Review of Cerebral Collateral Circulation and Insight into Cardiovascular Strategies to Limit Collateral Damage in Ischemic Stroke

Cerebral collateral circulation is a dynamic and adaptive process by which alternative vascular pathways supply perfusion to ischemic brain tissue in the event of an arterial occlusion. This complicated network of blood vessels that acts as a natural bypass plays a pivotal role in stroke pathophysiology and has become a key area of study given its significance in stroke treatment and patient outcomes. In this review, we will study the factors influencing the formation, recruitment, and endurance of collateral vessels; discuss imaging modalities for quantitative and qualitative assessment of this network; explore the role of collaterals in stroke management; and highlight several cardiovascular strategies to minimize damage to collaterals and optimize stroke outcomes.

Endovascular thrombectomy for treatment of isolated posterior cerebral artery occlusion: a real-world analysis of hospitalizations in the United States

BACKGROUND

Despite renewed interest and recently demonstrated efficacy for endovascular thrombectomy (EVT) for treatment of acute ischemic stroke (AIS) of the posterior circulation, to date, no randomized clinical trials have been conducted to evaluate EVT for isolated occlusions of the posterior cerebral artery (IPCA).

METHODS

Hospitalizations for adult patients with primary admission diagnoses of IPCA occlusion were identified in the National Inpatient Sample registry during the period of 2016-2020. The study exposure was treatment with EVT, and primary clinical endpoints included favorable functional outcome (defined as discharge disposition to home without services, previously shown to have high concordance with modified Rankin scale scores 0-2), in-hospital mortality, and any intracranial hemorrhage (ICH). Inverse probability of treatment weighting (IPTW) was performed to balance baseline clinical characteristics between those receiving EVT or medical management (MM).

RESULTS

This analysis identified 34,880 IPCA occlusion hospitalizations, 730 (2.1%) of which documented treatment with EVT. Following IPTW adjustment, EVT was associated with favorable outcome in IPCA patients presenting with mild deficits (M-D) (NIHSS < 6) [adjusted odds ratio (aOR) 2.36, 95% confidence interval (CI) 2.27, 2.45; p < 0.001] and in those presenting with moderate-to-severe deficits (M-S-D) (NIHSS 6-42) (aOR 2.00, 95% CI 1.86, 2.15; p < 0.001). Mortality rates did not differ among those with M-S-D [EVT 4.8% vs. MM 4.7%, p = 0.742], while ICH rates were lower.

CONCLUSION

Retrospective analysis of a large administrative registry in the Unites States demonstrates an association of EVT with favorable outcomes following IPCA occlusion, without concomitant risk of hemorrhagic transformation or mortality.

Mobile Stroke Units in Acute Ischemic Stroke: A Comprehensive Systematic Review and Meta-Analysis of 5 "T Letter" Domains

Intravenous thrombolysis (IVT) may be administered to stroke patients requiring immediate treatment more quickly than emergency medical services if certain conditions are met. These conditions include the presence of mobile stroke units (MSUs) with on-site treatment teams and a computed tomography scanner. We compared clinical outcomes of MSU conventional therapy by emergency medical services through a systematic review and meta-analysis. We searched key electronic databases from inception till September 2021. The primary outcomes were mortality at 7 and 90 days. The secondary outcomes included the modified Rankin Scale score at 90 days, alarm to IVT or intra-arterial recanalization, and time from symptom onset or last known well to thrombolysis. We included 19 controlled trials and cohort studies to conduct our final analysis. Our comparison revealed that 90-day mortality significantly decreased in the MSU group compared with the conventional care group [risk ratio = 0.82; 95% confidence interval (CI), 0.71-0.95], while there was no significant difference at 7 days (risk ratio = 0.89; 95% CI, 0.69-1.15). MSU achieved greater functional independence (modified Rankin Scale = 0-2) at 90 days (risk ratio = 1.08; 95% CI, 1.01-1.16). MSU was associated with shorter alarm to IVT or intra-arterial recanalization time (mean difference = -29.69; 95% CI, -34.46 to -24.92), treating patients in an earlier time window, as shown through symptom onset or last known well to thrombolysis (mean difference = -36.79; 95% CI, -47.48 to -26.10). MSU-treated patients had a lower rate of 90-day mortality and better 90-day functional outcomes by earlier initiation of IVT compared with conventional care.

Effect of chronic antiplatelet therapy on clinical outcomes of endovascular thrombectomy for treatment of acute ischemic stroke

OBJECTIVE

The objective of this study was to investigate the prognostic significance of chronic antiplatelet therapy (APT) usage in acute ischemic stroke (AIS) treated with endovascular thrombectomy (EVT). Long-term APT may enhance recanalization but may also predispose patients to an increased risk of hemorrhagic transformation.

METHODS

Weighted hospitalizations for anterior-circulation AIS treated with EVT were identified in a large United States claims-based registry. Baseline clinical characteristics and outcomes were compared between patients with and without chronic APT usage prior to admission. Multivariable logistic regression analysis was performed to assess adjusted associations between APT and study endpoints.

RESULTS

This analysis identified 36,560 patients, of whom 8170 (22.3%) were on a chronic APT regimen prior to admission. These patients were older and demonstrated a higher burden of comorbid disease, but had similar stroke severity on presentation in comparison with those not on APT. On unadjusted analysis, patients with prior APT demonstrated higher rates of favorable outcomes (24.3% vs 21.5%, p < 0.001), lower rates of mortality (7.0% vs 10.1%, p < 0.001), and lower rates of any intracranial hemorrhage (ICH; 20.3% vs 24.2%, p < 0.001), but no difference in rates of symptomatic ICH (sICH). Following multivariable adjustment for baseline clinical characteristics including age, acute stroke severity, and comorbidity burden, prior APT was associated with favorable outcome (adjusted odds ratio [aOR] 1.21, 95% CI 1.17-1.24, p < 0.001) and a lower likelihood of mortality (aOR 0.73, 95% CI 0.70-0.77, p < 0.001), without an increased likelihood of ICH (any ICH aOR 0.84, 95% CI 0.81-0.87, p < 0.001; sICH aOR 0.92, 95% CI 0.82-1.03, p = 0.131).

CONCLUSIONS

Retrospective evaluation of patients with AIS treated with EVT using registry-based data demonstrated an association of prior APT usage with favorable outcomes, without an increased risk of hemorrhagic transformation.

Intravenous thrombolysis plus mechanical thrombectomy versus mechanical thrombectomy alone for acute ischemic stroke: A systematic review and updated meta-analysis of clinical trials

BACKGROUND

Mechanical thrombectomy (MT) is the gold standard treatment for large vessel occlusion (LVO). A vital factor that might influence MT outcomes is the use of intravenous thrombolysis (IVT). A few clinical trials in this domain thus far have not yielded consistent outcomes. We conducted this meta-analysis to synthesize collective evidence in this regard.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement guidelines were followed, and we performed a comprehensive literature search of four databases (PubMed, Scopus, Web of Science, Cochrane CENTRAL). For outcomes constituting continuous data, the mean difference (MD) and its standard deviation (SD) were pooled. For outcomes constituting dichotomous data, the frequency of events and the total number of patients were pooled as the risk ratio (RR).

RESULTS

Seven clinical trials with a total of 2317 patients are included in this meta-analysis. Six trials are randomized, and one trial was nonrandomized. No significant differences were found between MT plus IVT and MT alone in successful recanalization (RR 1.04, 95% Confidence Interval (CI) [0.92 to 1.17], P = 0.53), 90-day functional independence (RR 1.03, 95% CI [0.90 to 1.19], P = 0.65), symptomatic intracranial hemorrhage (sICH) (RR 1.22, 95% CI [0.84 to 1.75], P = 0.30), or mortality (RR 0.94, 95% CI [0.76 to 1.18], P = 0.61).

CONCLUSION

The current evidence does not favor either MT plus IVT or MT alone for LVO except for the procedural time. More trials are needed in this regard, and certain factors should be considered when comparing the two approaches.

Trajectories of Neurologic Recovery 12 Months After Hospitalization for COVID-19: A Prospective Longitudinal Study

BACKGROUND AND OBJECTIVE

Little is known about trajectories of recovery 12 months after hospitalization for severe COVID-19.

METHODS

We conducted a prospective, longitudinal cohort study of patients with and without neurologic complications during index hospitalization for COVID-19 from March 10, 2020, to May 20, 2020. Phone follow-up batteries were performed at 6 and 12 months after COVID-19 onset. The primary 12-month outcome was the modified Rankin Scale (mRS) score comparing patients with or without neurologic complications using multivariable ordinal analysis. Secondary outcomes included activities of daily living (Barthel Index), telephone Montreal Cognitive Assessment (t-MoCA), and Quality of Life in Neurologic Disorders (Neuro-QoL) batteries for anxiety, depression, fatigue, and sleep. Changes in outcome scores from 6 to 12 months were compared using nonparametric paired-samples sign test.

RESULTS

Twelve-month follow-up was completed in 242 patients (median age 65 years, 64% male, 34% intubated during hospitalization) and 174 completed both 6- and 12-month follow-up. At 12 months, 197/227 (87%) had ≥1 abnormal metric: mRS >0 (75%), Barthel Index <100 (64%), t-MoCA ≤18 (50%), high anxiety (7%), depression (4%), fatigue (9%), or poor sleep (10%). Twelve-month mRS scores did not differ significantly among those with (n = 113) or without (n = 129) neurologic complications during hospitalization after adjusting for age, sex, race, pre-COVID-19 mRS, and intubation status (adjusted OR 1.4, 95% CI 0.8-2.5), although those with neurologic complications had higher fatigue scores (T score 47 vs 44; p = 0.037). Significant improvements in outcome trajectories from 6 to 12 months were observed in t-MoCA scores (56% improved, median difference 1 point; p = 0.002) and Neuro-QoL anxiety scores (45% improved; p = 0.003). Nonsignificant improvements occurred in fatigue, sleep, and depression scores in 48%, 48%, and 38% of patients, respectively. Barthel Index and mRS scores remained unchanged between 6 and 12 months in >50% of patients.

DISCUSSION

At 12 months after hospitalization for severe COVID-19, 87% of patients had ongoing abnormalities in functional, cognitive, or Neuro-QoL metrics and abnormal cognition persisted in 50% of patients without a history of dementia/cognitive abnormality. Only fatigue severity differed significantly between patients with or without neurologic complications during index hospitalization. However, significant improvements in cognitive (t-MoCA) and anxiety (Neuro-QoL) scores occurred in 56% and 45% of patients, respectively, between 6 and 12 months. These results may not be generalizable to those with mild or moderate COVID-19.

Modafinil in Recovery after Stroke (MIRAS): A Retrospective Study

BACKGROUND AND PURPOSE

Acute rehabilitation is known to enhance stroke recovery. However, poststroke lethargy and fatigue can hinder participation in rehabilitation therapies. We hypothesized that in patients with moderate to severe stroke complicated by poststroke fatigue and lethargy early stimulant therapy with modafinil increases favorable discharge disposition defined as transfer to acute inpatient rehabilitation or home.

METHODS

We retrospectively reviewed a cohort of patients with acute stroke admitted to the stroke service over a 3-year period. All patients 18 years or older with confirmed ischemic or hemorrhagic stroke, an NIHSS greater than or equal to 5 and documentation of fatigue/lethargy in clinical documentation were included. We compared patients that were treated with modafinil 50-200 mg to those managed with standard care. The primary outcome measure was discharge disposition. Secondary outcome was 90 day modified Rankin score (mRS). Statistical significance was determined using chi-square test for association and logistic regression models. Logistic regression models were derived in 2 ways with both raw data and an adjusted model that accounted for age, sex, and NIHSS score to account for the lack of randomization.

RESULTS

This study included 199 stroke patients (145 ischemic, 54 hemorrhagic). Seventy-two (36.2%) were treated with modafinil and 129 (64.8%) were discharged to acute inpatient rehabilitation, while none were recommended for discharge home. Median NIHSS for modafinil patients was 13.5 versus 11 for standard care patients (P = .059). In adjusted models, modafinil was associated with higher odds of favorable discharge disposition (OR 2.00, 95% CI 1.01-3.95). Favorable outcome at 90 days defined as mRS less than or equal to 2 occurred more frequently with modafinil (5.6% versus 3.3%) but this did not achieve statistical significance (P > .1). These results occurred despite the modafinil group requiring longer ICU stays and having more in-hospital complications such as infections and need for percutaneous gastrostomy tubes. The benefit of modafinil was seen across all subgroups except those with severe stroke (NIHSS ≥ 15). There were no significant adverse events associated with modafinil administration.

CONCLUSIONS

Modafinil use in acute in-hospital stroke patients with moderate stroke complicated by lethargy and fatigue was associated with improved discharge disposition. Randomized controlled trials are needed to further study the safety, efficacy, and long-term effects of modafinil in this patient population.

Abstract WP381: Modafinil in Recovery After Stroke: A Retrospective Study

Background: Acute rehabilitation is known to enhance stroke recovery. However, post-stroke lethargy and fatigue can hinder participation in rehabilitation therapies. We hypothesized that in patients with moderate to severe stroke, early stimulant therapy with modafinil increases favorable discharge disposition defined as transfer to acute rehabilitation.

Methods: We retrospectively reviewed a cohort of patients with acute stroke admitted over a 3 year period. Patients were excluded for low NIH Stroke Scale score (below 5) or absence of confirmed stroke on brain imaging. We compared patients that were treated with modafinil 50-200mg to those managed with standard care. The primary outcome measure was discharge disposition. Secondary outcome was modified Rankin Score after discharge. Statistical significance was determined using chi-square test for association and logistic regression models.

Results: The study cohort included 199 patients (145 ischemic, 54 hemorrhagic). 72 (36.2%) were treated with modafinil and 129 (64.8%) were discharged to acute rehab. Median NIHSS for modafinil patients vs standard care patients was higher but did not reach statistical significance (median (IQR): 13.5 (15) vs 11 (10), p=0.059). In adjusted models, modafinil was associated with higher odds of favorable discharge disposition (OR 2.00, 95% CI 1.01-3.95). Favorable outcome at 90 days (mRS ≤ 2) occurred more frequently with modafinil (5.6% vs. 3.3%) but this did not achieve statistical significance (p>0.1). The benefit of modafinil was seen across all subgroups of patients, except those with severe stroke (NIHSS > 15). There were no significant complications clearly linked to modafinil administration.

Conclusions: Modafinil use in acute stroke patients with moderate to severe stroke was associated with improved discharge disposition. Randomized controlled trials are needed to further study the safety, efficacy, and long-term effects of modafinil in this population.