What is the relationship between insular (island of Reil) stroke and autonomic dysfunction?

From the Guidelines

Insular stroke is strongly associated with autonomic dysfunction, which can lead to significant cardiovascular complications, including cardiac arrhythmias and blood pressure dysregulation, emphasizing the need for close cardiac monitoring and management. When a stroke affects the insular cortex, patients may experience a range of autonomic disturbances due to the insula's critical role in regulating autonomic nervous system function 1. The insular cortex, particularly the right insula, has extensive connections to the central autonomic network, influencing both sympathetic and parasympathetic outflow, which can be disrupted in the event of a stroke 2.

Key aspects of autonomic dysfunction following insular stroke include:

• Cardiac arrhythmias, such as atrial fibrillation, ventricular ectopy, tachycardia, and heart blocks, which can be life-threatening and require immediate attention 2
• Blood pressure dysregulation, often manifesting as hypertension, which necessitates careful management to prevent further cardiovascular complications 1
• Altered heart rate variability, indicating an imbalance in autonomic control over the heart 1
• Potential thermoregulatory disturbances, gastrointestinal dysfunction, and altered sweating patterns, reflecting the broad impact of autonomic dysfunction on various bodily systems

Management of patients with insular stroke should prioritize:

• Close cardiac monitoring for at least the first 24-72 hours after stroke onset, with continuous ECG monitoring to detect potentially life-threatening arrhythmias 2
• Careful management of blood pressure, potentially requiring antihypertensive medications like labetalol or nicardipine, and considering the use of beta-blockers for their dual benefit in addressing arrhythmias and hypertension
• Regular cardiovascular assessments during rehabilitation, with adjustments to medication as the patient's condition evolves, to address the potential for long-term autonomic dysfunction

The association between insular stroke and autonomic dysfunction underscores the importance of a comprehensive approach to patient management, incorporating both neurological and cardiovascular care to mitigate morbidity, mortality, and improve quality of life 1, 2.

From the Research

Relationship Between Insular Stroke and Autonomic Dysfunction

The relationship between insular (island of Reil) stroke and autonomic dysfunction is complex and has been studied in various research papers.

• Autonomic nervous system dysfunction is a common complication of ischemic stroke, and the insular cortex plays a crucial role in the central autonomic network 3.
• Studies have shown that insular stroke can lead to cardio-autonomic dysfunction, characterized by a predominance of sympathetic activity, which can be a negative prognostic factor 4.
• The insular cortex has been suspected to play an important role in causing sympathovagal imbalance, but its exact role and that of other brain regions remain unclear 4.

Hemispheric Lateralization in Autonomic Activity

• Research has indicated a hemispheric lateralization in autonomic activity, which is mediated by the right-sided insular cortex 3.
• Patients with right-hemisphere stroke involving the insular cortex are most susceptible to develop cardio-autonomic dysfunction 3.
• However, another study found that left insular injury tended to be more bradycardiac and exhibited significantly lower plasma norepinephrine and glucose levels 5.

Clinical Presentation of Isolated Insular Stroke

• Isolated insular stroke (IIS) can manifest with a combination of deficits, including motor, somatosensory, speaking, coordination, autonomic, and cognitive disturbances 6.
• IIS patients often show high frequency detection of cardiac disturbances, and atrial fibrillation (AF) manifestation can follow briefly after the major event 6.
• Continuous cardiac monitoring is required for IIS patients due to the risk of autonomic dysfunction and cardiac complications 6.

Assessment of Autonomic Dysfunction in Acute Ischemic Stroke

• Cardiac autonomic dysfunction is a common complication after acute ischemic stroke, and heart rate variability (HRV) can be used to assess autonomic function 7.
• Both large-artery atherosclerosis (LAA) and small-vessel occlusion (SVO) subtypes of acute ischemic stroke are predisposed to have cardiac autonomic dysfunction, manifesting as abnormalities in HRV 7.
• The high-frequency component of HRV, thought to be related to vagal control, might be a cardinal marker for predicting cardiac autonomic dysfunction after acute ischemic stroke 7.