A stroke occurs when the blood supply to part of your brain is interrupted or reduced, depriving brain tissue of oxygen and nutrients. Within minutes, brain cells begin to die.

A stroke is a medical emergency. Prompt treatment is crucial. Early action can minimize brain damage and potential complications.

The good news is that strokes can be treated and prevented, and many fewer Americans die of stroke now than in the past.

Symptoms
Watch for these signs and symptoms if you think you or someone else may be having a stroke. Pay attention to when the signs and symptoms begin. The length of time they have been present can affect your treatment options:

Trouble with speaking and understanding. You may experience confusion. You may slur your words or have difficulty understanding speech.
Paralysis or numbness of the face, arm or leg. You may develop sudden numbness, weakness or paralysis in your face, arm or leg. This often happens just on one side of your 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.
Trouble with 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 you're having a stroke.
Trouble with walking. You may stumble or experience sudden dizziness, loss of balance or 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 fluctuate or disappear. 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 up?
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 immediately.
Call 911 or your local emergency number right away. Don't wait to see if symptoms stop. Every minute counts. The longer a stroke goes untreated, the greater the potential for brain damage and disability.

If you're with someone you suspect is having a stroke, watch the person carefully while waiting for emergency assistance.

Causes
A stroke may be caused by a blocked artery (ischemic stroke) or the leaking or bursting of a blood vessel (hemorrhagic stroke). Some people may experience only a temporary disruption of blood flow to the brain (transient ischemic attack, or TIA) that doesn't cause permanent damage.

Ischemic stroke
About 80 percent of strokes are ischemic strokes. Ischemic strokes occur when the arteries to your brain become narrowed or blocked, causing severely reduced blood flow (ischemia). The most common ischemic strokes include:

Thrombotic stroke. A thrombotic stroke occurs when a blood clot (thrombus) forms in one of the arteries that supply blood to your brain. A clot may be caused by fatty deposits (plaque) that build up in arteries and cause reduced blood flow (atherosclerosis) or other artery conditions.
Embolic stroke. An embolic stroke occurs when a blood clot or other debris forms away from your brain — commonly in your heart — and is swept through your bloodstream to lodge in narrower brain arteries. This type of blood clot is called an embolus.
Hemorrhagic stroke
Hemorrhagic stroke occurs when a blood vessel in your brain leaks or ruptures. Brain hemorrhages can result from many conditions that affect your blood vessels. These include:

Uncontrolled high blood pressure (hypertension)
Overtreatment with anticoagulants (blood thinners)
Weak spots in your blood vessel walls (aneurysms)
A less common cause of hemorrhage is the rupture of an abnormal tangle of thin-walled blood vessels (arteriovenous malformation). Types of hemorrhagic stroke include:

Intracerebral hemorrhage. In an intracerebral hemorrhage, a blood vessel in the brain bursts and spills into the surrounding brain tissue, damaging brain cells. Brain cells beyond the leak are deprived of blood and are also damaged.

High blood pressure, trauma, vascular malformations, use of blood-thinning medications and other conditions may cause an intracerebral hemorrhage.

Subarachnoid hemorrhage. In a subarachnoid hemorrhage, an artery on or near the surface of your brain bursts and spills into the space between the surface of your brain and your skull. This bleeding is often signaled by a sudden, severe headache.

A subarachnoid hemorrhage is commonly caused by the bursting of a small sack-shaped or berry-shaped aneurysm. After the hemorrhage, the blood vessels in your brain may widen and narrow erratically (vasospasm), causing brain cell damage by further limiting blood flow.

Transient ischemic attack (TIA)
A transient ischemic attack (TIA) — sometimes known as a ministroke — is a temporary period of symptoms similar to those you'd have in a stroke. A temporary decrease in blood supply to part of your brain causes TIAs, which may last as little as five minutes.

Like an ischemic stroke, a TIA occurs when a clot or debris blocks blood flow to part of your nervous system — but there is no permanent tissue damage and no lasting symptoms.

Seek emergency care even if your symptoms seem to clear up. Having a TIA puts you at greater risk of having a full-blown stroke, causing permanent damage later. If you've had a TIA, it means there's likely a partially blocked or narrowed artery leading to your brain or a clot source in the heart.

It's not possible to tell if you're having a stroke or a TIA based only on your symptoms. Even when symptoms last for under an hour, there is still a risk of permanent tissue damage.

Risk factors
Many factors can increase your stroke risk. Some factors can also increase your chances of having a heart attack. Potentially treatable stroke risk factors include:

Lifestyle risk factors
Being overweight or obese
Physical inactivity
Heavy or binge drinking
Use of illicit drugs such as cocaine and methamphetamines
Medical risk factors
Blood pressure readings higher than 120/80 millimeters of mercury (mm Hg)
Cigarette smoking or exposure to secondhand smoke
High cholesterol
Diabetes
Obstructive sleep apnea
Cardiovascular disease, including heart failure, heart defects, heart infection or abnormal heart rhythm
Personal or family history of stroke, heart attack or transient ischemic attack.
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 — African-Americans have a higher risk of stroke than do people of other races.
Sex — Men have a higher risk of stroke than 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, as well as increased estrogen levels from pregnancy and childbirth.
Complications
A stroke can sometimes cause temporary or permanent disabilities, depending on how long the brain lacks blood flow and which part was affected. Complications may include:

Paralysis or loss of muscle movement. You may become paralyzed on one side of your body, or lose control of certain muscles, such as those on one side of your face or one arm. Physical therapy may help you return to activities affected by paralysis, such as walking, eating, and dressing.
Difficulty talking or swallowing. A stroke might affect control of the muscles in your mouth and throat, making it difficult for you to talk clearly (dysarthria), swallow (dysphagia) or eat. You also may have difficulty with language (aphasia), including speaking or understanding speech, reading, or writing. Therapy with a speech-language pathologist might help.
Memory loss or thinking difficulties. Many people who have had strokes experience some memory loss. Others may have difficulty thinking, making judgments, reasoning 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 strange sensations may occur in the parts of the body affected by stroke. For example, if a stroke causes you to lose feeling in your left arm, you may develop an uncomfortable tingling sensation in that arm.

People also may be sensitive to temperature changes, especially extreme cold, after a stroke. This complication is known as central stroke pain or central pain syndrome. This condition generally develops several weeks after a stroke, and it may improve over time. But because the pain is caused by a problem in your brain, rather than a physical injury, there are few treatments.

Changes in behavior and self-care ability. People who have had strokes may become more withdrawn and less social or more impulsive. They may need help with grooming and daily chores.
As with any brain injury, the success of treating these complications varies from person to person.

Prevention
Knowing your stroke risk factors, following your doctor's recommendations and adopting a healthy lifestyle are the best steps you can take to prevent a stroke. If you've had a stroke or a transient ischemic attack (TIA), these measures might help prevent another stroke. The follow-up care you receive in the hospital and afterward also may play a role as well.

Many stroke prevention strategies are the same as strategies to prevent heart disease. In general, healthy lifestyle recommendations include:

Controlling high blood pressure (hypertension). This is one of the most important things you can do to reduce your stroke risk. If you've had a stroke, lowering your blood pressure can help prevent a subsequent TIA or stroke.

Exercising, managing stress, maintaining a healthy weight and limiting the amount of sodium and alcohol you eat and drink can all help to keep high blood pressure in check. In addition to recommending lifestyle changes, your doctor may prescribe medications to treat high blood pressure.

Lowering the amount of cholesterol and saturated fat in your diet. Eating less cholesterol and fat, especially saturated fat and trans fats, may reduce the plaque in your arteries. If you can't control your cholesterol through dietary changes alone, your doctor may prescribe a cholesterol-lowering medication.
Quitting tobacco use. Smoking raises the risk of stroke for smokers and nonsmokers exposed to secondhand smoke. Quitting tobacco use reduces your risk of stroke.
Controlling diabetes. You can manage diabetes with diet, exercise, weight control and medication.
Maintaining a healthy weight. Being overweight contributes to other stroke risk factors, such as high blood pressure, cardiovascular disease and diabetes. Losing as little as 10 pounds may lower your blood pressure and improve your cholesterol levels.
Eating a diet rich in fruits and vegetables. A diet containing five or more daily servings of fruits or vegetables may reduce your risk of stroke. Following the Mediterranean diet, which emphasizes olive oil, fruit, nuts, vegetables, and whole grains, may be helpful.
Exercising regularly. Aerobic or "cardio" exercise reduces your risk of stroke in many ways. Exercise can lower your blood pressure, increase your level of high-density lipoprotein cholesterol, and improve the overall health of your blood vessels and heart. It also helps you lose weight, control diabetes and reduce stress. Gradually work up to 30 minutes of activity — such as walking, jogging, swimming or bicycling — on most, if not all, days of the week.

What causes paralysis?
Some people are born paralyzed. Others develop paralysis due to an accident or a medical condition.


Other causes of paralysis include:

cerebral palsy
post-polio syndrome
traumatic brain injury
neurofibromatosis
birth defects
How is paralysis diagnosed?
Diagnosing paralysis is often easy, especially when your loss of muscle function is obvious. For internal body parts where paralysis is more difficult to identify, your doctor may use X-rays, CT scans, MRI scans, or other imaging studies.

If you experience a spinal cord injury, your doctor may use myelography to assess your condition. In this procedure, they’ll insert a special dye into the nerves in your spinal cord. This will help them see your nerves more clearly on X-rays. They may also perform an electromyography. In this procedure, they’ll use sensors to measure electrical activity in your muscles.


How is paralysis treated?
A treatment plan will depend on the underlying cause of the paralysis, as well the symptoms experienced. For example, a doctor may prescribe:

surgery or possible amputation
physical therapy
occupational therapy
mobility aids, such as wheelchairs, braces, mobile scooters, or other devices
medications, such as Botox or muscle relaxers, if you have spastic paralysis
In many cases, paralysis isn’t curable. But a healthcare team can recommend a variety of treatments, tools, and strategies to help manage symptoms.


What is the outlook for people with paralysis?
Many people with paralysis never regain mobility or sensation in the affected areas of their bodies. But even if a person’s paralysis isn’t curable, their healthcare team can recommend assistive technologies, therapeutic interventions, or other strategies to help improve quality of life.

For example, special braces and electronic mobility devices may allow independent movement. Occupational therapists and other professionals can help modify the following to suit a patient’s abilities and needs:

clothes
home
car
workplace
A doctor may also recommend lifestyle changes, medications, surgery, or other treatments to help manage potential complications.

If you’re seeking treatment for paralysis, ask your doctor for more information about your specific diagnosis, treatment plan, and long-term outlook.

The symptoms of facial palsy are many and vary from person to person. The symptoms will depend on the cause of your facial palsy and here we discuss some of the more common symptoms experienced.

How quickly do symptoms occur?
The onset of your symptoms may be sudden (appearing overnight), or may appear over two or three days. Alternatively, your symptoms may develop slowly over time (over weeks, or even months). In either situation, you should visit your GP as soon as possible, as further investigations may be required. It is important that you have a clear diagnosis of the cause so that you are given the correct treatment and advice.

What are the symptoms of facial palsy?
Facial palsy normally affects only one side of the face although in rare cases it may affect both sides. It does not cause weakness in your arms or legs. If you experience weakness in your arms or legs as well as weakness on one side of your face, you should seek immediate medical attention. These symptoms grouped together may indicate a stroke.
A complete facial palsy on one side of the face affects the brow, eye, cheek, and mouth. This means the facial nerve signals that control movement in these muscles are not working. The face may appear flattened and movement may be lost.
Symptoms may improve or worsen over time depending on the type and degree of facial nerve damage and the cause of your facial palsy.
Some types of facial palsy will affect sensation including pain, as well as facial movement. This may mean that the nerve which is responsible for sensation (trigeminal nerve) has been damaged as well as the facial nerve. The facial nerve controls movement, tear production, saliva production and taste.
Loss of sensation may mean you cannot feel your face when you touch it.
Inability to blink or close the eye is a common symptom and needs prompt attention from your GP.
How does facial palsy affect facial muscles and facial function?
Forehead
Loss of forehead wrinkles and inability to frown
Eye area
Droopy eyebrow and inability to raise an eyebrow
Inability to close the eye fully or blink
Watery eye or dry eye
Inability to squint
Drooping of the lower eyelid which may make the eye appear wide
Painful eye with symptoms of grittiness or irritation
Sensitivity to light
Soreness or redness of the white of the eye
Please note: seek prompt advice from your GP if you are experiencing any problems with your eyes.

Mouth
The corner of the mouth pulls down/droops
Inability to smile on the affected side
Inability to puff up your cheeks, whistle or blow
Altered taste
Tingling of the affected half of the tongue
Difficulty eating and drinking
Difficulty brushing your teeth and spitting out
Drooling from the weak corner of your mouth
Excess or reduced salivation (dry mouth)
Inability to pout
Difficulty speaking because of weakness in the lips and cheek
Ear(s)
Pain in or near the affected ear
Loss of hearing
Increased sensitivity to high pitched noise
Nose
Nose runs or feels stuffy
Inability to flare nostril
Inability to wrinkle nose
If a person develops symptoms of facial palsy slowly (over weeks or months) then they should immediately be referred for further investigations.

Botulism is a serious illness caused by the botulinum toxin. The toxin causes paralysis. Paralysis starts in the face and spreads to the limbs. If it reaches the breathing muscles, respiratory failure can result.
The toxin is produced by Clostridium botulinum (C. botulinum), a type of bacterium.

All types of botulism eventually lead to paralysis, so any case of botulism is treated as a medical emergency.

In the past, it was often fatal, but antitoxins have significantly improved the outlook.

In 2015, the United States saw the biggest outbreak of botulism in 40 years. It stemmed from improperly home-canned potatoes that were shared at a potluck meal.

Symptoms
[botulinum toxin is responsible for botulism]
Botulism is a serious disease caused by the botulinum toxin.
The signs and symptoms depend on the type of botulism.

In food-borne botulism, signs and symptoms include nausea, vomiting, and diarrhea followed by constipation and abdominal distention. There may be weakness and difficulty breathing. Symptoms normally appear between 18 and 36 hours after consuming the contaminated food, but this can vary between 3 hours and 8 days.

In wound botulism, the nerves that connect the brain to the spine, known as the cranial nerves, experience the first symptoms. This then spreads to the rest of the body. The incubation period is from 4 days to 2 weeks.

Neurological signs and symptoms of adult, food-borne, and wound botulism are the same, but the symptoms of wound botulism ones may take longer to appear.

The patient may experience double or blurred vision, the eyelids may droop, there will be facial weakness, a dry mouth, dysphagia, or difficulty swallowing, and speech slurring. Muscles will become weak.

Next, paralysis will set in. Without treatment, the patient's breathing muscles will eventually become paralyzed, resulting in respiratory failure and death.

The patient remains conscious during this process.

In infant botulism, signs and symptoms may include:

constipation
poor feeding
bad temper
excessive drooling when feeding
sagging eyelids
flat facial expression
lethargy and listlessness
respiratory difficulties
slow or improper reflexes
weak crying weakly
floppiness and poor muscle tone
no gag reflex
unfocused eyes
weak sucking

Bell's palsy causes sudden, temporary weakness in your facial muscles. This makes half of your face appear to droop. Your smile is one-sided, and your eye on that side resists closing.

Bell's palsy, also known as facial palsy, can occur at any age. The exact cause is unknown. It's believed to be the result of swelling and inflammation of the nerve that controls the muscles on one side of your face. Or it might be a reaction that occurs after a viral infection.

For most people, Bell's palsy is temporary. Symptoms usually start to improve within a few weeks, with complete recovery in about six months. A small number of people continue to have some Bell's palsy symptoms for life. Rarely, Bell's palsy can recur.
Symptoms

Facial weakness
Facial paralysis

Signs and symptoms of Bell's palsy come on suddenly and may include:

Rapid onset of mild weakness to total paralysis on one side of your face — occurring within hours to days
Facial droop and difficulty making facial expressions, such as closing your eye or smiling
Drooling
Pain around the jaw or in or behind your ear on the affected side
Increased sensitivity to sound on the affected side
Headache
A decrease in your ability to taste
Changes in the amount of tears and saliva you produce

In rare cases, Bell's palsy can affect the nerves on both sides of your face


Causes

Although the exact reason Bell's palsy occurs isn't clear, it's often related to exposure to a viral infection. Viruses that have been linked to Bell's palsy include the virus that causes:

Cold sores and genital herpes (herpes simplex)
Chickenpox and shingles (herpes zoster)
Infectious mononucleosis (Epstein-Barr)
Cytomegalovirus infections
Respiratory illnesses (adenovirus)
German measles (rubella)
Mumps (mumps virus)
Flu (influenza B)
Hand-foot-and-mouth disease (coxsackievirus)

The nerve that controls your facial muscles passes through a narrow corridor of bone on its way to your face. In Bell's palsy, that nerve becomes inflamed and swollen — usually related to a viral infection. Besides facial muscles, the nerve affects tears, saliva, taste and a small bone in the middle of your ear.
Risk factors

Bell's palsy occurs more often in people who:

Are pregnant, especially during the third trimester, or who are in the first week after giving birth
Have an upper respiratory infection, such as the flu or a cold
Have diabetes

Recurrent attacks of Bell's palsy are rare. But in some of these cases, there's a family history of recurrent attacks — suggesting a possible genetic predisposition to Bell's palsy.