Epidemiological studies have shown an association between OSA and strokes. This may be partly due to common risk factors such as obesity, alcohol consumption, age, diabetes mellitus and hypertension, but the link is probably a direct one. Strokes occur most frequently at 6.00-8.00 am, suggesting that they are associated with the process of awakening, but no link has been found between OSA and the risk of transient cerebral ischaemic attacks.
The hypertensive surges during each apnoea may contribute to the risk of stroke, but sustained daytime hypertension is probably more important, together with endothelial dysfunction, inflammatory changes and increased fibrinogen, which are all seen in OSA. There also appears to be an increased risk of paradoxical embolization through a patent foramen ovale associated with severe oxygen desaturations during sleep .
OSA may occur following any type of stroke , but particularly with those involving the posterior inferior cerebellar artery, leading to pharyngeal and palatal dysfunction. Obstructive sleep apnoeas after a stroke correlate with early neurological deterioration and increased disability at 6 months, possibly because the lability of the blood pressure during each apnoea increases the extent of the cerebral damage. Treatment with nasal CPAP is poorly tolerated with only around 50% using it acutely and 10% at 3 months. Nasal CPAP could also have harmful effects, such as reducing the Pco2, which leads to cerebral vasoconstriction.
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Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...