A stroke is a serious medical emergency where blood flow to a part of the brain is interrupted or stopped. This deprives brain cells of oxygen and nutrients, causing them to die rapidly. While often associated with high blood pressure, low blood pressure (hypotension), defined as below 90/60 mmHg, can also lead to a stroke.
How Low Blood Pressure Can Lead to Stroke
Low blood pressure can lead to a stroke through a mechanism called hypoperfusion, which means insufficient blood flow. When blood pressure drops significantly, the brain may not receive an adequate supply of blood. This deprivation starves brain cells of oxygen and essential nutrients, leading to their damage and eventual death.
Several scenarios can cause a drastic drop in blood pressure, potentially leading to hypoperfusion. Severe dehydration, for example, reduces overall blood volume, which can lower blood pressure. Significant blood loss from injuries or internal bleeding can also lead to a sharp decline in blood pressure. Conditions such as a heart attack, severe infections like sepsis, or certain medications can similarly cause a sudden and severe reduction in blood pressure. When arteries are already narrowed or diseased, the brain becomes even more susceptible to damage from reduced blood flow.
Types of Stroke Linked to Low Blood Pressure
When low blood pressure causes a stroke, it typically results in an ischemic stroke, which accounts for the majority of all stroke cases. Specifically, a type known as a “watershed stroke” or “border zone infarct” is particularly associated with episodes of low blood pressure. These strokes occur in areas of the brain that are at the furthest reach of the major arterial blood supplies.
Because these “watershed” regions are highly sensitive to any reduction in overall blood flow or pressure, an extreme drop in blood pressure is a common trigger for these specific types of ischemic strokes. In contrast, hemorrhagic strokes, which involve bleeding within or around the brain, are not typically caused by low blood pressure.
Recognizing the Signs of Stroke
Recognizing the signs of a stroke quickly is important for favorable outcomes. The F.A.S.T. acronym serves as a helpful guide for identifying potential stroke symptoms. Other sudden symptoms can include confusion, problems seeing in one or both eyes, trouble walking, dizziness, or loss of balance.
Face drooping: One side of the person’s face might droop or feel numb.
Arm weakness: One arm may feel weak or numb, making it difficult to raise both arms equally.
Speech difficulty: Slurred speech, trouble speaking, or difficulty understanding what others are saying.
Time to call emergency services immediately.
Seeking Immediate Medical Care
If any signs of a stroke are observed, seeking immediate medical attention is crucial. Healthcare professionals often use the phrase “time is brain” to convey the urgency of stroke treatment. This means that with every passing minute that a stroke goes untreated, brain cells are rapidly damaged and lost.
Prompt treatment can significantly reduce the extent of brain damage and improve a person’s chances of recovery. Even if symptoms appear mild or temporary, such as in a transient ischemic attack (TIA), immediate medical evaluation is necessary. It is important to call 911 or your local emergency number right away rather than attempting to drive to the hospital.