Stroke: what it is, types, and how it differs from a heart attack

A stroke is a sudden disruption of the blood supply to an area of the brain, causing its cells to begin dying within minutes. The Latin insultus means "a leap, a blow," and the metaphor is accurate: the event unfolds over minutes or hours. Below are the mechanism, the types, and the boundary between a stroke and a heart attack.

Stroke: what it is

The brain does not store oxygen: blood delivers it and glucose continuously, and as soon as the flow in an artery stops, the cells in its territory die. Doctors call this acute cerebrovascular accident, and in everyday speech people say "cerebral stroke" — the qualifier is redundant but customary.

The definition is based on time: focal and general cerebral symptoms arise suddenly and persist for more than 24 hours or lead to death sooner. If the deficit resolves within a day, this is a transient disorder, or transient ischemic attack: the cell damage is not persistent. A minor stroke differs in that recovery takes up to three weeks.

Symptoms appear all at once and more often affect one side of the body:

• sudden weakness or numbness of the face, arm, or leg, especially on one side;
• confusion, difficulty speaking or understanding;
• visual disturbance in one or both eyes;
• difficulty walking, dizziness, loss of balance;
• sudden severe headache with no apparent cause.

Call 103 or 112 immediately if the corner of the mouth droops on one side when smiling, a raised arm "drifts" downward, speech becomes slurred, or there is sudden weakness of half the body, loss of vision, loss of balance, or a sudden severe headache with no cause.

Types of stroke: ischemic and hemorrhagic

There are two mechanisms. In ischemic stroke, a thrombus blocks an artery and an area of the brain is left without blood — this is a cerebral infarction; this occurs in approximately 80% of cases, by various estimates 70–85%.

In hemorrhagic stroke, a vessel ruptures and blood enters the brain tissue. Such events account for 20–25% of strokes, and nontraumatic subarachnoid hemorrhage for about 5%. The ratio of ischemic to hemorrhagic types is close to 4:1–5:1, so equating stroke with hemorrhage is incorrect.

Causes and risk factors

The main cause is atherosclerosis, fatty degeneration of the vessel wall that narrows the lumen of the arteries. Risk factors include high blood pressure, diabetes, heart disease, cardiac rhythm disorders, smoking, high cholesterol, excess body weight, physical inactivity, alcohol, and unhealthy diet. A personal and family history of stroke or transient ischemic attack is considered a risk factor.

Age is the most significant of the non-modifiable factors: incidence rises starting at age 30, 95% of strokes occur in people over 45, and two-thirds in those over 65. The term has a long history: the first description of a stroke is attributed to Hippocrates and dated to 467 BC, and Galen established the word "apoplexy" in medicine.

How a stroke differs from a heart attack

A heart attack (infarction) is a general medical concept: the death of an area of tissue due to cessation of blood flow. Cerebral infarction is ischemic stroke, so contrasting these words is meaningless. Myocardial infarction is a different event: the heart muscle is affected.

Stroke is broader. It includes hemorrhages, where the tissue is damaged not by ischemia but by escaped blood. The conditions are united by their vascular nature: cerebrovascular diseases rank second in mortality from circulatory pathology after coronary heart disease.

Consequences and complications of stroke

The outcome depends on which area was affected and how quickly blood flow was restored. Death of neurons produces persistent deficits: impairments of movement, speech, sensation, and coordination. Of survivors, 70–80% become disabled, and 20–30% of them require constant care. In 2015, stroke ranked second among causes of death worldwide after coronary heart disease — 6.3 million cases.

How doctors confirm the diagnosis

The diagnosis is based on history-taking and examination: they check clarity of consciousness, coordination and balance, strength and sensation in the face, arms, and legs, speech, and vision. Then brain imaging is performed — computed tomography or magnetic resonance imaging — to distinguish ischemia from hemorrhage. An electrocardiogram and echocardiography detect arrhythmias and thrombi that could be a source of embolism: the management of the acute period depends on the type of stroke.

This material is for reference: it explains the mechanism but does not replace a doctor's consultation.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer