Medical Matters with Dr Kevin McCarroll
Of the many illnesses that may strike us in later life, there are few others than stroke that conjure up as much fear. In truth, while stroke is the leading cause of acquired physical disability in Ireland, the outcome for many with stroke is very good and has improved in recent years due to more coordinated stroke care and modern medical advances.
Stroke should no longer be considered as a condition that inevitably leads to severe disability, and indeed a sizeable proportion of stroke survivors continue to live active lives.
There are approximately 10,000 strokes each year in Ireland with 65% occurring in those aged over 65. Most strokes (85%)result from a lack of blood supply to part of the brain caused by a clot in an artery. The remaining 15 % are due to bleeding as a consequence of a ruptured blood vessel, most commonly due to high blood pressure.
The effects of stroke vary hugely along a spectrum from minimal loss of power or sensory function to more severe disability and/or death.
This depends largely on both the size and location of the area of damage in the brain. Loss of power or sensation in the limbs, impairment of co-ordination or perception, balance, speech, vision and swallow problems are common after stroke. Some degree of cognitive decline is usually apparent, but for some may be very minimal.
As well as a greater focus on stroke prevention, early treatment with clot busting drugs in hospital (where appropriate) and management in dedicated acute stroke and rehabilitation units has led to major improvement in patient outcomes.
The greatest risk factors for stroke are smoking, high blood pressure, diabetes and to a lesser extent high cholesterol. In addition, having a condition called atrial fibrillation (a form of irregular heart rate) is a major risk factor and accounts for about one third of all strokes in Ireland.
It can lead to the development of clots in the heart that embolise to the brain and is associated with larger strokes than tend to have worse outcome. In particular, there has been an increasing interest in more recent years in identifying and treating those with atrial fibrillation as studies show that is often undiagnosed.
In fact, many will have no symptoms due to atrial fibrillation and it may only be brought to attention after getting a stroke. Furthermore, use of blood thinners such as warfarin or newer anticoagulant drugs will reduce the risk of stroke in those with atrial fibrillation by about two-thirds, making it one of the most important, preventative interventions.
Smoking, high blood-pressure and diabetes also substantially increase the risk by causing hardening and narrowing of the arteries that supply blood to and within the brain as well as predisposing to blood clot formation. High blood-pressure and smoking are also associated with haemorrhagic strokes.
The early recognition of the signs and symptoms of stroke is hugely important in ensuring a prompt referral to the hospital. This is because early identification of strokes due to arterial occlusions from blood clots may allow treatment with ‘clot busting drugs’ that can significantly improve outcomes.
The FAST campaign, launched by the Irish Heart Foundation, proved effective in alerting people to the signs of stroke and need for early admission to hospital. The campaign acronym is based on the ‘face’ falling to one side, the ability to raise the ‘arms’ on both sides, slurred ‘speech’ and the prompt for ‘time’ to call an ambulance.
To be eligible for treatment with clot-busting drugs (thrombolysis), they must be delivered within 4.5 hours of stroke onset as well as meeting some other medical criteria. However, time is of the essence as in acute stroke up to two million brain cells are dying per minute. In about one third of cases, treatment will result in a significant improvement and overall 15% will be left with a minimal or near normal neurological deficit. The outcome for some has been so great that in the early days of treatment it was cited as the ‘Lazarus affect’.
Recent advances in interventional radiology also now mean that clots can be physically retrieved from arteries under minimally invasive techniques guided by x-ray.
While still an evolving area, promising results from a recent study now mean that it is likely to become part of our standard treatment for carefully selected stroke patients in the future.
Some stroke presentations will be self resolving and are called mini-strokes or TIA’s (transient ischaemic attacks).
They are however, harbingers of potential future strokes and should always prompt a full medical workup for potential causes, particularly atrial fibrillation and narrowing of the carotid arteries in the neck (which is amenable to surgery).
In summary, outcome for strokes are continuing to improve and for many it is not the once thought of disabling condition that it used to be. Identifying and addressing risk factors adequately will go a long way in reducing stroke incidence. An awareness of stroke signs and early presentation to hospital may allow administration of clot busting drugs that can significantly improve outcome.
Dr Kevin McCarroll is a consultant physician in geriatric medicine in St James’s Hospital, Dublin.