What is a stroke?
According to Dr. Ishu Goyal, Department of Neurology, Sir HN Reliance Foundation Hospital (Mumbai India), stroke occurs when a blood vessel is blocked or ruptured, resulting in damage to the affected area due to lack of blood supply.
The affected area has two parts: the core, which is irreversibly damaged brain tissue, and the penumbra, which is an area with reduced blood supply, which can be saved if treated promptly.
According to the International Journal of Molecular Sciences, stroke is the second leading cause of death and a significant contributor to disability worldwide. Its incidence is particularly high in developing countries, and ischemic stroke is the most common type.
Immune response to stroke
“Once brain tissue is damaged, it is attacked by inflammatory mediators, such as macrophages, cytokines, and interleukins, which clear away dead and necrotic tissue,” says Dr. Goyal. “A broken blood-brain barrier allows these inflammatory markers to easily reach the affected area.”
In response, the hypothalamus, pituitary, and adrenal axes are stimulated to suppress the excessive inflammatory response after stroke, limiting the area targeted by inflammatory cells.
“Immediately after a stroke, there is increased autoimmunity in the brain, while systemic immunosuppression occurs. This dual response can make the patient susceptible to various acquired infections such as pneumonia and urinary tract infections being the most common in such cases,” Dr. Goyal added.
Factors influencing immunosuppression after stroke
Several factors can influence the degree of immune suppression after a stroke. Key factors include:
- Severity: The more severe the stroke, the greater the impact on the immune system.
- Volume of affected area: The larger the damaged area, the higher the immune response.
- Pre-existing medical conditions: Medical conditions such as diabetes and high blood pressure can aggravate immune disorders.
- Post-stroke complications: Hemodynamic disturbances and other complications can increase hospital stay and risk of acquired infection.
Prevention
While various therapies have been proposed to prevent systemic infections after stroke, such as stem cell therapy and beta-adrenergic blockers, these have not been shown to be clinically effective. Therefore, the best approach to avoiding immune dysfunction in the body is to prevent stroke in the first place.
Managing stroke risk factors
To help control the risk of stroke and related immune disorders, it is essential to control risk factors such as:
- Diabetes: Maintaining healthy blood sugar levels can significantly reduce your risk of stroke.
- Lipid disorders: Controlling cholesterol levels through diet, exercise, and medication can reduce the risk of stroke.
- Smoking: Quitting smoking is one of the most effective ways to reduce your risk of stroke.
