48 Neurological impairment may occur as a result of a variety of problems that directly or indirectly impair the central or peripheral nervous systems. Of most concern are those conditions that can quickly lead to an altered level of consciousness and have the potential to cause permanent neurological damage. Cerebrovascular accident (CVA) or stroke is one of the most common causes of sudden deterioration in neurological function, detectable by use of the acronym FAST (Chapter 47). General risk factors include: age, male gender, genetic predisposition, ethnicity (Asian or Afro-Caribbean), pre-existing hypertension and diabetes. There are two main types of stroke: Ischaemic strokes account for 85% of CVAs. This typically occur as a result of progressive occlusion of the larger arteries (often the carotids) with atherothrombotic plaques. Warning signs of progressive blood vessel narrowing include a diminished carotid pulse, a carotid bruit (a noise heard over the carotid pulse on auscultation, caused by turbulent blood flow) and transient ischaemic attack (TIA) which may cause neurological deficit for up to 24 h (Figure 48.1). TIA should be treated promptly as it often heralds a major ischaemic stroke, with severe hypoperfusion of the areas that the affected blood vessels serve. As ischaemic stroke usually leads to infarction of the cerebral cortex, the patient will also experience equal losses of motor and sensory function. Embolic stroke caused by the sudden impaction of a blood clot in a small cerebral artery is similar to ischaemic stroke. Patients with atrial fibrillation (see Chapter 31, Figure 31.1c) are at risk from embolic stroke. Haemorrhagic
Neurological impairment
Cerebrovascular accident
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