Clinical improvement within 24 hours from mechanical thrombectomy as a predictor of long-term functional outcome in a multicenter population-based cohort of patients with ischemic stroke.

BACKGROUND: Single-center studies have suggested that the early clinical course after mechanical thrombectomy (MT) in patients with ischemic stroke is a clinical predictor of long-term outcome. OBJECTIVE: To analyze the prognostic value of clinical improvement within 24 hours in a population-based multicenter cohort. METHODS: From a total of 3792 patients with acute ischemic stroke in Catalonia (CICAT registry), 1951 patients were treated with MT. The National Institutes of Health Stroke Scale (NIHSS) score within 24 hours, and follow-up was available in 1666 patients. Percentage variation in the NIHSS score was calculated in relation to a baseline assessment. Good outcome was defined as a modified Rankin Scale score ≤2 at 90 days. Predictive values of clinical improvement and adjusted OR to predict good outcomes were assessed in the whole cohort and the subgroup of patients with posterior circulation stroke (n=166). RESULTS: Good outcome was achieved in 656/1666 patients (39%) overall. Percentage improvements both at the end of MT and at 24 hours predicted good outcome, with higher predictive capacity at 24 hours (C-statistic, 0.85 vs 0.73, p<0.001). Positive and negative predictive values were 70% and 74% for the >30% cut-off point at the end of MT, and 69% and 84% for the >50% cut-off point at 24 hours, respectively. The adjusted OR for good outcome was 5.8 (95% CI 4.2 to 8.1) and 12.9 (95% CI 9.7 to 17.1), respectively. In patients with posterior circulation stroke, the predictive value of the improvement at 24 hours was similar (C-statistic 0.90). CONCLUSION: Clinical improvement of patients within 24 hours of MT is a reliable and robust predictor of long-term prognosis, including patients with posterior circulation occlusions.

Benefit from mechanical thrombectomy in acute ischemic stroke with fast and slow progression.

OBJECTIVE: The rate of progression of the ischemic lesion is variable in patients with stroke. We tested the hypothesis that the tissue saving effect of mechanical thrombectomy (MT) is greater in fast progressors. METHODS: A single-center cohort of consecutive patients (n=242) with occlusions of the terminal internal carotid or M1 segment of the middle cerebral artery treated with MT (n=195) or best medical treatment (n=47), known time from onset, and full imaging (baseline CT perfusion and follow-up MRI) available was studied. The estimated infarct progression rate (eIPR) was calculated at baseline and patients were categorized as fast/slow progressors according to the median eIPR of 4.8 mL/hour. The primary outcome measure was the interaction between eIPR category and MT on infarct growth. The secondary outcomes assessed the effect of MT on final infarct volume and functional status in relation to the eIPR category. The safety outcomes were mortality and symptomatic intracranial hemorrhage. RESULTS: The eIPR category had a modifying effect (Pi=0.017) of MT on infarct growth that was significantly reduced with MT only in fast progressors (median (IQR) 3.8 mL (-11-55) vs 41 mL (11-107) with medical treatment; p=0.009, adjusted p=0.045). There was also a significant interaction on final infarct volume (Pi=0.005), with a greater reduction after MT in fast progressors. The functional status improved with MT both in fast and slow progressors, with no significant modifying effect of eIPR category (Pi=0.201). There were also no significant interactions on safety outcomes. CONCLUSION: MT in stroke patients with large vessel occlusion limits infarct growth more significantly in fast progressors.

Greater infarct growth limiting effect of mechanical thrombectomy in stroke patients with poor collaterals.

OBJECTIVE: Stroke patients with good collateral circulation achieve the best recovery after mechanical thrombectomy (MT) but strict imaging selection may result in untreated patients that could benefit from MT. We assessed whether the extent of collaterals had modifying effects on the amount of ischemic tissue saved from infarction with MT over best medical treatment (BMT). METHODS: This was a single center cohort of consecutive patients (n=339) with proximal occlusions in the carotid territory. Patients were categorized according to a four point category scale on CT angiography as having good (scores 2-3) or poor (scores 0-1) collaterals. The primary outcome measure was the interaction between collaterals and MT on infarct growth. The secondary outcome assessed the treatment effect of MT over BMT on functional status in relation to collateral status. Safety outcomes were mortality and symptomatic intracranial hemorrhage. RESULTS: Collaterals had a modifying effect of MT on infarct growth (P=0.004), with a greater reduction in 96 patients with poor collaterals (38.8 mL) than in 243 patients with good collaterals (1.9 mL). There was also a significant (P<0.001) interaction between the effect of MT and functional outcome in relation to collateral status, with more benefits of MT in patients with poor collaterals. MT was associated with lower mortality than BMT in patients with poor collaterals only. CONCLUSION: Compared with BMT, the use of MT in the early time window in large vessel stroke results in a more substantial limitation of infarct growth in patients with poor collaterals.

Improved Framework for Tractography Reconstruction of the Optic Radiation.

The optic radiation (OR) is one of the major components of the visual system and a key structure at risk in white matter diseases such as multiple sclerosis (MS). However, it is challenging to perform track reconstruction of the OR using diffusion MRI due to a sharp change of direction in the Meyer's loop and the presence of kissing and crossing fibers along the pathway. As such, we aimed to provide a highly precise and reproducible framework for tracking the OR from thalamic and visual cortex masks. The framework combined the generation of probabilistic streamlines by high order fiber orientation distributions estimated with constrained spherical deconvolution and an automatic post-processing based on anatomical exclusion criteria (AEC) to compensate for the presence of anatomically implausible streamlines. Specifically, those ending in the contralateral hemisphere, cerebrospinal fluid or grey matter outside the visual cortex were automatically excluded. We applied the framework to two distinct high angular resolution diffusion-weighted imaging (HARDI) acquisition protocols on one cohort, comprised of ten healthy volunteers and five MS patients. The OR was successfully delineated in both HARDI acquisitions in the healthy volunteers and MS patients. Quantitative evaluation of the OR position was done by comparing the results with histological reference data. Compared with histological mask, the OR reconstruction into a template (OR-TCT) was highly precise (percentage of voxels within the OR-TCT correctly defined as OR), ranging from 0.71 to 0.83. The sensitivity (percentage of voxels in histological reference mask correctly defined as OR in OR-TCT) ranged from 0.65 to 0.81 and the accuracy (measured by F1 score) was 0.73 to 0.77 in healthy volunteers. When AEC was not applied the precision and accuracy decreased. The absolute agreement between both HARDI datasets measured by the intraclass correlation coefficient was 0.73. This improved framework allowed us to reconstruct the OR with high reliability and accuracy independently of the acquisition parameters. Moreover, the reconstruction was possible even in the presence of tissue damage due to MS. This framework could also be applied to other tracts with complex configuration.

Oblique triangular neurovascular osteocutaneous flap for hook nail deformity correction.

Hook nail deformity results in aesthetic and functional problems after fingertip amputations. Previously described techniques do not correct the osseous defect, which may be the principle cause of the problem. We present a surgical technique based on a compound homodigital advancement flap combining bone of the distal phalanx, finger pulp, and skin. We describe this technique, report a case, and discuss the advantages over former techniques.