Cerebrovascular disease and stroke

Epidemiology:

• Stroke is the 3^rd most common cause of death in developed countries
• 200 per 100,000 population die per year from strokes in the UK
• The death rate following a stroke is ~25%

Definitions:

Stroke (cerebrovascular accident, CVA):

• A focal neurological deficit due to a vascular lesion
• Usually of rapid onset
• Lasts longer than 24 hours

Completed stroke:

• Implies that the neurological deficit has reached its maximum
• Usually within 6 hours of onset

Stroke in evolution:

• Describes evolving and deteriorating symptoms and signs
• Usually during 24 hours from the onset

Minor stroke:

• Patients recover without a significant deficit, usually within 1 week

Transient ischaemic attack (TIA):

• A focal neurological deficit lasting from a few seconds up to a maximum of 24 hours
• There is complete clinical recovery
• Usually of sudden onset
• TIAs have a tendency to recur, and to herald thromboembolic stroke

Pathophysiology of a completed stroke:

This is usually caused by one of 4 principal mechanisms:

• Arterial embolism from a distant site
• Atheromatous carotid or vertebral artery occlusion
• Atheromatous arterial thrombosis within a cerebral vessel
• Haemorrhage into the brain

Less commonly, other processes cause the clinical picture of stroke:

• Venous infarction
• Dissection of the carotid or vertebral arteries
• Air embolism
• Multiple sclerosis – a plaque of demyelination
• Mass effects of an expanding lesion, e.g:
• Brain tumour
• Abscess
• Subdural haematoma

Risk factors for stroke:

• Hypertension
• Smoking
• Obesity
• Hyperlipidaemia
• Race (more common in Afro-Caribbeans in the UK)
• Family history