Provider Impressions of Inpatient Teleneurology Consultation.

Background and Objectives: Teleneurology usage has increased during the severe acute respiratory syndrome coronavirus 2 pandemic. However, studies evaluating physician impressions of inpatient teleneurology are limited. We implemented a quality improvement initiative to evaluate neurologists' impression following individual inpatient teleneurology consultation at a satellite hospital of a large academic center with no in-person neurology coverage. Methods: A REDCap survey link was embedded within templates used by neurologists for documentation of inpatient consultations to be completed immediately after encounters. All teleneurology encounters with completed surveys at a single satellite hospital of the University of Pennsylvania Health System Neurology Department between May 10, 2021, and August 14, 2022, were included. Individual patient-level and encounter-level data were extracted from the medical record. Results: A total of 374 surveys (response rate of 54.05%) were completed by 19 neurologists; 341 questionnaires were included in the analysis. Seven neurologists who specialized as neurohospitalists completed 231 surveys (67.74% of total surveys completed), while 12 non-neurohospitalists completed 110 (32.36%). The history obtained was rated as worse (14%) or the same (86%) as an in-person consult; none reported the history as better than nonteleneurology encounters. The physician-patient relationship was poor or fair in 25% of the encounters and good or excellent in 75% of visits. The overall experience was judged to be worse than in-person consultation in 32% of encounters, the same in 66%, and better in 2%. Fifty-one percent of providers responded that there were elements of the neurologic examination that might have changed their assessment and plan of care if performed in-person. Encounters with peripheral or neuromuscular-related chief complaints had the most inadequate examinations and worse overall experiences, while the most positive impressions of these clinical experiences were observed among seizure-related chief complaints. Discussion: Determining best practices for inpatient teleneurology should consider the patient chief complaint to use teleneurology in scenarios with the highest likelihood of a positive experience. Further efforts should be made to the patient experience and to improve the remote examination to enhance the applicability of teleneurology to the full spectrum of inpatient neurologic consultations.

Endovascular Thrombectomy Treatment Effect in Direct vs Transferred Patients With Large Ischemic Strokes: A Prespecified Analysis of the SELECT2 Trial.

Importance: Patients with large ischemic core stroke have poor clinical outcomes and are frequently not considered for interfacility transfer for endovascular thrombectomy (EVT). Objective: To assess EVT treatment effects in transferred vs directly presenting patients and to evaluate the association between transfer times and neuroimaging changes with EVT clinical outcomes. Design, Setting, and Participants: This prespecified secondary analysis of the SELECT2 trial, which evaluated EVT vs medical management (MM) in patients with large ischemic stroke, evaluated adults aged 18 to 85 years with acute ischemic stroke due to occlusion of the internal carotid or middle cerebral artery (M1 segment) as well as an Alberta Stroke Program Early CT Score (ASPECTS) of 3 to 5, core of 50 mL or greater on imaging, or both. Patients were enrolled between October 2019 and September 2022 from 31 EVT-capable centers in the US, Canada, Europe, Australia, and New Zealand. Data were analyzed from August 2023 to January 2024. Interventions: EVT vs MM. Main Outcomes and Measures: Functional outcome, defined as modified Rankin Scale (mRS) score at 90 days with blinded adjudication. Results: A total of 958 patients were screened and 606 patients were excluded. Of 352 enrolled patients, 145 (41.2%) were female, and the median (IQR) age was 66.5 (58-75) years. A total of 211 patients (59.9%) were transfers, while 141 (40.1%) presented directly. The median (IQR) transfer time was 178 (136-230) minutes. The median (IQR) ASPECTS decreased from the referring hospital (5 [4-7]) to an EVT-capable center (4 [3-5]). Thrombectomy treatment effect was observed in both directly presenting patients (adjusted generalized odds ratio [OR], 2.01; 95% CI, 1.42-2.86) and transferred patients (adjusted generalized OR, 1.50; 95% CI, 1.11-2.03) without heterogeneity (P for interaction = .14). Treatment effect point estimates favored EVT among 82 transferred patients with a referral hospital ASPECTS of 5 or less (44 received EVT; adjusted generalized OR, 1.52; 95% CI, 0.89-2.58). ASPECTS loss was associated with numerically worse EVT outcomes (adjusted generalized OR per 1-ASPECTS point loss, 0.89; 95% CI, 0.77-1.02). EVT treatment effect estimates were lower in patients with transfer times of 3 hours or more (adjusted generalized OR, 1.15; 95% CI, 0.73-1.80). Conclusions and Relevance: Both directly presenting and transferred patients with large ischemic stroke in the SELECT2 trial benefited from EVT, including those with low ASPECTS at referring hospitals. However, the association of EVT with better functional outcomes was numerically better in patients presenting directly to EVT-capable centers. Prolonged transfer times and evolution of ischemic change were associated with worse EVT outcomes. These findings emphasize the need for rapid identification of patients suitable for transfer and expedited transport. Trial Registration: ClinicalTrials.gov Identifier: NCT03876457.

Experience with a hybrid recruitment approach of patient-facing web portal screening and subsequent phone and medical record review for a neurosurgical intervention trial for chronic ischemic stroke disability (PISCES III).

BACKGROUND: Recruitment of participants is the greatest risk to completion of most clinical trials, with 20-40% of trials failing to reach the targeted enrollment. This is particularly true of trials of central nervous system (CNS) therapies such as intervention for chronic stroke. The PISCES III trial was an invasive trial of stereotactically guided intracerebral injection of CTX0E03, a fetal derived neural stem cell line, in patients with chronic disability due to ischemic stroke. We report on the experience using a novel hybrid recruitment approach of a patient-facing portal to self-identify and perform an initial screen for general trial eligibility (tier 1), followed by phone screening and medical records review (tier 2) prior to a final in-person visit to confirm eligibility and consent. METHODS: Two tiers of screening were established: an initial screen of general eligibility using a patient-facing web portal (tier 1), followed by a more detailed screen that included phone survey and medical record review (tier 2). If potential participants passed the tier 2 screen, they were referred directly to visit 1 at a study site, where final in-person screening and consent were performed. Rates of screening were tracked during the period of trial recruitment and sources of referrals were noted. RESULTS: The approach to screening and recruitment resulted in 6125 tier 1 screens, leading to 1121 referrals to tier 2. The tier 2 screening resulted in 224 medical record requests and identification of 86 qualifying participants for referral to sites. The study attained a viable recruitment rate of 6 enrolled per month prior to being disrupted by COVID 19. CONCLUSIONS: A tiered approach to eligibility screening using a hybrid of web-based portals to self-identify and screen for general eligibility followed by a more detailed phone and medical record review allowed the study to use fewer sites and reduce cost. Despite the difficult and narrow population of patients suffering moderate chronic disability from stroke, this strategy produced a viable recruitment rate for this invasive study of intracranially injected neural stem cells. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03629275.

Most Promising Approaches to Improve Stroke Outcomes: The Stroke Treatment Academic Industry Roundtable XII Workshop.

The Stroke Treatment Academic Industry Roundtable XII included a workshop to discuss the most promising approaches to improve outcome from acute stroke. The workshop brought together representatives from academia, industry, and government representatives. The discussion examined approaches in 4 epochs: pre-reperfusion, reperfusion, post-reperfusion, and access to acute stroke interventions. The participants identified areas of priority for developing new and existing treatments and approaches to improve stroke outcomes. Although many advances in acute stroke therapy have been achieved, more work is necessary for reperfusion therapies to benefit the most possible patients. Prioritization of promising approaches should help guide the use of resources and investigator efforts.

Linked Patient and Provider Impressions of Outpatient Teleneurology Encounters.

Background and Objectives: Teleneurology is common in clinical practice partly due to the SARS CoV-2 pandemic. Impressions about teleneurology from patients and providers alike are generally favorable; some of the reported benefits include ease of access to specialized health care, savings of time and money, and similar quality of care as an in-person visit. However, comparisons between patient and provider impressions about the same teleneurology encounter have not been described. In this study, we describe patient impressions about a teleneurology encounter and evaluate concordance with provider impressions about the same encounter. Methods: Patients and providers at the University of Pennsylvania Hospital Neurology Department were surveyed about their impressions of teleneurology between April 27, 2020, and June 16, 2020. A convenience sample of patients, whose providers completed a questionnaire, were contacted by telephone to solicit their impressions about the same encounter. Unique questionnaires for patients and providers focused on similar themes, such as adequacy of technology, assessment of history obtained, and overall quality of the visit. Summaries of patient responses are reported with the raw percent agreement between patients and providers for similar questions. Results: One hundred thirty-seven patients completed the survey; 64 (47%) were male and 73 (53%) were female. Sixty-six (47%) patients had a primary diagnosis of PD, 42 (30%) a non-PD/parkinsonism movement disorder, and 29 (21%) a nonmovement disorder neurologic disease. One hundred one (76%) were established patient visits and 36 (26%) were new patient visits. Provider responses from 8 different physicians were included. Most of the patients responded that the ease of joining their visit, their comfort engaging with their physicians during their visit, understanding their plan of care after their visit, and the quality of care from their teleneurology visit were satisfactory. Patients and providers agreed about their impressions of the quality of the history obtained (87% agreement), patient-provider relationship (88% agreement), and overall quality of their experience (70% agreement). Discussion: Patients had favorable impressions about their clinical experience with teleneurology and expressed an interest in incorporating telemedicine visits into their ongoing care. Patients and providers were highly concordant for the history obtained, patient-provider relationship, and overall quality.

Poststroke Intravenous Transplantation of Human Mesenchymal Stem Cells Improves Brain Repair Dynamics and Functional Outcomes in Aged Mice.

BACKGROUND: Stroke is the primary cause of chronic disability in the elderly, as there are no neurorestorative treatments for those who do not qualify for recanalization therapy. Experimental evidence in stroke animals suggests that transplantation of bone marrow-derived human mesenchymal stem cells (hMSCs) holds promise, but hMSC transplantation has not been systematically tested in aged animals. We tested the hypothesis that poststroke hMSC transplantation improves stroke recovery in aged mice by promoting brain repair. METHODS: Permanent focal cerebral ischemia was induced in 20-month-old C57BL/6 male mice by distal middle cerebral artery occlusion. Bone marrow-derived hMSCs were expanded in vitro and then administrated intravenously into mice (1×106 cells in PBS) 24 hours after distal middle cerebral artery occlusion. Sensorimotor and cognitive functions, brain atrophy, and brain repair processes (neurogenesis, angiogenesis, oligodendrogenesis) were assessed for up to 56 days after stroke. RESULTS: Poststroke hMSC transplantation did not mitigate brain atrophy or improve neuronal survival at 56 days after distal middle cerebral artery occlusion. However, hMSC-treated mice displayed superior neurobehavioral performances in the open field, rotarod, adhesive removal, novel object, and Morris water maze tests compared with PBS-treated controls. hMSCs promoted white matter integrity and enhanced angiogenesis and oligodendrogenesis-but not neurogenesis-in the stroke brain. Positive correlations between neurobehavioral performance and brain repair profiles or white matter integrity were observed in stroke mice. CONCLUSIONS: Poststroke hMSC transplantation improves long-term stroke recovery in aged mice, likely via mechanisms involving enhanced microvascular regeneration and white matter restoration.

Stroke Prevention in Symptomatic Large Artery Intracranial Atherosclerosis Practice Advisory: Report of the AAN Guideline Subcommittee.

BACKGROUND AND OBJECTIVES: To review treatments for reducing the risk of recurrent stroke or death in patients with symptomatic intracranial atherosclerotic arterial stenosis (sICAS). METHODS: The development of this practice advisory followed the process outlined in the American Academy of Neurology Clinical Practice Guideline Process Manual, 2011 Edition, as amended. The systematic review included studies through November 2020. Recommendations were based on evidence, related evidence, principles of care, and inferences. MAJOR RECOMMENDATIONS: Clinicians should recommend aspirin 325 mg/d for long-term prevention of stroke and death and should recommend adding clopidogrel 75 mg/d to aspirin for up to 90 days to further reduce stroke risk in patients with severe (70%-99%) sICAS who have low risk of hemorrhagic transformation. Clinicians should recommend high-intensity statin therapy to achieve a goal low-density lipoprotein cholesterol level <70 mg/dL, a long-term blood pressure target of <140/90 mm Hg, at least moderate physical activity, and treatment of other modifiable vascular risk factors for patients with sICAS. Clinicians should not recommend percutaneous transluminal angioplasty and stenting for stroke prevention in patients with moderate (50%-69%) sICAS or as the initial treatment for stroke prevention in patients with severe sICAS. Clinicians should not routinely recommend angioplasty alone or indirect bypass for stroke prevention in patients with sICAS outside clinical trials. Clinicians should not recommend direct bypass for stroke prevention in patients with sICAS. Clinicians should counsel patients about the risks of percutaneous transluminal angioplasty and stenting and alternative treatments if one of these procedures is being contemplated.

Provider Experience with Teleneurology in an Academic Neurology Department.

Introduction: Teleneurology has become widely adopted during severe acute respiratory syndrome coronavirus 2 pandemic. However, provider impressions about the teleneurology experience are not well described. Methods: A novel questionnaire was developed to collect provider impressions about video teleneurology encounters. All providers in the University of Pennsylvania Health System (UPHS) Neurology Department (N = 162) were asked to complete a questionnaire after each video teleneurology patient encounter between April and August 2020. Individual patient and encounter-level data were extracted from the electronic medical record. Results: One thousand six hundred three surveys were completed by 55 providers (response rate of 10.12%). The history obtained and the ability to connect with the patient were considered the same or better than an in-person visit in almost all encounters. The quality of the physician-patient relationship was good or excellent in 93%, while the overall experience was the same as an in-person visit in 73% of visits and better in 12%. Sixty-eight percent of respondents reported that none of the elements of the neurological examination if performed in person would have changed the assessment and plan. Assessment of the visit as the same or better increased from 83% in April to 89% in July and 95% in August. Headache (91%), multiple sclerosis and neuroimmunology (96%), and movement disorder (89%) providers had the highest proportion of ratings of same or better overall experience and neuromuscular providers the lowest (60%). Conclusions: Provider impressions about the teleneurology history, examination, and provider-patient relationship are favorable in the majority of responses. Important differences emerge between provider specialty and visit characteristics groups.

Differences in Inpatient Insertable Cardiac Monitor Placement after Ischemic Stroke.

BACKGROUND AND PURPOSE: Cryptogenic stroke accounts for 30% of ischemic stroke and in such patients, cardiac monitoring leads to increased detection of AF, increased utilization of anticoagulation, and decreased risk of recurrent stroke. We aim to identify differences in inpatient utilization of implantable cardiac monitors (ICMs) in patients with ischemic stroke. METHODS: This is an analysis of the National Inpatient Sample. We included all ischemic stroke hospitalizations nation-wide between Jan 1st 2016 and Dec 31st 2018. We excluded patients with history of atrial fibrillation or atrial flutter. We compared survey weighted baseline demographics and characteristics between patients who received an inpatient ICM versus those who didn't using logistic regression models. RESULTS: We identified a weighted total 1,069,395 patients who met the inclusion criteria; 2.2% received an inpatient ICM. In multivariable analyses, factors associated with decreased odds of inpatient ICM placement including Black race (OR 0.76 95% CI 0.68 - 0.84, p < 0.001), residence in a micropolitan area (OR 0.79 95% CI 0.67 - 0.94, p = 0.008), hospital region [Midwest (OR 0.74 95% CI 0.61 - 0.90, p = 0.002), South (OR 0.68 95% CI 0.57 - 0.81, p < 0.001), and West (OR 0.37 95% CI 0.29 - 0.45, p < 0.001)], hospital bed size [small (OR 0.38 95% CI 0.39-0.46, p < 0.001) and medium hospital bed size (OR 0.73 95% CI 0.63 - 0.84, p < 0.001)], insurance status [Medicaid (OR 0.86 95% CI 0.76 - 0.98, p = 0.02) and self-pay (OR 0.51 95% CI 0.41 - 0.62, p < 0.001)], and non-teaching hospital (OR 0.52 95% CI 0.47 - 0.60, p < 0.001). CONCLUSIONS: There are important differences in inpatient ICM placement in patients with ischemic stroke highlighting disparities in inpatient care for patients hospitalized with ischemic stroke. More studies are needed to validate our findings.

How to Establish the Outer Limits of Reperfusion Therapy.

Reperfusion therapy with intravenous alteplase and endovascular therapy are effective treatments for selected patients with acute ischemic stroke. Guidelines for treatment are based upon randomized trials demonstrating substantial treatment effects for highly selected patients based on time from stroke onset and imaging features. However, patients beyond the current established guidelines might benefit with lesser but still clinically significant treatment effects. The STAIR (Stroke Treatment Academic Industry Roundtable) XI meeting convened a workgroup to consider the "outer limits" of reperfusion therapy by defining the current boundaries, and exploring optimal parameters and methodology for determining the outer limits. In addition to statistical significance, the minimum clinically important difference should be considered in exploring the limits of reperfusion therapy. Societal factors and quality of life considerations should be incorporated into assessment of treatment efficacy. The threshold for perception of benefit in the medical community may differ from that necessary for the Food and Drug Administration approval. Data from alternative sources such as platform trials, registries and large pragmatic trials should supplement randomized controlled trials to improve generalizability to routine clinical practice. Further interactions between industry and academic centers should be encouraged.

Reliability of the Telemedicine Examination in the Neurologic Diagnosis of Death.

OBJECTIVE: To determine whether telemedicine technology can be used to reliably determine the neurologic diagnosis of death (NDD) in patients with catastrophic brain injury (CBI). METHODS: We included a convenience sample of patients with CBI at a single academic medical center from November 2016 through June 2018. We simultaneously performed brain death evaluation at the bedside and remotely via telemedicine. Remote examiners were neurointensivists who were experienced and knowledgeable in the NDD. In addition to standard clinical examination, we used quantitative pupillometry to evaluate pupil size and reactivity. We determined the proportion of agreement for each NDD examination element and the overall diagnosis of brain death between bedside and remote examiners. RESULTS: Twenty-nine patients with mean age 46 ± 18 years underwent 30 paired NDD examinations. Twenty-eight (97%) patients met the NDD criteria and were pronounced dead. One patient did not meet the NDD criteria and died after withdrawal of life support. With the exception of qualitative assessment of pupillary reactivity, we observed excellent agreement (97%-100% across NDD examination elements) between bedside and remote examiners and 97% agreement on the overall diagnosis of brain death. Unlike qualitative pupillary assessment, quantitative pupillometry was consistently interpretable by remote examiners. CONCLUSIONS: Our results suggest that remote telemedicine technology can be used to verify the findings of bedside examiners performing NDD examinations when a pupillometer is used to assess pupillary reactivity. When performed by neurocritical care experts, the telemedicine NDD examination has potential to facilitate timely and accurate certification of brain death in patients with CBI. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence on the concordance of neurologic diagnosis of death by telemedicine and bedside examiners.

Remote Longitudinal Inpatient Acute Stroke Care Via Telestroke.

OBJECTIVES: While telestroke 'hub-and-spoke' systems are a well-established model for improving acute stroke care at spoke facilities, utility beyond the hyperacute phase is unknown. In patients receiving intravenous thrombolysis via telemedicine, care at spoke facilities has been shown to be associated with longer length of stay and worse outcomes. We sought to explore the impact of ongoing stroke care by a vascular neurologist via telemedicine compared to care provided by local neurologists. METHODS: A network spoke facility protocol was revised to pilot telestroke consultation with a hub vascular neurologist for all patients presenting to the emergency department with ischemic stroke or transient ischemic attack regardless of time since onset or severity. Subsequent telestroke rounds were performed for patients who received initial telestroke consultation. Key outcome measures were length of stay, 30-day readmission and mortality and 90-day mRS. Results during the pilot (post-cohort) were compared to the same hospital's previous outcomes (pre-cohort). RESULTS: Of 257 enrolled patients, 67% were in the post-cohort. Forty percent (69) of the post-cohort received an initial telestroke consult. In spoke-retained patients followed by telestroke rounds (55), median length of stay decreased by 0.8 days (P = 0.01). Readmission and mortality rates did not differ significantly between groups (19.5 vs. 9.1%, P = 0.14 and 3.9 vs. 3.6%, P = 1, respectively). The favorable functional outcome rate was similar between groups (47.3% vs 65.9%, P = 0.50). CONCLUSIONS: Longitudinal stroke care via telestroke may be economically viable through length of stay reduction. Randomized prospective studies are needed to confirm our findings and further investigate this model's potential benefits.

A Department Approach to Teleneurology.

The coronavirus disease-19 (COVID-19) pandemic has compelled health care practices and academic departments to evaluate the suitability of telemedicine for various specialties and attempt rapid implementation to enable continuation of health care that is safe for providers and patients. Many patients with neurological disorders are well suited to evaluations through video. The department of neurology at the University of Pennsylvania (Penn Neurology), with the support of the health system, rapidly expanded telemedicine services to meet the needs of our patient population. This accomplishment required the complex coordination of multiple disciplines and roles within the department and the health care system, including faculty, residents, administrative staff, research and technical staff, information services, and the connected health team. Procedures for provider and patient education were established. Surveys of the provider and patient experience were developed and deployed. The process has demonstrated the vital role telemedicine in neurology (teleneurology) should play in the care of neurological patients beyond the pandemic. We describe our experience as a template for other departments and practices seeking to establish teleneurology programs, as well as an illustration of the challenges and barriers to its implementation.

Neurothrombectomy for Acute Ischemic Stroke Across Clinical Trial Design and Technique: A Single Center Pooled Analysis.

Introduction: The practice of endovascular therapy has evolved dramatically over the last 10 years with randomized clinical trials investigating the benefit of thrombectomy in select patient populations based on time of presentation, imaging criteria, and procedural technique. We sought to understand the benefit of thrombectomy in patients treated within the context of a clinical trial at a single academic center. Methods: Patient-level data recorded in case forms and core-lab adjudicated data were analyzed from patients enrolled in RCTs investigating the benefit of endovascular thrombectomy over medical management (IMSIII, MR RESCUE, ESCAPE, SWIFT PRIME, and DAWN) between 2007 and 2017 at a single academic referral center. Results: A total of 134 patients (intervention group, n = 81; medical group, n = 53) were identified across five clinical trials (IMSIII, n = 46; MR RESCUE, n = 4; ESCAPE, n = 24; SWIFT PRIME, n = 14; DAWN, n = 46). There were no significant differences between the treatment arm and control arm in terms of age, gender, baseline NIHSS, ASPECTS, and site of occlusion. Rates of good outcome were superior in the intervention group with early neurological recovery (NIHSS of 0-1 or increase NIHSS of 8 points at 24 h) at a higher rate of 49% vs. 17% (p = <0.001) and higher rates of functional independence (90 day mRS 0-2 of 53% vs. 26%, p = 0.002). In multivariate logistic regression analysis, lower NIHSS and younger age were predictors of good outcome. There were comparable rates of good outcome irrespective of clinical trial, imaging selection criteria (CTP vs. MRI), early vs. late time window (0-6 h vs. 6-24 h) and procedural technique (Merci vs. Solitaire/Trevo device). There were no differences in rates of sICH, PH-2 or mortality in the intervention group vs. medical group. Conclusions: At a large academic center, the benefit of endovascular therapy over medical therapy is observed irrespective of clinical trial design, patient selection or procedural technique.

Meta-Analysis of Perioperative Stroke and Mortality in CABG Patients With Carotid Stenosis.

BACKGROUND: Coronary artery bypass grafting (CABG) is a proven approach in the treatment of coronary heart disease, but the surgery has several complications, including stroke and death. Though it has been established that perioperative stroke is associated with higher rates of long-term mortality, the relationship between stroke and mortality in the perioperative period has not yet been systematically examined. METHODS: Online databases of peer-reviewed literature were searched to retrieve articles concerning mortality and stroke after CABG in patients with carotid stenosis. Six studies (n=3786) were included for analysis. This study was conducted at a single University hospital system, University of Pittsburgh Medical Center, on patients who underwent CABG. The data obtained from peer-reviewed literature originated from several sources, primarily single institution hospitals. RESULTS: Consistent with current literature, the incidence of stroke in CABG patients with significant carotid stenosis was 2.1%. Data were further analyzed to generate a summary odds ratio of stroke-related mortality after CABG, which showed that patients who died within 30 days of CABG were 7.3 times more likely to have had a perioperative stroke (95% confidence interval, 4.1-13.2). The 30-day mortality rate among perioperative stroke victims was 14.4% versus 2.3% for nonstroke patients. CONCLUSIONS: Together, these data suggest an association between stroke and mortality in the perioperative period in patients undergoing CABG, demonstrating a need for improved monitoring, screening, and treatment of stroke before, during, and shortly after surgery.

Genome-wide transcriptomic analysis of microglia reveals impaired responses in aged mice after cerebral ischemia.

Senescence-associated alterations in microglia may have profound impact on cerebral homeostasis and stroke outcomes. However, the lack of a transcriptome-wide comparison between young and aged microglia in the context of ischemia limits our understanding of aging-related mechanisms. Herein, we performed RNA sequencing analysis of microglia purified from cerebral hemispheres of young adult (10-week-old) and aged (18-month-old) mice five days after distal middle cerebral artery occlusion or after sham operation. Considerable transcriptional differences were observed between young and aged microglia in healthy brains, indicating heightened chronic inflammation in aged microglia. Following stroke, the overall transcriptional activation was more robust (>13-fold in the number of genes upregulated) in young microglia than in aged microglia. Gene clusters with functional implications in immune inflammatory responses, immune cell chemotaxis, tissue remodeling, and cell-cell interactions were markedly activated in microglia of young but not aged stroke mice. Consistent with the genomic profiling predictions, post-stroke cerebral infiltration of peripheral immune cells was markedly decreased in aged mice compared to young mice. Moreover, post-ischemic aged microglia demonstrated reduced interaction with neighboring neurons and diminished polarity toward the infarct lesion. These alterations in microglial gene response and behavior may contribute to aging-driven vulnerability and poorer recovery after ischemic stroke.

Transcriptomic and functional studies reveal undermined chemotactic and angiostimulatory properties of aged microglia during stroke recovery.

Age-dependent alterations in microglia behavior have been implicated in neurodegeneration and CNS injuries. Here, we compared the transcriptional profiles of young versus aged microglia during stroke recovery. CD45intermediateCD11b+ microglia were FACS-isolated from the brains of young (10-week-old) and aged (18-month-old) male mice with sham operation or 14 days after distal middle cerebral artery occlusion and subjected to RNA-sequencing analysis. Functional groups enriched in young microglia are indicative of upregulation in cell movement, cell interactions, inflammatory responses and angiogenesis, while aged microglia exhibited a reduction or no change in these features. We confirmed reduced chemoattractive capacities of aged microglia toward ischemic brain tissue in organotypic slide co-cultures, and delayed accumulation of aged microglia around dead neurons injected into the striatum in vivo. In addition, aging is associated with an overall failure to increase the expression of microglial genes involved in cell-cell interactions, such as CXCL10. Finally, impaired upregulation of pro-angiogenic genes in aged microglia was associated with a decline in neovascularization in aged mice compared to young mice after distal middle cerebral artery occlusion. This study provides a new resource to understand the mechanisms underlying microglial alterations in the aged brain milieu and sheds light on new strategies to improve microglial functions in aged stroke victims.