Brain Stroke Signs, Symptoms and What Causes a Stroke

A stroke is the death of brain tissue associated with an interruption in blood supply to the brain and results in impairment of normal brain activity. The brain is in need of a constant supply of oxygen and nutrients which reach it through the blood in the arteries, mainly the carotid and vertebral arteries and the relevant branches. When the artery is narrowed and then suddenly blocked, oxygen-rich blood cannot reach the brain and parts of the tissue die. This is known as an ischemic stroke and accounts for the majority of stroke cases. Another type of stroke known as hemorrhagic stroke arises when there is a rupture of a blood vessel and blood accumulates in and around the brain thereby compressing it.

The signs and symptoms of a stroke, whether due to ischemia or a hemorrhage are similar. However, with an ischemic stroke, the clinical features often arise suddenly and may gradually ease to some degree, but usually not entirely. In a hemorrhagic stroke, the signs and symptoms gradually develop and become worse over time. A stroke may be preceded by episodes of brain dysfunction that are temporary and not due to any death of brain cells. This is known as a transient ischemic attack (TIA), or commonly as a pre-stroke, mini-stroke or warning stroke. In these cases, the brain is temporarily starved of oxygen and injured (ischemia) but quickly recovers. With a stroke, there is death of brain tissue and the effect is permanent.

Signs and Symptoms of a Brain Stroke

The clinical features of a stroke depends on the part of the brain that is affected.The cerebrum is primarily affected in a stroke, hence the term cerebral infarction. Most symptoms tend to be one-sided (unilateral) but if it occurs on both sides (bilateral), then this may be an indication of a lesion in the brain stem or cerebellum. It is important to remember when assessing the symptoms that it is usually of sudden onset since most strokes are ischemic strokes.

Weakness and Paralysis

Muscle weakness is common in a stroke and is usually one-sided. This is referred to as hemiparesis. There may paralysis instead, which is referred to as hemiplegia. The weakness or paralysis may extend from the face all the way down to the feet. This is seen as difficulty walking, standing, talking (slurred speech ~ dysarthria) and coordinating movements. Patients tend to have poor balance, cannot support themselves and tend to fall frequently. The face may droop on one side and a patient will only have a one-sided smile, on the opposite side. There may be a complete loss of body movements which is known as ataxia.

Sensations and Senses

Abnormal sensations (paresthesia) typically involves tingling which progresses quickly to numbness. These sensations are usually on one side, particularly on the face, arms or legs. Patients may not be able to feel any sensation on the affected side, or very slightly so and in these cases there is difficulty differentiating between blunt and sharp stimuli.

The disturbance in vision is the most prominent sensorineural symptom in a stroke. This may include double vision, blurred vision, dimness or even blindness. The loss of vision may be in one half of the visual field and is known as hemianopia. Visual disturbances may be one sided (monocular) or affect both sides (binocular) and this includes hemianopia.

Patients may also report a feeling of lightheadedness or dizziness. At times, this may be specifically reported as vertigo.

Mental Faculties

Confusion particularly in interpreting when others talk may vary in severity or even be absent in some patients. There may also be difficulty in expressing speech. This impairment in understanding and speaking is known as aphasia. The patient may appear ‘out of touch’ with a discussion, have long pauses between words or difficulty initiating speech. There may also be a difficulty in concentrating, remembering and other cognitive functions. Coupled with the slurred speech, the patient may find it very difficult to communicate with others which, along with the other debilitating symptoms, may lead to depression.

Other signs and symptoms

The other signs and symptoms may depend on the type of stroke, cause and other underlying factors.  These clinical features include :

• Headache
• Nausea and vomiting
• Loss of consciousness
• High blood pressure
• Seizures

In a hemorrhagic stroke, there is an increase in intracranial pressure. Therefore symptoms typical of raised intracranial pressure, like a headache, nausea and vomiting, will be more prominent than in a hemorrhagic stroke.  Seizures are also more typical of a hemorrhagic stroke, especially within the first 24 hours.

Causes of a Stroke

The causes may vary among an ischemic stroke and hemorrhagic stroke.

Causes of an Ischemic Stroke

An ischemic stroke occurs when an artery supplying the brain is obstructed. In most cases, the artery is first narrowed and finally blocked by a blood clot. Therefore an ischemic stroke can be further classified as a thrombotic or embolic stroke. With a thrombotic stroke, a blood clot forms at the site in the artery (thrombus) which it eventually blocks. In an embolic stroke, the clot forms elsewhere, travels through the blood stream and lodges in the artery, usually narrowed already, which it then blocks. Sometimes the embolus is not a blood clot but other material that should not be traveling in the blood stream.

• Atherosclerosis
• Heart disease like arrhythmia and heart valve disorders where a blood clot is more likely to form. These clots may dislodge and obstruct one an artery supply blood to the brain.
• Vasculitis
• Arterial dissection
• Sympathomimetic drugs including OTC cough and cold medication and illicit substances like cocaine
• Hypotension, if sudden, in a patient with reduced blood flow (like a narrowed artery) or oxygen availability (like in anemia.
• Cardiac arrest
• Shock
• Tumors which may compress the carotid or vertebral arteries or its branches.

Risk Factors for an Ischemic Stroke

Patients with one or more of the following risk factors may be more likely to have an ischemic stroke :

• Advancing age
• Gender – males are at greater risk
• Family history
• Previous myocardial infarction (heart attack) or stroke
• Elevated fibrinogen levels

These are fixed or non-modifiable risk factors meaning that it cannot be changed. Other risk factors known as modifiable risk factors can be altered and includes :

• Hypertension (high blood pressure)
• Heart disease (mentioned above)
• Diabetes mellitus (sugar diabetes)
• Hyperlipidemia (elevated blood lipids)
• Polycythemia (excess red blood cells)
• Alcohol misuse
• Cigarette smoking
• Oral contraceptives

Causes of a Hemorrhagic Stroke

A hemorrhagic stroke occurs when a blood vessel ruptures, particularly within intracranial cavity, and blood accumulates in and around the brain. Failure of blood to reach all parts of the brain due to a rupture, the tissue irritation caused by contact with whole blood, and compression of the brain by pockets of blood (hematoma) or increased intracranial pressure may damage the brain.

• Hypertension (high blood pressure)
• Aneurysms
• Bleeding disorders (impaired blood clotting)
• Arteriovenous malformation (AVM)
• Small vessel disease

Risk factors for a Hemorrhagic Stroke

• Advancing age
• Hypertension (high blood pressure)
• History of stroke
• Substance abuse (alcohol, amphetamines, cocaine)