A stroke, sometimes called a brain attack, occurs when something blocks blood supply to part of the brain or when a blood vessel in the brain bursts.

In either case, parts of the brain become damaged or die. A stroke can cause lasting brain damage, long-term disability, or even death.

What happens in the brain during a stroke?

The brain controls our movements, stores our memories, and is the source of our thoughts, emotions, and language. The brain also controls many functions of the body, like breathing and digestion.

To work properly, your brain needs oxygen. Your arteries deliver oxygen-rich blood to all parts of your brain. If something happens to block the flow of blood, brain cells start to die within minutes, because they can’t get oxygen. This causes a stroke.

Quick treatment is critical for stroke

A stroke is a serious medical condition that requires emergency care. Act F.A.S.T. Call 9-1-1 right away if you or someone you are with shows any signs of a stroke.

Time lost is brain lost. Every minute counts.

What are the types of stroke?

The type of stroke you have affects your treatment and recovery.

There are two types of stroke:

• Ischemic stroke.
• Hemorrhagic stroke.

A transient ischemic attack (TIA) is sometimes called a “mini-stroke.” It is different from the major types of stroke, because blood flow to the brain is blocked for only a short time—usually no more than 5 minutes.

Ischemic stroke

Most strokes are ischemic strokes. An ischemic stroke occurs when blood clots or other particles block

Fatty deposits called plaque can also cause blockages by building up in the blood vessels.

Hemorrhagic stroke

A hemorrhagic stroke happens when an artery in the brain leaks blood or ruptures (breaks open). The leaked blood puts too much pressure on brain cells, which damages them.

High blood pressure and aneurysms—balloon-like bulges in an artery that can stretch and burst—are examples of conditions that can cause a hemorrhagic stroke.

Transient ischemic attack (TIA or “mini-stroke”)

TIAs are sometimes known as “warning strokes.” It is important to know that

• A TIA is a warning sign of a future stroke.
• A TIA is a medical emergency, just like a major stroke.
• Strokes and TIAs require emergency care. Call 9-1-1 right away if you feel signs of a stroke or see symptoms in someone around you.
• There is no way to know in the beginning whether symptoms are from a TIA or from a major type of stroke.
• Like ischemic strokes, blood clots often cause TIAs.
• More than a third of people who have a TIA and don’t get treatment have a major stroke within 1 year. As many as 10% to 15% of people will have a major stroke within 3 months of a TIA.

Recognizing and treating TIAs can lower the risk of a major stroke. If you have a TIA, your health care team can find the cause and take steps to prevent a major stroke.

A stroke happens when blood flow to the brain is blocked. This prevents the brain from getting oxygen and nutrients from the blood. Without oxygen and nutrients, brain cells begin to die within minutes. Sudden bleeding in the brain can also cause a stroke if it damages brain cells.

A stroke is a medical emergency. A stroke can cause lasting brain damage, long-term disability, or even death. Signs of a stroke can range from mild weakness to paralysis or numbness on one side of the face or body. Other signs include a sudden and severe headache, sudden weakness, trouble seeing, and trouble speaking or understanding speech.

If you think you or someone else is having a stroke, call 9-1-1 right away. Do not drive to the hospital or let someone else drive you. Call an ambulance so that medical personnel can begin life-saving treatment on the way to the emergency room. During a stroke, every minute counts.

At the hospital, a stroke team will assess your condition and treat your stroke with medicine, surgery, or another procedure. Your recovery will depend on how severe your stroke was and how quickly you got treatment. A rehabilitation plan may help you do the same things you used to do before your stroke.

What is a stroke?

A stroke happens when there is a loss of blood flow to part of the brain. Your brain cells cannot get the oxygen and nutrients they need from blood, and they start to die within a few minutes. This can cause lasting brain damage, long-term disability, or even death.

If you think that you or someone else is having a stroke, call 911 right away. Immediate treatment may save someone's life and increase the chances for successful rehabilitation and recovery.

What are the types of stroke?

There are two types of stroke:

• Ischemic stroke is caused by a blood clot that blocks or plugs a blood vessel in the brain. This is the most common type; about 80% of strokes are ischemic.
• Hemorrhagic stroke is caused by a blood vessel that breaks and bleeds into the brain

Another condition that's similar to a stroke is a transient ischemic attack (TIA). It's sometimes called a "mini-stroke." TIAs happen when the blood supply to the brain is blocked for a short time. The damage to the brain cells isn't permanent, but if you have had a TIA, you are at a much higher risk of having a stroke.

Who is at risk for a stroke?

Certain factors can raise your risk of a stroke. The major risk factors include:

• High blood pressure. This is the primary risk factor for a stroke.
• Diabetes.
• Heart diseases. Atrial fibrillation and other heart diseases can cause blood clots that lead to stroke.
• Smoking. When you smoke, you damage your blood vessels and raise your blood pressure.
• A personal or family history of stroke or TIA.
• Age. Your risk of stroke increases as you get older.
• Race and ethnicity. African Americans have a higher risk of stroke.

There are also other factors that are linked to a higher risk of stroke, such as:

• Alcohol and illegal drug use
• Not getting enough physical activity
• High cholesterol
• Unhealthy diet
• Having obesity

What are the symptoms of stroke?

The symptoms of stroke often happen quickly. They include:

• Sudden numbness or weakness of the face, arm, or leg (especially on one side of the body)
• Sudden confusion, trouble speaking, or understanding speech
• Sudden trouble seeing in one or both eyes
• Sudden difficulty walking, dizziness, loss of balance or coordination
• Sudden severe headache with no known cause

If you think that you or someone else is having a stroke, call 911 right away.

How are strokes diagnosed?

To make a diagnosis, your health care provider will:

• Ask about your symptoms and medical history
• Do a physical exam, including a check of
  • Your mental alertness
  • Your coordination and balance
  • Any numbness or weakness in your face, arms, and legs
  • Any trouble speaking and seeing clearly
• Run some tests, which may include
  • Diagnostic imaging of the brain, such as a CT scan or MRI
  • Heart tests, which can help detect heart problems or blood clots that may have led to a stroke. Possible tests include an electrocardiogram (EKG) and an echocardiography.

What are the treatments for stroke?

Treatments for stroke include medicines, surgery, and rehabilitation. Which treatments you get depend on the type of stroke and the stage of treatment. The different stages are:

• Acute treatment, to try to stop a stroke while it is happening
• Post-stroke rehabilitation, to overcome the disabilities caused by the stroke
• Prevention, to prevent a first stroke or, if you have already had one, prevent another stroke

Acute treatments for ischemic stroke are usually medicines:

• You may get tPA, (tissue plasminogen activator), a medicine to dissolve the blood clot. You can only get this medicine within 4 hours of when your symptoms started. The sooner you can get it, the better your chance of recovery.
• If you cannot get that medicine, you may get medicine that helps stop platelets from clumping together to form blood clots. Or you may get a blood thinner to keep existing clots from getting bigger.
• If you have carotid artery disease, you may also need a procedure to open your blocked carotid artery

Acute treatments for hemorrhagic stroke focus on stopping the bleeding. The first step is to find the cause of bleeding in the brain. The next step is to control it:

• If high blood pressure is the cause of bleeding, you may be given blood pressure medicines.
• If an aneurysm if the cause, you may need aneurysm clipping or coil embolization. These are surgeries to prevent further leaking of blood from the aneurysm. It also can help prevent the aneurysm from bursting again.
• If an arteriovenous malformation (AVM) is the cause of a stroke, you may need an AVM repair. An AVM is a tangle of faulty arteries and veins that can rupture within the brain. An AVM repair may be done through
  • Surgery
  • Injecting a substance into the blood vessels of the AVM to block blood flow
  • Radiation to shrink the blood vessels of the AVM

Stroke rehabilitation can help you relearn skills you lost because of the damage. The goal is to help you become as independent as possible and to have the best possible quality of life.

Prevention of another stroke is also important, since having a stroke increases the risk of getting another one. Prevention may include heart-healthy lifestyle changes and medicines.

Can strokes be prevented?

If you have already had a stroke or are at risk of having a stroke, you can make some heart-healthy lifestyle changes to try to prevent a future stroke:

• Eating a heart-healthy diet
• Aiming for a healthy weight
• Managing stress
• Getting regular physical activity
• Quitting smoking
• Managing your blood pressure and cholesterol levels

If these changes aren't enough, you may need medicine to control your risk factors.

The type of stroke you have affects your treatment and recovery.

The three main types of stroke are:

• Ischemic stroke.
• Hemorrhagic stroke.
• Transient ischemic attack (a warning or “mini-stroke”).

Learn about the health conditions and lifestyle habits that can increase your risk for stroke.

Ischemic Stroke

Most strokes (87%) are ischemic strokes.¹ An ischemic stroke happens when blood flow through the artery that supplies oxygen-rich blood to the brain becomes blocked.

Blood clots often cause the blockages that lead to ischemic strokes.

Hemorrhagic Stroke

A hemorrhagic stroke happens when an artery in the brain leaks blood or ruptures (breaks open). The leaked blood puts too much pressure on brain cells, which damages them.

High blood pressure and aneurysms—balloon-like bulges in an artery that can stretch and burst—are examples of conditions that can cause a hemorrhagic stroke.

There are two types of hemorrhagic strokes:

• Intracerebral hemorrhage is the most common type of hemorrhagic stroke. It occurs when an artery in the brain bursts, flooding the surrounding tissue with blood.
• Subarachnoid hemorrhage is a less common type of hemorrhagic stroke. It refers to bleeding in the area between the brain and the thin tissues that cover it.

Transient Ischemic Attack (TIA)

A transient ischemic attack (TIA) is sometimes called a “mini-stroke.” It is different from the major types of stroke because blood flow to the brain is blocked for only a short time—usually no more than 5 minutes.²

It is important to know that:

• A TIA is a warning sign of a future stroke.
• A TIA is a medical emergency, just like a major stroke.
• Strokes and TIAs require emergency care. Call 9-1-1 right away if you feel signs of a stroke or see symptoms in someone around you.
• There is no way to know in the beginning whether symptoms are from a TIA or from a major type of stroke.
• Like ischemic strokes, blood clots often cause TIAs.
• More than a third of people who have a TIA and don’t get treatment have a major stroke within 1 year. As many as 10% to 15% of people will have a major stroke within 3 months of a TIA.

Recognizing and treating TIAs can lower the risk of a major stroke. If you have a TIA, your health care team can find the cause and take steps to prevent a major stroke.

While stroke is one of our country’s leading causes of death and serious, long-term disability in adults, the good news is that treatments are available that can greatly reduce the damage. However, you need to recognize the symptoms of a stroke and get the stroke victim, which could be you, to a hospital quickly. Getting treatment within 60 minutes can prevent disability.

About Stroke

There are more than 800,000 strokes each year in our nation. Sometimes called a “brain attack,” a stroke occurs when blood flow to the brain is interrupted. When this happens, brain cells in the immediate area begin to die because they stop getting the oxygen and nutrients they need to function.

What causes a stroke?

There are two major kinds of stroke. About 80 percent are ischemic strokes, which are caused by a blood clot that blocks or plugs a blood vessel or artery in the brain. About 20 percent are hemorrhagic strokes, which are caused by a blood vessel in the brain that breaks and bleeds into the brain.

What disabilities can result from a stroke?

Although stroke is a disease of the brain, it can affect the entire body. The effects of a stroke range from mild to severe and can include paralysis, problems with thinking, problems with speaking, and emotional problems. Patients may also experience pain or numbness.

Know the Signs

Because stroke injures the brain, victims may not realize they’re having one and bystanders may think they just look unaware or confused. That’s why stroke victims have the best chance if someone around them recognizes the signs and acts quickly.

What are the signs of a stroke?

The symptoms are distinct because they happen quickly:

• Sudden NUMBNESS or weakness of face, arm, or leg, especially on one side of the body
• Sudden CONFUSION, trouble speaking, or trouble understanding speech
• Sudden TROUBLE SEEING in one or both eyes
• Sudden TROUBLE WALKING, dizziness, or loss of balance or coordination
• Sudden SEVERE HEADACHE with no known cause

What should a bystander do?

If you think someone is having a stroke—if they suddenly lose the ability to speak, move an arm or leg on one side, or experience facial paralysis on one side—call 911 immediately.

Act in Time

Stroke is a medical emergency. Every minute counts because the longer blood flow is cut off to the brain, the greater the damage. Immediate treatment can save people’s lives and enhance their chances for successful recovery.

Why is there a need to act fast?

Ischemic strokes, the most common type, can be treated with the drug t-PA, which dissolves blood clots obstructing blood flow to the brain. The window of opportunity to start treatment is three hours, but patients need to get to the hospital within 60 minutes to be evaluated and receive treatment.

What’s the benefit of treatment?

A five-year study by NINDS found that some stroke patients who received t-PA within three hours of the start of stroke symptoms were at least 30 percent more likely to recover with little or no disability after three months.

How can I reduce my risk of stroke?

The best treatment for stroke is prevention. Several factors increase your risk:

• High blood pressure
• Heart disease
• Smoking
• Diabetes
• High cholesterol
• Physical inactivity/obesity

If you smoke–quit. If you have high blood pressure, heart disease, diabetes, or high cholesterol, get them under control. If you’re overweight, start a healthy diet and exercise regularly.

There are three major branches of the aortic arch: the brachiocephalic artery, the left common carotid artery, and the left subclavian (literally “under the clavicle”) artery. As you would expect based upon proximity to the heart, each of these vessels is classified as an elastic artery.

The brachiocephalic artery is located only on the right side of the body; there is no corresponding artery on the left. The brachiocephalic artery branches into the right subclavian artery and the right common carotid artery. The left subclavian and left common carotid arteries arise independently from the aortic arch but otherwise follow a similar pattern and distribution to the corresponding arteries on the right side.

Each subclavian artery supplies blood to the arms, chest, shoulders, back, and central nervous system. It then gives rise to three major branches: the internal thoracic artery, the vertebral artery, and the thyrocervical artery. The internal thoracic artery, or mammary artery, supplies blood to the thymus, the pericardium of the heart, and the anterior chest wall. The vertebral artery passes through the vertebral foramen in the cervical vertebrae and then through the foramen magnum into the cranial cavity to supply blood to the brain and spinal cord. The paired vertebral arteries join together to form the large basilar artery at the base of the medulla oblongata. This is an example of an anastomosis. The subclavian artery also gives rise to the thyrocervical artery that provides blood to the thyroid, the cervical region of the neck, and the upper back and shoulder.

The common carotid artery divides into internal and external carotid arteries. The right common carotid artery arises from the brachiocephalic artery and the left common carotid artery arises directly from the aortic arch. The external carotid artery supplies blood to numerous structures within the face, lower jaw, neck, esophagus, and larynx. These branches include the lingual, facial, occipital, maxillary, and superficial temporal arteries. The internal carotid artery initially forms an expansion known as the carotid sinus, containing the carotid baroreceptors and chemoreceptors. Like their counterparts in the aortic sinuses, the information provided by these receptors is critical to maintaining cardiovascular homeostasis

The internal carotid arteries along with the vertebral arteries are the two primary suppliers of blood to the human brain. Given the central role and vital importance of the brain to life, it is critical that blood supply to this organ remains uninterrupted. Recall that blood flow to the brain is remarkably constant, with approximately 20 percent of blood flow directed to this organ at any given time. When blood flow is interrupted, even for just a few seconds, a transient ischemic attack (TIA), or mini-stroke, may occur, resulting in loss of consciousness or temporary loss of neurological function. In some cases, the damage may be permanent. Loss of blood flow for longer periods, typically between 3 and 4 minutes, will likely produce irreversible brain damage or a stroke, also called a cerebrovascular accident (CVA). The locations of the arteries in the brain not only provide blood flow to the brain tissue but also prevent interruption in the flow of blood. Both the carotid and vertebral arteries branch once they enter the cranial cavity, and some of these branches form a structure known as the arterial circle (or circle of Willis), an anastomosis that is remarkably like a traffic circle that sends off branches (in this case, arterial branches to the brain). As a rule, branches to the anterior portion of the cerebrum are normally fed by the internal carotid arteries; the remainder of the brain receives blood flow from branches associated with the vertebral arteries.

The internal carotid artery continues through the carotid canal of the temporal bone and enters the base of the brain through the carotid foramen where it gives rise to several branches (Figure 20.26 and Figure 20.27). One of these branches is the anterior cerebral artery that supplies blood to the frontal lobe of the cerebrum. Another branch, the middle cerebral artery, supplies blood to the temporal and parietal lobes, which are the most common sites of CVAs. The ophthalmic artery, the third major branch, provides blood to the eyes.

The right and left anterior cerebral arteries join together to form an anastomosis called the anterior communicating artery. The initial segments of the anterior cerebral arteries and the anterior communicating artery form the anterior portion of the arterial circle. The posterior portion of the arterial circle is formed by a left and a right posterior communicating artery that branches from the posterior cerebral artery, which arises from the basilar artery. It provides blood to the posterior portion of the cerebrum and brain stem. The basilar artery is an anastomosis that begins at the junction of the two vertebral arteries and sends branches to the cerebellum and brain stem. It flows into the posterior cerebral arteries. Table 20.6 summarizes the aortic arch branches, including the major branches supplying the brain.

Figure 20.26 Arteries Supplying the Head and Neck The common carotid artery gives rise to the external and internal carotid arteries. The external carotid artery remains superficial and gives rise to many arteries of the head. The internal carotid artery first forms the carotid sinus and then reaches the brain via the carotid canal and carotid foramen, emerging into the cranium via the foramen lacerum. The vertebral artery branches from the subclavian artery and passes through the transverse foramen in the cervical vertebrae, entering the base of the skull at the vertebral foramen. The subclavian artery continues toward the arm as the axillary artery.

Figure 20.27 Arteries Serving the Brain This inferior view shows the network of arteries serving the brain. The structure is referred to as the arterial circle or circle of Willis.

Aortic Arch Branches and Brain Circulation

The CNS is crucial to the operation of the body, and any compromise in the brain and spinal cord can lead to severe difficulties. The CNS has a privileged blood supply, as suggested by the blood-brain barrier. The function of the tissue in the CNS is crucial to the survival of the organism, so the contents of the blood cannot simply pass into the central nervous tissue. To protect this region from the toxins and pathogens that may be traveling through the blood stream, there is strict control over what can move out of the general systems and into the brain and spinal cord. Because of this privilege, the CNS needs specialized structures for the maintenance of circulation. This begins with a unique arrangement of blood vessels carrying fresh blood into the CNS. Beyond the supply of blood, the CNS filters that blood into cerebrospinal fluid (CSF), which is then circulated through the cavities of the brain and spinal cord called ventricles.

Blood Supply to the Brain

A lack of oxygen to the CNS can be devastating, and the cardiovascular system has specific regulatory reflexes to ensure that the blood supply is not interrupted. There are multiple routes for blood to get into the CNS, with specializations to protect that blood supply and to maximize the ability of the brain to get an uninterrupted perfusion.

Arterial Supply

The major artery carrying recently oxygenated blood away from the heart is the aorta. The very first branches off the aorta supply the heart with nutrients and oxygen. The next branches give rise to the common carotid arteries, which further branch into the internal carotid arteries. The external carotid arteries supply blood to the tissues on the surface of the cranium. The bases of the common carotids contain stretch receptors that immediately respond to the drop in blood pressure upon standing. The orthostatic reflex is a reaction to this change in body position, so that blood pressure is maintained against the increasing effect of gravity (orthostatic means “standing up”). Heart rate increases—a reflex of the sympathetic division of the autonomic nervous system—and this raises blood pressure.

The internal carotid artery enters the cranium through the carotid canal in the temporal bone. A second set of vessels that supply the CNS are the vertebral arteries, which are protected as they pass through the neck region by the transverse foramina of the cervical vertebrae. The vertebral arteries enter the cranium through the foramen magnum of the occipital bone. Branches off the left and right vertebral arteries merge into the anterior spinal artery supplying the anterior aspect of the spinal cord, found along the anterior median fissure. The two vertebral arteries then merge into the basilar artery, which gives rise to branches to the brain stem and cerebellum. The left and right internal carotid arteries and branches of the basilar artery all become the circle of Willis, a confluence of arteries that can maintain perfusion of the brain even if narrowing or a blockage limits flow through one part (image).

Venous Return

After passing through the CNS, blood returns to the circulation through a series of dural sinuses and veins (image). The superior sagittal sinus runs in the groove of the longitudinal fissure, where it absorbs CSF from the meninges. The superior sagittal sinus drains to the confluence of sinuses, along with the occipital sinuses and straight sinus, to then drain into the transverse sinuses. The transverse sinuses connect to the sigmoid sinuses, which then connect to the jugular veins. From there, the blood continues toward the heart to be pumped to the lungs for reoxygenation.

Protective Coverings of the Brain and Spinal Cord

The outer surface of the CNS is covered by a series of membranes composed of connective tissue called the meninges, which protect the brain. The dura mater is a thick fibrous layer and a strong protective sheath over the entire brain and spinal cord. It is anchored to the inner surface of the cranium and vertebral cavity. The arachnoid mater is a membrane of thin fibrous tissue that forms a loose sac around the CNS. Beneath the arachnoid is a thin, filamentous mesh called the arachnoid trabeculae, which looks like a spider web, giving this layer its name. Directly adjacent to the surface of the CNS is the pia mater, a thin fibrous membrane that follows the convolutions of gyri and sulci in the cerebral cortex and fits into other grooves and indentations (Figure).

Meningeal Layers of Superior Sagittal Sinus

The layers of the meninges in the longitudinal fissure of the superior sagittal sinus are shown, with the dura mater adjacent to the inner surface of the cranium, the pia mater adjacent to the surface of the brain, and the arachnoid and subarachnoid space between them. An arachnoid villus is shown emerging into the dural sinus to allow CSF to filter back into the blood for drainage.

Dura Mater

Like a thick cap covering the brain, the dura mater is a tough outer covering. The name comes from the Latin for “tough mother” to represent its physically protective role. It encloses the entire CNS and the major blood vessels that enter the cranium and vertebral cavity. It is directly attached to the inner surface of the bones of the cranium and to the very end of the vertebral cavity.

There are infoldings of the dura that fit into large crevasses of the brain. Two infoldings go through the midline separations of the cerebrum and cerebellum; one forms a shelf-like tent between the occipital lobes of the cerebrum and the cerebellum, and the other surrounds the pituitary gland. The dura also surrounds and supports the venous sinuses.

Arachnoid Mater

The middle layer of the meninges is the arachnoid, named for the spider-web–like trabeculae between it and the pia mater. The arachnoid defines a sac-like enclosure around the CNS. The trabeculae are found in the subarachnoid space, which is filled with circulating CSF. The arachnoid emerges into the dural sinuses as the arachnoid granulations, where the CSF is filtered back into the blood for drainage from the nervous system.

The subarachnoid space is filled with circulating CSF, which also provides a liquid cushion to the brain and spinal cord. Similar to clinical blood work, a sample of CSF can be withdrawn to find chemical evidence of neuropathology or metabolic traces of the biochemical functions of nervous tissue.

Pia Mater

The outer surface of the CNS is covered in the thin fibrous membrane of the pia mater. It is thought to have a continuous layer of cells providing a fluid-impermeable membrane. The name pia mater comes from the Latin for “tender mother,” suggesting the thin membrane is a gentle covering for the brain. The pia extends into every convolution of the CNS, lining the inside of the sulci in the cerebral and cerebellar cortices. At the end of the spinal cord, a thin filament extends from the inferior end of CNS at the upper lumbar region of the vertebral column to the sacral end of the vertebral column. Because the spinal cord does not extend through the lower lumbar region of the vertebral column, a needle can be inserted through the dura and arachnoid layers to withdraw CSF. This procedure is called a lumbar puncture and avoids the risk of damaging the central tissue of the spinal cord. Blood vessels that are nourishing the central nervous tissue are between the pia mater and the nervous tissue.

DISORDERS OF THE…

MeningesMeningitis is an inflammation of the meninges, the three layers of fibrous membrane that surround the CNS. Meningitis can be caused by infection by bacteria or viruses. The particular pathogens are not special to meningitis; it is just an inflammation of that specific set of tissues from what might be a broader infection. Bacterial meningitis can be caused by Streptococcus, Staphylococcus, or the tuberculosis pathogen, among many others. Viral meningitis is usually the result of common enteroviruses (such as those that cause intestinal disorders), but may be the result of the herpes virus or West Nile virus. Bacterial meningitis tends to be more severe.

The symptoms associated with meningitis can be fever, chills, nausea, vomiting, light sensitivity, soreness of the neck, or severe headache. More important are the neurological symptoms, such as changes in mental state (confusion, memory deficits, and other dementia-type symptoms). A serious risk of meningitis can be damage to peripheral structures because of the nerves that pass through the meninges. Hearing loss is a common result of meningitis.

The primary test for meningitis is a lumbar puncture. A needle inserted into the lumbar region of the spinal column through the dura mater and arachnoid membrane into the subarachnoid space can be used to withdraw the fluid for chemical testing. Fatality occurs in 5 to 40 percent of children and 20 to 50 percent of adults with bacterial meningitis. Treatment of bacterial meningitis is through antibiotics, but viral meningitis cannot be treated with antibiotics because viruses do not respond to that type of drug. Fortunately, the viral forms are milder.

The Ventricular System

Cerebrospinal fluid (CSF) circulates throughout and around the CNS. In other tissues, water and small molecules are filtered through capillaries as the major contributor to the interstitial fluid. In the brain, CSF is produced in special structures to perfuse through the nervous tissue of the CNS and is continuous with the interstitial fluid. Specifically, CSF circulates to remove metabolic wastes from the interstitial fluids of nervous tissues and return them to the blood stream. The ventricles are the open spaces within the brain where CSF circulates. In some of these spaces, CSF is produced by filtering of the blood that is performed by a specialized membrane known as a choroid plexus. The CSF circulates through all of the ventricles to eventually emerge into the subarachnoid space where it will be reabsorbed into the blood.

The Ventricles

There are four ventricles within the brain, all of which developed from the original hollow space within the neural tube, the central canal. The first two are named the lateral ventricles and are deep within the cerebrum. These ventricles are connected to the third ventricle by two openings called the interventricular foramina. The third ventricle is the space between the left and right sides of the diencephalon, which opens into the cerebral aqueduct that passes through the midbrain. The aqueduct opens into the fourth ventricle, which is the space between the cerebellum and the pons and upper medulla (image).

As the telencephalon enlarges and grows into the cranial cavity, it is limited by the space within the skull. The telencephalon is the most anterior region of what was the neural tube, but cannot grow past the limit of the frontal bone of the skull. Because the cerebrum fits into this space, it takes on a C-shaped formation, through the frontal, parietal, occipital, and finally temporal regions. The space within the telencephalon is stretched into this same C-shape. The two ventricles are in the left and right sides, and were at one time referred to as the first and second ventricles. The interventricular foramina connect the frontal region of the lateral ventricles with the third ventricle.

The third ventricle is the space bounded by the medial walls of the hypothalamus and thalamus. The two thalami touch in the center in most brains as the massa intermedia, which is surrounded by the third ventricle. The cerebral aqueduct opens just inferior to the epithalamus and passes through the midbrain. The tectum and tegmentum of the midbrain are the roof and floor of the cerebral aqueduct, respectively. The aqueduct opens up into the fourth ventricle. The floor of the fourth ventricle is the dorsal surface of the pons and upper medulla (that gray matter making a continuation of the tegmentum of the midbrain). The fourth ventricle then narrows into the central canal of the spinal cord.

The ventricular system opens up to the subarachnoid space from the fourth ventricle. The single median aperture and the pair of lateral apertures connect to the subarachnoid space so that CSF can flow through the ventricles and around the outside of the CNS. Cerebrospinal fluid is produced within the ventricles by a type of specialized membrane called a choroid plexus. Ependymal cells (one of the types of glial cells described in the introduction to the nervous system) surround blood capillaries and filter the blood to make CSF. The fluid is a clear solution with a limited amount of the constituents of blood. It is essentially water, small molecules, and electrolytes. Oxygen and carbon dioxide are dissolved into the CSF, as they are in blood, and can diffuse between the fluid and the nervous tissue.

Cerebrospinal Fluid Circulation

The choroid plexuses are found in all four ventricles. Observed in dissection, they appear as soft, fuzzy structures that may still be pink, depending on how well the circulatory system is cleared in preparation of the tissue. The CSF is produced from components extracted from the blood, so its flow out of the ventricles is tied to the pulse of cardiovascular circulation.

From the lateral ventricles, the CSF flows into the third ventricle, where more CSF is produced, and then through the cerebral aqueduct into the fourth ventricle where even more CSF is produced. A very small amount of CSF is filtered at any one of the plexuses, for a total of about 500 milliliters daily, but it is continuously made and pulses through the ventricular system, keeping the fluid moving. From the fourth ventricle, CSF can continue down the central canal of the spinal cord, but this is essentially a cul-de-sac, so more of the fluid leaves the ventricular system and moves into the subarachnoid space through the median and lateral apertures.

Within the subarachnoid space, the CSF flows around all of the CNS, providing two important functions. As with elsewhere in its circulation, the CSF picks up metabolic wastes from the nervous tissue and moves it out of the CNS. It also acts as a liquid cushion for the brain and spinal cord. By surrounding the entire system in the subarachnoid space, it provides a thin buffer around the organs within the strong, protective dura mater. The arachnoid granulations are outpocketings of the arachnoid membrane into the dural sinuses so that CSF can be reabsorbed into the blood, along with the metabolic wastes. From the dural sinuses, blood drains out of the head and neck through the jugular veins, along with the rest of the circulation for blood, to be reoxygenated by the lungs and wastes to be filtered out by the kidneys (image).

DISORDERS OF THE…

Central Nervous SystemThe supply of blood to the brain is crucial to its ability to perform many functions. Without a steady supply of oxygen, and to a lesser extent glucose, the nervous tissue in the brain cannot keep up its extensive electrical activity. These nutrients get into the brain through the blood, and if blood flow is interrupted, neurological function is compromised.

The common name for a disruption of blood supply to the brain is a stroke. It is caused by a blockage to an artery in the brain. The blockage is from some type of embolus: a blood clot, a fat embolus, or an air bubble. When the blood cannot travel through the artery, the surrounding tissue that is deprived starves and dies. Strokes will often result in the loss of very specific functions. A stroke in the lateral medulla, for example, can cause a loss in the ability to swallow. Sometimes, seemingly unrelated functions will be lost because they are dependent on structures in the same region. Along with the swallowing in the previous example, a stroke in that region could affect sensory functions from the face or extremities because important white matter pathways also pass through the lateral medulla. Loss of blood flow to specific regions of the cortex can lead to the loss of specific higher functions, from the ability to recognize faces to the ability to move a particular region of the body. Severe or limited memory loss can be the result of a temporal lobe stroke.

Related to strokes are transient ischemic attacks (TIAs), which can also be called “mini-strokes.” These are events in which a physical blockage may be temporary, cutting off the blood supply and oxygen to a region, but not to the extent that it causes cell death in that region. While the neurons in that area are recovering from the event, neurological function may be lost. Function can return if the area is able to recover from the event.

Recovery from a stroke (or TIA) is strongly dependent on the speed of treatment. Often, the person who is present and notices something is wrong must then make a decision. The mnemonic FAST helps people remember what to look for when someone is dealing with sudden losses of neurological function. If someone complains of feeling “funny,” check these things quickly: Look at the person’s face. Does he or she have problems moving Face muscles and making regular facial expressions? Ask the person to raise his or her Arms above the head. Can the person lift one arm but not the other? Has the person’s Speech changed? Is he or she slurring words or having trouble saying things? If any of these things have happened, then it is Time to call for help.

Sometimes, treatment with blood-thinning drugs can alleviate the problem, and recovery is possible. If the tissue is damaged, the amazing thing about the nervous system is that it is adaptable. With physical, occupational, and speech therapy, victims of strokes can recover, or more accurately relearn, functions.

Overview

The CNS has a privileged blood supply established by the blood-brain barrier. Establishing this barrier are anatomical structures that help to protect and isolate the CNS. The arterial blood to the brain comes from the internal carotid and vertebral arteries, which both contribute to the unique circle of Willis that provides constant perfusion of the brain even if one of the blood vessels is blocked or narrowed. That blood is eventually filtered to make a separate medium, the CSF, that circulates within the spaces of the brain and then into the surrounding space defined by the meninges, the protective covering of the brain and spinal cord.

The blood that nourishes the brain and spinal cord is behind the glial-cell–enforced blood-brain barrier, which limits the exchange of material from blood vessels with the interstitial fluid of the nervous tissue. Thus, metabolic wastes are collected in cerebrospinal fluid that circulates through the CNS. This fluid is produced by filtering blood at the choroid plexuses in the four ventricles of the brain. It then circulates through the ventricles and into the subarachnoid space, between the pia mater and the arachnoid mater. From the arachnoid granulations, CSF is reabsorbed into the blood, removing the waste from the privileged central nervous tissue.

The blood, now with the reabsorbed CSF, drains out of the cranium through the dural sinuses. The dura mater is the tough outer covering of the CNS, which is anchored to the inner surface of the cranial and vertebral cavities. It surrounds the venous space known as the dural sinuses, which connect to the jugular veins, where blood drains from the head and neck.

Strokes are caused by blocked blood flow to the brain (ischemic stroke) or sudden bleeding in the brain (hemorrhagic stroke). Many things raise your risk of stroke. Some of these risk factors can be changed to help prevent a stroke or future strokes.

Ischemic stroke

About 87% of strokes are ischemic. The blockage in the brain is usually caused by a piece of plaque or a blood clot. If the blockage occurs locally in the brain, the condition is called thrombosis. If the blood clot travels from somewhere else in the body, it is called an embolism. Ischemic strokes are classified specifically based on where in the brain the blockage occurs and where in the body an embolism developed. In some cases, the location of the original embolism is not known.

When plaque builds up on the inner walls of the arteries, it can lead to a disease called atherosclerosis. Plaque hardens and narrows the arteries, limiting blood flow to tissues and organs. Plaque can build up in any artery in the body, including arteries in the brain and neck. Carotid artery disease occurs when plaque builds up in the carotid arteries in the neck that supply blood to the brain. It is a common cause of ischemic stroke.

Plaque in an artery can also break open. Blood platelets stick to the site of the plaque injury and clump together to form blood clots. These clots can partly or fully block an artery.

Blood clots leading to stroke can happen when there are other heart and blood conditions, such as atrial fibrillation and sickle cell disease. MRI studies show that as many as 40% of children with sickle cell disease have had a stroke, even though a medical exam does not show signs of one. The only treatment for these undetected strokes (also called silent infarcts) is to receive regular blood transfusions.

Studies have found ischemic stroke in people who have COVID-19. However, it is too early to tell whether COVID-19 can cause stroke.

Inflammation

Chronic (long-term) Inflammation contributes to ischemic stroke. Researchers are still trying to understand this fully. Research shows that inflammation can damage the blood vessels and contribute to atherosclerosis. Ischemic stroke can also lead to inflammation that further damages brain cells.

Transient ischemic attack

A transient ischemic attack (TIA) is caused by a blockage in the brain just like an ischemic stroke. With a TIA, the blockage breaks up before there is any damage to your brain. It typically lasts less than an hour but can come and go. Eventually, it can become a full stroke. A TIA is also called a mini-stroke. If you are diagnosed with a TIA in an emergency room, you should follow up as soon as possible with a primary care provider and a neurologist, a doctor who specializes in treating disorders of the brain, spinal cord, and nervous system.

Hemorrhagic stroke

Sudden bleeding can cause a hemorrhagic stroke. This can happen when an artery in or on top of the brain breaks open. The leaked blood causes the brain to swell, raising pressure in the brain that can damage brain cells. There are two types of hemorrhagic stroke: intracranial hemorrhage, or bleeding within the skull, and subarachnoid hemorrhage (SAH), or bleeding between the brain and the membrane that surrounds it. Intracranial hemorrhage occurs in about 10% of stroke cases, and SAH occurs in about 3%.

Some conditions make blood vessels in the brain more likely to bleed.

• Aneurysm is a balloon-like bulge in an artery that can stretch and burst.
• Arteriovenous malformations (AVMs) are tangles of poorly formed arteries and veins that can break open in the brain.
• High blood pressure puts pressure on the inside walls of the arteries. This pressure makes them more likely to break open, especially if they are weakened from an aneurysm or AVM.

Strokes are caused by blocked blood flow to the brain (ischemic stroke) or sudden bleeding in the brain (hemorrhagic stroke). Many things raise your risk of stroke. Some of these risk factors can be changed to help prevent a stroke or future strokes.

There are many risk factors for stroke. You can treat or control some but not all of them.

Factors that you can control account for 82% to 90% of all strokes:

• High blood pressure
• Obesity
• Physical inactivity
• Poor diet
• Smoking

Ischemic and hemorrhagic strokes share many of the same risk factors, such as high blood pressure, diabetes, and high blood cholesterol. Other risk factors are specific to the type of stroke. Blood clots can arise from coronary heart disease, atrial fibrillation, heart valve disease, and carotid artery disease. Bleeding can occur after taking blood thinners.

Other risk factors are based on lifestyle, genetics , and environment.

• Age is a risk factor, too. A stroke can occur at any age, but the risk is higher for babies under the age of 1 and for adults as they grow older.
• Anxiety, depression, and high stress levels, as well as working long hours and not having much contact with family, friends, or others outside the home, may raise your risk for stroke.
• Family history and genetics play a role as well. Your risk of having a stroke is higher if a parent or other family member has had a stroke, particularly at a younger age. Certain genes affect your stroke risk, including those that determine your blood type. People with blood type AB (which is not common) have a higher risk.
• Living or working in areas with air pollution can also contribute to stroke risk.
• Other medical conditions, such as sleep apnea, kidney disease, and migraine headaches, are also factors.
• Other unhealthy lifestyle habits, including drinking too much alcohol, getting too much sleep (more than 9 hours), and using illegal drugs such as cocaine, may raise stroke risk.
• Race and ethnicity is another factor. In the United States, stroke occurs more often in Black, Alaska Native, American Indian, and Hispanic adults than in white adults.
• Sex can play a role in risk for stroke. At younger ages, men are more likely than women to have a stroke. But women tend to live longer, so their lifetime risk of having a stroke is higher. Women who take birth control pills or use hormone replacement therapy are at higher risk. Women are also at higher risk during pregnancy and in the weeks after giving birth. High blood pressure during pregnancy — such as from preeclampsia — raises the risk of stroke later in life.
• Viral infections or conditions, such as lupus or rheumatoid arthritis, can cause inflammation.

Some of the most important risk factors for stroke can be determined during a physical exam at your doctor's office. If you are over 55 years old, the information here can help you estimate your risk of stroke and show the benefit of risk factor control.

The worksheet was developed from NINDS-supported work in the well-known Framingham Study. Working with your doctor, you can develop a strategy to lower your risk to average or even below average for your age.

Many risk factors for stroke can be managed, some very successfully. Although risk is never zero at any age, by starting early and controlling your risk factors you can lower your risk of death or disability from stroke. With good control, the risk of stroke in most age groups can be kept below that for accidental injury or death.

Americans have shown that stroke is preventable and treatable. In recent years, a better understanding of the causes of stroke has helped Americans make lifestyle changes that have cut the stroke death rate nearly in half.

Scientists at the NINDS predict that, with continued attention to reducing the risks of stroke and by using currently available therapies and developing new ones, Americans should be able to prevent 80 percent of all strokes.

Score your stroke risk for the next 10 years-MEN

Key: SBP = systolic blood pressure (score one line only, untreated or treated); ; Diabetes = history of diabetes;Cigarettes = smokes cigarettes; CVD (cardiovascular disease) = history of heart disease; AF = history of atrial fibrillation;LVH = diagnosis of left ventricular hypertrophy

Score your stroke risk for the next 10 years-WOMEN

Key: SBP = systolic blood pressure (score one line only, untreated or treated); ; Diabetes = history of diabetes;Cigarettes = smokes cigarettes; CVD (cardiovascular disease) = history of heart disease; AF = history of atrial fibrillation;LVH = diagnosis of left ventricular hypertrophy

This example helps you assess your risk of stroke. Tally your points to score your stroke risk over the next 10 years.

Martha, age 65, wanted to determine her risk for having a stroke, so she took this stroke risk profile. This is how she arrived at her 10-year probability risk for having a stroke:

Interpretation:
15 points carries a 16 percent, 10-year probability of having a stroke. If Martha quits smoking she can reduce her points to 12, which carries a 9 percent, 10-year probability of having a stroke.

Her current point total does not mean Martha will have a stroke, but serves as a wake-up call to ways she can lower her risk or even prevent a stroke. A lower percent score doesn’t mean that Martha won’t have a stroke, only that she is at a lower risk of having one.

No matter what your score is, it is important to work on reducing your risk factors as Martha did in this example by quitting smoking.

Source: D’Agostino, R.B.; Wolf, P.A.; Belanger, A.J.; & Kannel, W.B. “Stroke Risk Profile: The Framingham Study.” Stroke, Vol. 25, No. 1, pp. 40-43, January 1994.

The signs and symptoms of a stroke often develop quickly. However, they can develop over hours or even days, such as when a transient ischemic attack (TIA) turns into a stroke.

The type of symptoms depends on the type of stroke and the area of the brain that is affected.

Signs and symptoms of a TIA or stroke may include:

• Sudden numbness or weakness, especially on one side of the body
• Sudden confusion or trouble speaking or understanding speech
• Sudden trouble seeing in one or both eyes
• Sudden trouble walking, dizziness, or loss of balance or coordination
• Sudden severe headache with no known cause

The FAST test can help you remember what to do if you think someone may be having a stroke:

F—Face: Ask the person to smile. Does one side of the face droop?

A—Arms: Ask the person to raise both arms. Does one arm drift downward?

S—Speech: Ask the person to repeat a simple phrase. Is their speech slurred or strange?

T—Time: If you observe any of these signs, call 9-1-1 right away. Early treatment is essential.

If you think you or someone else is having a TIA or stroke, don’t drive to the hospital or let someone else drive you. Call an ambulance so that medical personnel can begin life-saving treatment on the way to the emergency room. During a stroke, every minute counts.

Warning signs are clues your body sends that your brain is not receiving enough oxygen. If you observe one or more of these signs of a stroke or "brain attack," don't wait, call a doctor or 911 right away!

• Sudden numbness or weakness of face, arm, or leg, especially on one side of the body
• Sudden confusion, or trouble talking or understanding speech
• Sudden trouble seeing in one or both eyes
• Sudden trouble walking, dizziness, or loss of balance or coordination
• Sudden severe headache with no known cause

Other danger signs that may occur include double vision, drowsiness, and nausea or vomiting. Sometimes the warning signs may last only a few moments and then disappear. These brief episodes, known as transient ischemic attacks or TIAs, are sometimes called "mini-strokes." Although brief, they identify an underlying serious condition that isn't going away without medical help. Unfortunately, since they clear up, many people ignore them. Don't. Paying attention to them can save your life.

Call 9-1-1 right away if you have any of these warning signs of a heart attack

• pain or pressure in your chest that lasts longer than a few minutes or goes away and comes back
• pain or discomfort in one or both of your arms or shoulders, or your back, neck, or jaw
• shortness of breath
• sweating or light-headedness
• indigestion or nausea (feeling sick to your stomach)
• feeling very tired

Treatment works best when it is given right away. Warning signs can be different in different people. You may not have all the listed symptoms.

Women may experience chest pain, nausea, and vomiting; feel very tired (sometimes for days); and have pain that spreads to the back, neck, throat, arms, shoulders, or jaw. People with diabetes-related nerve damage may not notice any chest pain.

If you have angina, it’s important to know how and when to seek medical treatment.

Call 9-1-1 right away if you have any of these warning signs of a stroke, including sudden

• weakness or numbness of your face, arm, or leg on one side of your body
• confusion, or trouble talking or understanding
• dizziness, loss of balance, or trouble walking
• trouble seeing out of one or both eyes
• sudden, severe headache

If you have any one of these warning signs, call 9-1-1. You can help prevent permanent damage by getting to a hospital within an hour of a stroke.

Call 9-1-1 if you have the warning signs of a heart attack or stroke. Treatment works best when given right away.

How would you react to a medical emergency? When it comes to life-threatening conditions like heart attack or stroke, every minute counts. Get to know the signs and symptoms of these health threats. If you think you or someone else might be having a heart attack or stroke, get medical help right away. Acting fast could save your life or someone else’s.

Heart disease and stroke are 2 of the top killers among both women and men in the U.S. Nationwide, someone dies from a heart attack about every 90 seconds, and stroke kills someone about every 4 minutes, according to the U.S. Centers for Disease Control and Prevention. Quick medical help could prevent many of these deaths. Fast action can also limit permanent damage to the body.

Heart attack and stroke are caused by interruptions to the normal flow of blood to the heart or brain—2 organs that are essential to life. Without access to oxygen-rich blood and nutrients, heart or brain cells begin to malfunction and die. This cell death can set off a series of harmful effects throughout the body. The changes ultimately lead to the familiar symptoms of a heart or brain emergency.

You might know the most common symptoms of heart attack: sustained, crushing chest pain and difficulty breathing. A heart attack might also cause cold sweats, a racing heart, pain down the left arm, jaw stiffness, or shoulder pain.

Many don’t know that women often have different heart attack symptoms than men. For instance, instead of having chest pain during a heart attack, women may feel extremely exhausted and fatigued or have indigestion and nausea.

“Many women have a vague sense of gloom and doom, a sense of ‘I just don’t feel quite right and don’t know why,’ ” says Dr. Patrice Desvigne-Nickens, an NIH expert in heart health.

The symptoms of stroke include sudden difficulty seeing, speaking, or walking, and feelings of weakness, numbness, dizziness, and confusion. “Some people get a severe headache that’s immediate and strong, different from any kind you’ve ever had,” says Dr. Salina Waddy, an NIH stroke expert.

At the first sign of any of these symptoms, fast action by you, someone you know, or a passerby can make a huge difference. NIH-funded research has helped ensure that more people survive heart attacks and strokes every year. We now have medicines, procedures, and devices that can help limit heart and brain damage following an attack, as long as medical help arrives quickly.

If the heart is starved for blood for too long—generally more than 20 minutes—heart muscle can be irreversibly damaged, Desvigne-Nickens says. “You need to be in the hospital because there’s a risk of cardiac arrest [your heart stopping],” which could be deadly. At the hospital, doctors can administer clot-busting drugs and other emergency procedures.

With stroke, Waddy says, “The longer you wait, the more brain cells are dying,” and the greater the chance for permanent damage or disability.

Emergency treatment for stroke depends on the kind of stroke. The most common type, ischemic stroke, is caused by a clot that clogs a blood vessel in the brain. The clot-dissolving drug tPA works best when given soon after symptoms begin. NIH research shows that patients who received tPA within 3 hours of stroke onset were more likely to recover fully.

Other strokes are caused by a hemorrhage—when a blood vessel breaks and bleeds into the brain. “The patient can have a larger hemorrhage within the first 3 hours,” Waddy says. A hospital medical team can help contain the bleeding, so every moment counts.

Even if you’re unsure, don’t feel embarrassed or hesitate to call 9-1-1 if you suspect a heart attack or stroke. “You should not go get your car keys. Your spouse shouldn’t be driving you to the hospital,” advises Desvigne-Nickens. “The emergency crew is trained to treat these symptoms, and it could mean the difference between life and death.”

Heart attack or stroke can happen to anyone, but your risk increases with age. A family or personal history of heart attack or stroke also raises your risk. But some risk factors for heart attack and stroke are within your control. Treating them can dramatically reduce your risk.

“If you have high blood pressure, high cholesterol, or diabetes, work with your doctor to get these conditions under control,” Waddy says. “Know your numbers [blood pressure, blood sugar, and cholesterol] and what they mean.”

You can also prepare for a medical emergency, to some degree. A hospital may not have access to your medical records when you arrive. Keep important health information handy, such as the medicines you’re taking, allergies, and emergency contacts. It would be important for the medical team to know, for example, if you’ve been taking anticoagulants to help prevent blood clots; these blood thinners put you at increased risk of bleeding. You might consider carrying an NIH wallet card that lists heart attack symptoms and has room for your personal medical information.

NIH researchers are studying new drugs and procedures to help the heart and brain repair themselves and improve organ function. “But there is absolutely nothing that will save both your time and health as well as prevention,” says Dr. Jeremy Brown, director of NIH’s Office of Emergency Care Research. Studies show that making healthy lifestyle choices can help prevent these medical emergencies from happening in the first place. Eat a healthy diet rich in protein, whole grains, and fruits and vegetables, and low in saturated fat. Get regular physical activity and don’t smoke.

“I think one of the most important things we can do is to take a basic CPR and first aid course,” recommends Brown. “We know the majority of cardiac arrests happen outside of hospitals and of that many, many can be saved if we get people with basic training on the scene quickly. An ambulance can never get there as quickly as a citizen passing by.”

Whether or not you’re trained to offer help, if you see someone having symptoms of a heart attack or stroke, call for help immediately.

“If you’re even thinking about calling 9-1-1, you should call,” Desvigne-Nickens says. “Yes other conditions can mimic the signs and symptoms of a heart attack or stroke, but let the emergency physician figure that out in the emergency room.”

Know the Symptoms

Don’t hesitate to call 9-1-1 if you see these symptoms of heart attack or stroke. Every minute counts.

Heart attack:

• Chest pain or discomfort
• Pain, stiffness, or numbness in the neck, back, or one or both arms or shoulders
• Shortness of breath
• Cold sweat, nausea, dizziness

Stroke:

• Sudden numbness or weakness of the face, arm, or leg, especially on one side of the body
• Sudden severe headache, dizziness, confusion
• Sudden difficulty with vision, balance, speech

Your doctor will diagnose a stroke based on your symptoms, your medical history, a physical exam, and test results. Your doctor will want to find out the type of stroke you’ve had, its cause, the part of the brain that is affected, and whether you have bleeding in the brain. If your doctor thinks you’ve had a transient ischemic attack (TIA), he or she will look for its cause to help prevent a future stroke.

Diagnostic tests

Your doctor will order tests to help rule out other health problems with similar signs or symptoms.

Your doctor will order an imaging test to look at the blood vessels in your brain. This will help determine what type of stroke you have and where exactly it happened. The quicker these tests can be done, the better your doctor can treat you. Tests to diagnose stroke include the following:

• Computed tomography (CT) uses X-rays to take clear, detailed pictures of your brain. It is often done right after a stroke is suspected. A brain CT scan can show if there is bleeding in the brain or damage to the brain cells from a stroke.
• Magnetic resonance imaging (MRI) uses magnets and radio waves to create pictures of your brain. An MRI may be used instead of—or in addition to—a CT scan to diagnose a stroke. This test can detect changes in brain tissue and damage to brain cells.
• Other imaging tests to look for narrowed blood vessels in the neck or an aneurysm or tangled blood vessels in the brain.

Your doctor may also order the following blood or heart tests.

• Blood tests. Your doctor may test the blood and platelet count and glucose (sugar) levels in your blood to make sure they are stable and to see if a certain medicine can treat your stroke. Your doctor may also do blood tests to see how well your blood is clotting and to look for muscle damage.
• Electrocardiogram (EKG). An EKG can help detect heart problems that may have led to a stroke. For example, this test can help diagnose atrial fibrillation or a previous heart attack.
• Lumbar puncture (also called a spinal tap), if the imaging scan does not detect any bleeding in the brain but your doctor still thinks you may have had a hemorrhagic stroke. The doctor will use a needle to collect fluid from around your spine. The fluid will be tested for substances from broken-down blood cells.

Medical history and physical exam

Your doctor will ask you or a family member about your risk factors for stroke. Tell your doctor if you or someone in your family has had a stroke. Your doctor will also ask about your signs and symptoms and when they began.

During the physical exam, your doctor will check you for:

• Confusion
• Coordination and balance
• Mental alertness
• Numbness or weakness in your face, arms, and legs
• Trouble speaking or seeing clearly
• The exam will help your doctor determine how severe your stroke was and plan your treatment.

Your doctor will look for signs of carotid artery disease, a common cause of ischemic stroke. He or she will listen to your carotid arteries with a stethoscope. A whooshing sound called a bruit may suggest changed or reduced blood flow due to plaque buildup in the carotid arteries.