The association of insular stroke with lesion volume

Isolated insular stroke: topography is the answer with respect to outcome and cardiac involvement

Background and purpose

Isolated insular strokes (IIS) are a rare occurrence due to the frequent concomitant involvement of adjacent territories, supplied by the M2 segment of the middle cerebral artery (MCA), and clinical aspects are sometimes contradictory. We aimed to describe clinical and radiological characteristics of a pure IIS case series, focusing on its functional outcome and cardiac involvement.

Methods

We identified 15 isolated insular ischemic strokes from a pool of 563 ischemic strokes occurred between January 2020 and December 2021. Data collection consisted of demographic and baseline clinical characteristics, comorbidities, electrocardiograms, echocardiograms, stroke topography and etiology, reperfusive treatments, and outcome measures. Descriptive statistical analysis was carried out.

Results

Newly detected cardiovascular alterations were the prevalent atypical presentation. Cardioembolism was the most frequent etiology. Most of patients had major neurological improvement at discharge and good outcome at 3-months follow-up.

Discussion and conclusion

IIS are extremely rare, representing according to our study about 2.6% ischemic strokes cases per year, and patients have peculiar clinical manifestations, such as dysautonomia and awareness deficits. Our data suggest the possibility for these patients to completely recover after acute ischemic stroke notwithstanding the pivotal role of the insula in cerebral connections and the frequent association with MCA occlusion. Moreover, given the central role of the insula in regulating autonomic functions, newly detected cardiac arrhythmias must be taken into consideration, as well as a full diagnostic work-up for the research of cardioembolic sources. To our knowledge, this is the largest monocentric case series of IIS and it might be useful for future systematic reviews.

Direct Mechanical Thrombectomy Versus Prior Bridging Intravenous Thrombolysis in Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

BACKGROUND

The current guideline recommends using an intravenous tissue-type plasminogen activator (IV tPA) prior to mechanical thrombectomy (MT) in eligible acute ischemic stroke (AIS) with emergent large vessel occlusion (ELVO). Some recent studies found no significant differences in the long-term functional outcomes between bridging therapy (BT, i.e., IV tPA prior to MT) and direct MT (dMT).

METHODS

We conducted a systematic review and meta-analysis to compare the safety and functional outcomes between BT and dMT in AIS patients with ELVO who were eligible for IV tPA administration. Based on the ELVO location, patients were categorized as the anterior group (occlusion of the anterior circulation), or the combined group (occlusion of the anterior and/or posterior circulation). A subgroup analysis was performed based on the study type, i.e., RCT and non-RCT.

RESULTS

Thirteen studies (3985 patients) matched the eligibility criteria. Comparing the BT and dMT groups, no significant differences in terms of mortality and good functional outcome were observed at 90 days. Symptomatic intracranial hemorrhagic (sICH) events were more frequent in BT patients in the combined group (OR = 0.73, p = 0.02); this result remained significant only in the non-RCT subgroup (OR = 0.67, p = 0.03). The RCT subgroup had a significantly higher rate of successful revascularization in BT patients (OR = 0.73, p = 0.02).

CONCLUSIONS

Our meta-analysis uncovered no significant differences in functional outcome and mortality rate at 90 days between dMT and BT in patients with AIS who had ELVO. Although BT performed better in terms of successful recanalization rate, there is a risk of increased sICH rate in this group.

Neural network bases of thematic semantic processing in language production

Semantic processing is a central component of language and cognition. The anterior temporal lobe is postulated to be a key hub for semantic processing, but the posterior temporoparietal cortex is also involved in thematic associations during language. It is possible that these regions act in concert and depend on an anteroposterior network linking the temporal pole with posterior structures to support thematic semantic processing during language production. We employed connectome-based lesion-symptom mapping to examine the causal relationship between lesioned white matter pathways and thematic processing language deficits among individuals with post-stroke aphasia. Seventy-nine adults with chronic aphasia completed the Philadelphia Naming Test, and semantic errors were coded as either thematic or taxonomic to control for taxonomic errors. Controlling for nonverbal conceptual-semantic knowledge as measured by the Pyramids and Palm Trees Test, lesion size, and the taxonomic error rate, thematic error rate was associated with loss of white matter connections from the temporal pole traversing in peri-Sylvian regions to the posterior cingulate and the insula. These findings support the existence of a distributed network underlying thematic relationship processing in language as opposed to discrete cortical areas.

Internal border zone injury predicts the functional outcome of acute MCA stroke patients

BACKGROUND AND PURPOSE

Classification of deep (D), superficial (S) MCA territories and their junctional vascular area (the internal border zone, IBZ) can help to identify patients most likely to benefit from aggressive reperfusion therapy after stroke. We tested the prognostic value of an IBZ injury compared to DWI-ASPECTS and infarct volume.

MATERIALS AND METHODS

DW lesions of 168 patients with acute (4.2±6.5 h) MCA strokes were retrospectively examined and manually delineated. Patients with haemorrhagic transformation or other neurological diseases were excluded. Clinical data were recorded within 24 h following symptom onset and 48 h for patients who benefited from reperfusion therapy. The occurrence of an IBZ injury was determined using a standardized stereotaxic atlas. Performance to predict a good outcome (mRS<3 at 3 months) was estimated through ROC curves for DWI-ASPECTS≤6, lesion volume≥100 mL and IBZ injury. Logistic regression models were performed to estimate independent outcomes for infarct volume and IBZ injury.

RESULTS

Infarcts involving the IBZ were larger (94.9±98.8 mL vs. 30.2±31.3 mL), had higher NIHSS (13.8±7.2 vs. 7.2±5.7), more frequent MCA occlusions (64.9% vs. 28.3%), and worse outcomes (mRS 3.0±1.8 vs. 1.9±1.7), and were less responsive to IVtPA (34±47% vs. 55±48% of NIHSS improvement). The area under the ROC curves was comparable between the occurrence of IBZ injury (0.651), ASPECTS≤6 (0.657) and volume≥100 mL (0.629). Logistic regression analyses showed an independent effect of an IBZ injury, especially for superficial MCA strokes and for patients who benefited from reperfusion therapy.

CONCLUSION

An IBZ injury is an early and independent marker of stroke severity, functional prognosis and treatment responsiveness.

The role of disrupted structural connectivity in aphasia

Lesion-based studies are among the most informative approaches to determine a critical relationship between a particular brain region and specific function. Importantly, brain lesions cause disconnection of other brain areas that appear to be intact and may cause functional deficits in these regions due to a lack of afferent projections. If only the location of necrosis and gliosis after the stroke is considered to be the lesion, the full spectrum of brain dysfunction is only partly assessed, and there is a high probability that incomplete region-to-function inferences are made. In this chapter we (1) outline how structural connectivity can be measured in individuals with stroke, and (2) provide an overview of the importance of disrupted structural connectivity in aphasia. We conclude that connection-based and region/voxel-based symptom mapping yield complementary information and together provide an in-depth picture of brain and function relationships.

Workflow Intervals and Outcomes of Endovascular Treatment for Acute Large-Vessel Occlusion During On-Vs. Off-hours in China: The ANGEL-ACT Registry

Background: There may be a delay in or a poor outcome of endovascular treatment (EVT) among acute ischemic stroke (AIS) patients with large-vessel occlusion (LVO) during off-hours. By using a prospective, nationwide registry, we compared the workflow intervals and radiological/clinical outcomes between patients with acute LVO treated with EVT presenting during off- and on-hours.

Methods: We analyzed prospectively collected Endovascular Treatment Key Technique and Emergency Work Flow Improvement of Acute Ischemic Stroke (ANGEL-ACT) data. Patients presenting during off-hours were defined as those presenting to the emergency department from Monday to Friday between 17:30 and 08:00, on weekends (from 17:30 on Friday to 08:00 on Monday), and on national holidays. We used logistic regression models with adjustment for potential confounders to determine independent associations between the time of presentation and outcomes.

Results: Among 1,788 patients, 1,079 (60.3%) presented during off-hours. The median onset-to-door time and onset-to-reperfusion time were significantly longer during off-hours than during on-hours (165 vs. 125 min, P = 0.002 and 410 vs. 392 min, P = 0.027). The rates of successful reperfusion and symptomatic intracranial hemorrhage were similar in both groups. The adjusted odds ratio (OR) for the 90-day modified Rankin Scale score was 0.892 [95% confidence interval (CI), 0.748–1.064]. The adjusted OR for the occurrence of functional independence was 0.892 (95% CI, 0.724–1.098), and the adjusted OR for mortality was 1.214 (95% CI, 0.919–1.603).

Conclusions: Off-hours presentation in the nationwide real-world registry was associated with a delay in the visit and reperfusion time of EVT in patients with AIS. However, this delay was not associated with worse functional outcomes or higher mortality rates.

Clinical Trial Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03370939.

Investigating the neuroanatomy underlying proprioception using a stroke model

Neuroanatomical investigations have associated cortical areas, beyond Primary Somatosensory Cortex (S1), with impaired proprioception. Cortical regions have included temporoparietal (TP) regions (supramarginal gyrus, superior temporal gyrus, Heschl's gyrus) and insula. Previous approaches have struggled to account for concurrent damage across multiple brain regions. Here, we used a targeted lesion analysis approach to examine the impact of specific combinations of cortical and sub-cortical lesions and quantified the prevalence of proprioceptive impairments when different regions are damaged or spared. Seventy-seven individuals with stroke (49 male; 28 female) were identified meeting prespecified lesion criteria based on MRI/CT imaging: 1) TP lesions without S1, 2) TP lesions with S1, 3) isolated S1 lesions, 4) isolated insula lesions, and 5) lesions not impacting these regions (other regions group). Initially, participants meeting these criteria (1-4) were grouped together into right or left lesion groups and compared to each other, and the other regions group (5), on a robotic Arm Position Matching (APM) task and a Kinesthesia (KIN) task. We then examined the behaviour of individuals that met each specific criteria (groups 1-5). Proprioceptive impairments were more prevalent following right hemisphere lesions than left hemisphere lesions. The extent of damage to TP regions correlated with performance on both robotic tasks. Even without concurrent S1 lesions, TP and insular lesions were associated with impairments on the APM and KIN tasks. Finally, lesions not impacting these regions were much less likely to result in impairments. This study highlights the critical importance of TP and insular regions for accurate proprioception. SIGNIFICANCE STATEMENT: This work advances our understanding of the neuroanatomy of human proprioception. We validate the importance of regions, beyond the dorsal column medial lemniscal pathway and S1, for proprioception. Further, we provide additional evidence of the importance of the right hemisphere for human proprioception. Improved knowledge on the neuroanatomy of proprioception is crucial for advancing therapeutic approaches which target individuals with proprioceptive impairments following neurological injury or with neurological disorders.

Effects of insular involvement on functional outcome after intracerebral hemorrhage

OBJECTIVE

Ischemic stroke, as well as intracerebral hemorrhage (ICH), involving the insular cortex tends to be more severe. The impact of insular involvement on outcome of ICH remains enigmatic.

METHODS

We analyzed 159 patients with supratentorial ICH. Depending on insular involvement the patients were classified into two groups (ICH_non-insular vs. ICH_insular ). Volume and symptom severity of ICH were assessed. Electrocardiography, chest X-ray, and laboratory examinations including myocardial enzymes and inflammatory markers were made. In-hospital death and outcome at discharge from hospital were assessed on the modified Rankin scale (mRS).

RESULTS

The main finding was an association of insular involvement of ICH with worse short-term outcome as measured by mRS (common odds ratio: 4.08 (95% CI: 2.09-7.92); p < .001). This association survived adjustment to relevant covariates such as age, sex, ICH volume, intraventricular hemorrhage, pneumonia, and length of stay (adjusted common odds ratio: 2.51 (95% CI: 1.21-5.21); p = .014) but had no predictive value for side of ICH or rate of atrial fibrillation. There was no association of ICH localization with in-hospital death rate.

CONCLUSION

Insular localization of ICH lesions predicts worse short-term functional outcome independent of side of bleeding or cardiac dysfunction such as new AF. These findings need clarification in larger prospective cohorts assessed by detailed autonomic/cardiac testing, as well as neuroimaging sub-localization of ICH within the insular region.

Speech apraxia and oral apraxia: association or dissociation? A multivariate lesion-symptom mapping study in acute stroke patients

The anatomical relationship between speech apraxia (SA) and oral apraxia (OA) is still unclear. To shed light on this matter we studied 137 patients with acute ischaemic left-hemisphere stroke and performed support vector regression-based, multivariate lesion–symptom mapping. Thirty-three patients presented with either SA or OA. These two symptoms mostly co-occurred (n = 28), except for few patients with isolated SA (n = 2) or OA (n = 3). All patient with either SA or OA presented with aphasia (p < 0.001) and these symptoms were highly associated with apraxia (p < 0.001). Co-occurring SA and OA were predominantly associated with insular lesions, while the insula was completely spared in the five patients with isolated SA or OA. Isolated SA occurred in case of frontal lesions (prefrontal gyrus and superior longitudinal fasciculus), while isolated OA occurred in case of either temporoparietal or striatocapsular lesions. Our study supports the notion of a predominant, but not exclusive, role of the insula in verbal and non-verbal oral praxis, and indicates that frontal regions may contribute exclusively to verbal oral praxis, while temporoparietal and striatocapsular regions contribute to non-verbal oral praxis. However, since tests for SA and OA so far intrinsically also investigate aphasia and apraxia, refined tests are warranted.

Neural regions underlying object and action naming: Complementary evidence from acute stroke and primary progressive aphasia

BACKGROUND

Naming impairment is commonly noted in individuals with aphasia. However, object naming receives more attention than action naming. Furthermore, most studies include participants with aphasia due to only one aetiology, commonly stroke. We developed a new assessment, the Hopkins Action Naming Assessment (HANA), to evaluate action naming impairments.

AIMS

Our aims were to show that the HANA is a useful tool that can (1) identify action naming impairments and (2) be used to investigate the neural substrates underlying naming. We paired the HANA with the Boston Naming Test (BNT) to compare action and object naming. We considered participants with aphasia due to primary progressive aphasia (PPA) or acute left hemisphere stroke to provide a more comprehensive picture of brain-behaviour relationships critical for naming. Behaviourally, we hypothesised that there would be a double dissociation between object and action naming performance. Neuroanatomically, we hypothesised that different neural substrates would be implicated in object vs. action naming and that different lesion-deficit associations would be identified in participants with PPA vs. acute stroke.

METHODS & PROCEDURES

Participants (N=138 with PPA, N=37 with acute stroke) completed the BNT and HANA. Behavioural performance was compared. A subset of participants (N=31 with PPA, N=37 with acute stroke) provided neuroimaging data. The whole brain was automatically segmented into regions of interest (ROIs). For participants with PPA, the image variables were the ROI volumes, normalised by the brain volume. For participants with acute stroke, the image variables were the percentage of each ROI affected by the lesion. The relationship between ROIs likely to be involved in naming performance was modelled with LASSO regression.

OUTCOMES & RESULTS

Behavioural results showed a double dissociation in performance: in each group, some participants displayed intact performance relative to healthy controls on actions but not objects and/or significantly better performance on actions than objects, while others showed the opposite pattern. These results support the need to assess both objects and actions when evaluating naming deficits. Neuroimaging results identified different regions associated with object vs. action naming, implicating overlapping but distinct networks of regions. Furthermore, results differed for participants with PPA vs. acute stroke, indicating that critical information may be missed when only one aetiology is considered.

CONCLUSIONS

Overall, the study provides a more comprehensive picture of the neural bases of naming, underscoring the importance of assessing both objects and actions and considering different aetiologies of damage. It demonstrates the utility of the HANA.

Boundary and vulnerability estimation of the internal borderzone using ischemic stroke lesion mapping

Distinction between deep and superficial middle cerebral artery (MCA) territories and their junctional vascular area (the internal borderzone or IBZ) constitutes a predictor of stroke patient outcome. However, the IBZ boundaries are not well-defined because of substantial anatomical variance. Here, we built a statistical estimate of the IBZ and tested its vulnerability to ischemia using an independent sample. First, we used delineated lesions of 122 patients suffering of chronic ischemic stroke grouped in deep, superficial and territorial topographies and statistical comparisons to generate a probabilistic estimate of the IBZ. The IBZ extended from the insular cortex to the internal capsule and the anterior part of the caudate nucleus head. The IBZ showed the highest lesion frequencies (~30% on average across IBZ voxels) in our chronic stroke patients but also in an independent sample of 87 acute patients. Additionally, the most important apparent diffusion coefficient reductions (−6%), which reflect stroke severity, were situated within our IBZ estimate. The IBZ was most severely injured in case of a territorial infarction. Then, our results are in favour of an increased IBZ vulnerability to ischemia. Moreover, our probabilistic estimates of deep, superficial and IBZ regions can help the everyday spatial classification of lesions.

Stroke Severity, and Not Cerebral Infarct Location, Increases the Risk of Infection

Infection is a leading cause of death in patients with stroke; however, the impact of cerebral infarct size or location on infectious outcome is unclear. To examine the effect of infarct size on post-stroke infection, we utilised the intraluminal middle-cerebral artery occlusion (MCAO) mouse model of ischemic stroke and adjusted the duration of arterial occlusion. At 1 day following stroke onset, the proportion of mice with infection was significantly greater in mice that had larger infarct sizes. Additionally, the presence of lung infection in these mice with severe strokes extended past 2 days, suggestive of long-term immune impairment. At the acute phase, our data demonstrated an inverse relationship between infarct volume and the number of circulating leukocytes, indicating the elevated risk of infection in more severe stroke is associated with reduced cellularity in peripheral blood, owing predominately to markedly decreased lymphocyte numbers. In addition, the stroke-induced reduction of lymphocyte-to-neutrophil ratio was also evident in the lung of all post-stroke animals. To investigate the effect of infarct location on post-stroke infection, we additionally performed a photothrombotic (PT) model of stroke and using an innovative systematic approach of analysis, we found the location of cerebral infarct does not impact on the susceptibility of post-stroke infection, confirming the greater role of infarct volume over infarct location in the susceptibility to infection. Our experimental findings were validated in a clinical setting and reinforced that stroke severity, and not infarct location, influences the risk of infection after stroke.

Insula stroke: the weird and the worrisome

Infarction of the insula is a common scenario with large tissue-volume strokes in the middle cerebral artery territory. Considered to be part of the central autonomic network, infarction of this region is associated with autonomic disturbances, in particular cardiovascular dysregulation. Risk of aspiration following stroke is also associated with involvement of the insula, consistent with its purported participation in complex functions of the mouth and pharynx. Strokes restricted to the insula are rare and present with a broad range of symptoms that offer a window of insight into the diverse functionality of the insular cortex. Chemosensory, autonomic, vestibular, auditory, somatosensory, language and oropharyngeal functional deficits are all recognised, among others. Long-term sequelae are unknown but profound symptoms, such as hemiparesis, are usually transient. Understanding the patterns of dysfunction highlighted provides the basis for future strategies to optimise stroke management on the discovery of insula involvement.

Amino Acid Biosignature in Plasma among Ischemic Stroke Subtypes

Ischemic stroke is a neurovascular disorder caused by reduced or blockage of blood flow to the brain, which may permanently affect motor and cognitive abilities. The diagnostic of stroke is performed using imaging technologies, clinical evaluation, and neuropsychological protocols, but no blood test is available yet. In this work, we analyzed amino acid concentrations in blood plasma from poststroke patients in order to identify differences that could characterize the stroke etiology. Plasma concentrations of sixteen amino acids from patients with chronic ischemic stroke (n = 73) and the control group (n = 16) were determined using gas chromatography coupled to mass spectrometry (GC-MS). The concentration data was processed by Partial Least Squares-Discriminant Analysis (PLS-DA) to classify patients with stroke and control. The amino acid analysis generated a first model able to discriminate ischemic stroke patients from control group. Proline was the most important amino acid for classification of the stroke samples in PLS-DA, followed by lysine, phenylalanine, leucine, and glycine, and while higher levels of methionine and alanine were mostly related to the control samples. The second model was able to discriminate the stroke subtypes like atherothrombotic etiology from cardioembolic and lacunar etiologies, with lysine, leucine, and cysteine plasmatic concentrations being the most important metabolites. Our results suggest an amino acid biosignature for patients with chronic stroke in plasma samples, which can be helpful in diagnosis, prognosis, and therapeutics of these patients.

Prognostic Significance of Infarct Size and Location: The Case of Insular Stroke

The prognostic relevance of strokes in different locations is debated. For example, insular strokes have been associated with increased mortality, but this association could reflect their greater severity. In two independent cohorts of patients with supratentorial ischemic stroke (n = 90 and 105), we studied the prognostic consequences of lesion size and location using voxel-based lesion-symptom mapping before and after volume control, which better accounts for total lesion volume. Strokes affecting the insula were larger than non-insular strokes (28 vs 2cc and 25 vs 3cc, p < 0.001 in both cohorts). A number of supratentorial areas (mainly in the left hemisphere), including the insula, were associated with poor functional outcome in both cohorts before (4014 voxels) and after volume control (1378 voxels), while the associations with death were greatly reduced after volume control (from 8716 to 325 voxels). Exploratory analyses suggested that the method of lesion volume quantification, the National Institutes of Health Stroke Scale hemispheric bias and patient selection can result in false associations between specific brain lesions and outcomes. In conclusion, death in the first months after stroke is mainly explained by large infarct volumes, whereas lesions of specific supratentorial structures, mostly in the left hemisphere, also contribute to poor functional outcomes.

Neural Mechanisms of Swallowing Dysfunction and Apraxia of Speech in Acute Stroke

Speech and swallowing utilize overlapping anatomy and are thus inherently related processes. We sought to identify common neural mechanisms between risk of swallowing dysfunction and apraxia of speech (AOS). This was a retrospective analysis using data from a prospectively collected cohort. Left hemisphere stroke patients (68 subjects) tested with the Apraxia Battery for Adults II, a swallow screen, and MRI were included in the study. Main outcome measure was the presence of AOS or aspiration risk after stroke. We identified a significant association between AOS measures and increased aspiration risk (defined by failed swallow screen; p = 0.04; OR 5.2). Lesions in pars opercularis of Broca's area (BA 44) were associated with both AOS (p = 0.044; OR 9.7) and increased aspiration risk (p = 0.04; OR 5) but deficits rarely co-occurred in the same cases. Lesions in left premotor cortex (BA 6) were not significantly associated with increased aspiration risk (p = 0.06; OR 3.3) but were significantly associated with AOS (p = 0.008; OR 7). Impaired swallowing function was also associated with lesions in Wernicke's area (BA 22; p = 0.05; OR 3.5) and pars triangularis (BA 45; p = 0.02; OR 6.8). AOS and risk of aspiration are associated in patients with acute left hemisphere stroke. Acute infarct in the pars opercularis of Broca's area is associated with both deficits, though they rarely co-occur in the same individual. The co-occurrence of AOS and risk of aspiration likely reflects dependence on closely related neural structures.

Contemporary Approaches to the Management of Post-stroke Apraxia of Speech

Apraxia of speech (AOS) is a motor speech disorder that disrupts the planning and programming of speech motor movements. In the acute stage of stroke recovery, AOS following unilateral (typically) left hemisphere stroke can occur alongside dysarthria, an impairment in speech execution and control, and/or aphasia, a higher-level impairment in language function. At this time, perceptual evaluation (the systematic, although subjective, description of speech and voice characteristics) is perhaps the only "gold standard" for differential diagnosis when it comes to motor speech disorders. This poses a challenge for speech-language pathologists charged with the evaluation of poststroke communication abilities, as distinguishing production impairments associated with AOS from those that can occur in aphasia and/or dysarthria can be difficult, especially when more than one deficit is present. Given the need for more objective, reliable methods to identify and diagnose AOS, several studies have turned to acoustic evaluation and neuroimaging to supplement clinical assessment. This article focuses on these recent advances. Studies investigating acoustic evaluation of AOS will be reviewed, as well as those that have considered the extent that neuroimaging can guide clinical decision making. Developments in the treatment of AOS will also be discussed. Although more research is needed regarding the use of these methods in everyday clinical practice, the studies reviewed here show promise as emerging tools for the management of AOS.

Ischemic Strokes Due to Large-Vessel Occlusions Contribute Disproportionately to Stroke-Related Dependence and Death: A Review

Background

Since large-vessel occlusion (LVO)-related acute ischemic strokes (AIS) are associated with more severe deficits, we hypothesize that the endovascular thrombectomy (ET) may disproportionately benefit stroke-related dependence and death.

Methods

To delineate LVO-AIS impact, systematic search identified studies measuring dependence or death [modified Rankin Scale (mRS) 3–6] or mortality following ischemic stroke among consecutive patients presenting with both LVO and non-LVO events within 24 h of symptom onset.

Results

Among 197 articles reviewed, 2 met inclusion criteria, collectively enrolling 1,467 patients. Rates of dependence or death (mRS 3–6) within 3–6 months were higher after LVO than non-LVO ischemic stroke, 64 vs. 24%, odds ratio (OR) 4.46 (CI: 3.53–5.63, p < 0.0001). Mortality within 3–6 months was higher after LVO than non-LVO ischemic stroke, 26.2 vs. 1.3%, OR 4.09 (CI: 2.5–6.68), p < 0.0001. Consequently, while LVO ischemic events accounted for 38.7% (CI: 21.8–55.7%) of all acutely presenting ischemic strokes, they accounted for 61.6% (CI: 41.8–81.3%) of poststroke dependence or death and 95.6% (CI: 89.0–98.8%) of poststroke mortality. Using literature-based projections of LVO cerebral ischemia patients treatable within 8 h of onset, ET can be used in 21.4% of acutely presenting patients with ischemic stroke, and these events account for 34% of poststroke dependence and death and 52.8% of poststroke mortality.

Conclusion

LVOs cause a little more than one-third of acutely presenting AIS, but are responsible for three-fifths of dependency and more than nine-tenths of mortality after AIS. At the population level, ET has a disproportionate benefit in reducing severe stroke outcomes.

Activity associated with speech articulation measured through direct cortical recordings

The insula has been credited with a role in a number of functions, including speech production. Here, we recorded electrocorticography (ECoG) signals from the left insula during pseudoword articulation in two patients undergoing pre-surgical monitoring for the management of medically-intractable epilepsy. Event-related band power (ERBP) activity from electrodes implanted in the superior precentral gyrus of the insula (SPGI) was compared to that of other left hemisphere regions implicated in speech production. Results showed that SPGI contacts demonstrated significantly greater ERBP within the high-gamma frequency range (75-150Hz) during articulation compared to a listening condition. However, frontal and post-central regions demonstrated significantly greater responses to the articulation task compared to the SPGI. Results suggest the SPGI is active during articulation, but frontal and post-central regions demonstrate significantly more robust responses. Given the small sample size, and number of electrodes implanted in the SPGI, further study is warranted to confirm these findings.

Important considerations in lesion-symptom mapping: Illustrations from studies of word comprehension

Lesion-symptom mapping is an important method of identifying networks of brain regions critical for functions. However, results might be influenced substantially by the imaging modality and timing of assessment. We tested the hypothesis that brain regions found to be associated with acute language deficits depend on (1) timing of behavioral measurement, (2) imaging sequences utilized to define the "lesion" (structural abnormality only or structural plus perfusion abnormality), and (3) power of the study. We studied 191 individuals with acute left hemisphere stroke with MRI and language testing to identify areas critical for spoken word comprehension. We use the data from this study to examine the potential impact of these three variables on lesion-symptom mapping. We found that only the combination of structural and perfusion imaging within 48 h of onset identified areas where more abnormal voxels was associated with more severe acute deficits, after controlling for lesion volume and multiple comparisons. The critical area identified with this methodology was the left posterior superior temporal gyrus, consistent with other methods that have identified an important role of this area in spoken word comprehension. Results have implications for interpretation of other lesion-symptom mapping studies, as well as for understanding areas critical for auditory word comprehension in the healthy brain. We propose that lesion-symptom mapping at the acute stage of stroke addresses a different sort of question about brain-behavior relationships than lesion-symptom mapping at the chronic stage, but that timing of behavioral measurement and imaging modalities should be considered in either case. Hum Brain Mapp 38:2990-3000, 2017. © 2017 Wiley Periodicals, Inc.

Effect of Right Insular Involvement on Death and Functional Outcome After Acute Ischemic Stroke in the IST-3 Trial (Third International Stroke Trial)

Background and Purpose—

In patients with acute ischemic stroke, whether involvement of the insular cortex influences outcome is controversial. Much of the apparent adverse outcome may relate to such strokes usually being severe. We examined the influence of right and left insular involvement on stroke outcomes among patients from the IST-3 study (Third International Stroke Trial) who had visible ischemic stroke on neuroimaging.

Methods—

We used multiple logistic regression to compare outcomes of left versus right insular and noninsular strokes across strata of stroke severity, on death, proportion dead or dependent, and level of disability (ordinalized Oxford Handicap Score) at 6 months, with adjustment for the effects of age, lesion size, and presence of atrial fibrillation.

Results—

Of 3035 patients recruited, 2099 had visible ischemic strokes limited to a single hemisphere on computed tomography/magnetic resonance scans. Of these, 566 and 714 had infarction of right and left insula. Six months after randomization, right insular involvement was associated with increased odds of death when compared with noninsular strokes on the left side (adjusted odds ratio, 1.83; 95% confidence interval, 1.33−2.52), whereas the adjusted odds ratio comparing mortality after insular versus noninsular strokes on the left side was not significant. Among mild/moderate strokes, outcomes for right insular involvement were worse than for left insular, but among more severe strokes, the difference in outcomes was less substantial.

Conclusions—

We found an association between right insular involvement and higher odds of death and worse functional outcome. The difference between right- and left-sided insular lesions on outcomes seemed to be most evident for mild/moderate strokes.

Clinical Trial Registration—

URL: http://www.isrctn.com . Unique identifier: ISRCTN25765518.

The Efficacy of Prophylactic Antibiotics on Post-Stroke Infections: An Updated Systematic Review and Meta-Analysis

Post-stroke infections are common complications in acute stroke patients and are associated with an unfavorable functional outcome. However, reports on the effects of prophylactic antibiotics treatment on post-stroke infections are conflicting, especially those on post-stroke pneumonia and outcomes. We searched the PubMed, Embase, and Web of Knowledge databases up through March 11^th, 2016. Seven randomized controlled trials including 4261 patients were analyzed among this systematic review and meta-analysis. We found preventive antibiotics treatment at the time of stroke onset did reduce the incidence of infections in adults with acute stroke (OR = 0.57, 95% CI: 0.38–0.85, P = 0.005), including reducing the number of urinary tract infections (OR = 0.34, 95% CI: 0.26–0.46, P < 0.001), but did not significantly decrease the rate of post-stroke pneumonia (OR = 0.91, 95% CI: 0.73–1.13, P = 0.385). Importantly, antibiotics treatment also showed no significant effect on the number of fatalities among stroke patients (OR = 1.07, 95% CI: 0.90–1.26, P = 0.743) and functional outcome scores on the modified Rankin Scale (OR = 1.76, 95% CI: 0.86–3.63, p = 0.124). Our study indicated that preventive antibiotics treatment not reduced the rate of post-stroke pneumonia or mortality, even though decreased the risk of infections, especially urinary tract infections. Thus, preventive antibiotics treatment may not be recommended for acute stroke patients.

Ownership illusions in patients with body delusions: Different neural profiles of visual capture and disownership

The various neurocognitive processes contributing to the sense of body ownership have been investigated extensively in healthy participants, but studies in neurological patients can shed unique light into such phenomena. Here, we aimed to investigate whether visual capture by a fake hand (without any synchronous or asynchronous tactile stimulation) affects body ownership in a group of hemiplegic patients with or without disturbed sensation of limb ownership (DSO) following damage to the right hemisphere. We recruited 31 consecutive patients, including seven patients with DSO. The majority of our patients (64.5% overall and up to 86% of the patients with DSO) experienced strong feelings of ownership over a rubber hand within 15 sec following mere visual exposure, which correlated with the degree of proprioceptive deficits across groups and in the DSO group. Using voxel-based lesion-symptom mapping analysis, we were able to identify lesions associated with this pathological visual capture effect in a selective fronto-parietal network, including significant voxels (p < .05) in the frontal operculum and the inferior frontal gyrus. By contrast, lesions associated with DSO involved more posterior lesions, including the right temporoparietal junction and a large area of the supramarginal gyrus, and to a lesser degree the middle frontal gyrus. Thus, this study suggests that our sense of ownership includes dissociable mechanisms of multisensory integration.