Strokes usually begin very suddenly over a few seconds or minutes. Sometimes people wake up from sleep to find that they have had a stroke.
- Paralysis, weakness or numbness of one side of the body (this may include a drooping face, useless arm or hand and weak leg)
- Difficulty with speech (aphasia or dysphasia) - difficulty finding the right words, jumbled speech, using wrong words, difficulty understanding speech.
- Slurring of speech (dyasrthria) - the person uses the right words but they are come out slurred.
- Sudden loss of vision in one eye or loss of vision on one particular side.
- Sudden loss of balance, loss of coordination or clumsiness (particularly of one side) or sudden trouble walking.
- Sudden severe headache with no known cause (strokes can also be completely painless).
To help people recognise the symptoms of stroke quickly, the Stroke Association supports FAST - the Face Arm Speech Test - which is a simple test that anyone can perform. It is used by paramedics to diagnose stroke and fast track people into hospital for acute treatment.
How does the brain work and how does a stroke cause these symptoms?
The brain controls many vital functions, receives signals and sends out signals to different parts of the body. The symptoms produced by a stroke will depend on which parts of the brain are affected.
The main parts of the brain are the cerebrum, the cerebellum, and the brain stem.
The cerebrum is the largest and most advanced part of the human brain responsible for higher intellectual function, speech, analysis of sensation (including sight) , initiation of movement and fine control of movement. These functions are carried out by specialised cells in the most outer layer of the cerebrum called the cerebral cortex. Different areas of the cortex specialise to perform special functions such as speech, voluntary control of movement in different parts of the body, vision and so on. The cerebrum has a right and left hemisphere and is divided into frontal, parietal, temporal, and occipital lobes.
The left side of the brain controls the functions on the right side of the body and vice versa because nerve fibres from the brain cross over in the brainstem. Thus, injury to the left cerebral hemisphere produces paralysis of the right arm and leg. The left hemisphere is usually more developed than the right and specialised for speech and language in all right handed and most left handed people. Strokes affecting the left side therefore cause problems with spoken and written language and often right sided weakness.
The cerebellum is a structure at the back of the brain and is concerned with coordination of movement and balance. A stroke involving the cerebellum may result in a lack of coordination, clumsiness, shaking, or other muscular difficulties.
The brainstem is a narrow tube like structure that connects the brain to the spinal cord. It has several important structures including centres controlling the face, eye movements and tongue. It allows the passage of signals from the brain to the rest of the body and vice -versa. It is concerned with wakefulness, breathing, heartbeat and swallowing. Strokes in the brainstem can lead to severe strokes with paralysis of both sides of the body and involvement of the face and eye movements.
Functions of the lobes of the brain:
Frontal lobe - voluntary movement, production of speech, judgement, planning
Parietal lobe - appreciation of sensation, understanding language
Temporal lobe - understanding language, hearing, intellectual and emotional function
Occipital lobe - appreciation of vision
Problems that can be caused by a stroke
As shown above, the symptoms or effects caused by a stroke will depend on the area of the brain affected. These symptoms are described in greater detail below. This is a general and simplified account and individual patients may not have all of these symptoms. The symptoms of a transient ischaemic attack (TIA) are similar except for the fact that recovery takes place within minutes or hours.
Paralysis or weakness
This is usually on one side of the body (hemiparesis) and can affect the face, arm and leg either singly or in combination e.g. face and arm or arm and leg or all three together. The paralysis can be complete (hemiplegia) and the patient may not be able to move any of the affected muscles at all. More commonly, the affected side will be capable of some movement or may merely become clumsy or feel heavy.
The drawing shows facial weakness on the left side due to a stroke. The right side of the mouth is drawn up towards the normal side.
Lack of balance and in-coordination
Muscle weakness can make it difficult to do things steadily but sometimes, damage to the balance and coordination structures make it difficult for the person to sit, stand, or walk even if the muscles are not badly affected. It may cause difficulty in picking up things, feeding or writing if it affects the hands.
Problems with speech and language
Many people have difficulty with speaking in the form of slurring of speech. This is called dysarthria. They have no problems understanding speech or finding the right words to use when speaking. It is caused by in coordination or weakness of muscles used in speaking. It can also occur in many other conditions and does not always mean that the person has had a stroke.
In contrast, dysphasia or aphasia is a condition where the person affected finds it difficult to speak because he or she cannot find the right words to use, cannot name common objects or use language properly. They may substitute odd sounds or made up words for real words. Their speech may sound like a meaningless jumble of words. Sometimes the patient is temporarily unable to produce any speech at all.
They may also have difficulty in reading or writing as well. There are 2 types of dysphasia - if the person can understand what is being said and knows exactly what to say in reply internally but cannot express themselves as they are unable to find the right words to use, this is called expressive dysphasia. In the other type, patients cannot understand what is being said to them even though they can hear perfectly.
This is called receptive dysphasia. Some patients have a mixture of both forms of dysphasia. As described above, dysphasia is usually due to damage to the left side of the brain (except in some left handed people) and is often associated with weakness of the right side of the body.
Difficulty with swallowing
About half of all stroke patients have difficulty swallowing (dysphagia) in the early stages of the stroke. This may be due to drowsiness, lack of strength and in coordination of the muscles used for swallowing.
Patients have a test for swallowing after admission to hospital and if swallowing is unsafe, they may be kept 'nil by mouth' (not allowed to eat or drink temporarily). It is risky to attempt feeding patients with dysphagia because food and fluids may go down the wrong way into the wind pipe (aspiration) and cause pneumonia.
Swallowing usually returns to normal in most patients but some patients need food of pureed consistency or thickeners in their fluids temporarily. Some patients will also need to be fed by tubes directly into their stomachs.
Difficulty with vision
If the stroke damages the visual cortex in the back of the brain (occipital lobes) or the nerve connections from the eyes to the brain, it can cause visual problems because the brain interprets information from the eyes and enable us to see. This will happen even if the eyes are perfectly normal.
There may be loss of vision in part of the visual field (the total area in which objects can be seen by our peripheral vision when we fix our eyes on an object straight ahead). Most commonly people lose their vision in either the right or left half of the visual field. This means they cannot see things on their right or left sides when they look straight ahead.
They may ignore people or things on one side or may bump into things on one side. If the stroke damages both visual cortices (both right and left) it may result in total or near total blindness. Sometimes people may not be aware that their sight is so badly impaired.
Double vision can occur with strokes in the brainstem due to weakness of muscles that move the eyes.
Sudden, complete blindness of usually one eye may occur due to a TIA or damage (infarction) of the optic nerve or retina. If it is a TIA, the vision recovers within minutes but if a stroke affecting the eye, the visual loss may be permanent.
Difficulty with sensation (feeling) and pain
Patients may have difficulty with the sensations of touch, pain and temperature. They may lose feeling over the face, hand, arm and leg on one side of the body and describe this as a numbness or a dead sensation. Partial sensory loss can also occur.
They may lose the sense of pain or temperature. A stroke of the right side of the brain causes loss of sensation of the left side of the body and vice versa. Pins and needles can also occur but can also be caused by causes other than a stroke.
Some kinds of strokes can give rise to pain as a result of the stroke. More commonly, patients get pain from unrelated causes or pain as a result of shoulder problems or muscle stiffness following the stroke.
Difficulty with perception, awareness and tasks
Strokes can cause strange problems with some patients' ability to perceive sensory information and can hamper awareness of their own bodies in relation to the environment.
This can lead to problems like ignoring one side of the body, neglect of stimulation (such as touch or vision) on one side of the body, denial of weakness on one side of the body or denial of ownership of a paralysed limb (the patient may wake up in the middle of the night and wonder whose arm is lying in bed besides them).
They may not eat food from one half of their plate or may not be able to dress properly (in spite of having no weakness) because of disordered body image. They may be lost in familiar surroundings in spite of being able to see.
They may not be able to recognise familiar objects by touch with their eyes closed. These problems are usually caused by damage to the parietal lobes particularly the right side.
They can cause a lot of disability and can impede rehabilitation and recovery.
Problems with memory, thinking, attention or learning (cognitive problems)
Diffuse damage to several parts of the cortex can cause problems with attention and concentration and may make a patient easily distractible. Patients may be unable to think clearly and precisely.
This may hamper decision making, reasoning and planning. There may be problems with memory which may be due to damage caused by the stroke or due to lack of attention and concentration.
Strokes can lead to vascular cognitive impairment, which is a type of dementia.
Problems with bowel or bladder control
Incontinence can occur quite commonly (about half of all strokes admitted to hospital) after a stroke but in most cases, control is regained quickly. About 15% remain incontinent at one year.
The most common reasons for incontinence are bladder over activity as a result of the stroke, impaired sphincter control, immobility, difficulty communicating, drowsiness, constipation, urinary infections and pre-existing problems.
Several methods are used to try and overcome this problem. See life after a stroke (toileting) for further details.
Most stroke patients suffer from tiredness in the first few days or weeks after a stroke. Becoming tired very quickly may limit the person's participation and performance in a rehabilitation program.
Sudden outbursts of emotion
Strokes can sometimes lead to sudden outburst of uncontrollable emotion such as crying (or sometimes laughing). This is called emotional lability and can be controlled by antidepressant medication or counselling.
Sadness, feelings of loss, concern about the future and confusion are common in the early days after a stroke. These feelings are to be expected as people try to adjust to what has happened. Sometimes these feelings can persist and intensify leading to depression and anxiety.