Angiographic Systems for Classifying Distal Arterial Occlusions.

BACKGROUND: Extensive randomized controlled clinical trials for endovascular thrombectomy in anterior circulation large vessel occlusions (internal carotid arteries and M1 segment of middle cerebral arteries) have been published over the past decade, but there have not been randomized controlled trials for distal arterial occlusions to date. Distal arterial occlusion randomized controlled trials are essential to decide on patient selection, imaging criteria, and endovascular approach to improve the outcome and reduce complications. SUMMARY: The definition of distal arterial occlusion is however unclear, and we believe that a uniform nomenclature of distal arterial occlusions is essential for the design of robust randomized controlled studies. We undertook a systematic literature review and comprehensive analysis of 70 articles looking at distal arterial occlusions and previous attempts at classifying them as well as comparing their similarities and differences with a more selective look at the middle cerebral artery. Thirty-two articles were finally deemed suitable and included for this review. In this review article, we present 3 disparate classifications of distal arterial occlusions, namely, classical/anatomical, functional/imaging, and structural/calibre, and compare the similarities and differences between them. KEY MESSAGES: We propose the adoption of functional/imaging classification to guide the identification of distal arterial occlusions with the M2 segment starting at the point of bifurcation of the middle cerebral artery trunk/M1 segment. With regards to the anterior temporal artery, we propose that it will be considered a branch of the M1 and only be considered as the M2 segment if it is a holo-temporal artery. We believe that this is a practical method of classification in the time-critical decision-making period.

C-reactive Protein is A Predictor of Deterioration of Acute Internal Carotid Artery M1 Qcclusion Following Recanalization.

INTRODUCTION: Administration of intravenous recombinant tissue plasminogen activator (rt-PA) and mechanical thrombectomy (MT) have become standard therapeutic approaches for acute internal carotid artery and middle cerebral artery M1 segment occlusion (ICA/M1O). However, clinical deterioration of the condition is still observed in some cases. OBJECTIVE: We aimed to identify patients' factors associated with exacerbation. This was a single-center, retrospective study of 35 consecutive patients with acute ICA/M1O who underwent rt-PA/rt-PA and MT at our hospital between January 2016 and September 2019. We divided patients into two groups based on the total NIHSS score at discharge: the "improvement" and "exacerbation" groups. Clinical characteristics, laboratory data, and imaging findings were compared between the groups. RESULTS: The improvement group (13 patients [37%]) had a lower mean age (70 vs. 81 years, p = 0.02), National Institutes of Health Stroke Scale score (NIHSS, 13 vs. 19, p = 0.02), and C-reactive protein (CRP) levels (0.24 vs. 0.92 mg/dl, p < 0.01) than the exacerbation group (22 patients [63%]). Receiver operating characteristic curve analysis revealed the cut-off age to be 79 (sensitivity 76.9%, specificity 72.7%), NIHSS score to be 20 (sensitivity 92.3%, specificity 63.6%), and CRP to be 0.14 mg/dl (sensitivity 69.2%, specificity 81.8%). Multivariate analysis confirmed a CRP level of >0.14 mg/dl (odds ratio, 10.16; 95% confidence interval 1.38-75.13; p = 0.01) to be independently associated with clinical deterioration at discharge. CONCLUSIONS: A CRP level of >0.14 mg/dl is a strong predictor of clinical deterioration at discharge in patients with acute ICA/M1O undergoing recanalization therapy.

One-year single-center experience with the Aperio thrombectomy device in large vessel occlusion in the anterior circulation: safety, efficacy, and clinical outcome.

BACKGROUND AND PURPOSE: The Aperio thrombectomy device (Aperio) is a stent retriever designed to achieve rapid and substantial flow restoration in acute ischemic stroke due to large-vessel occlusions (LVOs). We evaluated the safety and efficacy of the Aperio device and compared it with published data of established stent retrievers. METHODS: We retrospectively analyzed institutional data of consecutive stroke procedures in patients with LVO in the anterior circulation that were treated between January 2017 and December 2017 with the Aperio. Reperfusion rate regarding to the extended thrombolysis in cerebral infarction scale (eTICI), procedural times, early clinical outcome, and complications were documented. RESULTS: Eighty-two patients were treated by using the Aperio in LVO in the anterior circulation. Median age was 77 (± 12) years (w = 59.8%). Median Baseline National Institutes of Health Stroke Scale (NIHSS) score was 14. Fifty-three (64.6%) patients received intravenous thrombolysis. Successful recanalization (eTICI≥2b) was achieved in 85.3%. Mean time from groin puncture to final recanalization was 52.3 ± 34.8 min. Embolization to new territories occurred in one case. Symptomatic intracranial hemorrhage within 24 h was observed in six patients (7.3%). Twenty-eight (41.2%) out of 68 patients available for assessment of functional outcome at 3 months achieved favorable outcome (mRS 0-2). CONCLUSION: The Aperio stent retriever mechanical thrombectomy device demonstrated high rates of successful reperfusion and a good safety profile in patients with acute ischemic stroke due to LVO in the anterior circulation.

Impact of preaneurysmal M1 length in unruptured middle cerebral artery aneurysm: mid-term outcome and single-center experience.

OBJECTIVE: This study was design to investigate the surgical and functional outcome based on the preaneurysmal M1 length for unruptured MCA aneurysm. METHODS: Among 250 consecutive patients with unruptured aneurysms operated in our institution between 2015 and 2017, 72 were MCA aneurysms. Risk factors for IR (i.e., intraoperative rupture) were investigated including age, sex, preaneurysmal M1 length, maximal MCA aneurysm diameter, neck size, aneurysm shape, sphenoid ridge proximation sign. Outcome was measured at discharge, 1 yr and last follow-up. Outcome was compared according to the preaneurysmal M1 length. RESULTS: Among 68 patients included, five patients (7.3%) suffered IR. Mean maximal diameter of MCA aneurysm (7.9 mm ± 3.4 vs. 4.5 ± 1.8; p = 0.01) was significantly associated with IR risk. Mean M1 length seemed to be shorter in the IR group although not statistically significant (16.2 mm ± 5.1 vs. 11.5 mm ± 4.8; p = 0.053). Mid-term outcome was favorable for all patients at last follow-up but was worsen in case of short preaneurysmal M1 segment (10.7 mm ± 4.8 vs. 16.4 mm ± 5.3, p = 0.02). Complete aneurysm occlusion was achieved for sixty-nine patients (95.5%) with 6.9% of early postoperative complications. CONCLUSIONS: The microsurgical treatment of unruptured MCA aneurysm was associated with favorable mid-term outcome in all patients and high rates of complete occlusion. Aneurysm size was significantly associated with the intraoperative rupture risk for unruptured MCA aneurysm and patients with a short preaneurysmal M1 segment seemed to have a greater risk of intraoperative rupture although not statistically significant. Short preaneurysmal M1 patients had worsen mid-term outcome.

Mechanical thrombectomy in M1 and M2 segments of middle cerebral arteries: A meta-analysis of prospective cohort studies.

BACKGROUND: Recent studies indicate that endovascular therapy is superior to intravenous thrombolysis in treating M1 segment MCA occlusions, however, the effectiveness of mechanical thrombectomy in MI vs. M2 segment occlusions is unclear. METHODS: The meta-analysis was conducted by searching databases from January 2016 to January 2023, without language constraints. The quality of the studies was assessed using the Newcastle-Ottawa Scale. Pooled data analysis of outcomes, pre-existing medical comorbidities, and baseline scores were performed. RESULTS: Six prospective cohort studies with 6356 patients were included (4405 vs. 1638). Patients with M2 occlusion had a significantly lower mean baseline NIHSS at admission (MD: -2.14; 95 %CI: -3.48 to -0.81; p = 0.002). Conversely, patients with M1 occlusion had a lower ASPECTS at admission score (MD: 0.29; 95 %CI: 0.00-0.59; p = 0.05). No significant difference was found between segments in terms of pre-existing medical comorbidities (OR: 0.96; 95 %CI: 0.87-1.05; p = 0.36), mortality rate at 90 days (OR: 0.88; 95 %CI: 0.76-1.02; p = 0.10), and hemorrhage occurrence within 24-hours (OR: 1.06; 95 %CI: 0.89-1.25; p = 0.53). Patients with M2 occlusion were more likely to have good outcomes after therapy (OR: 1.18; 95 %CI: 1.05-1.32; p = 0.006). Successful recanalization rates were comparatively higher among patients with an M1 occlusion (OR: 0.79; 95 %CI: 0.68-0.92; p = 0.003). Functional outcomes at 90 days are better in M2 occlusion patients, while successful recanalization rates are higher in M1 occlusion patients. No significant differences were found in mortality rates or hemorrhage incidence. CONCLUSIONS: These results suggest that mechanical thrombectomy is a safe and effective treatment for MCA occlusions in both M1 and M2 segments.

Long Sylvian Approach for Proximal Middle Cerebral Artery Aneurysm.

This case involved a 66-year-old woman with unruptured proximal middle cerebral artery (MCA) aneurysm that had been found 4 years earlier and followed up with annual magnetic resonance imaging examinations. Considering several risk factors for rupture, such as increasing size and irregular shape of the aneurysm, we offered clipping surgery (Video 1). Preoperative 3-dimensional digital subtraction angiography demonstrated an irregularly shaped aneurysm 6 mm in maximum diameter with multiple daughter sacs. Preoperative magnetic resonance imaging clearly showed that the aneurysm dome was buried in the posterior orbital gyrus. Left pterional craniotomy was performed with a long-distance dissection through the sylvian fissure from the distal M2 segment of the MCA to the internal carotid artery to achieve proximal control. The irregularly shaped aneurysm was completely isolated from the circulation with multiple miniclips under motor evoked potential monitoring with a subdural electrode. Doppler ultrasonography and indocyanine green confirmed complete clipping and patent flow through the MCA bifurcation. Postoperative 3-dimensional computed tomography angiography confirmed no aneurysm filling, and diffusion-weighted imaging demonstrated no ischemic complications. Depending on the positional relationship of the aneurysm and limen insulae, different surgical procedures for head positioning, distance of Sylvian fissure dissection, and securing the site for proximal control are essential for safe clipping of MCA aneurysms.

Usefulness of Orbitocranial Approach in Neck Clipping of Aneurysms Arising from Middle Cerebral Artery Proximal to the Limen Insulae: A Case Series.

BACKGROUND: Neck clipping of the aneurysms arising from the middle cerebral artery (MCA) proximal to the limen insulae is often difficult because of difficulties in securing a bright and wide operative field to observe the aneurysms and surrounding structures, such as the anterior perforated substance, lenticulostriate arteries, and early frontal branch. Our objective was to determine the usefulness of the orbitocranial approach in neck clipping of the aneurysms arising from the MCA proximal to the limen insulae. METHODS: This prospective study included 7 patients who underwent neck clipping of aneurysms arising from the MCA proximal to the limen insulae through the orbitocranial approach. In addition to conventional pterional craniotomy, the superiolateral orbital rim was resected with a 1-piece fashion. Its procedures, complications, and outcomes were reviewed. RESULTS: Removal of the superolateral orbital rim facilitated a bright and wide observation from the skull base side. It was much easier to identify the anterior perforated substance, lenticulostriate arteries, and early frontal branch around the aneurysm through the orbitocranial approach than through the conventional pterional approach. Neck clipping could be performed completely and safely in all cases. CONCLUSIONS: The orbitocranial approach to aneurysms arising from the MCA proximal to the limen insulae provides us a bright and wide operative field compared with the conventional pterional approach, which is useful to secure complete and safe neck clipping by avoiding cerebral contusion and unexpected obstruction of the early frontal branch.

Mechanical thrombectomy in stroke patients with acute occlusion of the M1- compared to the M2-segment: Safety, efficacy, and clinical outcome.

PURPOSE: Endovascular treatment (ET) in occlusions of the M1- and proximal M2-segment of the middle cerebral artery (MCA) is an established procedure. In contrast, ET in distal M2-occlusions has not been sufficiently evaluated yet. The purpose of this study was to assess relevant parameters for clinical outcome, efficacy, and safety of patients undergoing ET in M1-, proximal M2-, and distal M2-occlusions. METHODS: One hundred seventy-four patients undergoing ET in acute ischemic stroke with an occlusion of the M1- or M2-segment of the MCA were enrolled prospectively. Non-parametric analysis of variance in 3-month mRS, TICI scale, and complication rates were performed with Kruskal-Wallis test between M1- and proximal and distal M2-occlusions. Subsequent pairwise group comparisons were calculated using Mann-Whitney U-tests. Binary logistic regression models were calculated for each occlusion site. RESULTS: There were no significant group differences in 3-month mRS, mTICI scale, or complication rates between M1- and M2-occlusions nor between proximal and distal M2-occlusions. Binary logistic regression in patients with M1-occlusions showed a substantial explanation of variance (NR2=0.35). NIHSS (p=0.009) and Maas Score as parameter for collateralization (p=0.01) appeared as significant contributing parameters. Binary logistic regression in M2-occlusions showed a high explanation of variance (NR2=0.50) of mRS but no significant factors. CONCLUSIONS: Clinical outcome and procedural safety of patients with M2-occlusions undergoing ET are comparable to those of patients with M1-occlusions. Clinical outcome of patients with M1-occlusions undergoing ET is primarily influenced by the initial neurological deficit and the collateralization of the occlusions. By contrast, clinical outcome in patients with M2-occlusions undergoing ET is more multifactorial.

Feasibility and safety of partial resection of the anterior insular cortex for microsurgical treatment of middle cerebral artery aneurysms located in the limen recess: patient series.

BACKGROUND: When performing clip ligation of superior projecting aneurysms of the proximal (M1) segment of the middle cerebral artery (MCA), meticulous sylvian fissure dissection alone may be inadequate for safe clip application, especially in cases in which the aneurysm is buried in the limen recess, since the limen insulae may be positioned lateral to the aneurysm. In the present patient series, the authors present their surgical technique for clip ligation of aneurysms located in the limen recess, with partial resection of the limen insulae. OBSERVATIONS: A retrospective analysis of patients who had undergone clip ligation of MCA aneurysms located at the limen recess at a single institute was performed. Patients with angiographic and clinical follow-up data were considered eligible. A total of 11 aneurysms (4 ruptured and 7 unruptured aneurysms) in 11 patients were evaluated. Postoperative ischemic lesions were observed on images obtained within 1 week after surgery in 5 (45.5%) patients who had undergone partial resection of the limen insulae, although none of them presented with neurological deterioration. LESSONS: Partial resection of limen insulae may be feasible to avoid severe ischemic complications following clip ligation of M1 aneurysms embedded in the limen recess.

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.

Mechanical thrombectomy in MCA-mainstem occlusion in patients with low NIHSS scores.

Introduction While effectiveness of mechanical thrombectomy (MTE) in M1 segment occlusion is approved for patients with severe impairment, there is a lack of evidence for a potential benefit of MTE in patients with minor to moderate symptoms. The purpose of this study was to evaluate neurological outcome and occurrence of periprocedural complications after MTE in patients with low National Institutes of Health Stroke Scale (NIHSS) scores. Materials and methods A retrospective analysis of 1081 consecutive patients with anterior circulation ischemic stroke due to M1 occlusion detected by computed tomography angiography and treated with MTE at our hospital between February 2012 and November 2017 was performed. NIHSS, Barthel Index (BI) and modified Rankin Scale (mRS) scores between admission and discharge were compared with paired Mann-Whitney test, and recanalization rate and complications were assessed in patients with NIHSS ≤ 5 at admission. Results Thirty patients were included with a median NIHSS score of 4. NIHSS score (median: 4 vs. 1; p < 0.001), BI (median: 43 vs. 80; p < 0.001) and mRS (2 vs. 1; p < 0.001) showed significant improvement from admission to discharge after MTE. Recanalization rate was Thrombolysis in Cerebral Infarction (TICI) 2b to 3 in 29 of 30 patients (96.7%). One case of an intracerebral reperfusion hematoma (ECASS: PH2) required surgical treatment. Conclusion MTE might lead to a significantly improved clinical outcome also for patients with low NIHSS score due to M1 segment occlusion. Periprocedural complications appeared infrequently. These results encourage further evaluation of the benefit-risk profile of MTE compared to standard treatment in patients with low NIHSS scores in future randomized trials.

A Comparison of Mechanical Thrombectomy in the M1 and M2 Segments of the Middle Cerebral Artery: A Review of 585 Consecutive Patients.

BACKGROUND: Mechanical thrombectomy for anterior-circulation large-vessel occlusion has shown benefit; however, the question of whether this technique is safe and effective in the distal vasculature remains unanswered. We sought to compare the outcome data from mechanical thrombectomy of the M2 branches of the middle cerebral artery (MCA) with those of the M1 segment. METHODS: We performed a retrospective analysis of prospectively collected data of patients with acute ischaemic stroke undergoing mechanical thrombectomy of isolated M1 or M2 branches of the MCA between August 2008 and August 2016. RESULTS: We identified 585 patients, 479 with M1 occlusions and 106 with M2 occlusions. The average age was 72 ± 12.8 and 68 ± 13.8 years, respectively (p = 0.007). The baseline Alberta Stroke Program Early Computed Tomographic (ASPECT) score was similar in both cohorts, but patients with M1 occlusions presented with higher mean National Institutes of Health Stroke Scale (NIHSS) scores of 15.7 compared to 11.8 (p < 0.001). There was no significant difference in the average procedure time for each cohort; fewer thrombectomy attempts were required in the M2 cohort (2.3 vs. 1.8, p = 0.0004), but the overall time to recanalization was longer in the M2 cohort (353 vs. 399 min, p < 0.001). Similar rates of successful reperfusion (Thrombolysis in Ischaemic Stroke score [TICI] ≥2b 88.5 vs. 90.5%, p = 0.612) were seen, but food outcome (modified Rankin Scale ≤2) was lower in M1 occlusions (37.2 vs. 54.3%, p < 0.001). Rates of symptomatic intracranial haemorrhage were similar. CONCLUSION: Good clinical outcomes can be achieved for both groups with no significant differences in procedure length, final TICI recanalization rates or intracranial haemorrhage between the M1 and M2 cohorts.

Aneurysms of The Middle Cerebral Artery Proximal Segment (M1) · Anatomical and Therapeutic Considerations · Revision of A Series. Analysis of a series of the pre bifurcation segment aneurysms.

Aneurysms of the middle cerebral artery represent almost a third of all the aneurysms of the circle of Willis anterior sector. Among them, those located at its so-called M1 segment (from its origin up to the bifurcation) range between 2% and 7% of all the aneurysms. It is highly important to know the anatomy of the M1 segment, as well as of the arterial branches that arise from it, since causing its damage during dissection or occlusion of an aneurysm may determine the neurological sequelae.The authors of the present work, based on a recent anatomical analysis carried out by one of them (FM), have performed a study of the aneurysms of the M1 segment in a series of 1059 aneurysms treated with surgery along 25 years. At the mentioned location 23 aneurysms were found, which represented 2.2% of the total operated aneurysms. The cases, location of the aneurysms and their relation with the early branches of the middle cerebral artery were studied, as well as the surgical difficulties that they pose.A review of the scanty bibliography referring specifically to the aneurysms in this topography has been carried out.