What is a Stroke?

Stroke refers to a condition in which there is reduced blood flow to the brain resulting in injury to brain cells causing permanent damage to it. Its incidence has been steadily rising in the developing world. It is ranked after heart disease and before cancer. Stroke is a frequent cause of death and about half of people who have had a stroke live less than one year. It commonly occurs in those over 65 years old.

What are the symptoms of Stroke?

The warning signs of stroke are FAST (facial droop, arm weakness, speech difficulty, and time to call emergency services) Stroke symptoms usually start suddenly, in a matter of seconds to minutes. In most cases symptoms do not progress further.

Stroke results in poor functioning of the part of the brain affected. Signs and symptoms of a stroke depend on the part of the brain affected and include (but not restricted to)

1. Inability to move or feel on one side of the body
2. Difficulty in understanding the speech or in speaking
3. Dizziness
4. Loss of vision to one side
5. Severe headache
6. Loss of consciousness, headache, and vomiting commonly occurs in hemorrhagic stroke.

The symptoms of a stroke can be permanent. The more extensive the area of the brain affected, the more functions that are likely to be lost. Most forms of stroke are not associated with a headache, except subarachnoid haemorrhage and cerebral venous thrombosis and occasionally intracerebral haemorrhage.

Brainstem stroke

A brainstem stroke affects the brainstem (a vital part of the brain that deals with the critical functions like breathing, heartbeat etc.,). It can produce symptoms relating to deficits in these cranial nerves such as:

1. Altered smell, taste, hearing, or vision (total or partial)
2. Drooping of eyelid (ptosis) and weakness of ocular muscles
3. Decreased reflexes: gag, swallow, pupil reactivity to light
4. Decreased sensation and muscle weakness of the face
5. Balance problems and nystagmus
6. Altered breathing and heart rate
7. Inability to turn head to one side
8. Weakness in tongue

Cerebral cortex involvement can produce the following symptoms:

1. Aphasia (difficulty in verbal expression/comprehension/reading/writing)
2. Dysarthria (difficulty in saying words clearly due to neurological injury)
3. Apraxia (altered voluntary movements)
4. Visual field defect
5. Memory deficits (involvement of temporal lobe)
6. Hemineglect (involvement of parietal lobe)
7. Disorganized thinking, confusion, hypersexual gestures (frontal lobe)
8. Lack of insight of his or her, usually stroke-related, disability

Cerebellum involvement can cause

1. Altered walking gait
2. Altered movement coordination
3. Vertigo and or disequilibrium

What are the Causes of Stroke?

Thrombotic stroke: In thrombotic stroke, a blood clot is formed inside the blood vessel

• Atherosclerosis
• Vasoconstriction (tightening of the artery),
• Aortic, carotid or vertebral artery dissection,
• Inflammation of blood vessel (Takayasu arteritis, giant cell arteritis, vasculitis),
• Noninflammatory vasculopathy,
• Moyamoya disease
• Fibromuscular dysplasia
• Lipohyalinosis (due to high blood pressure and aging)
• Fibrinoid degeneration (lacunar stroke)
• Microatheroma (small atherosclerotic plaques)
• Sickle-cell anemia

Embolic stroke: In an embolic stroke blockage is by a travelling clot in the arterial bloodstream originating from elsewhere.

An embolus is usually a broken thrombus, but it can also be fat , air, cancer cells, from a deep vein thrombosis or clumps of bacteria (usually from infectious endocarditis). Emboli most commonly arise from the heart (Atrial fibrillation)

A special form of embolic stroke is the embolic stroke of undetermined source (ESUS). This subset of cryptogenetic stroke is defined as a non-lacunar brain infarct without proximal arterial stenosis or cardioembolic sources. About one out of six ischemic strokes could be classified as ESUS.