Seizure Prophylaxis in Unruptured Aneurysm Repair: A Randomized Controlled Trial.

BACKGROUND: Prophylactic antiepileptic drugs (pAEDs) are often prescribed for seizure prophylaxis in patients undergoing surgical treatment of unruptured intracranial aneurysms (UIAs). We aimed to evaluate the benefit of pAEDs in patients undergoing surgical repair of UIAs. METHODS: We randomly assigned eligible patients undergoing surgical repair of UIAs to receive levetiracetam for seven days post-operatively or standard care alone. The primary outcome was the evaluation of seizures in the perioperative period (within 4 weeks). We also evaluated seizure occurrence throughout follow-up and assessed functional outcomes using the modified Rankin scale score (mRS). RESULTS: 35 patients were randomized to the "no-levetiracetam" group and 41 patients were randomized to receive levetiracetam. The two study groups had similar overall baseline characteristics and the surgical complication rate was similar for both groups (p = 0.8). One patient in the "no-levetiracetam" group had a seizure in the perioperative period versus 2 patients in the group randomized to receive levetiracetam (2.9% vs 4.9%, respectively, p = 1.00). No patients in the "no-levetiracetam" group had any additional late seizures (mean follow-up of 20.4 months), but three patients in the levetiracetam group had late seizures during follow-up (mean follow-up of 19.1 months) (0% vs 7.3%, p = 0.2). mRS score of 0-2 at 90 days and at the latest follow-up were similar between the two groups (p = 1.00). CONCLUSIONS: Perioperative seizure prophylaxis with levetiracetam does not reduce the rate of seizures as compared to controls in patients undergoing surgical repair of UIAs.

Stereotactic Radiosurgery for Brain Arteriovenous Malformations: Evaluation of Obliteration and Review of Associated Predictors.

BACKGROUND: High arteriovenous malformation (AVM) obliteration rates have been reported with stereotactic radiosurgery (SRS), and multiple factors have been found to be associated with AVM obliteration. These predictors have been inconsistent throughout studies. We aimed to analyze our experience with linear accelerator (LINAC)-based SRS for brain AVMs, evaluate outcomes, assess factors associated with AVM obliteration and review the various reported predictors of AVM obliteration. METHODS: Electronic medical records were retrospectively reviewed to identify consecutive patients with brain AVMs treated with SRS over a 27-year period with at least 2 years of follow-up. Logistic regression analysis was performed to identify factors associated with AVM obliteration. RESULTS: One hundred twenty-eight patients with 142 brain AVMs treated with SRS were included. Mean age was 34.4 years. Fifty-two percent of AVMs were associated with a hemorrhage before SRS, and 14.8% were previously embolized. Mean clinical and angiographic follow-up times were 67.8 months and 58.6 months, respectively. The median Spetzler-Martin grade was 3. Mean maximal AVM diameter was 2.8 cm and mean AVM target volume was 7.4 cm3 with a median radiation dose of 16 Gy. Complete AVM obliteration was achieved in 80.3%. Radiation-related signs and symptoms were encountered in 32.4%, only 4.9% of which consisted of a permanent deficit. Post-SRS AVM-related hemorrhage occurred in 6.3% of cases. In multivariate analysis, factors associated with AVM obliteration included younger patient age (P = .019), male gender (P = .008), smaller AVM diameter (P = .04), smaller AVM target volume (P = .009), smaller isodose surface volume (P = .005), a higher delivered radiation dose (P = .013), and having only one major draining vein (P = .04). CONCLUSIONS: AVM obliteration with LINAC-based radiosurgery was safe and effective and achieved complete AVM obliteration in about 80% of cases. The most prominent predictors of AVM success included AVM size, AVM volume, radiation dose, number of draining veins and patient age.

Introduction: Endovascular Neurosurgery.

Remarkable developments in the field of endovascular neurosurgery have been witnessed in the last decade. The success of endovascular therapy for ischemic stroke treatment is now irrefutable, making it an accepted standard of care. Endovascular treatment of cerebral aneurysms is no longer limited to primary coiling but now includes options such as stent or balloon assistance and flow diversion and applications utilizing neck reconstruction, intrasaccular, and bifurcation-specific devices. Balloons, liquid embolic agents, and flow-directed catheters have revolutionized the treatment of arteriovenous malformations and fistulae. The ongoing development of endovascular tools has led to novel and expanding approaches (for example, transvenous arteriovenous malformation embolization and transradial access). With improved technology, transposterior communicating artery access and other endovascular strategies are being applied successfully across the anterior and posterior circulations and to lesions once deemed only surgically approachable. Yet, we would be remiss to attribute the successes of endovascular strategies only to the development of their tools. Improvements in both noninvasive and angiographic imaging (such as three-dimensional road map guidance) have provided a greater understanding of pathologic entities and allowed the pursuit of endovascular cures.In this issue of Neurosurgical Focus, we present a wide range of endovascular strategies for a variety of neurovascular pathologies. We hope this video supplement will not only demonstrate the applicability of tried-and-true endovascular strategies to difficult clinical situations but also highlight new and developing endovascular technologies. We thank the authors for their outstanding contributions.

Penetrating Head Injury by a Nail Gun: Case Report, Review of the Literature, and Management Considerations.

Our objective is to discuss penetrating head injuries (PHIs) which, although rare, lead to considerable morbidity and mortality. One of the most significant culprits of PHI is the nail gun, which was introduced in 1959 and has gained substantial popularity. We describe our successful strategy for removing an 8-cm nail that penetrated through the orbit and middle cranial fossa, with the tip lodged within the posterior fossa. Vascular imaging and balloon test occlusion are imperative in circumstances where vessel sacrifice is necessary. In addition, positioning of balloons within large vessels that are in close proximity to the penetrating object is necessary to control bleeding that may occur during removal of the object. It is of paramount importance to have a multidisciplinary team participating in the management and eventual removal of foreign objects within the intracranial compartment. Included is a review of the literature and a discussion on management approaches to such injuries.

Intraventricular Injection of Noncellular Cerebrospinal Fluid from Subarachnoid Hemorrhage Patient into Rat Ventricles Leads to Ventricular Enlargement and Periventricular Injury.

Early brain injury and hydrocephalus (HCP) are important mediators of poor outcome in subarachnoid hemorrhage (SAH) patients. We aim to understand the development of HCP and subependymal cellular injury after intraventricular injection of noncellular human SAH cerebrospinal fluid (CSF) into rat ventricles. Two-hundred microliters of noncellular CSF from SAH patients or normal controls were injected into the right lateral ventricle of seven adult male Sprague-Dawley rats. Propidium iodide (PI) was simultaneously injected to detect necrotic cellular death. Rats were then sacrificed 24 h after surgery and the brain specimens were cut and stained for heme oxygenase 1 (HO-1), an oxidative stress marker. We found that the ventricular area at the bregma level in the CSF injection group was significantly larger than that in the control group (p < 0.05). The periventricular tissue in the CSF injection group had significantly more necrotic cell death as well as HO-1 expression as compared with the control group (p < 0.05). In conclusion, injection of SAH patients' CSF into the rat ventricle leads to HCP as well as subependymal injury compared with injection of control CSF.

Aspirin and Clopidogrel Inhibit Aneurysm Healing after HydroCoil Implantation in External Carotid Artery Aneurysm Model.

PURPOSE: To understand whether the use of antiplatelet agents leads to less intra-aneurismal tissue formation following coil implantation in a rat end-pouch external carotid artery (ECA) aneurysm model. METHODS: End-pouch ECA aneurysms were created in adult rats and were then embedded with either platinum or HydroCoils. Rats were treated either with aspirin, clopidogrel, aspirin + clopidogrel, or saline for 2 weeks after coil implantation. At 2 weeks after coil implantation, rats were sacrificed and the aneurysm pouch was removed for histological and immunohistochemical analysis. A blinded single observer calculated the percentage of the organized area and the residual length of elastic lamina within the aneurysm. Student's t-test was used to compare data from image analysis between the different groups. RESULTS: Within the platinum group, the organized tissue area was not affected by antiplatelet administration (aspirin versus saline, P = .83; clopidogrel versus saline, P = .46; aspirin + clopidogrel versus saline, P = .54). For the HydroCoil group, the organized tissue area was significantly reduced (aspirin versus saline, P = .02; clopidogrel versus saline, P = .04; aspirin + clopidogrel versus saline, P = .02) in rats treated with antiplatelet agents; however, no difference (aspirin versus clopidogrel, P = .8; aspirin versus aspirin + clopidogrel, P = .3; clopidogrel versus aspirin + clopidogrel, P = .5) was found among type or combination of antiplatelets administered. HydroCoil-treated aneurysms had a similar number of macrophages compared to the platinum group (P = .3819); however, the HydroCoil group had significant suppression of macrophages in the groups treated with combined antiplatelets (P = .02). CONCLUSION: Following HydroCoil implantation, the area of organized tissue is diminished significantly in a rat end-pouch ECA aneurysm model treated with antiplatelets.

Intra-arterial Stroke Treatment prior to the Stent-Retriever Era: High Mortality and Lack of Volume-Outcome Association.

BACKGROUND: Mechanical thrombectomy for acute large-vessel occlusive stroke is beneficial when performed with stent-retriever devices; however, little is known about real-world experience with intra-arterial treatment (IAT). We aimed to clarify how hospitals influence outcomes for Medicare thrombectomy patients to inform future delivery of effective mechanical thrombectomy treatment. METHODS: This is a retrospective cohort study that includes a Medicare fee-for-service patient population. Patients with a primary stroke discharge (ICD-9-CM 433.x1, 434.x1, 436) were included; billing codes were used to identify patients receiving IAT, intravenous thrombolytics (IVT), or a combination of these treatments. Characteristics of treated patients were summarized using descriptive statistics; long-term mortality was summarized via Kaplan-Meier curves; and multilevel logistic regression models with random hospital-level intercept were built to determine hospital influence on outcome and whether a volume-outcome association existed. RESULTS: A total of 4557 patients received IAT at 544 hospitals. The mean age of IAT patients was 76 years. IAT patients had longer hospital stay (9.7 versus 6.8 days), longer stay in the ICU (5.5 versus 3.3 days), and greater probability of intubation (36.7% versus 9.5%) compared with IVT patients. Ninety-day mortality was 46% IAT versus 26% IVT. Hospitals had little influence on outcomes (intraclass correlation coefficient, <.01). No association between procedural volume and outcomes was identified. CONCLUSIONS: IAT for 2007-2010 was associated with higher patient mortality than recent and prior clinical trials. Treated Medicare patients were considerably older than clinical trial populations. Hospitals had little influence on mortality, and increased hospital volume was not associated with lower mortality. Future real-world experience should monitor these parameters as use of stent retrievers disseminates.

Guidelines for the Management of Patients With Unruptured Intracranial Aneurysms: A Guideline for Healthcare Professionals From the American Heart Association/American Stroke Association.

PURPOSE: The aim of this updated statement is to provide comprehensive and evidence-based recommendations for management of patients with unruptured intracranial aneurysms. METHODS: Writing group members used systematic literature reviews from January 1977 up to June 2014. They also reviewed contemporary published evidence-based guidelines, personal files, and published expert opinion to summarize existing evidence, indicate gaps in current knowledge, and when appropriate, formulated recommendations using standard American Heart Association criteria. The guideline underwent extensive peer review, including review by the Stroke Council Leadership and Stroke Scientific Statement Oversight Committees, before consideration and approval by the American Heart Association Science Advisory and Coordinating Committee. RESULTS: Evidence-based guidelines are presented for the care of patients presenting with unruptured intracranial aneurysms. The guidelines address presentation, natural history, epidemiology, risk factors, screening, diagnosis, imaging and outcomes from surgical and endovascular treatment.

Management of pediatric craniocervical arterial dissections.

PURPOSE: Craniocervical arterial dissections (CCADs) represent a preventable cause of acute ischemic stroke (AIS). Our objective was to describe clinical presentation, imaging features, treatment strategies, and report clinical and imaging outcomes of CCADs at a large pediatric tertiary referral center. METHODS: Electronic medical records were queried using variations of the word dissection for patients under 25 years of age with neuroimaging over a 13-year period. Medical and imaging records were reviewed to identify carotid, vertebral, or intracranial dissections. Demographics, presenting symptoms, presence of AIS, mechanism of injury, dissection location, dissection treatment, and complications stemming from treatment were collected. Clinical outcome was classified according to modified Rankin Scale (mRS) score. Imaging follow-up was obtained until the dissection healed or stabilized. RESULTS: A total 6,289 patients met initial search criteria. Of the 42 (0.7%) patients with CCADs, 23 (54.8%) had internal carotid artery (ICA) dissections, and 17 (40.5%) had vertebrobasilar (VB) dissections. More females had ICA dissections (p = 0.002), and more males had VB dissections (p = 0.01). CCADs associated with traumatic presentation occurred in 34 patients (81.0%), while 8 (19.0%) were spontaneous. Good outcomes (mRS 0-3) were noted for 36 patients, and 5 had poor outcomes (mRS 4-6). In the 17 patients with vessel occlusion, 50.0% had partial or complete recanalization at a mean follow-up of 23.9 months. CONCLUSIONS: CCAD is commonly related to trauma and presents with AIS. The majority of patients experience good clinical outcome. Recanalization of initial vessel occlusion occurs in half of cases at 2 years.

The Association Between Spontaneous Hyperventilation, Delayed Cerebral Ischemia, and Poor Neurological Outcome in Patients with Subarachnoid Hemorrhage.

BACKGROUND: The frequency and associations of spontaneous hyperventilation in subarachnoid hemorrhage (SAH) are unknown. Because hyperventilation decreases cerebral blood flow, it may exacerbate delayed cerebral ischemia (DCI) and worsen neurological outcome. METHODS: This is a retrospective analysis of data from a prospectively collected cohort of SAH patients at an academic medical center. Spontaneous hyperventilation was defined by PaCO2 <35 mmHg and pH >7.45 and subdivided into moderate and severe groups. Clinical and demographic characteristics of patients with and without spontaneous hyperventilation were compared using χ (2) or t tests. Bivariate and multivariable logistic regression analyses were conducted to examine the association of moderate and severe hyperventilation with DCI and discharge neurological outcome. RESULTS: Of 207 patients, 113 (55 %) had spontaneous hyperventilation. Spontaneously hyperventilating patients had greater illness severity as measured by the Hunt-Hess, World Federation of Neurosurgical Societies (WFNS), and SAH sum scores. They were also more likely to develop the following complications: pneumonia, neurogenic myocardial injury, systemic inflammatory response syndrome (SIRS), radiographic vasospasm, DCI, and poor neurological outcome. In a multivariable logistic regression model including age, gender, WFNS, SAH sum score, pneumonia, neurogenic myocardial injury, etiology, and SIRS, only moderate [odds ratio (OR) 2.49, 95 % confidence interval (CI) 1.10-5.62] and severe (OR 3.12, 95 % CI 1.30-7.49) spontaneous hyperventilation were associated with DCI. Severe spontaneous hyperventilation (OR 4.52, 95 % CI 1.37-14.89) was also significantly associated with poor discharge outcome in multivariable logistic regression analysis. CONCLUSION: Spontaneous hyperventilation is common in SAH and is associated with DCI and poor neurological outcome.

Transfer time to a high-volume center for patients with subarachnoid hemorrhage does not affect outcomes.

OBJECTIVES: The objective of our study was to examine patients with aneurysmal subarachnoid hemorrhage transferred and directly admitted to our institution in order to determine how transfer time affects outcomes. METHODS: A retrospective cohort study was performed of all patients undergoing treatment for aneurysmal subarachnoid hemorrhage between 2005 and 2012 at the University of Michigan. Variables, including transfer time, were tested for their independent association with the primary outcomes of symptomatic vasospasm and 12-month outcome as well as secondary outcomes of aneurysm rebleeding and 12-month mortality. RESULTS: During the study period, 263 (87.4%) patients were transferred to our institution and 38 (12.6%) were directly admitted for treatment of aneurysmal subarachnoid hemorrhage. Transfer time was not associated with the occurrence of symptomatic vasospasm, 12-month outcome, rebleeding, or 12-month mortality. Higher Hunt-Hess grade was associated with the occurrence of symptomatic vasospasm as well as with poorer 12-month outcome. CONCLUSIONS: Transfer time was not associated with the occurrence of symptomatic vasospasm, 12-month outcome, rebleeding, or 12-month mortality. We believe our data argue that protocols should emphasize early resuscitation and stabilization followed by safe transfer rather than a hyperacute transfer paradigm. However, transfer time should be minimized as much as possible so as not to delay time to definitive treatment.

Dual antiplatelet therapy plus postoperative heparin and dextran is safe and effective for reducing risk of embolic stroke during aneurysm coiling.

BACKGROUND: Thromboembolic events represent a clinically significant cause of neurological morbidity during the endovascular management of cerebral aneurysms. We have implemented an anti-thromboembolic regimen consisting of pre- and postoperative dual antiplatelet therapy, as well as postoperative anticoagulation using heparin and dextran. The aims of our study were to examine the effect of this regimen on thromboembolic rates during elective aneurysm coiling, and to elucidate risk factors associated with the development of thromboembolic events in this setting. METHODS: We conducted a retrospective review of patients who underwent elective intracranial aneurysm coiling between January 2005 and February 2012. The primary outcome of interest was the occurrence of a clinically significant peri-procedural thromboembolic event. Secondary outcomes included the occurrence of a central nervous system (CNS) or systemic hemorrhage. RESULTS: During the study period, 312 patients underwent elective aneurysm coiling and six (2 %) thromboembolic events occurred; three (1 %) occurred in the group that received the anti-thromboembolic regimen (261 patients) and three (6 %) occurred in the group that did not receive the regimen (51 patients), resulting in a statistically significant difference (P = 0.024). Both the presence of a hypercoagulable state (P = 0.014) and the lack of the anti-thromboembolic regimen (P = 0.043) were significantly associated with the occurrence of a thromboembolic event. CONCLUSIONS: This study provides evidence that the regimen described here is safe and reduces thromboembolic complications during elective aneurysm coiling. Ours is likely the most aggressive regimen in the published literature and significantly reduced the rate of thromboembolism without any significant increase hemorrhagic complications.

Neuroendovascular Procedures in Patients with Ehlers-Danlos Type IV: Multicenter Case Series and Systematic Review.

BACKGROUND: Ehlers-Danlos type IV or vascular Ehlers-Danlos syndrome (vEDS) is a rare inherited disorder characterized by profound vascular fragility resulting from defective production of type III procollagen. Cerebrovascular diseases including spontaneous dissections, cerebral aneurysms, and cavernous carotid fistulae are common. Endovascular therapies in this patient population are known to be higher risk, although many studies (before 2000) involved older techniques and equipment. The purpose of this study is to investigate the safety and efficacy of modern neuroendovascular techniques in the treatment of cerebrovascular diseases in patients with vEDS. METHODS: We combined a multi-institutional retrospective case series at 3 quaternary-care centers with a systematic literature review of individual case reports and case series spanning 2000-2021 to evaluate the safety and efficacy of neuroendovascular procedure in patients with vEDS with cerebrovascular diseases. RESULTS: Fifty-nine patients who underwent 66 neuroendovascular procedures were evaluated. Most of the patients had direct cavernous carotid fistulas (DCCF). Neuroendovascular procedures had a 94% success rate, with a complication rate of 30% and a mortality of 7.5%. CONCLUSIONS: Neuroendovascular procedures can be performed with a high rate of success in the treatment of cerebrovascular diseases in patients with vEDS, although special care is required because complication rates and mortality are high. Access site and procedure-related vascular injuries remain a significant hurdle in treating vEDS with cerebrovascular diseases, even with modern techniques.

Guidelines for the management of aneurysmal subarachnoid hemorrhage: a guideline for healthcare professionals from the American Heart Association/american Stroke Association.

PURPOSE: The aim of this guideline is to present current and comprehensive recommendations for the diagnosis and treatment of aneurysmal subarachnoid hemorrhage (aSAH). METHODS: A formal literature search of MEDLINE (November 1, 2006, through May 1, 2010) was performed. Data were synthesized with the use of evidence tables. Writing group members met by teleconference to discuss data-derived recommendations. The American Heart Association Stroke Council's Levels of Evidence grading algorithm was used to grade each recommendation. The guideline draft was reviewed by 7 expert peer reviewers and by the members of the Stroke Council Leadership and Manuscript Oversight Committees. It is intended that this guideline be fully updated every 3 years. RESULTS: Evidence-based guidelines are presented for the care of patients presenting with aSAH. The focus of the guideline was subdivided into incidence, risk factors, prevention, natural history and outcome, diagnosis, prevention of rebleeding, surgical and endovascular repair of ruptured aneurysms, systems of care, anesthetic management during repair, management of vasospasm and delayed cerebral ischemia, management of hydrocephalus, management of seizures, and management of medical complications. CONCLUSIONS: aSAH is a serious medical condition in which outcome can be dramatically impacted by early, aggressive, expert care. The guidelines offer a framework for goal-directed treatment of the patient with aSAH.

Patterns in neurosurgical adverse events: endovascular neurosurgery.

As part of a project to devise evidence-based safety interventions for specialty surgery, the authors sought to review current evidence in endovascular neurosurgery concerning the frequency of adverse events in practice, their patterns, and current methods of reducing the occurrence of these events. This review represents part of a series of papers written to consolidate information about these events and preventive measures as part of an ongoing effort to ascertain the utility of devising system-wide policies and safety tools to improve neurosurgical practice. Based on a review of the literature, thromboembolic events appeared to be the most common adverse events in endovascular neurosurgery, with a reported incidence ranging from 2% to 61% depending on aneurysm rupture status and mode of detection of the event. Intraprocedural and periprocedural prevention and rescue regimens are advocated to minimize this risk; however, evidence on the optimal use of anticoagulant and antithrombotic agents is limited. Furthermore, it is unknown what proportion of eligible patients receive any prophylactic treatment. Groin-site hematoma is the most common access-related complication. Data from the cardiac literature indicate an overall incidence of 9% to 32%, but data specific to neuroendovascular therapy are scant. Manual compression, compression adjuncts, and closure devices are used with varying rates of success, but no standardized protocols have been tested on a broad scale. Contrast-induced nephropathy is one of the more common causes of hospital-acquired renal insufficiency, with an incidence of 30% in high-risk patients after contrast administration. Evidence from medical fields supports the use of various preventive strategies. Intraprocedural vessel rupture is infrequent, with the reported incidence ranging from 1% to 9%, but it is potentially devastating. Improvements in device technology combined with proper endovascular technique play an important role in reducing this risk. Occasionally, anatomical or technical difficulties preclude treatment of the lesion of interest. Reports of such occurrences are scant, but existing series suggest an incidence of 4% to 6%. Management strategies for radiation-induced effects are also discussed. The incidence rates are unknown, but protective techniques have been demonstrated. Many of these complications have strategies that appear effective in reducing their risk of occurrence, but development and evaluation of systematic guidelines and protocols have been widely lacking. Furthermore, there has been little monitoring of levels of adherence to potentially effective practices. Protocols and monitoring programs to support integrated implementation may be broadly effective.

Patterns in neurosurgical adverse events: open cerebrovascular neurosurgery.

OBJECT: As part of a project to devise evidence-based safety interventions for specialty surgery, we sought to review current evidence concerning the frequency of adverse events in open cerebrovascular neurosurgery and the state of knowledge regarding methods for their reduction. This review represents part of a series of papers written to consolidate information about these events and preventive measures as part of an ongoing effort to ascertain the utility of devising system-wide policies and safety tools to improve neurosurgical practice. METHODS: The authors performed a PubMed search using search terms "cerebral aneurysm", "cerebral arteriovenous malformation", "intracerebral hemorrhage", "intracranial hemorrhage", "subarachnoid hemorrhage", and "complications" or "adverse events." Only papers that specifically discussed the relevant complication rates were included. Papers were chosen to be included to maximize the range of rates of occurrence for the reported adverse events. RESULTS: The review revealed hemorrhage-related hyperglycemia (incidence rates ranging from 27% to 71%) and cerebral salt-wasting syndromes (34%-57%) to be the most common perioperative adverse events related to subarachnoid hemorrhage (SAH). Next in terms of frequency was new cerebral infarction associated with SAH, with a rate estimated at 40%. Many techniques are advocated for use during surgery to minimize risk of this development, including intraoperative neurophysiological monitoring, but are not universally used due to surgeon preference and variable availability of appropriate staffing and equipment. The comparative effectiveness of using or omitting monitoring technologies has not been evaluated. The incidence of perioperative seizure related to vascular neurosurgery is unknown, but reported seizure rates from observational studies range from 4% to 42%. There are no standard guidelines for the use of seizure prophylaxis in these patients, and there remains a need for prospective studies to support such guidelines. Intraoperative rupture occurs at a rate of 7% to 35% and depends on aneurysm location and morphology, history of rupture, surgical technique, and surgeon experience. Preventive strategies include temporary vascular clipping. Technical adverse events directly involving application of the aneurysm clip include incomplete aneurysm obliteration and parent vessel occlusion. The rates of these events range from 5% to 18% for incomplete obliteration and 3% to 12% for major vessel occlusion. Intraoperative angiography is widely used to confirm clip placement; adjuncts include indocyanine green video angiography and microvascular Doppler ultrasonography. Use of these technologies varies by institution. DISCUSSION: A significant proportion of these complications may be avoidable through development and testing of standardized protocols to incorporate monitoring technologies and specific technical practices, teamwork and communication, and concentrated volume and specialization. Collaborative monitoring and evaluation of such protocols are likely necessary for the advancement of open cerebrovascular neurosurgical quality.

Unifying theory of carotid plaque disruption based on structural phenotypes and forces expressed at the lumen/wall interface.

OBJECTIVES: To integrate morphological, haemodynamic and mechanical analysis of carotid atheroma driving plaque disruption. MATERIALS AND METHODS: First, we analysed the phenotypes of carotid endarterectomy specimens in a photographic dataset A, and matched them with the likelihood of preoperative stroke. Second, laser angioscopy was used to further define the phenotypes in intact specimens (dataset B) and benchmark with histology. Third, representative vascular geometries for each structural phenotype were analysed with Computational Fluid Dynamics (CFD), and the mechanical strength of the complicated atheroma to resist penetrating forces was quantified (n=14). RESULTS: In dataset A (n=345), ulceration (fibrous cap disruption) was observed in 82% of all plaques, intraplaque haemorrhage in 68% (93% subjacent to an ulcer) and false luminal formation in 48%. At least one of these 'rupture' phenotypes was found in 97% of symptomatic patients (n=69) compared with 61% in asymptomatic patients. In dataset B (n=30), laser angioscopy redemonstrated the structural phenotypes with near-perfect agreement with histology. In CFD, haemodynamic stress showed a large pulse magnitude, highest upstream to the point of maximal stenosis and on ulceration the inflow stream excavates the necrotic core cranially and then recirculates into the true lumen. Based on mechanical testing (n=14), the necrotic core is mechanically weak and penetrated by the blood on fibrous cap disruption. CONCLUSIONS: Fibrous cap ulceration, plaque haemorrhage and excavation are sequential phenotypes of plaque disruption resulting from the chiselling effect of haemodynamic forces over unmatched mechanical tissue strength. This chain of events may result in thromboembolic events independently of the degree of stenosis.

Rapid Automated Analysis of Skull Base Tumor Specimens Using Intraoperative Optical Imaging and Artificial Intelligence.

BACKGROUND: Accurate specimen analysis of skull base tumors is essential for providing personalized surgical treatment strategies. Intraoperative specimen interpretation can be challenging because of the wide range of skull base pathologies and lack of intraoperative pathology resources. OBJECTIVE: To develop an independent and parallel intraoperative workflow that can provide rapid and accurate skull base tumor specimen analysis using label-free optical imaging and artificial intelligence. METHODS: We used a fiber laser-based, label-free, nonconsumptive, high-resolution microscopy method (<60 seconds per 1 × 1 mm2), called stimulated Raman histology (SRH), to image a consecutive, multicenter cohort of patients with skull base tumor. SRH images were then used to train a convolutional neural network model using 3 representation learning strategies: cross-entropy, self-supervised contrastive learning, and supervised contrastive learning. Our trained convolutional neural network models were tested on a held-out, multicenter SRH data set. RESULTS: SRH was able to image the diagnostic features of both benign and malignant skull base tumors. Of the 3 representation learning strategies, supervised contrastive learning most effectively learned the distinctive and diagnostic SRH image features for each of the skull base tumor types. In our multicenter testing set, cross-entropy achieved an overall diagnostic accuracy of 91.5%, self-supervised contrastive learning 83.9%, and supervised contrastive learning 96.6%. Our trained model was able to segment tumor-normal margins and detect regions of microscopic tumor infiltration in meningioma SRH images. CONCLUSION: SRH with trained artificial intelligence models can provide rapid and accurate intraoperative analysis of skull base tumor specimens to inform surgical decision-making.

The effect of age on arteriovenous malformations in children and young adults undergoing magnetic resonance imaging.

OBJECTIVE: Arteriovenous malformations (AVMs) are the most frequently encountered structural cause of spontaneous intracerebral hemorrhage in childhood, excluding hemorrhages of prematurity. The goal of our study was to examine the relationship between age and AVM prevalence on imaging in children, which to date has not been well described. METHODS: We queried the electronic and radiographic records of 14,936 consecutive patients aged 25 years or less who had undergone brain magnetic resonance imaging (MRI) at a single institution over an 11-year period to identify those with a cerebral AVM. We collected age, gender, and other demographic characteristics for all patients. For all patients with a cerebral AVM, we recorded the location, size, drainage pattern, Spetzler-Martin grade, medical history, and presence of neurological symptoms. RESULTS: Cerebral AVMs were identified in 55 patients (0.37%). The prevalence of AVMs detected on MRI significantly increased with age (p = 0.001). AVMs were found in 0.34% of boys (25 of 7,447) and 0.40% of girls (30 of 7,489). AVMs were most commonly identified in the frontal lobes (36%), followed by parietal (20%) and temporal lobes (13%). Sixty percent (n = 33) of AVMs were less than 3 cm in size, 35% (n = 19) were 3-6 cm in size, and 5.5% (n = 3) were greater than 6 cm in size. As for Spetzler-Martin grade of the AVMs, 25.5% were grade I, 18.2% were grade II, 36.4% were grade III, 16.4% were grade IV, and 3.6% were grade V. CONCLUSIONS: AVMs are seen more frequently on MRI with advancing age in children and young adults.