Strokes are the third most common cause of death in developed countries, following coronary diseases and cancer. It affects 0.2% of the population, and is fatal in one third of the cases. At least half of the people who have survived a stroke are permanently disabled, which makes stroke the main cause of long-term physical, cognitive, emotional, and social disability.
Stroke is a clinical syndrome characterized by acute loss of brain function, and lasts more than 24 hours or leads to death. It occurs due to a spontaneous bleeding into the brain parenchyma (intracerebral hemorrhage) or in the space surrounding the brain (subarachnoid hemorrhage), i.e. hemorrhagic stroke, or as a result of an inadequate supply of blood to the brain tissue (ischemic stroke) as a result of thrombosis, embolism or poor blood flow, associated with diseases of the blood vessels, the heart or the blood. This definition includes patients whose subarachnoid hemorrhage is manifested through acute, severe headaches, with or without stiffness in the neck, without any signs of focal or global neurologic dysfunction.
A stroke is manifested with a sudden loss of function of a body part or speech loss, or loss of conscience due to a discontinuation of blood flow.
Recognize a stroke – symptoms and signs
Each stroke is manifested differently, and the symptoms depend on the affected region of the brain and its size. The symptoms and signs of this disease usually occur suddenly and are immediately detectable. In some patients, they can occur during the night, and the patients detect them when they wake up. Sudden and rapid onset of symptoms is the most recognizable sign of a stroke, so if the symptoms develop slowly and gradually worsen in the course of several days, weeks or months, then the cause might not be stroke. The most common symptoms of stroke are:
- Muscle weakness or paralysis – may invade other parts of the body but it usually affects one side of the face, arm and leg (hemiparesis). The weakness on the right side of the body occurs if the left side of the brain is impaired, and vice versa;
- Loss of sensation – a stroke can cause a loss of sensation in certain parts of the body. It usually causes numbness in the face, arm or leg, on one side of the body (hemianesthesia);
- Speech difficulties – a stroke can cause slurred speech as a result of the weakness and loss of coordination in the face, throat, or throat muscles. This results in dysarthria – unclear articulation of speech. Another type of speech disorder is dysphasia, when the person is unable to understand others’ speech or unable to find the right words and doesn’t speak fluently, and has reading (dyslexia) or writing (dysgraphia) difficulties. Dysphasia occurs due to an impairment of the dominant hemisphere of the brain. The left hemisphere is dominant in almost all right-handed people. The right side of the brain is dominant in about half of the individuals who are left-handed, and the left size is dominant in the other half;
- Visual symptoms – a stroke and TIA (transient ischemic attack) cause a loss of vision that encompasses the entire field of vision (Monocular blindness) or blindness on half of the field of vision (hemianopia) or cause double vision (diplopia). The loss of vision in one eye, which occurs suddenly and improves in a period of 24 hours (usually after 5 – 10 minutes) usually represents a short-term lack of blood supply to the eye, called amaurosis fugax. Homonymous hemianopia is a loss of vision on one side (right or left, depending on the side of the stroke). The double vision occurs when the visual axis of the two eyes is different, which is a result of a damage of the nerves that control the movements of the eyeballs;
- Dizziness – a stroke and TIA can cause dizziness and loss of balance which is sometimes accompanied with vomiting and nausea;
- Headache – a stroke and TIA don’t usually cause headaches. However, a headache may occur during stretching or irritation of the linings of the brain (meninges) or blood vessels in the brain. Stretching of the meninges may occur during a swelling of the brain which can occur shortly (minutes to hours) after a bleeding in the brain or a few days after a cerebral infarction when the brain swelling (edema) is at its greatest extent. Bleeding on the surface of the brain (subarachnoid hemorrhage) typically causes a very strong headache because the blood directly irritates the meninges which are sensitive to pain;
- Vomiting – vomiting may be caused due to a direct lesion on the centers for vomiting at the base of the brain (medulla) or by an increased pressure within the skull (increased intracranial pressure) which puts pressure on them. If the nerves that receive information about maintaining of balance are damaged, this may result in dizziness, nausea and vomiting;
- Disturbance of consciousness – a stroke or TIA may cause disruption or loss of consciousness. This can occur as a complication due to strokes (e.g. seizures); due to the direct involvement of the centers that maintain awareness and are located in a part of the brain (brain stem); during infarctions in that region or increased intracranial pressure that directly or indirectly pressures the centers in the brainstem.