Left Insular Stroke and Cardiac Complications
Left Insular Stroke and Cardiac Complications
Abstract & Commentary
By Alan Z. Segal, MD, Assistant Professor, Department of Neurology, Weill-Cornell Medical College, Attending Neurologist, NewYork-Presbyterian Hospital. Dr. Segal is on the speaker's bureau for Boehringer-Ingelheim.
Synopsis: Left insular strokes are associated with more cardiac complications than strokes that damage other brain regions.
Source: Laowattana S, et al. Left Insular Stroke is Associated with Adverse Cardiac Outcome. Neurology. 2006;66:477-483.
It is well known that central nervous system injuries such as subarachnoid hemorrhage or ischemic stroke may produce adverse cardiac outcomes. This may manifest as EKG changes in the form of cerebral T waves or may produce cardiac arrhythmias (both brady and tachy), myocardial cell necrosis, and congestive heart failure. Autonomic alterations shifting the balance towards the sympathetic nervous system may produce systemic, as well as intracardiac release of catecholamines. The left insula, with its connections to the amygdala and hypothalamus, has long been the suspected anatomic culprit of this type of pathology. Laowattana and colleagues provide prospective evidence supporting the hypothesis that autonomic derangements may arise from the left insular cortex.
Thirty-two patients with strokes involving the left insula (Group 1) were compared with 84 patients with non-insular stroke, right insular stroke, or TIA (Group 2). Workup included transesophageal echocardiography, as well as adenosine thallium cardiac stress testing. Groups were evenly matched except for a trend towards more African-Americans in Group 1 and a higher prevalence of coronary artery disease (CAD) in Group 2 (P = 0.06). There was an increased risk of cardiac end points (including sudden cardiac death, congestive heart failure, MI) in Group 1, with a relative risk of 3.19 (P = 0.007). This applied only to patients without underlying CAD. For patients with CAD, there was no significant difference between Group 1 and Group 2. Patients in Group 1 showed increased mortality compared to Group 2, and showed a strong trend towards decreased myocardial contractility, again among patients without CAD. Interestingly, for patients with symptomatic CAD, there was a trend towards a protective effect among patients with a left insular location.
Commentary
Infarct size and clinical severity remain the most important predictors of outcome in stroke. As these data indicate, however, anatomical location, specifically the left insula, may separately contribute to stroke mortality. Particularly in patients without CAD, this brain region appears to have potent adverse effects on the myocardium. While certainly real, however, the true effect of left insular stroke on the heart may be relatively weak. It is easily negated by intrinsic CAD and is likely blunted by beta-blocker therapy. In fact, for reasons that are unclear, left insular location may actually be protective for patients with established CAD.
Despite some of these contradictions, it is important for the clinician to be wary of the potential cardiac and other autonomic effects of any stroke, especially those located in the left insula. Hospitalization of patients in dedicated stroke units, with continuous telemetry and close blood pressure monitoring, will facilitate more rapid diagnosis and intervention for dangerous cardiac complications.
Left insular strokes are associated with more cardiac complications than strokes that damage other brain regions.Subscribe Now for Access
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