Electrical impedance measurements can identify red blood cell-rich content in acute ischemic stroke clots ex vivo associated with first-pass successful recanalization.

Background: Electrochemical impedance spectroscopy can determine characteristics such as cell density, size, and shape. The development of an electrical impedance-based medical device to estimate acute ischemic stroke (AIS) clot characteristics could improve stroke patient outcomes by informing clinical decision making. Objectives: To assess how well electrical impedance combined with machine learning identified red blood cell (RBC)-rich composition of AIS clots ex vivo, which is associated with a successfully modified first-pass effect. Methods: A total of 253 clots from 231 patients who underwent thrombectomy in 5 hospitals in France, Japan, Serbia, and Spain between February 2021 and October 2023 were analyzed in the Clotbase International Registry. Electrical impedance measurements were taken following clot retrieval by thrombectomy, followed by Martius Scarlet Blue staining. The clot components were quantified via Orbit Image Analysis, and RBC percentages were correlated with the RBC estimations made by the electrical impedance machine learning model. Results: Quantification by Martius Scarlet Blue staining identified RBCs as the major component in clots (RBCs, 37.6%; white blood cells, 5.7%; fibrin, 25.5%; platelets/other, 30.3%; and collagen, 1%). The impedance-based RBC estimation correlated well with the RBC content determined by histology, with a slope of 0.9 and Spearman's correlation of r = 0.7. Clots removed in 1 pass were significantly richer in RBCs and clots with successful recanalization in 1 pass (modified first-pass effect) were richer in RBCs as assessed using histology and impedance signature. Conclusion: Electrical impedance estimations of RBC content in AIS clots are consistent with histologic findings and may have potential for clinically relevant parameters.

The reversed umbrella: displacement of a Contour device into an MCA aneurysm 18 months after treatment.

SummaryThe Contour is a promising new device designed to treat large-neck intra-cranial aneurysms. We describe a first case of Contour device displacement 18 months after initial treatment.A patient with a 10 mm unruptured right middle cerebral artery bifurcation aneurysm was treated with a 9 mm Contour. The device was correctly positioned at the neck during treatment and at the 6 month angiography follow-up. At 18 months follow-up we noticed a full displacement of the device into the aneurysm dome. The Contour had a reversed shape and the aneurysm was still fully opacified. No neurological event occurred during the whole follow-up. Contour may be a promising tool but needs to be assessed over a long-term period.

Rescue intracranial permanent stenting for refractory occlusion following thrombectomy: a propensity matched analysis.

BACKGROUND: Rescue intracranial stenting (RIS) can be used in refractory large vessel occlusion (LVO) after mechanical thrombectomy (MT). We aimed to assess the safety and efficacy of RIS versus a propensity matched sample of patients with persistent LVO. METHODS: We retrospectively analysed a multicenter retrospective pooled cohort of patients with anterior LVO (2015-2021) treated with MT, and identified patients with at least three passes and a modified Thrombolysis In Cerebral Infarction (mTICI) score of 0 to 2a. Propensity score matching was used to account for determinants of outcome in patients with or without RIS. The study outcomes included 3 months modified Rankin Scale (mRS) and symptomatic hemorrhagic transformation (HT). RESULTS: 420 patients with a refractory anterior occlusion were included, of which 101 were treated with RIS (mean age 69 years). Favorable outcome (mRS 0-2) was more frequent in patients with a patent stent at day 1 (53% vs 6%, P<0.001), which was independently associated with an early dual antiplatelet regimen (P<0.05). In the propensity matched sample, patients treated with RIS versus without RIS had similar rates of favorable outcomes (36.8% vs 30.3%, P=0.606). Patients with RIS showed a favorable shift in the overall mRS distributions (common adjusted OR 0.74, 95% CI 0.60 to 0.91, P=0.006). Symptomatic HT was marginally more frequent in the RIS group (9% vs 3%, P=0.07), and there was no difference in 3-month mortality. CONCLUSION: In selected patients with a refractory intracranial occlusion despite at least three thrombectomy passes, RIS may be associated with an overall shift towards more favorable clinical outcome, and no significant increase in the odds of symptomatic HT or death.

Antithrombotic therapies for neurointerventional surgery: a 2021 French comprehensive national survey.

BACKGROUND: Neurointerventionists lack guidelines for the use of antithrombotic therapies in their clinical practice; consequently, there is likely to be significant heterogeneity in antithrombotic use between centers. Through a nationwide survey, we aimed to obtain an exhaustive cross-sectional overview of antithrombotic use in neurointerventional procedures in France. METHODS: In April 2021, French neurointerventional surgery centers were invited to participate in a nationwide 51-question survey disseminated through an active trainee-led research collaborative network (the JENI-RC). RESULTS: All 40 centers answered the survey. Fifty-one percent of centers reported using ticagrelor and 43% used clopidogrel as premedication before intracranial stenting. For flow diversion treatment, dual antiplatelet therapy was maintained for 3 or 6 months in 39% and 53% of centers, respectively, and aspirin was prescribed for 12 months or more than 12 months in 63% and 26% of centers, respectively. For unruptured aneurysms, the most common heparin bolus dose was 50 IU/kg (59%), and only 35% of centers monitored heparin activity for dose adjustment. Tirofiban was used in 64% of centers to treat thromboembolic complications. Fifteen percent of these comprehensive stroke centers reported using tenecteplase to treat acute ischemic strokes. Cangrelor appeared as an emergent drug in specific indications. CONCLUSION: This nationwide survey highlights the important heterogeneity in clinical practices across centers. There is a pressing need for trials and guidelines to further evaluate and harmonize antithrombotic regimens in the neurointerventional field.

Leptomeningeal enhancement on post-contrast FLAIR images for early diagnosis of Susac syndrome.

BACKGROUND: Leptomeningeal enhancement (LME) is a key feature of Susac syndrome (SuS) but is only occasionally depicted on post-contrast T1-weighted images (T1-WI). OBJECTIVE: As post-contrast fluid-attenuated inversion recovery (FLAIR) may be more sensitive, our aim was to assess LME in SuS on this sequence. METHODS: From 2010 to 2020, 20 patients with definite SuS diagnosis were retrospectively enrolled in this multicentre study. Two radiologists independently assessed the number of LME on post-contrast FLAIR and T1-WI acquisitions performed before any treatment. A chi-square test was used to compare both sequences and the interrater agreement was calculated. RESULTS: Thirty-five magnetic resonance imagings (MRIs) were performed before treatment, including 19 post-contrast FLAIR images in 17 patients and 25 post-contrast T1-WI in 19 patients. In terms of patients, LME was observed on all post-contrast FLAIR, contrary to post-contrast T1-WI (17/17 (100%) vs. 15/19 (79%), p < 0.05). In terms of sequences, LME was observed on all post-contrast FLAIR, contrary to post-contrast T1-WI (19/19 (100%) vs. 16/25 (64%), p < 0.005). LME was disseminated at both supratentorial (19/19) and infratentorial (18/19) levels on post-contrast FLAIR, contrary to post-contrast T1-WI (3/25 and 9/25, respectively). Interrater agreement was excellent for post-contrast FLAIR (κ = 0.95) but only moderate for post-contrast T1-WI (κ = 0.61). CONCLUSION: LME was always observed and easily visible on post-contrast FLAIR images prior to SuS treatment. In association with other MRI features, it is highly indicative of SuS.

Flow diversion for internal carotid artery aneurysms with compressive neuro-ophthalmologic symptoms: clinical and anatomical results in an international multicenter study.

BACKGROUND: Scientific data on the safety and efficacy of flow diverter stents (FDS) for the treatment of unruptured internal carotid artery (ICA) aneurysms with compressive neuro-ophthalmological symptoms are scarce. We studied this subject in a retrospective international multicenter series, pooling data of 9 tertiary care neurointerventional departments. OBJECTIVE: To investigate, in a retrospective, multicentric cohort of patients presenting with visual or oculomotor symptoms attributed to a compressive carotid artery in an unruptured intracranial aneurysm, the safety and efficacy profiles of FDS, by analyzing neuro-opthalmologic symptom evolution following FDS placement, complications, and aneurysm obliteration rates. METHODS: All patients treated since 2015 with a FDS for an unruptured aneurysm of the ICA with signs of compressive cranial nerve symptoms (CN II, III, IV, VI) were included. RESULTS: We treated 55 patients with 55 aneurysms; 21 (38.2%) patients had oculomotor and 15 (27.3%) visual symptoms only; 19 (34.5%) presented with a combination of both. Treatment-related morbidity/mortality occurred in 7.2% and 3.6%, respectively. At last imaging follow-up (13.1±10.5 months) rates of complete aneurysm occlusion, neck remnant, and aneurysm remnant were 72%, 14%, and 14%, respectively. At last clinical follow-up after 13±10.5 months, 19/51 (37.3%) patients had recovered completely and 18/51 (35.3%) had recovered at least partially from their neuro-ophthalmological symptoms. In multivariable models, a longer delay between symptom onset and treatment was associated with higher odds for incomplete recovery and lower odds for any improvement (aOR 1.03 (95% CI 1.01 to 1.07), p=0.047 and 0.04 (0-0.81), p=0.020). Incomplete recovery was independently associated with older age and fusiform aneurysms. CONCLUSION: FDS are effective to treat patients with compressive aneurysms of the ICA causing neuro-ophthalmological symptoms, especially when treatment is initiated early after symptom onset, and aneurysm occlusion is adequate. However, serious complications are not rare.

Absence of susceptibility vessel sign is associated with aspiration-resistant fibrin/platelet-rich thrombi.

BACKGROUND: The composition of the thrombus influences its retrievability by mechanical thrombectomy. PURPOSE: Our study aimed to report on thrombi resistant to aspiration, regarding susceptibility vessel sign and histologic composition. METHODS: This observational study was based on a prospective database of acute anterior circulation ischemic strokes treated by mechanical thrombectomy. Endovascular first-line strategy was aspiration and in case of failure, combined therapy-rescue was performed. The positivity of susceptibility vessel sign (SVS+) or its negativity (SVS-) was assessed on T2* sequences. The thrombus composition was analyzed with hematoxylin eosin staining. RESULTS: Histological analysis was performed on 102 clots. Thrombi with SVS- were significantly richer in fibrin/platelets, p = 0.04. Out of 210 mechanical thrombectomy, aspiration first pass strategy was performed in 131/210 (62%) patients. Combined therapy-rescue was needed in 37% of aspiration first pass strategy cases (n = 131). Clots retrieved combined therapy-rescue were richer in fibrin/platelets 63.9% versus 50.8% for aspiration first pass strategy, p = 0.03. Logistic regression analysis showed that fibrin/platelet-poor clots (<60%) were significantly more likely to be recanalized by aspiration first pass strategy compared to fibrin/platelet-rich clots (>60%) that were more likely recanalized by combined therapy-rescue after aspiration first pass strategy failure (OR = 3.5; 95% CI = 1.2-10.8; p = 0.0054). CONCLUSIONS: Our results confirm that SVS- clots are rich in fibrin/platelets and suggest that these "white clots" are less likely to be retrieved by aspiration alone and more often require the use of combined therapy.

What is the Relevance of the Systematic Use of Gadolinium During the MRI Follow-Up of Multiple Sclerosis Patients Under Natalizumab?

BACKGROUND: Multiple sclerosis (MS) patients represent a population potentially affected by the intracerebral accumulation of gadolinium-based contrast agents (GBCA) due to repeated magnetic resonance imaging (MRI) performed during their lifetime; however, MRI is still the best tool to monitor MS inflammatory activity. OBJECTIVE: This study aimed to evaluate the relevance of GBCA injections during the MRI follow-up of MS patients under natalizumab (Tysabri) treatment. METHODS: The MRI data results were retrospectively reviewed in a monocentric study (University Hospital of Toulouse, France) from all consecutive patients treated with natalizumab from January 2014 to January 2017. For each examination during the whole MRI follow-up, new lesions (enhancing and non-enhancing) were analyzed. RESULTS: A total of 129 patients were included in this study (65% female, mean age = 41 years, mean treatment duration 6.5 years, 50% positive for John Cunningham virus) and benefited from 735 MRIs with GBCA. Only 3 MRIs showed a new enhancing lesion, systematically encountered after treatment discontinuation. CONCLUSION: According to this study based on the clinical and radiological practice, the systematic use of GBCA seems of limited relevance in the MRI follow-up of asymptomatic patients treated continuously with natalizumab.

Predictive Value of Susceptibility Vessel Sign for Arterial Recanalization and Clinical Improvement in Ischemic Stroke.

Background and Purpose- Our goal was to evaluate whether the presence of a low signal intensity known as susceptibility vessel sign (SVS) on T2*-gradient echo imaging sequence was predictive of arterial recanalization and the early clinical improvement after mechanical thrombectomy. Methods- This observational study was based on a prospective database of acute ischemic strokes treated by mechanical thrombectomy. Inclusion criteria were patients with acute anterior ischemic stroke, diagnosed by magnetic resonance imaging, including a T2*-gradient echo imaging sequence, and treated by mechanical thrombectomy. Two independent readers assessed the presence of an SVS. Successful recanalization was defined as a Thrombolysis in Cerebral Infarction score of 2b-3 after mechanical thrombectomy. Early clinical improvement was estimated by the difference between the baseline National Institutes of Health Stroke Scale and the National Institutes of Health Stroke Scale on day 1 after treatment Results- The SVS was detected in 137 (76%) out of 180 patients. The kappa interrater agreement was 0.71 with a 95% CI of 0.59 to 0.82. Successful recanalization was associated with an SVS+ with odds ratio, 2.48; 95% CI, 1.05-5.74; P=0.03. The early clinical improvement was better in patients with an SVS+ (median, -6; interquartile range, -11 to 0) compared with SVS- patients (median, -1; interquartile range, -10 to 3) with P=0.01. Conclusions- The visualization of SVS is a reliable and easily accessible predictive factor of recanalization success and early clinical improvement.