It is possible to experience a stroke even when blood pressure levels are considered normal. While elevated blood pressure is widely recognized as a significant risk factor for stroke, it is not the only contributing factor. A stroke can occur due to various underlying conditions or circumstances unrelated to blood pressure readings.
The Mechanics of Stroke
A stroke occurs when the supply of blood to a part of the brain is interrupted, leading to brain cells being deprived of oxygen and nutrients. Brain cells begin dying within minutes. Understanding the two main types of stroke helps clarify how these events unfold.
An ischemic stroke, accounting for approximately 87% of all strokes, happens when a blood clot blocks an artery that supplies blood to the brain. These clots often form in arteries narrowed by fatty deposits, or they can travel from other parts of the body to the brain. This lack of blood flow damages or kills brain tissue.
A hemorrhagic stroke occurs when a blood vessel in the brain ruptures and bleeds into the surrounding brain tissue. This bleeding damages brain cells directly and also increases pressure within the skull, further harming brain tissue. This type of stroke can result from weakened blood vessel walls that balloon outward, known as aneurysms, or from abnormal tangles of blood vessels, called arteriovenous malformations.
Risk Factors Beyond Blood Pressure
Several conditions and lifestyle factors can significantly increase stroke risk, even in individuals with normal blood pressure. Atrial fibrillation (AFib), an irregular and often rapid heartbeat, is a notable example. In AFib, the heart’s upper chambers beat chaotically, causing blood to pool and potentially form clots, which can then travel to the brain and cause an ischemic stroke.
High cholesterol and atherosclerosis, the hardening and narrowing of arteries due to plaque buildup, also contribute to stroke risk. Even with normal blood pressure, these plaques can rupture, triggering the formation of blood clots that block blood flow to the brain. These plaques can also narrow arteries in the neck that supply the brain, reducing blood flow.
Diabetes can damage blood vessels throughout the body over time, making them more prone to narrowing and clot formation, increasing stroke risk independently of blood pressure levels. Smoking is another risk factor, as it damages blood vessels, thickens the blood, and promotes the formation of blood clots. The chemicals in cigarette smoke contribute to inflammation and vessel wall injury.
Obesity and a lack of physical activity can increase stroke risk by contributing to conditions like high cholesterol and diabetes. Genetic factors and a family history of stroke can indicate an inherited predisposition to stroke.
Certain heart conditions, such as a patent foramen ovale (PFO) or valvular heart disease, can lead to clot formation and subsequent stroke. Vascular malformations like aneurysms or arteriovenous malformations (AVMs) can also cause hemorrhagic strokes.
Recognizing the Signs
Recognizing stroke signs and acting quickly is important, regardless of blood pressure status. The acronym FAST is a widely used tool for identifying stroke symptoms. FAST stands for Face drooping, Arm weakness, Speech difficulty, and Time to call emergency services.
If one side of the face droops or feels numb, or if one arm becomes weak or numb, these are potential indicators of a stroke. Difficulty speaking, slurred speech, or trouble understanding others’ speech also warrant immediate concern. If any of these signs appear, it is crucial to call emergency medical services immediately.
Timely medical attention improves outcomes and reduces long-term disability. Brain cells continue to die while blood flow is interrupted, making every minute count. Ignoring symptoms because one believes their blood pressure is normal can delay critical treatment and lead to more severe consequences.