stroke

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Stroke occurs due to a decrease or blockage in the brain’s blood supply. A person experiencing a stroke needs immediate emergency treatment.

Stroke is the fifth leading cause of death in the United States. In fact, nearly 800,000 people have a stroke each year. That equates to around one person every 40 seconds.

There are three main types of stroke:

• Ischemic stroke: This is the most common type of stroke, making up 87% of all cases. A blood clot prevents blood and oxygen from reaching an area of the brain.
• Hemorrhagic stroke: This occurs when a blood vessel ruptures. These are usually the result of aneurysms or arteriovenous malformations (AVMs)
• Transient ischemic attack (TIA): This occurs when blood flow to a part of the brain is inadequate for a brief period of time. Normal blood flow resumes after a short amount of time, and the symptoms resolve without treatment. Some people call this a ministroke.

Stroke can be fatal. According to the American Heart Association (AHA), the age-adjusted mortality rate for 2017 was 37.6 in every 100,000 stroke diagnoses. Doctors have made a great deal of progress in managing strokes, meaning that this mortality rate is 13.6% lower than it was in 2007.

This article explains why strokes occur and how to treat them. It also explores the different types of stroke, as well as the steps a person can take to prevent them.

In hemorrhagic stroke, bleeding occurs directly into the brain parenchyma. The usual mechanism is thought to be leakage from small intracerebral arteries damaged by chronic hypertension. The terms intracerebral hemorrhage and hemorrhagic stroke are used interchangeably in this article and are regarded as separate entities from hemorrhagic transformation of ischemic stroke. 

Pathophysiology

In intracerebral hemorrhage, bleeding occurs directly into the brain parenchyma. The usual mechanism is thought to be leakage from small intracerebral arteries damaged by chronic hypertension. Other mechanisms include bleeding diatheses, iatrogenic anticoagulation, cerebral amyloidosis, and cocaine abuse.

Intracerebral hemorrhage has a predilection for certain sites in the brain, including the thalamus, putamen, cerebellum, and brainstem. In addition to the area of the brain injured by the hemorrhage, the surrounding brain can be damaged by pressure produced by the mass effect of the hematoma. A general increase in intracranial pressure may occur.

Subarachnoid hemorrhage

The pathologic effects of subarachnoid hemorrhage (SAH) on the brain are multifocal. SAH results in elevated intracranial pressure and impairs cerebral autoregulation. These effects can occur in combination with acute vasoconstriction, microvascular platelet aggregation, and loss of microvascular perfusion, resulting in profound reduction in blood flow and cerebral ischemia.

Symptoms

If you or someone you’re with may be having a stroke, pay particular attention to the time the symptoms began. Some treatment options are most effective when given soon after a stroke begins.

Signs and symptoms of stroke include:

• Trouble speaking and understanding what others are saying. You may experience confusion, slur words or have difficulty understanding speech.
• Paralysis or numbness of the face, arm or leg. You may develop sudden numbness, weakness or paralysis in the face, arm or leg. This often affects just one side of the body. Try to raise both your arms over your head at the same time. If one arm begins to fall, you may be having a stroke. Also, one side of your mouth may droop when you try to smile.
• Problems seeing in one or both eyes. You may suddenly have blurred or blackened vision in one or both eyes, or you may see double.
• Headache. A sudden, severe headache, which may be accompanied by vomiting, dizziness or altered consciousness, may indicate that you’re having a stroke.
• Trouble walking. You may stumble or lose your balance. You may also have sudden dizziness or a loss of coordination.

When to see a doctor

Seek immediate medical attention if you notice any signs or symptoms of a stroke, even if they seem to come and go or they disappear completely. Think “FAST” and do the following:

• Face. Ask the person to smile. Does one side of the face droop?
• Arms. Ask the person to raise both arms. Does one arm drift downward? Or is one arm unable to rise?
• Speech. Ask the person to repeat a simple phrase. Is his or her speech slurred or strange?
• Time. If you observe any of these signs, call 911 or emergency medical help immediately.

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Causes

There are two main causes of stroke: a blocked artery (ischemic stroke) or leaking or bursting of a blood vessel (hemorrhagic stroke). Some people may have only a temporary disruption of blood flow to the brain, known as a transient ischemic attack (TIA), that doesn’t cause lasting symptoms.

Ischemic stroke

Ischemic stroke Open pop-up dialog box

This is the most common type of stroke. It happens when the brain’s blood vessels become narrowed or blocked, causing severely reduced blood flow (ischemia). Blocked or narrowed blood vessels are caused by fatty deposits that build up in blood vessels or by blood clots or other debris that travel through the bloodstream, most often from the heart, and lodge in the blood vessels in the brain.

Some initial research shows that COVID-19 infection may increase the risk of ischemic stroke, but more study is needed.

Hemorrhagic stroke

Hemorrhagic stroke occurs when a blood vessel in the brain leaks or ruptures. Brain hemorrhages can result from many conditions that affect the blood vessels. Factors related to hemorrhagic stroke include:

• Uncontrolled high blood pressure
• Overtreatment with blood thinners (anticoagulants)
• Bulges at weak spots in your blood vessel walls (aneurysms)
• Trauma (such as a car accident)
• Protein deposits in blood vessel walls that lead to weakness in the vessel wall (cerebral amyloid angiopathy)
• Ischemic stroke leading to hemorrhage

A less common cause of bleeding in the brain is the rupture of an irregular tangle of thin-walled blood vessels (arteriovenous malformation).

Transient ischemic attack (TIA)

A transient ischemic attack (TIA) — sometimes known as a ministroke — is a temporary period of symptoms similar to those in a stroke. A TIA doesn’t cause permanent damage. A TIA is caused by a temporary decrease in blood supply to part of the brain, which may last as little as five minutes.

Like an ischemic stroke, a TIA occurs when a clot or debris reduces or blocks blood flow to part of the nervous system.

Seek emergency care even if you think you’ve had a TIA because your symptoms got better. It’s not possible to tell if you’re having a stroke or TIA based only on the symptoms. If you’ve had a TIA, it means you may have a partially blocked or narrowed artery leading to the brain. Having a TIA increases your risk of having a full-blown stroke later.

Risk factors

Many factors can increase the risk of stroke. Potentially treatable stroke risk factors include:

Lifestyle risk factors

• Being overweight or obese
• Physical inactivity
• Heavy or binge drinking
• Use of illegal drugs such as cocaine and methamphetamine

Medical risk factors

• High blood pressure
• Cigarette smoking or secondhand smoke exposure
• High cholesterol
• Diabetes
• Obstructive sleep apnea
• Cardiovascular disease, including heart failure, heart defects, heart infection or irregular heart rhythm, such as atrial fibrillation
• Personal or family history of stroke, heart attack or transient ischemic attack
• COVID-19 infection

Other factors associated with a higher risk of stroke include:

• Age — People age 55 or older have a higher risk of stroke than do younger people.
• Race or ethnicity — African Americans and Hispanics have a higher risk of stroke than do people of other races or ethnicities.
• Sex — Men have a higher risk of stroke than do women. Women are usually older when they have strokes, and they’re more likely to die of strokes than are men.
• Hormones — Use of birth control pills or hormone therapies that include estrogen increases risk.

Complications

A stroke can sometimes cause temporary or permanent disabilities, depending on how long the brain lacks blood flow and which part is affected. Complications may include:

• Paralysis or loss of muscle movement. You may become paralyzed on one side of the body, or lose control of certain muscles, such as those on one side of the face or one arm.
• Difficulty talking or swallowing. A stroke might affect control of the muscles in the mouth and throat, making it difficult for you to talk clearly, swallow or eat. You also may have difficulty with language, including speaking or understanding speech, reading, or writing.
• Memory loss or thinking difficulties. Many people who have had strokes experience some memory loss. Others may have difficulty thinking, reasoning, making judgments and understanding concepts.
• Emotional problems. People who have had strokes may have more difficulty controlling their emotions, or they may develop depression.
• Pain. Pain, numbness or other unusual sensations may occur in the parts of the body affected by stroke. For example, if a stroke causes you to lose feeling in the left arm, you may develop an uncomfortable tingling sensation in that arm.
• Changes in behavior and self-care ability. People who have had strokes may become more withdrawn. They may need help with grooming and daily chores.

Diagnostic Considerations

Intracerebral hemorrhage may be clinically indistinguishable from ischemic stroke, and a thorough history and physical examination are important. An acute onset of neurologic deficit, altered level of consciousness/mental status, or coma is more common with hemorrhagic stroke than with ischemic stroke. A history of trauma, even if minor, may be important, as extracranial arterial dissections can result in ischemic stroke.

Seizures are more common in hemorrhagic stroke than in ischemic stroke and occur in up to 28% of hemorrhagic strokes, generally at the onset of the intracerebral hemorrhage or within the first 24 hours. Postictal (Todd) paralysis and hyperosmolality should also be considered.

Differential Diagnoses

• Acute Hypoglycemia
• Brain Neoplasms
• Encephalitis
• Headache, Migraine
• Hypernatremia in Emergency Medicine
• Hyperosmolar Hyperglycemic Nonketotic Coma
• Hypertensive Emergencies
• Hyponatremia
• Labyrinthitis Ossificans
• Meningitis
• Stroke, Ischemic
• Subarachnoid Hemorrhage
• Subdural Hematoma
• Transient Ischemic Attack

History

Obtaining an adequate history includes determining the onset and progression of symptoms, as well as assessing for risk factors and possible causative events.

A history of trauma, even if minor, may be important, as extracranial arterial dissections can result in ischemic stroke.

Hemorrhagic versus ischemic stroke

Symptoms alone are not specific enough to distinguish ischemic from hemorrhagic stroke. However, generalized symptoms, including nausea, vomiting, and headache, as well as an altered level of consciousness, may indicate increased intracranial pressure and are more common with hemorrhagic strokes and large ischemic strokes.

Seizures are more common in hemorrhagic stroke than in the ischemic kind. Seizures occur in up to 28% of hemorrhagic strokes, generally at the onset of the intracerebral hemorrhage or within the first 24 hours.

Focal neurologic deficits

The neurologic deficits reflect the area of the brain typically involved, and stroke syndromes for specific vascular lesions have been described. Focal symptoms of stroke include the following:

• Weakness or paresis that may affect a single extremity, one half of the body, or all 4 extremities
• Facial droop
• Monocular or binocular blindness
• Blurred vision or visual field deficits
• Dysarthria and trouble understanding speech
• Vertigo or ataxia
• Aphasia

Symptoms of subarachnoid hemorrhage may include the following:

• Sudden onset of severe headache
• Signs of meningismus with nuchal rigidity
• Photophobia and pain with eye movements
• Nausea and vomiting
• Syncope – Prolonged or atypical

The most common clinical scoring systems for grading aneurysmal subarachnoid hemorrhage are the Hunt and Hess grading scheme and the World Federation of Neurosurgeons (WFNS) grading scheme, which incorporates the Glasgow Coma Scale. The Fisher Scale incorporates findings from noncontrast computed tomography (NCCT) scans.

Physical Examination

The assessment in patients with possible hemorrhagic stroke includes vital signs; a general physical examination that focuses on the head, heart, lungs, abdomen, and extremities; and a thorough but expeditious neurologic examination. 

Hypertension (particularly systolic blood pressure [BP] greater than 220 mm Hg) is commonly a prominent finding in hemorrhagic stroke. Higher initial BP is associated with early neurologic deterioration, as is fever. 

An acute onset of neurologic deficit, altered level of consciousness/mental status, or coma is more common with hemorrhagic stroke than with ischemic stroke. Often, this is caused by increased intracranial pressure. Meningismus may result from blood in the subarachnoid space.

Examination results can be quantified using various scoring systems. These include the Glasgow Coma Scale (GCS), the Intracerebral Hemorrhage Score (which incorporates the GCS; see Prognosis), and the National Institutes of Health Stroke Scale.

Focal neurologic deficits

The type of deficit depends upon the area of brain involved. If the dominant hemisphere (usually the left) is involved, a syndrome consisting of the following may result:

• Right hemiparesis
• Right hemisensory loss
• Left gaze preference
• Right visual field cut
• Aphasia
• Neglect (atypical)

If the nondominant (usually the right) hemisphere is involved, a syndrome consisting of the following may result:

• Left hemiparesis
• Left hemisensory loss
• Right gaze preference
• Left visual field cut

Nondominant hemisphere syndrome may also result in neglect when the patient has left-sided hemi-inattention and ignores the left side.

If the cerebellum is involved, the patient is at high risk for herniation and brainstem compression. Herniation may cause a rapid decrease in the level of consciousness and may result in apnea or death.

Specific brain sites and associated deficits involved in hemorrhagic stroke include the following:

• Putamen – Contralateral hemiparesis, contralateral sensory loss, contralateral conjugate gaze paresis, homonymous hemianopia, aphasia, neglect, or apraxia
• Thalamus – Contralateral sensory loss, contralateral hemiparesis, gaze paresis, homonymous hemianopia, miosis, aphasia, or confusion
• Lobar – Contralateral hemiparesis or sensory loss, contralateral conjugate gaze paresis, homonymous hemianopia, abulia, aphasia, neglect, or apraxia
• Caudate nucleus – Contralateral hemiparesis, contralateral conjugate gaze paresis, or confusion
• Brainstem – Quadriparesis, facial weakness, decreased level of consciousness, gaze paresis, ocular bobbing, miosis, or autonomic instability
• Cerebellum – Ipsilateral ataxia, facial weakness, sensory loss; gaze paresis, skew deviation, miosis, or decreased level of consciousness

Other signs of cerebellar or brainstem involvement include the following:

• Gait or limb ataxia
• Vertigo or tinnitus
• Nausea and vomiting
• Hemiparesis or quadriparesis
• Hemisensory loss or sensory loss of all 4 limbs
• Eye movement abnormalities resulting in diplopia or nystagmus
• Oropharyngeal weakness or dysphagia
• Crossed signs (ipsilateral face and contralateral body)

Many other stroke syndromes are associated with intracerebral hemorrhage, ranging from mild headache to neurologic devastation. At times, a cerebral hemorrhage may present as a new-onset seizure.

Approach Considerations

The treatment and management of patients with acute intracerebral hemorrhage depends on the cause and severity of the bleeding. Basic life support, as well as control of bleeding, seizures, blood pressure (BP), and intracranial pressure, are critical. Medications used in the treatment of acute stroke include the following:

• Anticonvulsants – To prevent seizure recurrence
• Antihypertensive agents – To reduce BP and other risk factors of heart disease
• Osmotic diuretics – To decrease intracranial pressure in the subarachnoid space

Management begins with stabilization of vital signs. Perform endotracheal intubation for patients with a decreased level of consciousness and poor airway protection. Intubate and hyperventilate if intracranial pressure is elevated, and initiate administration of mannitol for further control. Rapidly stabilize vital signs, and simultaneously acquire an emergent computed tomography (CT) scan. Glucose levels should be monitored, with normoglycemia recommended.  Antacids are used to prevent associated gastric ulcers.

No effective targeted therapy for hemorrhagic stroke exists yet. Studies of recombinant factor VIIa (rFVIIa) have yielded disappointing results. Evacuation of hematoma, either via open craniotomy or endoscopy, may be a promising ultra-early-stage treatment for intracerebral hemorrhage that may improve long-term prognosis.

A combined analysis of INTERACT (Intensive Blood Pressure Reduction in Acute Cerebral Hemorrhage Trial) 1 and 2 suggested that in patients with intracerebral hemorrhage, intensive BP reduction early in their treatment lessens the absolute growth of hematomas, with the effect being especially pronounced in patients who have undergone prior antithrombotic therapy. 

The study involved 1310 patients who had undergone repeat 24-hour CT scans, including 665 who received intensive BP reduction therapy (target BP < 140 mm Hg systolic) and 645 controls (target BP < 180 mm Hg systolic).  A total of 235 patients in the intensive reduction and control groups had received antithrombotic medication prior to intracerebral hemorrhage.

The investigators found that, in patients who had not had prior antithrombotic therapy, hematoma volume increased 1.1 mL on repeat CT scan in those who underwent intensive BP reduction, compared with 2.4 mL in controls. In patients who had previously taken antithrombotics, however, the difference between the intensive-reduction and control groups was much greater, with the increase in hematoma volume being 3.4 mL in the intensive-reduction and 8.1 mL in the controls.

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