Select a condition Absence seizures Acne ADHD Age-related macular degeneration AIDS Alzheimer's disease AMD Amebic dysentery Anal tears Angina, stable Angina, unstable Ankle sprain Anorexia Anxiety Appendicitis Arthritis Asthma in adults Asthma in children Athlete's foot Atrial fibrillation Attention deficit hyperactivity disorder (ADHD) Autism Back pain Bacterial vaginosis Bad breath Bedsores Bedwetting Bell's palsy Benign prostatic hyperplasia Bipolar disorder Bladder infection in women Blood pressure Breast cancer Breast pain Bronchiectasis Bronchiolitis Bronchitis Bulimia Bunions Burning mouth syndrome Burns and scalds Canker sores Cardiac arrest Carpal tunnel syndrome Cataracts Cellulitis and erysipelas Chickenpox Childbirth, heavy bleeding Childbirth, tear or cut Chlamydia Chronic bronchitis Chronic fatigue syndrome Chronic obstructive pulmonary disease Chronic prostatitis Chronic tension type headache Cold sores Colic in babies Colon and rectal cancer Colon and rectal cancer screening Colonic diverticular disease Common cold Conjunctivitis Constipation in adults Constipation in children COPD Crib death Deep vein thrombosis Dementia Depression in adults Depression in children Diabetes, type 1 Diabetes, type 2 Diarrhea in adults Diarrhea in children Diverticular disease Ear infection, middle ear Ear infection, outer ear Ear infection with discharge Ear infection with fluid Ear pain during air travel Ear wax Eczema Emphysema Endometriosis Enlarged prostate Epilepsy Episiotomy Erection problems Essential tremor Febrile seizures Fertility problems Fibroids Flu Gallstones Genital herpes Genital warts GERD GERD in children Glaucoma Gonorrhea Gout Group B streptococcus H. pylori infection Halitosis Hay fever Headache, chronic tension type Head lice Heart and circulation problems in diabetes Heart attack Heartburn Heart failure Heavy periods Heel pain Hemorrhoids Hepatitis B Hepatitis C Hernia Herpes, genital Herpes simplex eye infection High blood pressure High blood pressure in pregnancy High cholesterol HIV infection Hyperactivity IBS Incontinence in women Infection in newborn babies Infertility Influenza Insomnia in adults Irritable bowel syndrome Jaundice in newborn babies Jet lag Kidney infection Kidney stones Leg cramps Leg ulcers Lewy body dementia Lung cancer Lyme disease Macular degeneration Malaria prevention Manic depression Mastalgia Measles, mumps and rubella: prevention Melanoma Meniere's disease Meningococcal disease Menopause Migraine in adults Migraine in children MMR prevention Morning sickness Multiple sclerosis Nail infection, fungal Neck pain Nicotine addiction Non-Hodgkin's lymphoma Nosebleeds in children Obesity Obsessive-compulsive disorder OCD Oral thrush Osteoarthritis Osteoporosis Ovarian cancer Painful periods Pancreas cancer Panic attacks Parkinson's disease PCOS Pelvic inflammatory disease Perineal care Peripheral arterial disease Peripheral vascular disease Pneumonia Polycystic ovary syndrome Postpartum depression Postpartum hemorrhage Post-traumatic stress disorder Preeclampsia Pregnancy, nausea Premature birth Pressure sores Prostate cancer Prostatitis, chronic Psoriasis PTSD Raynaud's disease Rectal cancer screening Recurrent cystitis Reflux in children Rheumatoid arthritis Scabies Schizophrenia Seasonal allergy Shoulder pain Sickle cell anemia Sickle cell disease SIDS Sinusitis Skin cancer (melanoma) Skin cancer (squamous cell) Sleep apnea Sleep problems in children Slipped disk Smoking Sore throat Stomach ulcers Stress headache Stress incontinence Stroke, emergency care Stroke prevention Sudden infant death syndrome Swimmer's ear Tennis elbow Tension headache Testicular cancer Thrush (oral) Tic douloureux Tinnitus Tonsillitis Toxoplasmosis in pregnancy Trigeminal neuralgia Underactive thyroid Urinary tract infections in children Varicocele Varicose veins Vascular dementia Warts Whiplash Wisdom teeth, impacted Wrinkles Yeast infection, vagina

Select treatment area Bladder & Kidneys Blood Brain & nervous system Cancer Children's health Diabetes Digestive system Ear, nose & throat Eating & weight Eyes Fertility Heart and circulation Hormones Infections Lungs & breathing Men's health Mental health Mouth Muscles & bones Pregnancy & childbirth Sexual health Skin Sleep Staying healthy Travel health Women's health

A stroke is an emergency. A stroke happens when the blood supply to part of your brain is cut off. This can cause brain damage. The earlier you are treated, the better your chance of making a good recovery.

If your brain cells don't have a supply of blood, they won't get enough food and oxygen. If they go without food and oxygen for too long, brain cells can die. That's why some doctors call a stroke a brain attack.¹

Strokes affect people in different ways. If you have a stroke you may not be able to move one side of your body, or you may have difficulty speaking or swallowing. You may black out (lose consciousness) for a while. Or your symptoms may be mild: you may feel dizzy and have blurred vision for a few minutes. You should get medical help immediately, even if you think your symptoms are not very serious.

In most people who have a stroke, the blood supply to their brain is blocked by a blood clot. But a stroke can also happen when a blood vessel in the brain bursts.

If you or someone close to you has just had a stroke, you will probably be shocked and worried about the future. Many people worry that a stroke will leave them disabled and they will have to depend on others to care for them. This may be true for some people, but it's certainly not true for everyone. With the right treatment and follow-up care, it's possible to limit the effects of a stroke. If you stick with your treatment, you can live for many years after a stroke.

Strokes tend to happen without warning. They can happen at any age, although they are more common in older people.

• A stroke is an emergency. If you think you or someone you know is having a stroke, you should call 911 right away. You need to get to the hospital immediately.
• The symptoms of a stroke can include sudden numbness or weakness (especially if it's on one side of the body), sudden confusion or trouble speaking, sudden problems seeing, sudden dizziness, loss of balance or trouble walking, and a sudden, severe headache for no reason.
• If you're treated in a specialized stroke unit you'll probably make a better recovery than if you're treated in an ordinary hospital ward.
• The symptoms you have in the first few days after a stroke may not last forever. Your symptoms are most likely to improve in the first two months after you have a stroke.
• Your symptoms are less likely to change after six months, but many people learn to adapt to the differences in their abilities caused by a stroke.
• Feeling depressed after having a stroke is common, and some people may need treatment. But depression usually goes away within six months to a year.
• Many people are able to live at home after having a stroke, with the help of physical therapists, occupational therapists, speech therapists, psychologists and dietitians.

Many of the symptoms of a stroke make more sense once you understand how your brain works, how blood is supplied to your brain and what happens when things go wrong. It will also make it easier to understand how treatment can help control the damage a stroke causes to your body and what you can do to prevent another stroke.

Your brain enables you to think, and to control the movements of your body. For example, your brain allows you to move your arm to pick up your coffee. It also controls lots of the things that you do without thinking. For example, it automatically makes sure you keep breathing and your heart keeps beating. Different parts of your brain are in control of breathing, moving and talking.

Your brain is connected to the rest of your body by the spinal cord. This is a tube of fibers that runs down your back from your brain. Your spinal cord is about the width of a finger, and it sits inside the bones that make up your spine. These bones protect your spinal cord against injury.

Nerves from your spinal cord reach every part of your body. When you touch something with your fingers, a signal travels along the nerves to your spinal cord and up to your brain.

There are three main parts to the brain:

• The cerebrum (the largest part of the brain)
• The brainstem
• The cerebellum.

The cerebrum is what most people think of when you mention the brain. It sits just under your skull and is the largest part of your brain. It is split into two by a deep groove. The two sides of the cerebrum, called the right and left cerebral hemispheres, communicate with each other.

The brainstem sits at the bottom of the brain. It connects the brain to the spinal cord.

The cerebellum sits between the cerebrum and the brainstem.

Each part of the brain has its own function, although the different parts also work together.

To work, your brain needs a constant supply of oxygen and food. These are carried by your blood. Blood reaches your brain through blood vessels called arteries. If the flow of blood to your brain is interrupted, you have a stroke. Doctors sometimes name strokes after the blood vessel that has had its blood flow interrupted. You don't have to know the names of arteries, but we explain a few of them here.

The blood flows to your brain along two separate paths: the front path goes to the cerebral hemispheres and the back path goes to the cerebellum and brainstem.

The front path is called the anterior circulation. The back path is called the posterior circulation.

The blood flow to the front of the brain comes from the left and right internal carotid arteries. The blood flow to the back of the brain comes from the left and right vertebral arteries.

The Circle of Willis is where these two blood flows meet. It is a circle of arteries, deep within your brain.

A stroke happens when the blood supply to part of the brain is cut off and the cells in that area are starved of oxygen and food. Brain cells can survive for a few minutes without food and oxygen. But if the blood supply is interrupted for much longer, then the brain cells die. This is why a stroke is an emergency and you should get medical help quickly if you think you, or someone you know, is having a stroke.

There are two main types of stroke.

• A blood vessel to the brain gets blocked by a blood clot. The blockage stops blood from getting to the brain. Doctors call this an ischemic stroke. About 4 in 5 strokes are ischemic. To learn more, see Ischemic strokes.
• A blood vessel in or near the brain bursts. Blood seeps into the spaces between brain cells. Doctors call this a hemorrhagic stroke. About 1 in 5 strokes are caused by bleeding into the brain. To learn more, see Hemorrhagic stroke.

Doctors normally find out the type of stroke you've had by doing a CT scan or an MRI scan.² (CT stands for computed tomography, MRI stands for magnetic resonance imaging.) These produce images of your brain. It's important to have a scan because if you have bleeding into your brain from a burst blood vessel, you may need different treatment from someone who has a blocked blood vessel.

To learn more, see How do doctors diagnose a stroke?

There is no treatment that can bring dead brain cells back to life. But around the dead brain cells, other brain cells will still be alive. These cells are in danger of dying too, unless the blood supply is quickly started up again.

This is why you need to get treatment urgently if you have a stroke. The aim of emergency treatment is to limit the area of the brain that is damaged. Doctors try to save the brain cells that are still alive but could die if they don't get their oxygen and food supply back soon.

There are many things that affect your chance of having a stroke. Things that make it more likely that certain people will have a stroke are called risk factors. Here are some of the main risk factors:³

Things you can't change

• Getting older
• Being male
• Being African-American
• Having a close relative who has had a stroke
• Having had a stroke before.

Things you can change

• Having high blood pressure
• Having heart disease
• Smoking
• Having high cholesterol level
• Drinking too much alcohol
• Being obese
• Not being active
• Not eating healthily
• Abusing drugs (such as cocaine, amphetamines)
• Having poorly controlled diabetes.

Remember that even if you have certain risk factors, it doesn't mean you will have a stroke. No-one can say for sure what will happen to you as an individual.

To learn more, see Risk factors for stroke.

You can't control all of your risk factors but here are a few things you can do:

• Take medications that reduce your blood pressure and cholesterol (if necessary)
• Quit smoking
• Eat healthily
• Exercise regularly
• Don't drink too much alcohol.

For more tips on protecting yourself from a stroke, see How to reduce your risk of a stroke

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.