Introduction

Stroke is a major medical disorder caused by interruption of blood supply to the brain which results in a loss of neurological function. It usually occurs suddenly without warning and frequently results in death or disability. The two main mechanisms are blocking of the arteries causing ischaemia and rupture of the arteries causing haemorrhage. The aim of management of stroke is to try to limit the area of damage in the brain, assist recovery and prevent any recurrence. The management of stroke in high income countries over the last two decades has witnessed marked improvement with the creation of dedicated stroke care units in hospitals and a more active approach to the management and prevention of stroke. This chapter presents an overview of the main characteristics of stroke. The student should aim for an overall understanding of stroke, including its increasing burden, main causes and prevention, and in particular to be able to diagnose and manage a patient presenting with stroke.

Definition: Stroke is a sudden neurological deficit lasting more than 24 hours with no explanation other than a vascular cause. If the patient recovers fully within 24 hours without any neurological deficit, then this is classified as a transient ischaemic attack (TIA).

Epidemiology

Stroke is the third most common cause of death worldwide after heart disease and cancer. It is reported to be the leading neurological cause of death in Africa (Chapter 3). The annual incidence of stroke in high income countries is 2-3 per 1000 persons and the prevalence reaches 0.5 to >1% of the population in older age groups (>65 yrs). A similar high incidence rate has been reported recently in one study in Tanzania. The overall prevalence of stroke is reported to be lower in Africa with age adjusted rates being less than half that in high income countries. However with increasing urbanization and life style changes the burden of stroke is steadily increasing and it is now one of the leading causes of neurological admissions and death in urban hospitals throughout Africa.

AETIOLOGY

Stroke occurs as a result of ischaemia or haemorrhage

Ischaemia

Ischaemia accounts for >80% of strokes worldwide and for 60–80% in Africa. Ischaemia is caused by thrombosis or embolism resulting in loss of blood supply to part of the brain (Fig. 5.1).