruptured IAs in 1750 patients (mean age 44 [range: 6-84], 62.0% [1085/1750] female) were treated surgically during the study period. Of the aneurysms treated, 84.9% (1632/1923) were small, 11.1% (213/1923) were large, and 4.1% (78/1923) were giant. Aneurysm locations included the middle cerebral artery (44.2% [850/1923]), internal carotid artery (29.1% [560/1923]), anterior cerebral artery (21.0% [404/1923]), and vertebrobasilar system (5.7% [109/1923]). The overall mortality rate was 0.3% (5/1750). Surgical complications occurred in 7.4% (129/1750) of patients, but only 0.4% (7/1750) experienced permanent disability. The majority of patients were able to return to their preoperative lifestyles with no modifications (95.9% [1678/1750]). CONCLUSIONS: At a high-volume, multidisciplinary center, open microsurgery in carefully selected patients with unruptured IAs yields favorable clinical outcomes with low complication rates. The improvement of EVT techniques and the ability to refer cases for EVT when a high complication rate with open microsurgery was expected have contributed to an overall decrease in surgical complication rates. These results may serve as a useful point of reference for physicians involved in treatment decision-making for patients with unruptured IAs.

Delayed sudden hearing recovery after treatment of a large vertebral artery aneurysm causing hearing loss and imbalance: a case report.

PURPOSE: Cerebral aneurysms that compress cranial nerve VIII can cause hearing loss and imbalance. Hearing function that does not recover after aneurysm occlusion can signal neurological damage with the potential for permanent deafness. CASE DESCRIPTION: A 72-year-old woman presented with gradually worsening left-sided hearing loss and imbalance over a period of 10 years. She was found to have a lesion of the cerebellopontine angle, which proved to be a large fusiform vertebral artery aneurysm with mass effect on cranial nerve VIII. The patient underwent surgical clip occlusion of the vertebral artery distal to the posterior inferior cerebellar artery and proximal to the aneurysm, which no longer filled on catheter angiography. Postoperatively, the patient experienced delayed complete loss of ipsilateral hearing on the third post-operative day. Otherwise, she made a good recovery with improvement in her balance issues. At that time, we suspected that delayed occlusion of a perforating vessel had probably caused irreversible hearing loss. Ten months later, the patient awoke with significant subjective recovery of her hearing. Audiometry confirmed substantial improvement in her hearing likely due to the aneurysm shrinking away from and decompressing the cranial nerve. CONCLUSION: This case highlights the continued usefulness of vascular occlusion in the management of selected cases of intracranial aneurysms and also that neurological function may recover suddenly, even in very delayed fashion, following treatment.

Bilateral Vestibular Schwannomas in a Patient with Ring Chromosome 22: Case Report and Review of the Literature.

INTRODUCTION: Ring chromosome 22 (r[22]) can lead to the development of intracranial tumors such as meningiomas, neurofibromas, and schwannomas similar to neurofibromatosis 2 (NF2). CASE PRESENTATION: An 18-year-old female with r(22) and a history of global development delay and cognitive impairment presented with sudden hearing loss. MRI revealed bilateral vestibular schwannomas. Given documented audiologic decline in the patient's hearing, the larger tumor was treated with CyberKnife fractionated stereotactic radiosurgery, and the smaller tumor is being monitored. CONCLUSION: This case provides further evidence that patients with r(22) can develop clinical features of NF2, including the development of bilateral vestibular schwannomas, and should be monitored for hearing disturbances starting in puberty as a warning sign for these tumors.

Adenosine-induced transient asystole to control intraoperative rupture of intracranial aneurysms: institutional experience and systematic review of the literature.

BACKGROUND: Intraoperative rupture of an intracranial aneurysm is a life-threatening situation that carries a high risk of morbidity and mortality. Since 2000, adenosine has been used successfully to induce transient hypotension and/or asystole to control bleeding and facilitate surgical clipping of aneurysms that rupture intraoperatively. Given the paucity of reports describing this method in a limited number of patients, we performed a systematic review of the literature detailing the use and outcomes of this technique. METHODS: The authors performed a systematic review and identified all studies in which adenosine was used in the setting of an intracranial aneurysm that ruptured intraoperatively. We then determined overall morbidity and mortality rates, adding an additional six of our own patients. RESULTS: Data was analyzed for a total of 29 patients, including 23 previously reported patients from the literature and 6 additional cases from our own experience (mean age 54.8 years, 58.6% female). Most patients (82.8%, 24/29) presented with subarachnoid hemorrhage (SAH). Overall mean dose of adenosine was 51.8 mg. Successful clipping was achieved in 100% of patients. Transient or permanent morbidity was reported in 5/29 (17.2%) and the overall mortality rate was 31% (9/29), which occurred primarily due to an initial severe SAH and its resultant complications. CONCLUSIONS: Adenosine-induced circulatory arrest appears to safely control intraoperative bleeding and facilitate the clipping of ruptured intracranial aneurysms based on the limited published literature available. Further studies comparing patient outcomes using this technique to traditional approaches are required to validate the safety and efficacy of adenosine in this high-risk setting.

Primary intracranial angiomatoid fibrous histiocytoma: a case report and literature review.

Angiomatoid fibrous histiocytoma (AFH) is a tumour primarily occurring in the extremities which can very rarely occur as an isolated intracranial lesion. We report a case of a 22-year-old woman presenting with generalized seizure and visual field deficit due to an occipital mass, which immunohistochemistry showed to be an AFH.

Superficial temporal artery to middle cerebral artery (STA-MCA) bypass via retrograde arterial anastomosis in a patient with common carotid artery occlusion: a case report.

The standard superficial temporal artery to middle cerebral artery (STA-MCA) bypass depends on adequate antegrade flow in the STA. In the setting of occlusion of the common or external carotid arteries, revascularization requires modification of the standard bypass procedure. A patient with prior history of irradiation for head and neck carcinoma presented with an ischemic injury and fluctuating neurologic deficit not responsive to medical therapy. His left common carotid artery was occluded, but angiographic evaluation demonstrated retrograde filling of his left STA. Reverse STA-MCA bypass was performed, taking advantage of spontaneous collateralization which allowed for retrograde filling of the STA.

De novo cavernous malformation arising in the wall of vestibular schwannoma following stereotactic radiosurgery: case report and review of the literature.

We report a novel case of a radiation-induced cavernous malformation developing in a vestibular schwannoma previously treated with stereotactic radiosurgery. Eleven years after treatment, the patient presented with a large predominantly cystic lesion in the cerebellopontine angle. We performed surgery, and a solid vascular lesion was identified within the schwannoma, which was determined to be a cavernous malformation after histopathological analysis. We review the literature of radiation-induced cavernous lesions, illustrating that while rare, these lesions do pose concern as a long-term complication of brain radiation therapy. We also discuss the possibility that radiation-induced cavernous malformation-like lesions are pathologically distinct from cavernous malformations.

Unexpected immediate postoperative resolution of long-standing neurological deficits following extracranial-intracranial bypass: a report of three cases.

While intracranial ischemic insults often result in neuronal death and permanent neurological deficits, some patients may develop potentially reversible neurological dysfunction from persistent hypoperfusion, as surviving neurons remain in an "idling" state. We report a unique series of three patients with long-standing neurological deficits who underwent EC-IC bypass for repeated TIAs and demonstrated unexpected, rapid resolution of long-standing pre-existing neurological deficits. We suggest that these individuals harbored regions of underperfused, idling neurons that responded rapidly to restored cerebral reperfusion.

Surgical treatment of a gauzoma with associated obliterative arteriopathy and review of the literature.

We report a case of a 50-year-old woman whose 0.5 mm middle cerebral artery (MCA) aneurysm was treated with gauze wrapping at an outside facility. She returned 9 months later with seizures and an inflammatory process in the region of the prior aneurysm. Surgical re-exploration at that time was aborted. Two years later, she presented with a gauzoma associated with local inflammatory response and severe narrowing of the MCA. A common carotid artery to MCA bypass was performed, followed by surgical removal of the gauze and inflammatory material. Over a 3-month period, she recovered with significant improvement in her preoperative neurological deficits.

CT cisternography to visualize epidermoid tumors for stereotactic radiosurgery treatment planning.

The visualization of intracranial epidermoid tumors is often limited by difficulties associated with distinguishing the tumor from the surrounding cerebrospinal fluid using traditional computed tomography (CT) or magnetic resonance imaging (MRI) modalities. This report describes our experience using CT cisternography to visualize intracranial epidermoid tumors in three illustrative cases. CT cisternography of the epidermoid tumor provides more clarity and precision compared to traditional neuroimaging modalities. We demonstrate the feasibility of using CT cisternography to produce high-resolution images with well-defined tumor margins that can be used effectively for precise SRS treatment planning.

Microsurgical Treatment of Unruptured Anterior Communicating Artery Aneurysms: Approaches and Outcomes in a Large Contemporary Series and Review of the Literature.

BACKGROUND: With advances in endovascular techniques, the relative roles of microsurgery and endovascular therapy in the management of intracranial aneurysms have become less clear, and data regarding treatment-specific outcomes are increasingly important. OBJECTIVE: To describe our experience with microsurgery in a large series of unruptured anterior communicating artery aneurysms (ACOMMAAs) and detail our treatment decision-making process based on individual aneurysm morphology. METHODS: We retrospectively reviewed unruptured ACOMMAAs treated microsurgically at our center between 1997 and 2018, recording aneurysm size, surgical approach, occlusion rates, neurological outcomes, and complications. RESULTS: We treated 300 unruptured ACOMMAAs in 300 patients, mean age 49 yr, 180 (60.0%) female, including 245 (81.7%) small, 50 (16.7%) large, and 5 (1.7%) giant aneurysms. Most underwent a pterional approach (253, 84.3%), with orbitozygomatic or anterior interhemispheric approaches in 35 (11.7%) and 12 (4%), respectively. Greater than 95% occlusion was achieved in 284 (94.7%), 90% to 95% occlusion in 13 (4.3%), and 3 (1.0%) underwent wrapping. Serious complications occurred in 3 patients (1.0%) resulting in 2 deaths (0.7%), and minor complications in 12 (4.0%). At final follow-up, good neurological outcome was observed in 297 (99.0%) patients. CONCLUSION: Given clinical equipoise regarding optimal treatment of unruptured ACOMMAAs, this work provides a benchmark for achievable microsurgical outcomes. Future surgical/endovascular studies should separate results of ruptured and unruptured lesions and describe aneurysm morphology to allow for better comparison of outcomes between treatments. We suggest that open microsurgery represents an important option for select, morphologically complex ACOMMAAs, and that a multidisciplinary approach offers optimal patient outcomes.

Peripheral intracranial aneurysms: management challenges in 60 consecutive cases.

OBJECT: The authors report the management and outcomes of 55 patients with 60 intracranial aneurysms arising distal to the major branch points of the circle of Willis and vertebrobasilar system. METHODS: Between July 1997 and December 2006, the authors' neurovascular service treated 2021 intracranial aneurysms in 1850 patients. The database was reviewed retrospectively to identify peripherally located intracranial aneurysms. Aneurysms that were mycotic and aneurysms that were associated with either an arteriovenous malformation or an atrial myxoma were excluded from review. RESULTS: The authors encountered 60 peripheral intracranial aneurysms in 55 patients. There were 42 small, 7 large, and 11 giant lesions. Forty-one (68%) were unruptured, and 19 (32%) had bled. Fifty-three aneurysms were treated surgically by using direct clip reconstruction in 26, trapping or proximal occlusion with distal revascularization in 21, excision with end-to-end anastomosis in 3, and circumferential wrap/clip reconstruction in 3. Coils were used to treat 6 aneurysms, and 1 was treated by endovascular parent artery occlusion. Overall, 49 patients had good outcomes, 4 were left with new neurological deficits, and 2 died. CONCLUSIONS: Peripherally situated intracranial aneurysms are rare lesions that present unique management challenges. Despite the fact that in the authors' experience these lesions were rarely treatable with simple clipping of the aneurysm neck or endovascular coil occlusion, preservation of the parent artery was possible in most cases, and the majority of patients had a good outcome.

Remote distal outflow occlusion: a novel treatment option for complex dissecting aneurysms of the posterior inferior cerebellar artery. Report of 3 cases.

The authors report a novel management option for patients with complex dissecting aneurysms of the posterior inferior cerebellar artery (PICA). The authors reviewed the medical records and neuroimaging studies of 3 patients who underwent a novel surgical treatment for complicated dissecting PICA aneurysms. The mean follow-up period was 1.1 years, and no patient was lost to follow-up. Two patients were in poor condition following an acute, severe subarachnoid hemorrhage, and 1 presented with headaches and a remote history of bleeding. All patients underwent surgical occlusion of the PICA beyond the tonsillar loop, distal to the aneurysmal segment. Intraoperative and delayed follow-up angiography demonstrated progressive diminution in size of the aneurysmal dilation but persistent filling of the proximal PICA segments supplying the brainstem. Outcome was good in all cases. This novel technique has been used successfully in 3 cases and, to the authors' knowledge, has not been reported previously.

Fenestration of the middle cerebral artery with an associated ruptured aneurysm.

Intracranial arterial fenestrations are uncommon developmental anomalies that may alter local hemodynamic stress patterns and may be associated with intracranial aneurysms. A 75-year-old woman presented with a mild subarachnoid hemorrhage. Cerebral angiography demonstrated a 5 mm aneurysm arising from the middle cerebral artery (MCA) associated with a dramatic fenestration of the proximal M1 segment of the MCA. The patient underwent craniotomy with microsurgical aneurysm clipping. The aneurysm arose immediately distal to the fenestration. Several fine perforating arteries were dissected away from the neck of the aneurysm to allow for safe clip placement. Postoperatively, the patient awoke without deficit and was discharged to home on the fifth postoperative day in good condition. Anomalies of the intracranial vasculature are common and we describe a rare proximal MCA fenestration with an associated ruptured aneurysm at the site of the fenestration. Neurosurgeons should be thoroughly familiar with such potential "normal variants" to avoid operative complications that may result from the anomalous circulation in such cases.

Endovascular aspiration to treat acute ischemic stroke caused by embolic carcinoma.

Although cardiac myxomas have been known to cause acute ischemic stroke and other cerebrovascular complications, intracranial embolization of metastatic tumor fragments is rare. This is likely because venous emboli generally cause pulmonary embolism. Pulmonary vein metastases and patent foramen ovales have previously shown to propagate intracranial embolic carcinomas, but these events are very uncommon, and are not well characterized. We report a rare case of large-cell, high-grade neuroendocrine lung cancer embolus occluding the basilar artery, which likely detached into the bloodstream from the lung after intruding into a pulmonary vein. The embolus was treated with endovascular aspiration, and achieved modified Thrombolysis In Cerebral Infarction 2c revascularization. After initial neurological recovery, the patient suffered respiratory arrest and support was withdrawn 48 h later. We discuss the tumor characteristics and implications for treatment of acute ischemic stroke in patients with cancer diagnoses.

Routine screening for hepatitis C viral infection in patients undergoing elective cranial neurosurgery.

OBJECTIVE: Undiagnosed hepatitis C virus (HCV) and HIV in patients present risks of transmission of bloodborne infections to surgeons intraoperatively. Presurgical screening has been suggested as a protocol to protect surgical staff from these pathogens. The authors sought to determine the incidence of HCV and HIV infection in elective craniotomy patients and analyze the cost-effectiveness of universal and risk factor-specific screening for protection of the surgical staff. METHODS: All patients undergoing elective craniotomy between July 2009 and July 2016 at the National Brain Aneurysm Center who did not refuse screening were included in this study. The authors utilized rapid HCV and HIV tests to screen patients prior to elective surgery, and for each patient who tested positive using the rapid HCV or HIV test, qualitative nucleic acid testing was used to confirm active viral load, and risk factor information was collected. Patients scheduled for nonurgent surgery who were found to be HCV positive were referred to a hepatologist for preoperative treatment. The authors compared risk factors between patients who tested positive on rapid tests, patients with active viral loads, and a random sample of patients who tested negative. The authors also tracked the clinical and material costs of HCV and HIV rapid test screening per patient for cost-effectiveness analysis and calculated the cost per positive result of screening all patients and of screening based on all patient risk factors that differed significantly between patients with and those without positive HCV test results. RESULTS: The study population of patients scheduled for elective craniotomy included 1461 patients, of whom 22 (1.5%) refused the screening. Of the 1439 patients screened, 15 (1.0%) tested positive for HCV using rapid HCV screening; 9 (60%) of these patients had active viral loads. No patient (0%) tested positive for HIV. Seven (77.8%) of the 9 patients with active viral loads underwent treatment with a hepatologist and were referred back for surgery 3-6 months after sustained virologic response to treatment, but the remaining 2 patients (22.2%) required urgent surgery. Of the 9 patients with active viral loads, 1 patient (11%) had a history of both intravenous drug abuse and tattoos. Two of the 9 patients (22%) had tattoos, and 3 (33%) were born within the age-screening bracket (born 1945-1965) recommended by the Centers for Disease Control and Prevention. Rates of smoking differed significantly (p < 0.001) between patients who had active viral loads of HCV and patients who were HCV negative, and rates of smoking (p < 0.001) and IV drug abuse (p < 0.01) differed significantly between patients who were HCV rapid-test positive and those who were HCV negative. Total screening costs (95% CI) per positive result were $3,877.33 ($2,348.05-$11,119.28) for all patients undergoing HCV rapid screening, $226.29 ($93.54-$312.68) for patients with a history of smoking, and $72.00 ($29.15-$619.39) for patients with a history of IV drug abuse. CONCLUSIONS: The rate of undiagnosed HCV infection in this patient population was commensurate with national levels. While the cost of universal screening was considerable, screening patients based on a history of smoking or IV drug abuse would likely reduce costs per positive result greatly and potentially provide cost-effective identification and treatment of HCV patients and surgical staff protection. HIV screening found no infected patients and was not cost-effective.

Cerebral revascularization for the management of complex intracranial aneurysms: a single-center experience.

OBJECTIVEBecause simple intracranial aneurysms (IAs) are increasingly treated endovascularly, neurovascular surgery has become focused on complex IAs that may require deconstructive aneurysm therapy with concomitant surgical bypass. The authors describe the decision-making process concerning cerebral revascularization and present outcomes that were achieved in a large case series of complex IAs managed with cerebral revascularization and parent artery occlusion.METHODSThe authors retrospectively reviewed the medical records, including neuroimaging studies, operative reports, and follow-up clinic notes, of all patients who were treated at the National Brain Aneurysm Center between July 1997 and June 2015 using cerebral revascularization as part of the management of an IA. They recorded the location, rupture status, and size of each IA, as well as neurological outcome using the modified Rankin Scale (mRS), aneurysm and bypass status at follow-up, and morbidity and mortality.RESULTSThe authors identified 126 patients who underwent revascularization surgery for 126 complex, atheromatous, calcified, or previously coiled aneurysms. Ninety-seven lesions (77.0%) were unruptured, and 99 (78.6%) were located in the anterior circulation. Aneurysm size was giant (≥ 25 mm) in 101 patients, large (10-24 mm) in 9, and small (≤ 9 mm) in 16 patients. Eighty-four low-flow bypasses were performed in 83 patients (65.9%). High-flow bypass was performed in 32 patients (25.4%). Eleven patients (8.7%) underwent in situ or intracranial-intracranial bypasses. Major morbidity (mRS score 4 or 5) occurred in 2 (2.4%) low-flow cases and 3 (9.1%) high-flow cases. Mortality occurred in 2 (2.4%) low-flow cases and 2 (6.1%) high-flow cases. At the 12-month follow-up, 83 (98.8%) low-flow and 30 (93.8%) high-flow bypasses were patent. Seventy-five patients (90.4%) undergoing low-flow and 28 (84.8%) high-flow bypasses had an mRS score ≤ 2. There were no statistically significant differences in patency rates or complications between low- and high-flow bypasses.CONCLUSIONSWhen treating challenging and complex IAs, incorporating revascularization strategies into the surgical repertoire may contribute to achieving favorable outcomes. In our series, low-flow bypass combined with isolated proximal or distal parent artery occlusion was associated with a low rate of ischemic complications while providing good long-term aneurysm control, potentially supporting its wider utilization in this setting. The authors suggest that consideration should be given to managing complex IAs at high-volume centers that offer a multidisciplinary team approach and the full spectrum of surgical and endovascular treatment options to optimize patient outcomes.