What Is an Acute (or Sudden) Stroke?

An acute stroke starts suddenly and worsens rapidly—which is the case for most (if not all) strokes. Some strokes may be preceded by a transient ischemic attack (TIA), which is a temporary stroke that resolves before it causes any lasting effects. There are two types of acute stroke—ischemic and hemorrhagic—both of which bring on similar symptoms such as muscle weakness, vision loss, trouble speaking, severe head pain, and more. These symptoms should be evaluated immediately: Diagnosing a stroke is done with a physical exam, imaging tests of the brain, and blood tests. The results will determine the type of treatment most likely to result in recovery and rehabilitation.

Types of Acute Stroke

Acute strokes are classified in one of two ways:

Ischemic Stroke

During an ischemic stroke, the blood supply to a region of the brain is cut off because a blood vessel has been blocked by a blood clot. Several conditions can predispose a person to an ischemic stroke, including heart disease, high cholesterol, and high blood pressure. Other causes of an ischemic stroke include recreational drug use (in particular, alcohol, cocaine, and heroin), blood clotting disorders, or trauma to the blood vessels in the neck.

Hemorrhagic Stroke

A hemorrhagic stroke occurs when an artery in the brain bleeds. This can happen when an abnormally shaped artery, such as an arterial venous malformation (AVM), or an aneurysm bursts. The blood that seeps into the brain when a blood vessel bleeds causes pressure to build up within the skull, compressing the brain and potentially causing permanent brain damage.

Symptoms

Stroke symptoms can progress quickly but may wax and wane over the course of a few hours. It is not possible to predict how severe a stroke will become or how long it will persist.

The most common symptoms of an acute stroke include:

• Numbness or weakness on one side of the body
• Difficulty speaking or trouble understanding what others are saying
• Trouble seeing or loss of vision
• Loss of balance or coordination
• Difficulty walking or falling
• A sudden, severe headache characterized by a stiff neck, facial pain, pain between the eyes, and vomiting
• Confusion

Causes and Risk Factors

An acute stroke is caused by interruption of blood flow to a region in the brain. It can be either ischemic or hemorrhagic.

Ischemic Stroke

During an ischemic stroke, the blood supply to a region of the brain is cut off because a blood vessel has been blocked by a blood clot. Several conditions can predispose a person to an ischemic stroke. These conditions include heart disease, high cholesterol, and high blood pressure. Other causes of an ischemic stroke include the use of recreational drugs, blood clotting disorders, or trauma to the blood vessels in the neck.

Hemorrhagic Stroke

A hemorrhagic stroke occurs when an artery in the brain bleeds. This can happen when an abnormally shaped artery, such as an arterial venous malformation (AVM) or an aneurysm, bursts. The blood that seeps into the brain when a blood vessel bleeds causes pressure to build up within the skull, compressing the brain and potentially causing permanent brain damage.

Risk Factors

Many of the risk factors for stroke can be eliminated with lifestyle changes. These risk factors include heart disease, high blood pressure, high cholesterol, smoking, and diabetes. Additional risk factors for stroke include the following:

• Prior stroke or TIA
• Prior heart attack
• A family history of stroke
• Obesity
• Carotid artery disease
• Inactivity/sedentary lifestyle
• Use of birth control pills or other hormone therapies
• Pregnancy
• Heavy or binge drinking
• Recreational drug use

Diagnosis

If you experience symptoms of an acute stroke or are with someone who you suspect is having a stroke, seek urgent medical attention at the nearest emergency department. The medical team there will do a neurological examination to confirm the diagnose of stroke.

This will likely be followed by various imaging tests to determine the cause of stroke and to make a plan for treatment, such as:

• Computed tomography (CT) scan of the head to look for bleeding or damage to brain cells
• Magnetic resonance imaging (MRI) of the brain to reveal changes in the brain, bleeding, and to rule out problems such as a tumor as a source of the symptoms
• CT or MR angiogram—an X-ray movie that reveals how blood flows using a dye injected into the arteries and veins. 
• Carotid ultrasound of the arteries that supply blood to the brain. Using sound waves, this test can show if an accumulation of plaque is blocking blood flow.
• Transcranial Doppler (TCD) ultrasound, another test using sound waves to determine where an artery blockage may be located.
• Electroencephalogram (EEG), a recording of electrical activity in the brain to rule out a seizure.
• Electrocardiogram (ECG or EKG) to record the electrical activity of the heart. It can help determine if atrial fibrillation (irregular heart rate) may have caused the stroke.

Blood tests also may be performed:

• Complete blood count (CBC), which can help detect infection, anemia, or clotting problems
• Serum electrolytes, which can rule out an electrolyte problem that may be causing stroke-like symptoms and also show up any kidney problems
• Coagulation panel to measure how quickly blood clots
• Heart attack tests—especially important for women, many of whom have heart attack symptoms in conjunction with stroke symptoms
• Thyroid tests: Elevated levels of thyroid hormones (hyperthyroidism) can increase the risk of atrial fibrillation. 
• Blood glucose: Low blood sugar, a common complication of diabetes medications, can cause stroke-like symptoms.
• Cholesterol tests to determine if high cholesterol might have triggered a stroke
• C-reactive protein test and blood protein test to look for signs of inflammation that indicate damage to arteries

Treatments

An acute ischemic stroke is potentially manageable with a number of medical treatments, including a powerful treatment called tissue plasminogen activator (t-PA). This treatment is effective if the stroke is quickly diagnosed and evaluated and treatment can begin within a few hours of the onset of symptoms.

A combination of blood vessel surgery and medication to control bleeding may be used to treat an acute hemorrhagic stroke. Treatment may include procedures that involve clipping the ruptured aneurysm or an endovascular embolization in which a coil is placed into the aneurysm in order to diminish blood flow.

A Word From Verywell

There is no question a stroke can have potentially life-altering consequences, particularly if symptoms aren't obvious right away and treatment is delayed. That said, a promptly treated stroke is likely to have a positive outcome. And while recovery from an acute stroke takes time, there are multiple therapies dedicated to stroke rehabilitation available, as well as promising new approaches in the works, such as electrical therapy and mirror therapy, that are likely to make those positive outcomes ever more likely.