Microsurgical anatomy of the early branches of the middle cerebral artery: morphometric analysis and classification with angiographic correlation

Three-Dimensional Morphometric Analysis of Anterior Cerebral Circulation Aneurysms

This article assesses the association between anterior circulation morphometry and the presence of intracranial aneurysm using three-dimensional rotational angiography (3DRA). A retrospective analysis at a Peruvian academic medical center between December 2018 and February 2020 identified 206 patients with unruptured intracranial aneurysms and matched controls who underwent 3DRA. Angiographic images were obtained per standard of care, and measurements of the vasculature were performed using 3DRA vascular automated software. A total of 163 aneurysms and 43 control angiograms were evaluated. Women represented 82.5% of the cases and the mean age was 55.9 years (standard deviation ± 14.2). In multivariate analysis, five specific features were found to be statistically significant predictors for presence of an anterior circulation aneurysm: female sex (odds ratio [OR] = 2.71; p  = 0.048), C-shape of the middle cerebral artery (MCA) (OR = 2.73; p  = 0.018), distal internal carotid artery (ICA) diameter (OR = 3.42; p  = 0.012), ICA bifurcation angle (OR = 1.02; p  = 0.036), and length of the carotid siphon (OR = 1.08; p  = 0.047). Features detected on 3DRA suggest morphological characteristics of the ICA and MCA may be predictive for intracranial aneurysm. Our findings build from prior reports by demonstrating five specific patient and imaging features associated with anterior circulation aneurysms. While 3DRA is the standard of care in many settings, medical centers with resource limitations may not have access to this technique. The demographic and morphological features identified in our study may have correlates that if detected on contrast computed tomography or magnetic resonance imaging studies, may be used to help screen for a higher level of care in select patients.

Endovascular treatment of middle cerebral artery aneurysms: current status and future prospects

Middle cerebral artery (MCA) aneurysms are complex and widely distributed throughout the course of the MCA. Various types of aneurysms can occur in the MCA. Ruptured as well as unruptured MCA aneurysms may require treatment to avoid bleeding or rebleeding. Currently, clipping is regarded as the first-line choice for the treatment of MCA aneurysms. However, endovascular treatment (EVT) is emerging as an alternative treatment in selected cases. EVT techniques vary. Therefore, it is necessary to review EVT for MCA aneurysms. In this review, the following issues were discussed: MCA anatomy and anomalies, classifications of MCA aneurysms, the natural history of MCA aneurysms, EVT status and principle, deployments of traditional coiling techniques and flow diverters (FDs), and deployments and prospects of intrasaccular flow disruptors and stent-like devices. According to the review and our experience, traditional coiling EVT is still the preferred therapy for most MCA aneurysms. FD deployment can be used in selective MCA aneurysms. Parent artery occlusion (PAO) can be used to treat distal MCA aneurysms. In addition, new devices can be used to treat MCA aneurysms, such as intrasaccular flow disruptors and stent-like devices. In general, EVT is gaining popularity as an alternative treatment option; however, there is still a lack of evidence regarding EVT, and longer-term data are not currently available for most EVT devices.

Using deep learning for an automatic detection and classification of the vascular bifurcations along the Circle of Willis

Most of the intracranial aneurysms (ICA) occur on a specific portion of the cerebral vascular tree named the Circle of Willis (CoW). More particularly, they mainly arise onto fifteen of the major arterial bifurcations constituting this circular structure. Hence, for an efficient and timely diagnosis it is critical to develop some methods being able to accurately recognize each Bifurcation of Interest (BoI). Indeed, an automatic extraction of the bifurcations presenting the higher risk of developing an ICA would offer the neuroradiologists a quick glance at the most alarming areas. Due to the recent efforts on Artificial Intelligence, Deep Learning turned out to be the best performing technology for many pattern recognition tasks. Moreover, various methods have been particularly designed for medical image analysis purposes. This study intends to assist the neuroradiologists to promptly locate any bifurcation presenting a high risk of ICA occurrence. It can be seen as a Computer Aided Diagnosis scheme, where the Artificial Intelligence facilitates the access to the regions of interest within the MRI. In this work, we propose a method for a fully automatic detection and recognition of the bifurcations of interest forming the Circle of Willis. Several neural networks architectures have been tested, and we thoroughly evaluate the bifurcation recognition rate.

Distal stenting technique for coil embolization of early branch aneurysms of middle cerebral artery

BACKGROUND AND PURPOSE

Stent-assisted coil embolization of early branch aneurysms of the middle cerebral artery (MCA) can sometimes be challenging due to the small diameter and acute angle of the branches. This study aimed to analyze the treatment results and report the feasibility and outcomes of the distal stenting technique for these aneurysms.

MATERIALS AND METHODS

The distal stenting technique was used for 15 wide-neck MCA aneurysms (females, 10; males, 5; mean age, 65.1 years) originating from the early branch between December 2018 and October 2021. The average sizes of the dome, depth, and neck of the aneurysms were 4.17 mm (range: 2.99-6.21 mm), 2.86 mm (range: 1.82-3.72 mm), and 3.42 mm (range: 2.44-4.32 mm), respectively.

RESULTS

The average diameter of the stents was 4.0 mm (3.0 mm, 3; 4.0 mm, 6; 4.5 mm, 6). Stents were successfully deployed in all 15 aneurysms (100%). The average length of the procedure was 69 min (range: 45-117 min). On postoperative angiography, nine (60.0%) aneurysms were completely occluded, four (26.7%) had neck remnants, and two (13.3%) had contrast flow in the sac. During the procedure, vasospasm and thrombus formation occurred in one case each, but no neurological sequelae were observed. On follow-up digital subtraction angiography of the 10 aneurysms after an average of 13.7 months (range: 12-18 months), the branches were well preserved, and neck remnants were noted in four aneurysms (40.0%). No thromboembolic events occurred during the clinical follow-up.

CONCLUSION

The distal stenting technique using an open-cell stent can be a good option for coil embolization of early branch MCA aneurysms.

Bioglue endovascular treatment of fusiform aneurysm rupture of the distal anterior temporal artery of the middle cerebral artery: a case report

The treatment of a ruptured fusiform distal anterior temporal artery aneurysm is a challenge for the stroke physician, however surgical closure and coil endovascular intervention are options. A total blockage can result in memory problems as well as object-related questions. We'd like to provide the clinical example of a 56-year-old woman with many underlying medical illnesses who was admitted to the hospital with a grade 7/10 headache and a Glasgow score of 15, but no focal neurological deficits, and was diagnosed with a ruptured distal temporal artery aneurysm. The aneurysm is positioned in the distal region, making endovascular intervention difficult to perform. As a result, we used an endovascular approach to repair with bioglue. When a patient develops fusiform aneurysms of the distal temporal artery, our findings provide an additional therapy option.

Sensitivity of three-dimensional time-of-flight 3.0 ​T magnetic resonance angiography in visualizing the number and course of lenticulostriate arteries in patients with insular gliomas

Background

Neurosurgical resection of insular gliomas is complicated by the possibility of iatrogenic injury to the lenticulostriate arteries (LSAs) and is associated with devastating neurological complications, hence the need to accurately assess the number of LSAs and their relationship to the tumor preoperatively.

Methods

The study included 24 patients with insular gliomas who underwent preoperative 3D-TOF MRA to visualize LSAs. The agreement of preoperative magnetic resonance imaging with intraoperative data in terms of the number of LSAs and their invasion by the tumor was assessed using the Kendall rank correlation coefficient and Cohen's Kappa with linear weighting. Agreement between experts performing image analysis was estimated using Cohen's Kappa with linear weighting.

Results

The number of LSAs arising from the M1 segment varied from 0 to 9 (mean 4.3 ​± ​0.37) as determined by 3D-TOF MRA and 2-6 (mean 4.25 ​± ​0.25) as determined intraoperatively, κ ​= ​0.51 (95% CI: 0.25-0.76) and τ ​= ​0.64 (p ​< ​0.001). LSAs were encased by the tumor in 11 patients (confirmed intraoperatively in 9 patients). LSAs were displaced medially in 8 patients (confirmed intraoperatively in 8 patients). The tumor partially involved the LSAs and displaced them in 5 patients (confirmed intraoperatively in 7 patients), κ ​= ​0.87 (95% CI: 0.70-1), τ ​= ​0.93 (p ​< ​0.001). 3D-TOF MRA demonstrated high sensitivity (100%, 95% CI: 0.63-1) and high specificity (86.67%, 95% CI: 0.58-0.98) in determining the LSA-tumor interface.

Conclusions

3D-TOF MRA at 3T demonstrated sensitivity in determining the LSA-tumor interface and the number of LSAs in patients with insular gliomas.

A review of the anatomy of the middle cerebral artery for the era of thrombectomy: A radiologic tool based on CT angiography and perfusion CT

The middle cerebral artery (MCA) is one of the principal intracranial vessels. It is also the one that is most often involved in ischemic cerebrovascular disease, which accounts for a significant volume of brain imaging tests. With recent updates in the management of ischemic stroke (including intravascular treatment in increasingly distal vessels and in an increasingly widening spectrum of patients), it is becoming more important to know the details of the cerebral vascular anatomy to reach accurate diagnoses quickly and thereby improve patients' prognoses. For these reasons, we present this anatomic review of the MCA, reviewing its segments and anatomic limits, its branching patterns, and its anatomic variants. We also provide a radiologic tool based on correlations between CT angiography and perfusion CT to facilitate the identification of the points of occlusion within the branches of the MCA, taking into account its different variants.

Artery diameter ratio after recanalization in endovascular therapy for acute ischemic stroke: a new predictor of clinical outcomes

PURPOSE

This study aimed to investigate the relationship between the artery diameter ratio (ADR) after recanalization and clinical outcomes.

METHODS

Patients with middle cerebral artery occlusion confirmed by DSA from 1 January 2018, to 31 December 2019, were retrospectively analyzed. All patients confirmed TICI grade 2b or 3. The ADR was calculated as M2 segment diameter/M1 segment diameter. Multivariate regression analysis was used to describe clinical outcomes of two groups (ADR < 0.6 and ≥ 0.6). ROC curves were used to compare different models and find the best cutoff.

RESULTS

A total of 143 patients were included in the study, including 77 males and 66 females, with an average age of 67.79 ± 12 years. The NIHSS at discharge was significantly higher in the ADR < 0.6 group than another group (mean, 16.37 vs. 6.19, P < 0.001). At 90 days, the cases of functional independence was significantly less in the ADR < 0.6 group (20.97% vs. 83.95%, OR 0.05, 95% CI 0.02-0.12, P < 0.001). The ADR < 0.6 group had a higher incidence of cerebral edema (P = 0.027) and sICH (P = 0.038). The ADR had the strongest power to distinguish mRS > 2 (AUC = 0.851) and DC (AUC = 0.805), and the best cutoff value are 0.6 (specificity 85.19%, sensitivity 75.81%) and 0.58 (specificity 65.96%, sensitivity 100%), respectively.

CONCLUSION

The low ADR is associated with poor outcomes. The decrease in ADR may be an indirect manifestation of the loss of cerebrovascular autoregulation.

A review of the anatomy of the middle cerebral artery for the era of thrombectomy: a radiologic tool based on CT angiography and perfusion CT

The middle cerebral artery (MCA) is one of the principal intracranial vessels. It is also the one that is most often involved in ischemic cerebrovascular disease, which accounts for a significant volume of brain imaging tests. With recent updates in the management of ischemic stroke (including intravascular treatment in increasingly distal vessels and in an increasingly widening spectrum of patients), it is becoming more important to know the details of the cerebral vascular anatomy to reach accurate diagnoses quickly and thereby improve patients' prognoses. For these reasons, we present this anatomic review of the MCA, reviewing its segments and anatomic limits, its branching patterns, and its anatomic variants. We also provide a radiologic tool based on correlations between CT angiography and perfusion CT to facilitate the identification of the points of occlusion within the branches of the MCA, taking into account its different variants.

Constructing an Individualized Middle Cerebral Artery Model Using 3D Printing and Hydrogel for Bypass Training

The importance and complexity of cerebral bypass surgery (CBS) highlight the necessity for intense and dedicated training. Several available training models are yet to satisfy this need. In this technical note, we share the steps to construct a digital imaging and communications in medicine (DICOM)-based middle cerebral artery (MCA) model that is anatomically accurate, resembles handling properties of living tissue, and enables trainers to observe the cerebrovascular anatomy, improve and maintain microsurgical dexterity, and train in the essential steps of CBS. The internal and external molds were created from the geometry of DICOM-based MCA using Fusion 360 software (Autodesk, San Rafael, USA). They were then three-dimension (3D) printed using a polylactic acid filament. The 15% w/v solution of polyvinyl alcohol (PVA) was prepared and injected between the molds. Using five freeze-thaw cycles the solution was converted to tissue-mimicking cryo-gel. The model was then placed in a chloroform bath until the internal mold dissolved. To evaluate the accuracy of the MCA model, selected characteristics were measured and compared with the MCA mesh. The DICOM-based MCA model was produced using 3D printing that was available in the lab and the overall cost was less than $5 per model. The external mold required six and a half hours to be 3D printed, while the internal mold only required 23 minutes. Overall, the time required to 3D print the DICOM-based MCA model was just short of seven hours. The greatest statistically significant difference between the virtual MCA model and the DICOM-based MCA model was found in the length of the pre-bifurcation part of the M1 segment and the total length of the superior bifurcation trunk of M1 and superior branch of M2. The smallest statistically significant difference was found at the diameter of the inferior post-bifurcation trunk of the M1 segment and the diameter at the origin of the artery. This technical report aims to show the construction of a CBS training system involving the DICOM-based MCA model that demonstrates the shape of the vascular tree, resembles the handling/suturing properties of living tissue, and helps set up a homemade training station. We believe that our DICOM-based MCA model can serve as a valuable resource for CBS training throughout the world due to its cost-effectiveness and straightforward construction steps. Moreover, once the DICOM-based MCA model is used with our training station, it may offer an option for trainers to gain and maintain CBS skills despite limitations on time, cost, and space. This work was presented in February 2019 at the American Association of Neurological Surgeons/Congress of Neurological Surgeons (AANS/CNS) Cerebrovascular Section Annual Meeting held in Honolulu, Hawaii.

Variable Anatomy of the Middle Cerebral Artery from Its Origin to the Edge of the Sylvian Fissure: A Direct Fresh Brain Study

The middle cerebral artery (MCA) is a major artery supplying blood to the brain and a common site of surgically treatable intracranial aneurysms. The MCA has anatomic variations that may have clinical significance. In order to investigate and document the extent of such variations, the MCA in 100 fresh brain hemispheres from 50 deceased patients, obtained from the Police Surgeon Office, Yangon General Hospital, Myanmar, was dissected and examined. Double MCA was observed in 2% of specimens. The termination patterns were bifurcation (72%), trifurcation (16%), and primary trunk (12%); early bifurcation was also observed (3%). The mean length of the main trunk (MT) was 20.6 ± 6.2 mm. The number of perforators ranged from 4 to 15 (mean = 9); most arose from the MT (96%), and the others originated at the bifurcation point (3%) and in postbifurcation divisions (1%). All of the perforators (100%) had a single branching pattern. The number of cortical branches ranged from 6 to 13 and included the orbitofrontal (98%), prefrontal (99%), precentral (95%), central (98%), temporopolar (87%), anterior temporal (89%), middle temporal (24%), posterior temporal (62%), temporo-occipital (69%), anterior parietal (88%), angular (83%), and posterior parietal (57%) arteries. Early cortical branches emerged from the MT in 52% of specimens. These data can help anatomists, radiologists, and neurosurgeons in preoperative assessment, surgical planning, and selection of surgical approach.

Microsurgical Management of the Middle Cerebral Artery Bifurcation Aneurysms: An Anatomic Feasibility Study

BACKGROUND

The proper head positioning decreases the surgical complications by enabling a better surgical maneuverability. Middle cerebral artery (MCA) bifurcation aneurysms have been classified by Dashti et al. [Surg Neurol. 2007 May;67(5):441-56] as the intertruncal, inferior, lateral, insular, and complex types based on dome projection. Our aim was to identify the optimum head positions and to explain the anatomic variables, which may affect the surgical strategy of MCA bifurcation aneurysms.

METHODS

The lateral supraorbital approach bilaterally was performed in the 4 cadaveric heads. All steps of the dissection were recorded using digital camera.

RESULTS

The distal Sylvian fissure (SF) dissection may be preferred for insular type and the proximal SF dissection may be preferred for all other types. Fifteen degrees head rotation was found as the most suitable position for the intertruncal, lateral type and subtype of complex aneurysms related with superior trunk. Thirty degrees head rotation was found the most suitable position for the inferior type, insular type, and subtype of complex aneurysms related with inferior trunk.

CONCLUSIONS

The head positioning in middle cerebral bifurcation aneurysms surgery is a critical step. It should be tailored according to the projection and its relationship with the parent vessels of the middle cerebral bifurcation.

Temporal Artery and Temporal Region Supplied by the Middle Cerebral Artery: An Anatomical Study

ABSTRACT

This study was conducted to describe in detail the branching patterns of cortical branches from the middle cerebral artery supplying the feeding of the temporal region, to define the arterial structure of temporal artery (TA) and to determine the effect of this arterial supply to the temporal region. The arteries of brains (n = 22; 44 hemispheres) were prepared for dissection after filling them with colored latex. TA was defined, and its classification was described, specifying its relationship with other cortical branches. A new classification was defined related to TA terminology. TA was found in 95% of cadavers, and it originated as an early branch in 75% and from the inferior trunk in 24% of cadavers. TA was classified as Type 0: No TA, Type I: single branch providing two cortical branches, Type II: single branch providing three or more cortical branches and Type III: double TA. Type I-TA (45%) was the most common, and Type II-TA arterial diameter was significantly larger than that of other types. All cadavers showed the cortical branches of temporal region from middle cerebral artery, anterior TA , middle TA, posterior TA and temporooccipital artery, except temporopolar artery (81%). Temporopolar artery, anterior TA, and middle TA primarily originated from TA, an early branch, but posterior TA and temporooccipital artery primarily originated from the inferior trunk. Detailed knowledge about cortical branches together with TA and also this region's blood supply would enable increased prediction of complications, especially in cases with these region-related pathologies, and would make interventions safer.

Endoscopic transorbital approach to the insular region: cadaveric feasibility study and clinical application (SevEN-005)

OBJECTIVE

The insula is a complex anatomical structure. Accessing tumors in the insula remains a challenge due to its anatomical complexity and the high chance of morbidity. The goal of this study was to evaluate the feasibility of an endoscopic transorbital approach (ETOA) to the insular region based on a cadaveric study.

METHODS

One cadaveric head was used to study the anatomy of the insula and surrounding vessels. Then, anatomical dissection was performed in 4 human cadaveric heads using a dedicated endoscopic system with the aid of neuronavigation guidance. To assess the extent of resection, CT scanning was performed before and after dissection. The insular region was directly exposed by a classic transcranial approach to check the extent of resection from the side with a classic transcranial approach.

RESULTS

The entire procedure consisted of two phases: an extradural orbital phase and an intradural sylvian phase. After eyelid incision, the sphenoid bone and orbital roof were extensively drilled out with exposure of the frontal and temporal dural layers. After making a dural window, the anterior ramus of the sylvian fissure was opened and dissected. The M2 segment of the middle cerebral artery (MCA) was identified and traced posterolaterally. A small corticectomy was performed on the posterior orbital gyrus. Through the window between the lateral lenticulostriate arteries and M2, the cortex and medulla of the insula were resected in an anteroposterior direction without violation of the M2 segment of the MCA or its major branches. When confirmed by pterional craniotomy, the sylvian fissure and the MCA were found to be anatomically preserved. After validation of the feasibility and safety based on a cadaveric study, the ETOA was successfully performed in a patient with a high-grade glioma (WHO grade III) in the right insula.

CONCLUSIONS

The transorbital route can be considered a potential option to access tumors located in the insula. Using an ETOA, the MCA and its major branches were identified and preserved while removal was performed along the long axis of the insula. In particular, lesions in the anterior part of the insula are most benefited by this approach. Because this approach was implemented in only one patient, additional discussion and further verification is required.

Clinical features of ischemic complications after unruptured middle cerebral artery aneurysm clipping: patients and radiologically related factors

Postoperative ischemic complication results in neurological sequelae and longer hospitalization after unruptured middle cerebral artery (MCA) aneurysm clipping surgery. We evaluated the radiological and patient-related factors associated with ischemic complications after unruptured MCA aneurysm clipping surgery. Patient demographics, radiological findings, and intraoperative factors were compared between patients with and without postoperative ischemic complications. The clinical courses and outcomes of postoperative ischemic complications were compared according to the types of ischemic complication. Forty-two out of 2227 patients (1.9%) developed postoperative ischemic complications after MCA aneurysm clipping. Multivariate analysis revealed that diabetes mellitus (DM) was a patient-related factor. Intraarterial (IA) calcification of the distal internal carotid artery (ICA), preoperative M1 stenosis, and M1 aneurysm were radiological factors that increased the risk of postoperative ischemic complications. DM was significantly associated with divisional branch territory infarction (P = 0.04). The time to first presentation of ischemic complication was significantly longer in divisional branch territory infarction than perforator territory infarction (67.8 ± 75.9 h vs. 22 ± 20.7, P = 0.023). Twelve out of 42 patients with ischemic complications (28.6%) had unfavorable outcome (mRS > 3). Perforator territory infarction was significantly associated with an unfavorable outcome (mRS > 3, P = 0.019). IA calcification of the distal ICA, M1 stenosis and aneurysms, and DM were significantly associated with postoperative ischemic complications after unruptured MCA aneurysm clipping. Patients with DM should be closely monitored postoperatively to detect delayed occurrence of divisional branch infarction. Trial registration number: 2019-1002, Date of registration: January 1, 2005, "retrospectively registered".

The Angiographic Anatomy of the Sphenoidal Segment of the Middle Cerebral Artery and Its Relevance in Mechanical Thrombectomy

Objective

The middle cerebral artery (MCA) is the most commonly treated artery in mechanical thrombectomy stroke trials; however, there is no pragmatic agreement about the segmental anatomy and nomenclature utilized. It results in significant clinical-radiological dissociation and introduces bias in research trials. The purpose of the study is to review and compare angiographic anatomy with microsurgical anatomy literature of the MCA with emphasis on the discrepancy.

Methodology

Consecutive cerebral angiograms between January 2011 and March 2014 were retrospectively reviewed by endovascular surgical neuroradiologists. Information about the anatomy of the sphenoidal segment of the MCA classified as classic and non-classic pattern, the lenticulostriate artery takeoff pattern, and the course angulation of the sphenoidal segment were studied.

Results

A total of 500 patients, 886 cerebral angiograms, were reviewed. We found the classic pattern of the main trunk MCA bifurcation and a straight angulation course in less than half of the cases. The lenticulostriate arteries arose not only from the main trunk but also from its divisions in more than half of the cases.

Conclusion

It is important to corroborate our findings and to develop a pragmatic classification to accurately assess MCA occlusions from the radiological and clinical perspective.

Strategically acquired gradient echo (STAGE)-derived MR angiography might be a superior alternative method to time-of-flight MR angiography in visualization of leptomeningeal collaterals

OBJECTIVES

This study aimed to compare the performance of strategically acquired gradient echo (STAGE)-derived MR angiography and time-of-flight MR angiography (TOF-MRA) in visualization of leptomeningeal collaterals (LMCs).

METHODS

Between May 2018 and January 2020, 75 participants (47 healthy volunteers and 28 intracranial atherosclerotic disease [ICAD] patients) undergoing TOF-MRA and STAGE-MRA were prospectively included. Image quality was scored at the internal carotid artery (ICA) terminus, proximal middle cerebral artery (MCA), and LMCs. Quantitative analysis included calculation of contrast-to-noise ratios (CNRs) in the M1-4 segments and number of LMCs counted in the line signal intensity profiles. Comparisons of image qualitative scores, CNRs, and number of LMCs were calculated using the Wilcoxon rank-sum test.

RESULTS

Image qualitative scores were significantly higher in STAGE-MRA than in TOF-MRA for the ICA terminus, proximal MCA, and LMCs (ps < 0.05) in 75 participants. When referred to digital subtraction angiography (DSA) in 25 ICAD patients, STAGE-MRA showed higher qualitative scores only at LMCs. CNRs in the M1-4 segments were significantly higher in STAGE-MRA than in TOF-MRA (218.7 ± 90.7 vs 176.2 ± 72.6, 195.7 ± 86.0 vs 146.6 ± 71.7, 176.4 ± 71.6 vs 125.8 ± 61.1, 126.2 ± 62.9 vs 78.8 ± 43.6; all ps < 0.001). STAGE-MRA showed more LMCs (11.4 ± 3.4) than TOF-MRA (8.4 ± 3.3) with p < 0.05.

CONCLUSIONS

STAGE-MRA might be superior to TOF-MRA in qualitative and quantitative assessment of LMCs in both healthy volunteers and ICAD patients; thus, it may serve as an alternative method in evaluating LMC.

KEY POINTS

• Strategically acquired gradient echo (STAGE)-derived magnetic resonance angiography is a newly developed sequence with a pair of rephasing/dephasing gradient echoes. • STAGE-MRA enables higher image qualitative score, improves contrast-to-noise ratio, and shows greater number of leptomeningeal collaterals (LMCs) in healthy volunteers and patients with intracranial atherosclerotic disease. • LMC visualization by STAGE-MRA shows good to excellent inter-observer agreement.

Preservation of the Lenticulostriate Arteries During Insular Glioma Resection

Insular gliomas represent 25% and 10% of low- and high-grade gliomas, respectively. Their resection proves challenging due to the intimate involvement of eloquent parenchyma and the lenticulostriate arteries (LSAs), limiting facility of achieving maximal safe resection. The majority of postoperative deficits following insular glioma resection is attributed to compromise of the LSAs. It is contemporaneously critical and challenging to preserve these vessels, given they are numerous and small, with an intraparenchymal course hidden from direct visualization during the operative intervention. A lesser degree of medially directed displacement of the LSAs predicts tumoral encasement of these vessels, which portends a decreased likelihood for achieving a gross total resection and increased probability of postoperative morbidity. Preservation of these vessels thus requires knowledge of their location during the entirety of the insular glioma resection and is facilitated by pre- and intra-operative imaging. Intraoperative real-time tracking, however, may prove rather challenging, especially with transcortical access. Conventional catheter digital subtraction angiography, computed tomographic angiography, magnetic resonance imaging and angiography, and three-dimensional ultrasound powered Doppler have proven effective modalities in assessing lenticulostriate position, and their use facilitates a greater extent of resection while minimizing the attendant morbidity consequent to LSA injury.

Neuroanatomy of the middle cerebral artery: implications for thrombectomy

Our perspective on anatomy frequently depends on how this anatomy is utilized in clinical practice, and by which methods knowledge is acquired. The thrombectomy revolution, of which the middle cerebral artery (MCA) is the most common target, is an example of a clinical paradigm shift with a unique perspective on cerebrovascular anatomy. This article reviews important features of MCA anatomy in the context of thrombectomy. Recognizing that variation, frequently explained by evolutionary concepts, is the rule when it comes to branching pattern, vessel morphology, territory, or collateral potential is key to successful thrombectomy strategy.

The microneurosurgical anatomy legacy of Albert L. Rhoton Jr., MD: an analysis of transition and evolution over 50 years

The authors chronologically categorized the 160 original articles written by Dr. Rhoton and his fellows to show why they selected their themes and how they carried out their projects. The authors note that as neurosurgery progresses and new techniques and approaches are developed, accurate and safe treatment will depend upon continued clarification of microsurgical anatomy.

Correlation Between the Number of Lenticulostriate Arteries and Imaging of Cerebral Small Vessel Disease

Background and purpose: Hypoperfusion plays an important role in the pathophysiology of cerebral small vessel disease (SVD). Lenticulostriate arteries (LSAs) are some of the most important cerebral arterial small vessels. This study aimed to investigate whether the number of LSAs was associated with the cerebral perfusion in SVD patients and determine the correlation between the number of LSAs and SVD severity.

Methods: Five hundred and ninety-four consecutive patients who underwent digital subtraction angiography were enrolled in this study. The number of LSAs was determined. Computed tomography perfusion (CTP) was used to calculate the cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time to peak (TTP). Magnetic resonance imaging (MRI) was performed to assess cerebral infarct, cerebral microbleeds (CMBs), white matter hyperintensities (WMHs), enlarged perivascular spaces (EPVSs), and lacunes. An SVD compound score was calculated to express the level of cerebral SVD load.

Results: The SVD scores were negatively correlated with the number of the LSAs (P < 0.001, r_s = −0.44). The number of LSAs was inversely associated with the presence of any type of SVD (P < 0.001). The adjusted ORs of the SVD severity were 0.31 for LSA group 1 (LSA > 20) vs. group 2 (LSA = 10–20) and 0.47 for LSA group 2 (LSA = 10–20) vs. group 3 (LSA < 10). MTT and TTP were significantly higher and CBF was significantly lower when the number of LSAs was between 5 and 10 on each side of the basal ganglia (P < 0.001, <0.001, and <0.001, respectively). The CBV was slightly lower when the number of LSAs was between 5 and 10, while it was significantly lower when the number was <5 on each side of the basal ganglia (P < 0.05, <0.0001, respectively).

Conclusion: LSA count was lower in SVD patients than the non-SVD participants and there was a positive correlation between the cerebral perfusion and the number of LSAs. The LSA number was negatively associated with SVD severity, hypoperfusion might play an important role. This finding may have potentially important clinical implications for monitoring LSA in SVD patients.

Study of Middle Cerebral Artery in Human Cadaveric Brain

Background:

Middle cerebral artery (MCA) is the larger terminal branch of the internal carotid artery. It travels through the Sylvian fissure on the insula.

Objective:

MCA supplies a large area of distribution than the other two cerebral arteries. Though it is so, there are very few articles in the literature describing MCA. Aim of the present work is to study the MCA regarding its origin, course, termination, branching pattern, morphometry and symmetry.

Materials and Methods:

340 MCAs from 170 formalin preserved brains were dissected. Morphology, morphometry and symmetry of MCAs, were studied in detail and well photographed. The data collected in the study was analyzed.

Results:

Accessory MCA was found in seven specimens (2.05%). Duplicated MCA was seen in three specimens (0.88%). Aneurysm was found in three specimens (0.88%). MCA with bifurcated, trifurcated, quadrifurcated and single trunk termination was seen in 220 (64.70%), 42 (12.35%), 8 (2.35%), and in 70 (20.58%) specimens respectively. Bifurcated pattern as upper prominent trunk (type A), lower prominent trunk (type B) and both equal prominent trunks (type C) were seen in 63 (28.63%), 129 (58.63%), and 28 (12.72%) specimens respectively. Asymmetry was seen in 102 specimens (60%). Mean length and diameter of the MCA was 25.5-27.8 mm and 3 mm respectively.

Conclusion:

Awareness of these anatomical variations in branching patterns is important in neurovascular procedures. As very few Anatomical studies on MCA are there in the literature, this type of research work should be done by a number of scientists from a different region of the world in large scale.

Anatomical Assessment of the Temporopolar Artery for Revascularization of Deep Recipients

BACKGROUND

Intracranial-intracranial and extracranial-intracranial bypass options for revascularization of deep cerebral recipients are limited and technically demanding.

OBJECTIVE

To assess the anatomical feasibility of using the temporopolar artery (TPA) for revascularization of the anterior cerebral artery (ACA), posterior cerebral artery (PCA), and superior cerebellar arteries (SCA).

METHODS

Orbitozygomatic craniotomy was performed bilaterally on 8 cadaveric heads. The cisternal segment of the TPA was dissected. The TPA was cut at M3-M4 junction with its proximal and distal calibers and the length of the cisternal segment measured. Feasibility of the TPA-A1-ACA, TPA-A2-ACA, TPA-SCA, and TPA-PCA bypasses were assessed.

RESULTS

A total of 17 TPAs were identified in 16 specimens. The average distal TPA caliber was 1.0 ± 0.2 mm, and the average cisternal length was 37.5 ± 9.4 mm. TPA caliber was ≥ 1.0 mm in 12 specimens (70%). The TPA-A1-ACA bypass was feasible in all specimens, whereas the TPA reached the A2-ACA, SCA, and PCA in 94% of specimens (16/17). At the point of anastomosis, the average recipient caliber was 2.5 ± 0.5 mm for A1-ACA, and 2.3 ± 0.7 mm for A2-ACA. The calibers of the SCA and PCA at the anastomosis points were 2.0 ± 0.6 mm, and 2.7 ± 0.8 mm, respectively.

CONCLUSION

The TPA-ACA, TPA-PCA, and TPA-SCA bypasses are anatomically feasible and may be used when the distal caliber of the TPA stump is optimal to provide adequate blood flow. This study lays foundations for clinical use of the TPA for ACA revascularization in well-selected cases.

Visualization of the lenticulostriate arteries at 3T using black-blood T1-weighted intracranial vessel wall imaging: comparison with 7T TOF-MRA

OBJECTIVES

The objective of this study was to explore the feasibility of using intracranial T1-weighted vessel wall imaging (VWI) to visualize the lenticulostriate arteries (LSAs) at 3T.

MATERIAL AND METHODS

Thirteen healthy volunteers were examined with VWI at 3T and TOF-MRA at 7T during the same day. On the vascular skeletons obtained by manual tracing, the number of stems and branches of LSAs were counted. On the most prominent branch in every hemisphere, the contrast-to-noise ratio (CNR), the full length and the local length (5-15 mm above MCAs) were measured and compared between the two methods. Nine stroke patients with intracranial artery stenosis were also recruited into the study. The branches of LSAs were compared between the symptomatic and asymptomatic side.

RESULTS

The extracted vascular trees were in good agreement between 7T TOF-MRA and 3T VWI. The two acquisitions showed similar numbers of the LSA stems. The number of branches revealed by 3T VWI was slightly lower than 7T TOF. The full lengths were slightly lower by VWI at 3T (p = 0.011, ICC = 0.917). The measured local lengths (5-15 mm from MCAs) showed high coherence between VWI and TOF-MRA (p = 0.098, ICC = 0.970). In stroke patients, 12 plaques were identified on MCA segments, and nine plaques were located on the symptomatic side. The average numbers of LSA visualized by 3T VWI were 4.3±1.3 on the symptomatic side and 5.0±1.1 on the asymptomatic side.

CONCLUSION

3T VWI is capable of depicting LSAs, particularly the stems and the proximal segments, with comparable image quality to that of 7T TOF-MRA.

KEY POINTS

• T1-weighted intracranial VWI at 3T allows for black-blood MR angiography of lenticulostriate artery. • 3T intracranial VWI depicts the stems and proximal segments of the lenticulostriate arteries comparable to 7T TOF-MRA. • It is feasible to assess both large vessel wall lesions and lenticulostriate vasculopathy in one scan.

Stent retriever placement in embolectomy: the choice of the post-bifurcational trunk influences the first-pass reperfusion result in M1 occlusions

Background

Embolectomy using Stent retriever Assisted Vacuum-locked Extraction (SAVE) is effective in intracranial large vessel occlusion. Which post-bifurcational trunk should be chosen for distal stent retriever placement in M1 occlusions is, however, elusive.

Methods

We conducted a retrospective analysis of prospectively collected data from a comprehensive stroke center between 2015 and 2017. Eighty-nine consecutive patients with M1 occlusions were treated with SAVE. Digital subtraction angiography (DSA) series were studied to determine the anatomy of middle cerebral artery division, the position of the stent retriever, and to measure vessel diameters. The primary endpoint was first-pass complete/near-complete reperfusion, defined as a modified Thrombolysis in Cerebral Infarction (mTICI) score of 2c or 3, after distal stent retriever placement in the inferior trunk.

Results

In 76/89 (85%) patients, microcatheter series were documented. A microcatheter was placed within the inferior trunk in 30/76 (40%) cases. First-pass near-complete/complete reperfusion was more likely to be achieved when the inferior trunk was used for stent retriever placement rather than the superior trunk (mTICI ≥2c: 22/30 (73%) vs 22/46 (48%), P=0.034; and mTICI 3: 20/30 (67%) vs 17/46 (37%), P=0.018). Median diameter of the inferior trunk was larger than the superior trunk (1.4 mm (IQR 1.26–1.62) vs 1.18 mm (IQR 0.98–1.43), P=0.011). The inferior trunk was dominant in 56/76 (74%) cases. Successful reperfusion was associated with placement within the dominant trunk (33/40 (83%) vs 22/36 (61%), P=0.044).

Conclusion

The choice of the inferior trunk for distal stent retriever placement in M1 occlusions is associated with a high rate of first-pass near-complete/complete reperfusion when using SAVE.

Middle cerebral artery extension and the risk for aneurysmal disease

The intracranial artery aneurysm is an abnormal dilatation at the wall and the most serious complication is its rupture that is associated with high rates of neurological mortality and morbidity. Its most common location in arterial bifurcations suggests that the hemodynamic of blood flow plays a key role, but the effect of the length of the M1 segment of the middle cerebral artery is poorly explored. We analyzed biplanar brain angiograms to measure the extent of the M1 segment and its relationship to the presence of aneurysm at the bifurcation. Of 475 patients, a total of 682 bilateral measurements were analyzed. Women accounted for 58.7% and the mean age was 50.2 ± 15.5. Aneurysms were detected in 45 arteries, about the average length of the M1 artery; the right segment measure (2.98 ± 0.99 cm) was statistically lesser than the left (3.09 ± 1.38 cm). Applying the regression coefficient, arteries with aneurysm have an average length of 0.419 cm smaller than an artery without aneurysm, and this difference was statistically significant (p < 0.05). Though the wall shear stress component is a proven risk factor for the development of aneurysms in bifurcations, a smaller extension of the M1 segment may also be implicated in its development.

Characterization of aphasia in aneurysmal subarachnoid hemorrhage

PURPOSE

Characterize the profile of aphasic syndromes determined by aneurysmal subarachnoid hemorrhage (aSAH) of the left middle cerebral artery (LMCA).

METHODS

An analytical, retrospective, cross-sectional study was conducted using a database of cognitive assessments of 193 patients with aSAH admitted to Hospital da Restauração between March 2007 and November 2009. Of these, a total of 26 patients with aSAH in the LMCA territory confirmed by digital angiography were selected. Aphasia was assessed through the Montreal-Toulouse Language Assessment Alpha Version Protocol (Alpha Version) and the CERAD Neuropsychological Test Battery (Verbal fluency).

RESULTS

Language and verbal fluency impairments were identified in patients with aSAH in the LMCA territory when compared with the control population (50 individuals). Of the 26 patients with aSAH, 11 presented aphasic characteristics preoperatively.

CONCLUSION

The results of this research corroborate the literature, showing that the aSAH frame causes cognitive impairments even in the preoperative phase for aneurysm occlusion. Considering the observed aspects, the predominant aphasic syndromes characterize comprehension aphasia due to sequels in the posterior cerebral artery territory.

Stem Cell Therapies in Peripheral Vascular Diseases — Current Status

Peripheral artery diseases include all arterial diseases with the exception of coronary and aortic involvement, more specifically diseases of the extracranial carotids, upper limb arteries, mesenteric and renal vessels, and last but not least, lower limb arteries. Mononuclear stem cells, harvested from various sites (bone marrow, peripheral blood, mesenchymal cells, adipose-derived stem cells) have been studied as a treatment option for alleviating symptoms in peripheral artery disease, as potential stimulators for therapeutic angiogenesis, thus improving vascularization of the ischemic tissue. The aim of this manuscript was to review current medical literature on a novel treatment method — cell therapy, in patients with various peripheral vascular diseases, including carotid, renal, mesenteric artery disease, thromboangiitis obliterans, as well as upper and lower limb artery disease.

A population-based incidence of M2 strokes indicates potential expansion of large vessel occlusions amenable to endovascular therapy

Background

M2 occlusions may result in poor outcomes and potentially benefit from endovascular therapy. Data on the rate of M2 strokes is lacking.

Methodology

Patients with acute ischemic stroke discharged over a period of 3 years from a tertiary level hospital in the ‘stroke belt’ were evaluated for M2 occlusions on baseline vascular imaging. Regional and national incidence was calculated from discharge and multicounty data.

Results

There were 2739 ICD-9 based AIS discharges. M2 occlusions in 116 (4%, 95% CI 3.5% to 5%) patients constituted the second most common occlusion site. The median National Institute of Health Stroke Scale (NIHSS) score was 12 (IQR 5–18). Good outcomes were observed in 43% (95% CI 34% to 53%), poor outcomes in 57% (95% CI 47% to 66%), and death occurred in 27% (95% CI 19% to 37%) of patients. Receiver operating characteristics curves showed the NIHSS to be predictive of outcomes (area under the curve 0.829, 95% CI 0.745 to 0.913, p<0.0001). An NIHSS score ≥9 was the optimal cut-off point for predicting poor outcomes (sensitivity 85.7%, specificity 67.4%). 71 (61%) patients had an NIHSS score ≥9 and 45 (39%) an NIHSS score <9. The rate of good-outcome was 22.6% for NIHSS score ≥9 versus 78.4% for NIHSSscore <9 (OR=0.08, 95% CI 0.03 to 0.21, p<0.0001). Mortality was 42% for NIHSS score ≥9 versus 2.7% for NIHSS score <9 (OR=26, 95% CI 3.3 to 202, p<0.0001). Infarct volume was 57 (±55.7) cm³ for NIHSS score ≥9 versus 30 (±34)cm³ for NIHSS score <9 (p=0.003). IV recombinant tissue plasminogen activator (rtPA) administered in 28 (24%) patients did not affect outcomes. The rate of M2 occlusions was 7 (95% CI 5 to 9)/100 000 people/year (3%, 95% CI 2% to 4%), giving an incidence of 21 176 (95% CI 15 282 to 29 247)/year. Combined with M1, internal carotid artery terminus and basilar artery, this yields a ‘large vessel occlusion (LVO)+M2’ rate of 31 (95% CI 26 to 35)/100 000 people/year and a national incidence of 99 227 (95% CI 84 004 to 112 005) LVO+M2 strokes/year.

Conclusion

M2 occlusions can present with serious neurological deficits and cause significant morbidity and mortality. Patients with M2 occlusions and higher baseline deficits (NIHSS score ≥9) may benefit from endovascular therapy, thus potentially expanding the category of acute ischemic strokes amenable to intervention.

The anterior temporal artery: an underutilized but robust donor for revascularization of the distal middle cerebral artery

OBJECTIVE The anterior temporal artery (ATA) supplies an area of the brain that, if sacrificed, does not cause a noticeable loss of function. Therefore, the ATA may be used as a donor in intracranial-intracranial (IC-IC) bypass procedures. The capacities of the ATA as a donor have not been studied previously. In this study, the authors assessed the feasibility of using the ATA as a donor for revascularization of different segments of the distal middle cerebral artery (MCA). METHODS The ATA was studied in 15 cadaveric specimens (8 heads, excluding 1 side). First, the cisternal segment of the artery was untethered from arachnoid adhesions and small branches feeding the anterior temporal lobe and insular cortex, to evaluate its capacity for a side-to-side bypass to insular, opercular, and cortical segments of the MCA. Any branch entering the anterior perforated substance was preserved. Then, the ATA was cut at the opercular-cortical junction and the capacity for an end-to-side bypass was assessed. RESULTS From a total of 17 ATAs, 4 (23.5%) arose as an early MCA branch. The anterior insular zone and the frontal parasylvian cortical arteries were the best targets (in terms of mobility and caliber match) for a side-to-side bypass. Most of the insula was accessible for end-to-side bypass, but anterior zones of the insula were more accessible than posterior zones. End-to-side bypass was feasible for most recipient cortical arteries along the opercula, except for posterior temporal and parietal regions. Early ATAs reached significantly farther on the insular MCA recipients than non-early ATAs for both side-to-side and end-to-side bypasses. CONCLUSIONS The ATA is a robust arterial donor for IC-IC bypass procedures, including side-to-side and end-to-side techniques. The evidence provided in this work supports the use of the ATA as a donor for distal MCA revascularization in well-selected patients.

Low-flow and high-flow neurosurgical bypass and anastomosis training models using human and bovine placental vessels: a histological analysis and validation study

OBJECTIVE

Microvascular anastomosis is a basic neurosurgical technique that should be mastered in the laboratory. Human and bovine placentas have been proposed as convenient surgical practice models; however, the histologic characteristics of these tissues have not been compared with human cerebral vessels, and the models have not been validated as simulation training models. In this study, the authors assessed the construct, face, and content validities of microvascular bypass simulation models that used human and bovine placental vessels.

METHODS

The characteristics of vessel segments from 30 human and 10 bovine placentas were assessed anatomically and histologically. Microvascular bypasses were performed on the placenta models according to a delineated training module by “trained” participants (10 practicing neurosurgeons and 7 residents with microsurgical experience) and “untrained” participants (10 medical students and 3 residents without experience). Anastomosis performance and impressions of the model were assessed using the Northwestern Objective Microanastomosis Assessment Tool (NOMAT) scale and a posttraining survey.

RESULTS

Human placental arteries were found to approximate the M2–M4 cerebral and superficial temporal arteries, and bovine placental veins were found to approximate the internal carotid and radial arteries. The mean NOMAT performance score was 37.2 ± 7.0 in the untrained group versus 62.7 ± 6.1 in the trained group (p < 0.01; construct validity). A 50% probability of allocation to either group corresponded to 50 NOMAT points. In the posttraining survey, 16 of 17 of the trained participants (94%) scored the model's replication of real bypass surgery as high, and 16 of 17 (94%) scored the difficulty as “the same” (face validity). All participants, 30 of 30 (100%), answered positively to questions regarding the ability of the model to improve microsurgical technique (content validity).

CONCLUSIONS

Human placental arteries and bovine placental veins are convenient, anatomically relevant, and beneficial models for microneurosurgical training. Microanastomosis simulation using these models has high face, content, and construct validities. A NOMAT score of more than 50 indicated successful performance of the microanastomosis tasks.

Three-Dimensional Angiographic Evaluation of Middle Cerebral Artery Trunk Aneurysms: Demonstration of the Close Relationship Between the Early Frontal Cortical Branches and Lateral Lenticulostriate Arteries

BACKGROUND

For the treatment planning of a patient with a middle cerebral artery (MCA) trunk aneurysm, understanding the anatomic relationship among the aneurysm, branching vessels, and lenticulostriate arteries (LSAs) is important. We aimed to demonstrate the branching-vessel anatomy related to an MCA trunk aneurysm using 3-dimensional (3D) angiography.

METHODS

We retrospectively reviewed 3D angiographic findings of 64 cases of MCA trunk aneurysms using a 3D workstation with various postprocessing conditions. We classified the aneurysms into 4 groups (early frontal cortical branch [EFCB], early temporal cortical branch [ETCB], LSA, and nonbranching aneurysms) and analyzed the relationship between the branching vessels and the LSAs.

RESULTS

There were 30 EFCB aneurysms, 25 ETCB aneurysms, 7 LSA aneurysms, and 2 nonbranching aneurysms. Twenty-six (86.7%) of the 30 EFCB aneurysms shared common origins and were associated with the LSAs, but none of the 25 ETCB aneurysms were. Three of 24 patients who received clipping for an EFCB aneurysm experienced a postoperative infarction in the LSA territory. In these 3 patients, the LSA originated from the EFCB and was closely related with the aneurysm.

CONCLUSIONS

We have identified a clinically important anatomic relationship between the MCA trunk aneurysm and branching vessels, including the LSAs. EFCB aneurysms show a close relationship with the LSAs. Pretreatment identification of the origin of the LSAs is important to obviate any perforator injury in EFCB aneurysms.

The Microsurgical Anatomy of the Orbitofrontal Arteries

OBJECTIVE

The orbitofrontal (or frontobasal) arteries (OFAs) are the medial (MOFA) and lateral (LOFA) orbitofrontal artery, branches of the anterior and middle cerebral artery, respectively. They supply the orbitofrontal cortex. The purpose of this microscopic cadaveric study was the detailed and precise anatomic identification of the OFAs along their course.

METHODS

Twenty formalin-fixed, colored latex-injected cadaveric heads were studied with the aid of an operating microscope and microsurgical instrumentation. The anatomy of the OFAs was examined after removing the cerebrum from the cranial vault. Anatomic features of the MOFA and LOFA were investigated and assessed in relation to demographic and anthropometric variables.

RESULTS

The MOFA supplies approximately 15 branches and LOFA almost 16 branches. The MOFA provides 1 branch to the olfactory bulb and 4 branches to the olfactory tract, and there are approximately 2 MOFA-LOFA anastomoses per hemisphere (novel finding). The MOFA origin is located approximately 7.9 mm anterior to the anterior communicating artery and 4.7 cm posterior to the anterior limit of the gyrus rectus. The LOFA origin is located approximately 11.1 mm from the middle cerebral artery bifurcation. Younger, shorter, and lighter individuals have more MOFA-LOFA anastomoses. Finally, the number of MOFA branches for the olfactory bulb is positively correlated with the number of MOFA branches for the olfactory tract, as well as with the number of MOFA-LOFA anastomoses.

CONCLUSIONS

The present study provides a detailed description of the OFAs' microsurgical anatomy and can help neurosurgeons to easily identify, manipulate, and preserve these vessels during surgery.

Arteries and Veins of the Sylvian Fissure and Insula: Microsurgical Anatomy

We present a vascular anatomical study of the arteries and veins of the sylvian fissure and insula.A good knowledge of the sylvian fissure, the insula, and their vascular relationship would seem mandatory before performing surgery in this area, whatever the type of surgery (aneurysms, arteriovenous malformations, insular tumors).We start with the sylvian fissure and insula morphology, followed by the MCA description and its perforators, with special attention paid to the insular perforators. We demonstrate that the long insular perforators penetrating in the superior part of the posterior short gyrus and long gyri vascularize, respectively, the corticonuclear and corticospinal fasciculi. We particularly insist too on three anatomical constants regarding the vascularization of the insula, already described in the literature: The superior periinsular sulcus is the only sulcus on the lateral surface of the brain without an artery along its axis; the superior branch of the MCA supplies the anterior insular pole and both the anterior and middle short gyri in 100 % of cases; in at least 90 % of cases, the artery that supplied the central insular sulcus continued on to become the central artery.We end with the anatomical study of the veins and cisterns.

Mechanical Thrombectomy for Isolated M2 Occlusions: A Post Hoc Analysis of the STAR, SWIFT, and SWIFT PRIME Studies

BACKGROUND AND PURPOSE

Mechanical thrombectomy is beneficial for patients with acute ischemic stroke and a proximal anterior occlusion, but it is unclear if these results can be extrapolated to patients with an M2 occlusion. The purpose of this study was to examine the technical aspects, safety, and outcomes of mechanical thrombectomy with a stent retriever in patients with an isolated M2 occlusion who were included in 3 large multicenter prospective studies.

MATERIALS AND METHODS

We included patients from the Solitaire Flow Restoration Thrombectomy for Acute Revascularization (STAR), Solitaire With the Intention For Thrombectomy (SWIFT), and Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment (SWIFT PRIME) studies, 3 large multicenter prospective studies on thrombectomy for ischemic stroke. We compared outcomes and technical details of patients with an M2 with those with an M1 occlusion. All patients were treated with a stent retriever. Imaging data and outcomes were scored by an independent core laboratory. Successful reperfusion was defined as modified Thrombolysis in Cerebral Infarction score of 2b/3.

RESULTS

We included 50 patients with an M2 and 249 patients with an M1 occlusion. Patients with an M2 occlusion were older (mean age, 71 versus 67 years; P = .04) and had a lower NIHSS score (median, 13 versus 17; P < .001) compared with those with an M1 occlusion. Procedural time was nonsignificantly shorter in patients with an M2 occlusion (median, 29 versus 35 minutes; P = .41). The average number of passes with a stent retriever was also nonsignificantly lower in patients with an M2 occlusion (mean, 1.4 versus 1.7; P = .07). There were no significant differences in successful reperfusion (85% versus 82%, P = .82), symptomatic intracerebral hemorrhages (2% versus 2%, P = 1.0), device-related serious adverse events (6% versus 4%, P = .46), or modified Rankin Scale score 0-2 at follow-up (60% versus 56%, P = .64).

CONCLUSIONS

Endovascular reperfusion therapy appears to be feasible in selected patients with ischemic stroke and an M2 occlusion.

Endovascular management of fusiform aneurysm of anterior temporal artery: Technical report

Background:

The treatment of a rare, nontraumatic, fusiform aneurysm of the anterior temporal artery (ATA) via endovascular techniques is presented, and procedural nuances are highlighted.

Methods:

We performed a retrospective chart review and collected demographic and clinical data on the patient presented here; procedural details were extracted from operative notes.

Results:

Following successful balloon test occlusion (BTO) of the ATA, complete coil embolization of the ATA, and its associated fusiform aneurysm was performed. Postprocedurally, the patient did not suffer any adverse neurological sequelae.

Conclusion:

Selective BTO of intracranial branch vessels is safe, technically feasible, and could serve as a useful technical tool in the treatment of complex, fusiform intracranial aneurysms.

Transcranial color-coded duplex sonography of the middle cerebral artery: more than just the M1 segment

OBJECTIVES

Routine sonography of the middle cerebral artery in acute ischemic stroke usually focuses on the main stem (M1 segment). However, stenoses and occlusions affect not only proximal but also more distal vessel branches, such as the M2 segments. Transcranial color-coded duplex sonography allows visualization of these segments; however, a formal analysis and description of normal blood flow values are missing. The purpose of this study was to analyze middle cerebral artery branching patterns with transcranial color-coded duplex sonography and to establish reference flow velocity values in the detectable M2 branches as well as the early temporal M1 branch.

METHODS

Transcranial color-coded duplex sonography in the axial and coronal planes was performed in 50 participants without vascular disease and with a good temporal bone window (ie, fully visible M1 middle cerebral artery segment and A1 anterior cerebral artery segment). We analyzed the course and branching pattern of the M1 segment, including anatomic variants such as an early temporal M1 branch, and measured the length and flow parameters of the detectable M2 branches.

RESULTS

Assessment of 100 hemispheres allowed classification into 3 anatomic patterns: M1 bifurcation (63%), M1 trifurcation (32%), and medial M1 branching into 2 major segments (2%). A clear distinction was not possible in 3 cases (3%). An early temporal M1 branch was detected in the coronal plane in 26%.

CONCLUSIONS

Transcranial color-coded duplex sonography is a useful tool for analyzing anatomic variants and branching patterns of the middle cerebral artery as well as flow characteristics of M2 segments. Therefore, it also has potential to increase the diagnostic yield for the detection of middle cerebral artery disease in these vessel segments.

Microanatomical study of the insular perforating arteries

BACKGROUND

The insular perforating arteries originate from the middle cerebral artery. They have only been very partially described up to now. In the literature, they come from the M2 segment and three types are listed: the short, medium and long perforators. The first two types supply the claustrum as well as the external and extreme capsules.

OBJECTIVE

We describe the anatomy of long perforating insular arteries and their arterial contribution to the main white matter bundles of the oval center of Vieussens.

MATERIALS AND METHOD

Twenty adult cadaveric hemispheres were studied after perfusion of the arteries and veins with colored latex. The arteries were dissected and photographed under an operating microscope.

RESULTS

The long insular perforating arteries come from the M2 segment or from the junction of the M2 and M3 segments and sometimes from the M3 segment. They often perforate the insular cortex on the top of the posterior short insular gyrus and the insular long gyri, or in the superior peri-insular sulcus, before coming together in the oval center. At this level, they give arterial contribution to the main white matter bundles such as corticospinal and corticonuclear tracts for motricity, and the arcuate fasciculus and the occipitofrontal tract for language in the dominant hemisphere.

CONCLUSION

These perforating arteries have to be carefully respected during insular surgery to avoid neurologic weakness.

Anatomical labeling of the Circle of Willis using maximum a posteriori probability estimation

Anatomical labeling of the cerebral arteries forming the Circle of Willis (CoW) enables inter-subject comparison, which is required for geometric characterization and discovering risk factors associated with cerebrovascular pathologies. We present a method for automated anatomical labeling of the CoW by detecting its main bifurcations. The CoW is modeled as rooted attributed relational graph, with bifurcations as its vertices, whose attributes are characterized as points on a Riemannian manifold. The method is first trained on a set of pre-labeled examples, where it learns the variability of local bifurcation features as well as the variability in the topology. Then, the labeling of the target vasculature is obtained as maximum a posteriori probability (MAP) estimate where the likelihood of labeling individual bifurcations is regularized by the prior structural knowledge of the graph they span. The method was evaluated by cross-validation on 50 subjects, imaged with magnetic resonance angiography, and showed a mean detection accuracy of 95%. In addition, besides providing the MAP, the method can rank the labelings. The proposed method naturally handles anatomical structural variability and is demonstrated to be suitable for labeling arterial segments of the CoW.

A New, More Accurate Classification of Middle Cerebral Artery Aneurysms

BACKGROUND:

Classification of middle cerebral artery (MCA) aneurysms is sometimes difficult because the identification of the main MCA bifurcation, the key for accurate classification of MCA aneurysms, is inconsistent and somewhat subjective.

OBJECTIVE:

To use the meeting point of the M1 and M2 trunks as an objective, generally accepted, and angiographically evident hallmark for identification of MCA bifurcation and more accurate classification of MCA aneurysms.

METHODS:

We reviewed the computed tomographic angiography data of 1009 consecutive patients with 1309 MCA aneurysms. The M2 trunks were followed proximally until their meeting with the M1 trunk at the main MCA bifurcation. The aneurysms were classified according to their relative location: proximal, at, or distal to the MCA bifurcation. The M1 aneurysms were further subgrouped into M1 early cortical branch aneurysms and M1 lenticulostriate artery aneurysms, extending the classic 3-group classification of MCA aneurysms into a 4-group classification.

RESULTS:

The main MCA bifurcation was the most common location for MCA aneurysms, harboring 829 aneurysms (63%). The 406 M1 aneurysms comprised 242 M1 early cortical branch aneurysms (60%) and 164 M1 lenticulostriate artery aneurysms (40%). We found 106 MCA aneurysms (8%) at the origin of large early frontal branches simulating M2 trunks liable to be misclassified as MCA bifurcation aneurysms. Even though 51% of the 407 ruptured MCA aneurysms were associated with an intracerebral hematoma, this did not affect the classification.

CONCLUSION:

Studying MCA angioarchitecture and applying the 4-group classification of MCA aneurysms is practical and facilitates the accurate classification of MCA aneurysms, helping to improve surgical outcome.

Endovascular treatment for saccular aneurysms of the proximal (M1) segment of the middle cerebral artery

BACKGROUND

Saccular aneurysms located at the M1 segment of the middle cerebral artery (MCA) are uncommon, and endovascular treatment (EVT) for them is not well documented. We performed this study to evaluate the feasibility, safety, and efficacy of EVT for proximal (M1) segment saccular aneurysm of the middle cerebral artery.

METHODS

Of 153 MCA aneurysms between January 2007 and September 2011, 29 patients with 29 M1 segment saccular aneurysms were treated at our institution via endovascular approach. There were 14 men and 15 women with a mean age of 56.2 years (range 36-78 years).

RESULTS

Treatments were successful in 28 (96.6 %) cases, including coiling alone in 19 patients, stent-assisted coiling in 8, and balloon-assisted coiling in 1. In the failed case, coiling was not successful, and only a stent was deployed. Immediate angiograms showed total occlusion in 13 patients, neck remnant in 7, partial occlusion in 8, and contrast stasis in the patient who was not coiled successfully. Two (6.9 %) procedure-related complications occurred, including early temporal branch (ETB) obliteration in one patient and lenticulostriate artery (LSA) occlusion in the other one, which resulted in hemiparalysis of one patient. Three patients died from initial severe SAH during hospitalization. One patient died from heart infarction 1 month after operation. Twenty-three of 25 surviving patients underwent follow-up cerebral angiography at intervals ranging from 1 to 21 months (mean, 7.3 months). The result showed 14/23 (60.9 %) aneurysms were completely occluded, 3/23 (13 %) were recanalized, and others were stable or improved. The clinical follow-up (mean, 22.5 months) of all survived patients demonstrated no neurologic deterioration or rebleeding.

CONCLUSION

Our preliminary experience demonstrates that EVT for proximal MCA aneurysm is feasible and safe. However, more adequate follow-up is required to evaluate its long-term results.