Preserved Corticospinal Tract Revealed by Acute Perfusion Imaging Relates to Better Outcome After Thrombectomy in Stroke

Abstract

BACKGROUND: The indication for mechanical thrombectomy (MT) in stroke patients with large vessel occlusion has been constantly expanded over the past years. Despite remarkable treatment effects at the group level in clinical trials, many patients remain severely disabled even after successful recanalization. A better understanding of this outcome variability will help to improve clinical decision-making on MT in the acute stage. Here, we test whether current outcome models can be refined by integrating information on the preservation of the corticospinal tract as a functionally crucial white matter tract derived from acute perfusion imaging. METHODS: We retrospectively analyzed 162 patients with stroke and large vessel occlusion of the anterior circulation who were admitted to the University Medical Center Lübeck between 2014 and 2020 and underwent MT. The ischemic core was defined as fully automatized based on the acute computed tomography perfusion with cerebral blood volume data using outlier detection and clustering algorithms. Normative whole-brain structural connectivity data were used to infer whether the corticospinal tract was affected by the ischemic core or preserved. Ordinal logistic regression models were used to correlate this information with the modified Rankin Scale after 90 days. RESULTS: The preservation of the corticospinal tract was associated with a reduced risk of a worse functional outcome in large vessel occlusion–stroke patients undergoing MT, with an odds ratio of 0.28 (95% CI, 0.15–0.53). This association was still significant after adjusting for multiple confounding covariables, such as age, lesion load, initial symptom severity, sex, stroke side, and recanalization status. CONCLUSIONS: A preinterventional computed tomography perfusion–based surrogate of corticospinal tract preservation or disconnectivity is strongly associated with functional outcomes after MT. If validated in independent samples this concept could serve as a novel tool to improve current outcome models to better understand intersubject variability after MT in large vessel occlusion stroke.

The lesion core extent modulates the impact of early perfusion mismatch imaging on outcome variability after thrombectomy in stroke

“…Complete clinical and demographical data, including the mRS 90 days after stroke, were accessible in 190 patients included in the final analysis ( Figure 1 ). The same cohort was studied in a separate analysis evaluating white matter disconnectivity based on pre-interventional perfusion imaging ( 21 ). The clinical and demographic characteristics of the study cohort are presented in Table 1 .…”

“…Thus, it is plausible that it is not solely the volume itself but the implicated anatomical regions, which most accurately reflect associations with functional outcomes. In this context, we have recently introduced the functional significance of the preserved corticospinal tract based on CTP for functional outcomes after MT ( 21 ).…”

“…Additional neuroradiological and clinical markers are known to be related to functional outcome which were not included as cofactors in the presented analysis. Here, the collateral status ( 34 ), lesion water uptake ( 35 ), the time between imaging and reperfusion ( 36 ), and affection of essential white matter pathways ( 21 ) relate to the functional outcome and might add complexity to the presented statistical models. Furthermore, the premorbid mRS might significantly affect the post-MT outcome and was not accessible in the retrospective clinical data.…”

Altered functional connectivity between cortical premotor areas and the spinal cord in chronic stroke

“…Structural 2 and functional imaging 3,4 have built a robust body of evidence showing how acute stroke lesions affect brain activation and multi-site communication patterns as well as the structural integrity of the human motor network and its key areas and interconnecting pathways comprising the primary motor cortices (M1), frontal secondary motor areas including the ventral premotor cortex (PMV), and the supplementary motor area (SMA), subcortical brain regions, and the cerebellum. The corticospinal tract (CST), as the main outflow system of the motor network, has been mostly addressed structurally at various cerebral levels via lesion load 5 , fibre count 6,7 and diffusion-imaging based analyses of white matter microstructure 2,8 . Recently, advanced structural MRI extended the field of view towards the brain stem and the cervical spinal cord regarding structural CST alterations 9 .…”

Frontoparietal structural network disconnections correlate with outcome after a severe stroke

“…Here, profiles of single regions disconnected from larger brain networks, and profiles of disturbed interconnecting pathways at a pairwise region-to-region level have been found to carry relevant information 12 . Treatment-related insights have been provided by assessing effects of thrombolysis onto network disconnections 19 and topology 20 , or the influence of tract-specific disconnections before thrombectomy for outcome inference 21 . As one important limitation however, at least some of these disconnectome analyses have primarily focused on patients with rather mild to moderate deficits with initial National Institutes of Health Stroke Scale (NIHSS) scores ranging between 1 and 3 7,11,13,18 or up to 7 12,20 .…”