Family doctor

What is it?

A stroke occurs when the part of the brain tissue dies as a result of alteration in the blood supply. In most cases this is the result of blockage of a blood vessel, causing starvation of blood to the brain (ischaemia). This is also called brain infarction. However, in some cases a stroke occurs because of haemorrhage (bleeding) from a blood vessel. On occasion, the alteration in the blood supply can be temporary and reversible. In these cases, provided the reversal occurs promptly, the symptoms may resolve. In these cases the patient is termed to have undergone a transient ischaemic attack (TIA). By international convention, symptoms that last longer than 24 hours are considered a stroke and not a TIA.

Risk factors for infarction/stroke include:

• Increased age
• Increased blood pressure (hypertension)
• Smoking
• Diabetes
• Increased plasma cholesterol
• Excessive alcohol consumption
• Angina or previous heart attack
• Previous stroke or TIA
• Irregular cardiac rhythm, such as atrial fibrillation

In addition a number of other rarer causes are well recognised. For example, abnormalities of the heart valves, trauma to the carotid artery, arterial inflammation as well as some blood disorders such as leukaemia can all cause, in certain circumstances, stroke. These associations (and others not mentioned) are all uncommon.

Risk factors for brain haemorrhage(bleeding) include:

• High Blood Pressure (hypertension)
• Aneurysms (weaknesses in the blood vessel wall, causing vessel swellings)
• Abnormalities of blood clotting (including certain drugs, such as warfarin)
• Asian race

What are the symptoms?

The symptoms of a stroke typically occur abruptly, as the blood supply to an area of the brain alters. The particular symptoms depend on what the affected function of that part of the brain is. Common symptoms include:

• Weakness or paralysis (usually, but not always, one side of the body)
• Loss of speech, ability to understand language and to read (all to differing degrees)
• Loss of part of vision
• Double vision
• Difficulty swallowing
• Loss of balance (with the risk of falls)
• Impaired awareness of the parts of the body
• Impaired awareness of three dimensional space
• Confusion
• Change in sensation, such as numbness or pins-and-needles

In addition, the person may experience difficulty in bowel or bladder control. A brief episode of loss of consciousness at the onset of the stroke often occurs. Loss of consciousness beyond this initial spell is a poor prognostic sign that a large stroke has occurred. Other poor prognostic signs include persistent urinary incontinence following the stroke, severe weakness, advanced age and dementia.

What tests are needed?

All patients with a suspected stroke should be seen by a doctor. Some may require admission to hospital, or specialist assessment. The reason for this is to confirm the diagnosis accurately, and arrange medical treatment and rehabilitation. In the vast majority of cases, blood tests and a brain scan are required (either CAT scan or a MRI scan). The chief purpose of the brain scan is to identify if the stroke is ischaemic or haemorrhagic, and to exclude another cause for the symptoms.

Often, scans of the heart and carotid arteries are needed to plan treatment. These scans are usually performed by painless ultrasound. Occasionally, special x-rays of the arteries of the brain are performed (angiography). Newer techniques using MRI scanners have made invasive angiography, where a catheter is introduced through a blood vessel and dye is injected, less common.

What can be done to help?

There are three aspects of treatment:

1. Immediate treatment

The majority of patients should be admitted to hospital promptly for assessment. Exception to this include very minor strokes, those already in hospital, and those where acute treatment is not required (for example, the patient already has a terminal illness).

Haemorrhagic strokes are treated differently from ischaemic strokes. In haemorrhages, it is important to control the blood pressure and to avoid therapies that interfere with blood clotting. A special case is that of subarachnoid haemorrhage, where bleeding occurs under the lining of the brain (usually a result of an aneurysm). Patients with subarachnoid haemorrhage should be referred to a specialist neurosurgery unit, where surgery is often required.

There is evidence, in ischaemic strokes, that prompt administration of aspirin is of benefit. However, the aspirin should only be taken after the brain scan, as aspirin can worsen bleeding in the brain.

There is some evidence that drugs that dissolve clots (thrombolytic drugs), particularly a drug called TPA, may improve the outcome of the ischaemic stroke. However, these thrombolytic drugs do carry a significant risk of causing a haemorrhage, possibly fatal, in those that receive them. At present it is difficult to recommend their use universally, and all cases need to be individually assessed. It appears that patients who arrive in hospital less than three hours after the onset of their stroke, and with smaller strokes, do better with thrombolysis.

Other important aspects of immediate treatment include maintaining the hydration of the patient, preventing skin damage, optimising oxygenation, and preventing aspiration pneumonia.

2. Rehabilitation

All but the most mild stroke victims should be assessed for rehabilitation. Rehabilitation is the process by which return of muscular power and adaptive abilities are optimised with a team of physiotherapists, occupational therapists, speech therapists and doctors.

Most of the raw power return that is going to occur following a stroke occurs in the first month. However, functionally useful power occurs thereafter, and adaptation continues for up to two years after a stroke.

In most cases, rehabilitation also involves a check of the patient's home environment to optimise the patient's safety. Unfortunately in some cases the patient requires institutionalisation following a stroke.

Rehabilitation time varies according to the severity of the stroke, and may be offered both as an inpatient or outpatient.

3. Further stroke prevention

It is important to prevent further strokes. This may involve:

• Aspirin
• Control of blood pressure
• Anticoagulation (such as warfarin ) - particularly in cases of atrial fibrillation
• Surgery on the carotid arteries - in cases of narrowing of the carotid arteries
• Treatment of raised blood lipids (fat)

Future trends

A large amount of research continues world wide into stroke. Areas of interest include:

• Technologies for the early diagnosis of stroke, allowing differentiation from reversible strokes ("TIA's")
• Clot dissolving drugs, and instillation of these drugs at the site of the clot
• New drugs that inhibit platelet (clotting) action
• Use of "nerve growth factors", which encourage new nerve growth.
• New surgical approaches
• Early discharge from hospital, and community rehabilitation

Getting help

Stroke Foundation, Auckland, P O Box 31237, Milford. Phone: 4860899

The Stroke Foundation also has branches elsewhere in New Zealand. They have field officers, Stroke Clubs and provide assistance and advice regarding many aspects of stroke.