Strokes are one of the top three most common causes of death in the UK. Gareth Hurst investigates the symptoms, causes and underwriting issues for this core critical illness
Alongside cancer and heart disease, a stroke is among the top three causes of death in the UK, and it is the most common cause of disability. While anyone can suffer a stroke (including children), 90% of those affected are over the age of 55.
Also known as a cerebrovascular accident (CVA), a stroke occurs when a part of the brain is deprived of its blood supply for more than 24 hours.
Of all the organs in your body, the brain is by far the most complex. Its correct functioning, which regulates everything a person does, is dependent on a continuous uninterrupted supply of oxygen and nutrients, delivered by the blood. A loss of blood supply causes the starved brain cells to die, in turn, losing the function performed by the affected part of the brain. The functions lost depend on which area of the brain is affected and for how long.
Symptoms
Symptoms of strokes include (but not exclusively) the following:
n Sudden numbness or weakness of the face, arm, or leg, especially on one side of the body.
n Sudden confusion, trouble talking, or understanding speech.
n Sudden trouble seeing in one or both eyes.
n Sudden trouble walking, dizziness, loss of balance or co-ordination.
n Sudden severe headache with no known cause.
There are two main types of stroke - ischaemic stroke and haemorrhagic stroke. In ischaemic strokes (sometimes referred to as thrombo-embolic strokes), an artery supplying the brain with its vital blood supply is blocked by a blood clot. This blockage may occur in the main arteries, which supply the brain with its blood. Alternatively, it may occur elsewhere in the circulatory system but then travel to and eventually block the blood vessels supplying the brain.
While ischaemic strokes are the most common, a further 15% to 20% of strokes are known as haemorrhagic. In this event, part of a blood vessel in or around the brain is weakened by one or more of a variety of disorders, which can include uncontrolled elevated blood pressure, a longstanding congenital weakness or malformation of a vessel. Eventually, the weakened blood vessel can haemorrhage, causing bleeding inside or onto the brain. Damage is caused by the accumulating blood causing pressure on the highly delicate brain tissue. Elsewhere, brain cells die due to the interruption of the blood supply caused by the leaking vessel. While only a few strokes are classed as haemorrhagic, this type of stroke is responsible for approximately 30% of stroke-related deaths.
Other types of stroke include lacunar infarct, also known as small vessel disease, where the flow of blood is occluded in the very small arterial vessels. While these are rarer and usually less severe, they still carry a significantly increased mortality risk.
Transient ischaemic attacks (TIA), or mini-strokes as they are more commonly known, occur when the brain's blood supply is interrupted for a period of time that can range from a matter of minutes up to 24 hours. The symptoms experienced are similar to those of a stroke, with the difference being that the impairment is usually short-lived and the symptoms subside swiftly. Consciousness is usually retained during the occurrence.
Despite this usually prompt recovery, a TIA should always be taken very seriously. Although statistics vary, a TIA is a stark warning that a person is at an increased risk of a future repeat cerebrovascular event, of which death or permanent disability is a possibility.
There are numerous risk factors and causes for strokes but, as alluded to previously, in ischaemic strokes, the biggest cause is vascular disease. Atherosclerosis, which is the accumulation of cholesterol and other fatty substances in the walls of the arteries, causes narrowing of the vessels. Atherosclerosis can occur in any artery, and in strokes, the main arteries affected are the intracranial and extracranial. Atherosclerosis is also a major cause of heart disease and peripheral vascular disease.
Individuals with hypertension (thought to be in excess of one in four adults in developed countries), which is not controlled to a satisfactory standard, are also at major risk, while those with diabetes have double the normal chance of suffering a stroke.
Other underlying causes include atrial fibrillation (where an abnormally increased heart rate can cause a blood clot to form in a chamber of the heart, which may then travel to the blood vessels supplying the brain), congenital heart disease, aneurysm, trauma and brain tumours. Use of the oral contraceptive pill also increases the probability of a future CVA.
While proper management of any existing risk factors will help reduce the risk of a stroke, lifestyle choice is also a major factor. For example, those who smoke are two times as likely to suffer a stroke than someone who does not. Similarly, lack of adequate exercise doubles the risk of future stroke. Excess alcohol consumption and poor diet also increase the risk, as these are linked to elevations in blood pressure and cholesterol levels, which effectively leads to fatty build-up inside of the arteries.
Unfortunately, some risk factors are unavoidable, such as age (over-55s carry a higher risk), sex (males - especially under-65s - are at higher risk), ethnic background (south Asians, Africans and Afro-Caribbeans are at higher risk), and family history of a stroke at an early age.
If the symptoms previously referred to occur, investigations will be performed to confirm the diagnosis. These include a variety of blood tests to exclude other possibilities, as well as a variety of different scanning and imaging techniques.
If a stroke has been diagnosed, the prognosis is variable. The symptoms already covered may persist permanently, and may be joined by the following:
n Difficulties in swallowing, affecting both eating and drinking, potentially leading to malnutrition, dehydration, breathing difficulties or constipation.
n Perception difficulties, where there can be confusion in recognising everyday objects and even people.
n Impairment of thought processes, logical thinking and understanding.
n Incontinence - urinary or faecal.
n Mood changes (including depression due to disability following the event).
n Pain - with no known cause and non-respondent to painkillers.
n New onset epilepsy.
Treatment depends on any residual symptoms post diagnosis. Therapy normally follows the course of prevention of stroke (or if a TIA/stroke has already occurred, prevention of further strokes), treatment immediately after the stroke, and post-stroke rehabilitation.
Prevention of stroke - or CVA recurrence - would be to address known and potential risk factors and maintain them. For example, establish and maintain good blood pressure and cholesterol levels, modify lifestyle risks and address known existing diseases and conditions.
Immediate treatment during or after a stroke can include trying to stop a stroke while it is happening by quickly dissolving the clot in ischaemic stroke, or by stopping the bleeding in haemorrhagic stroke surgically.
Post stroke therapy involves rehabilitation to attempt to overcome disabilities resulting from damage caused by stroke. The extent of recovery is widely variable depending on severity of the residual stroke effects, but with timely intervention at the event of the stroke and a strong rehabilitation regime, certain residual affects can often be treated, reduced and in some instances overcome.
Gareth Hurst is life and disability underwriter at Aegon Scottish Equitable
