Fatima Pagani Cassara

Atrial Fibrillation Detected after Acute Ischemic Stroke: Evidence Supporting the Neurogenic Hypothesis

BACKGROUND It is unknown whether atrial fibrillation (AF) detected after acute ischemic stroke is caused by neurogenic or cardiogenic mechanisms. Based on the potential damage to the autonomic nervous system, neurogenic mechanisms could be implicated in the pathophysiology of newly diagnosed AF. To test this hypothesis, we developed a mechanistic approach by comparing a prespecified set of indicators in acute ischemic stroke patients with newly diagnosed AF, known AF, and sinus rhythm. METHODS We prospectively assessed every acute ischemic stroke patient undergoing continuous electrocardiographic monitoring from 2008 through 2011. We compared newly diagnosed AF, known AF, and sinus rhythm patients by using 20 indicators grouped in 4 domains: vascular risk factors, underlying cardiac disease, burden of neurological injury, and in-hospital outcome. RESULTS We studied 275 acute ischemic stroke patients, 23 with newly diagnosed AF, 64 with known AF, and 188 with sinus rhythm. Patients with newly diagnosed AF had a lower proportion of left atrial enlargement (60.9% versus 91.2%, P=.001), a smaller left atrial area (22.0 versus 26.0 cm2, P=.021), and a higher frequency of insular involvement (30.4% versus 9.5%, P=.017) than participants with known AF. Compared with patients in sinus rhythm, those with newly diagnosed AF had a higher proportion of brain infarcts of 15 mm or more (60.9% versus 37.2%, P=.029) and a higher frequency of insular involvement (30.4% versus 7.3%, P<.001). CONCLUSIONS The low frequency of underlying cardiac disease and the strikingly high proportion of concurrent strategic insular infarctions in patients with newly diagnosed AF provide additional evidence supporting the role of neurogenic mechanisms in a subset of AF detected after acute ischemic stroke.

Newly diagnosed atrial fibrillation linked to wake-up stroke and TIA: Hypothetical implications

Background: Based on the higher frequency of paroxysmal atrial fibrillation during night and early morning hours, we sought to analyze the association between newly diagnosed atrial fibrillation and wake-up ischemic cerebrovascular events. Methods: We prospectively assessed every acute ischemic stroke and TIA patient admitted to our hospital between 2008 and 2011. We used a forward step-by-step multiple logistic regression analysis to assess the relationship between newly diagnosed atrial fibrillation and wake-up ischemic stroke or TIA, after adjusting for significant covariates. Results: The study population comprised 356 patients, 274 (77.0%) with a diagnosis of acute ischemic stroke and 82 (23.0%) with TIA. A total of 41 (11.5%) of these events occurred during night sleep. A newly diagnosed atrial fibrillation was detected in 27 patients of 272 without known atrial fibrillation (9.9%). We found an independent association between newly diagnosed atrial fibrillation and wake-up ischemic stroke and TIA (odds ratio 3.6, 95% confidence interval 1.2–7.7, p = 0.019). Conclusions: The odds of detecting a newly diagnosed atrial fibrillation were 3-fold higher among wake-up cerebrovascular events than among non–wake-up events. The significance of this independent association between newly diagnosed atrial fibrillation and wake-up ischemic stroke and TIA and the role of other comorbidities should be investigated in future studies.

Stroke Severity Score based on Six Signs and Symptoms The 6S Score: A Simple Tool for Assessing Stroke Severity and In-hospital Mortality.

Background and Purpose Ascertaining stroke severity and predicting risk of in-hospital mortality is crucial to advise patients and families about medical decisions. We developed and tested the validity of a new stroke score, the 6S Score (Stroke Severity Score based on Six Signs and Symptoms), for quantifying ischemic stroke severity and predicting in-hospital mortality. Methods We prospectively assessed 210 consecutive acute ischemic stroke patients. The cohort was further divided into a derivation (n=120) and a validation (n=90) sample. From a total of 10 stroke signs and symptoms, we selected those with likelihood ratios P<0.005. We tested the validity of the score for predicting in-hospital mortality by using receiver operating characteristic curves. We used a scatterplot and the Spearmans test to evaluate the correlation between the 6S Score and the National Institutes of Health Stroke Scale as a marker of stroke severity. We used principal component and exploratory factor analyses for assessing qualitative aspects of the 6S Score. Results The C statistic for in-hospital mortality was 0.82 for the 6S Score and 0.86 for the National Institutes of health Stroke Scale, respectively, with no significant differences between each other (P=0.79). The correlation between both scores was strong (Spearmans rho 0.68, P<0.001). The factor analyses showed a good balance between left/right hemispheres and anterior/posterior circulations. Conclusions The 6S Score may constitute a tool for easily assessing stroke severity and predicting stroke mortality. Further research is needed for further assessing its external validity.

Altered neural signatures of interoception in multiple sclerosis

Multiple sclerosis (MS) patients present several alterations related to sensing of bodily signals. However, no specific neurocognitive impairment has yet been proposed as a core deficit underlying such symptoms. We aimed to determine whether MS patients present changes in interoception—that is, the monitoring of autonomic bodily information—a process that might be related to various bodily dysfunctions. We performed two studies in 34 relapsing–remitting, early‐stage MS patients and 46 controls matched for gender, age, and education. In Study 1, we evaluated the heartbeat‐evoked potential (HEP), a cortical signature of interoception, via a 128‐channel EEG system during a heartbeat detection task including an exteroceptive and an interoceptive condition. Then, we obtained whole‐brain MRI recordings. In Study 2, participants underwent fMRI recordings during two resting‐state conditions: mind wandering and interoception. In Study 1, controls exhibited greater HEP modulation during the interoceptive condition than the exteroceptive one, but no systematic differences between conditions emerged in MS patients. Patients presented atrophy in the left insula, the posterior part of the right insula, and the right anterior cingulate cortex, with abnormal associations between neurophysiological and neuroanatomical patterns. In Study 2, controls showed higher functional connectivity and degree for the interoceptive state compared with mind wandering; however, this pattern was absent in patients, who nonetheless presented greater connectivity and degree than controls during mind wandering. MS patients were characterized by atypical multimodal brain signatures of interoception. This finding opens a new agenda to examine the role of inner‐signal monitoring in the body symptomatology of MS.