A closer look at stroke

  • Health
  • Sunday, 05 Jun 2005

Stroke, otherwise known as a brain attack, is the third most common cause of death in many countries, including Malaysia. There are various types, and the effects of some strokes, with timely intervention, can be reversible, to a certain extent.

The shrivelled part of the brain (right side) has been affected by a stroke.

LAM, a 35-year-old lawyer, had an accident while driving to meet a client one morning. He rammed his car against the divider along the highway. He did not have any obvious injuries, and stepped out of the car to inspect the extent of the damage. However, while he was getting out of the car, he fell on the road because he did not realise that the left half of his body was weak and numb.  

His colleague, who happened to be with him, rushed him to a hospital, but by then he had fully recovered. The doctor did not find anything wrong with him and advised him to go back without further observation or investigations. 

Lam felt exhausted after the incident and had a good four hours sleep at home. Unfortunately, on waking up, he was completely paralysed on the left, confused, and slurred when he attempted to speak.  

He was rushed to another medical centre. An urgent CT (computer tomography) scan showed a moderate area of stroke changes in the right brain. An MRI (magnetic resonance imaging) demonstrated severe stroke with a large area of brain tissue at risk of dying.  

An MR angiogram (an image of a blood vessel after it is filled with a contrast material) showed a tight narrowing of a major artery in the brain. An emergency procedure called thrombolysis (lysing of blood clot) and intracranial balloon angioplasty/stenting (the surgical repair of a blood vessel, either by inserting a balloon-tipped catheter to unblock it, or by reconstructing or replacing part of the vessel) was carried out.  

Lam is a lucky man. He recovered almost fully from the ordeal, regaining strength on the left half of his body and was able to resume his work. After the incident, a full medical examination was carried out and he was found to have high blood pressure and high cholesterol. He was a heavy smoker, obese and carried out minimal exercise.  

Lam suffered what we call a TIA (transient ischaemic attack) initially, and this was followed by a catastrophic stroke. 

Haemorrhagic stroke: A large blood clot has formed in the brain, typically due to uncontrolled high blood pressure.

What is a brain attack? 

A brain attack, or stroke, as it is medically known, is the loss of brain function caused by loss of blood circulation to areas of the brain. There are two types of strokes: 

·Ischaemic stroke 

This is due to a blockage of the brain blood vessels or a major artery leading to the brain. This usually results in temporary or permanent loss of one or more normal functions of the body. About 85% of strokes are ischaemic, and the rest haemorrhagic. 

·Haemorrhagic stroke 

This is the result of bleeding into or on the surface of the brain causing damage.  

What causes an ischaemic stroke? 

Ischaemic stroke (infarction) occurs as the result of loss of blood circulation to areas of the brain. Neuronal death (infarction) occurs four minutes after the cessation of blood supply to the area. This is usually due to blockage of the brain artery. It could be due to a clot that has built up in the brain and ultimately blocks the blood vessel, called a “cerebral thrombosis”; or due to stuff that travel from a distance, like from the heart or lung, called “cerebral embolism”.  

The blockage can involve a big arterial branch or a tiny hair-sized perforating vessel at the basal aspect of the brain. The perforating artery occlusion usually produces a small coin-sized stroke, called a lacunar infarction.  

What causes a haemorrhagic stroke? 

Extensive plaque deposition in the neck (carotid) artery resulting in severe narrowing and secondary clot formation. The clots and plaque can migrate dwonstream into the brain.

The vast majority of haemorrhagic stroke is due to traumatic injury in a young patient, and high blood pressure that ruptures a tiny artery in the elderly.  

Another common cause is a ruptured “cerebral aneurysm”. An aneurysm is a weakened section of a brain artery that has ballooned out and burst. Other causes are brain vascular malformation (commonly called an “arteriovenous malformation” or AVM). 

How frequently do strokes occur? 

Stroke is the third major cause of death after heart disease and cancer in most countries, including Malaysia. The incidence of stroke (ischaemic) varies. It is estimated to be about 150/100,000 of the population in the US. Each year, more than 700,000 Americans suffer an acute ischaemic stroke, resulting in death in more than 90,000 women and 60,000 men.  

In Malaysia, it is about 160/100,000 population, or equivalent to 110 cases/day or 40,000 cases/year. About 25% of the patients will have another stroke.  

In the US, the cost of stroke to society exceeds US$50bil (RM190bil) each year. Over US$30bil (RM114bil) is spent on hospitalisation, medical equipment and rehabilitation. Loss of productivity from stroke survivors (being unable to return to their jobs) accounts for nearly US$20bil (RM76bil), and the cost to individuals and their family members is immeasurable. 

What will happen if I have a stroke? 

One of three things can happen: about 24% of strokes are fatal; 50% to 70% of survivors will have a mild disability or will improve; and 15% to 30% who survive will be permanently disabled. 

Of those who survive, the majority suffer permanent disability or residual neurological impairment.  

Stroke is a leading cause of adult disability, often requiring in-patient rehabilitation. Institutional care is required in 20% of patients three months post-stroke. 

Rehabilitation may benefit stroke survivors, but the underlying cause of the stroke still needs to be treated. 

Intracranial atherosclerotic stenosis (IAS): Severe hardening and narrowing of the brain arteries due to cholesterol and fatty deposits.

What are the symptoms of stroke? 

Stroke is a medical emergency. The signs and symptoms of stroke vary depending on the location, the extent of damage, and the cause of the disorder.  

Know these warning signs of stroke and teach them to others. Every second counts: 

1. Sudden numbness or weakness of the face, arm or leg, especially on one side of the body.  

2. Sudden confusion and trouble speaking or understanding.  

3. Sudden trouble seeing in one or both eyes. 

4. Sudden trouble walking, dizziness, loss of balance or coordination.  

5. Sudden, severe headache with no known cause.  

What is a transient ischaemic attack (TIA)? 

A TIA occurs when a person briefly experiences stroke symptoms that last from several seconds to minutes, and then go away. There is usually no permanent brain damage. 

However, a person experiencing a TIA should be examined immediately, because a TIA is often a sign that a major stroke will occur. Never ignore the warning signs of a stroke. 

A TIA is a very important warning sign! If the neurological signs and symptoms persist for more than a day, then it is called a stroke. 

What factors increase the risk of stroke? 

There are two types of risk factors – those you cannot control and those that you can. 

Factors you cannot control: 

·Age – The older you are, the higher your risk. 

·Gender – Males are at higher risk than females. 

·Race – Blacks, Hispanics/Latinos and Asians have higher risk than Caucasians. 

·Family history of stroke and heart disease. 

·A prior stroke, TIA (transient ischaemic attack) or heart attack. 

Factors you can control: 

·High blood pressure – Should be controlled and maintained at less than 140/90mm Hg. 

·Heart disease – Atrial fibrillation (a rapid, irregular heartbeat) should be treated. 

·Carotid artery disease – Can be treated by surgery, balloon angioplasty/stenting, or medical therapy. 

·Smoking – Should be stopped. 

·High cholesterol – Should be lowered with diet and medication. Eat a diet low in saturated fat, cholesterol and salt. 

·Diabetes – Increases the risk for stroke and should be controlled through diet, medications or insulin. 

·Obesity – The more the weight, the higher the risk. 

·Excess alcohol intake – Should be avoided. 

·Physical inactivity – Being inactive increases your risk. 

In general, the predisposing factors for stroke are similar to a heart attack and peripheral arterial disease (narrowing of arteries in the legs). A peculiar factor, which is very common in Asians, especially the Chinese, is a condition known as intracranial artherosclerotic stenosis (IAS).  

IAS is a condition where cholesterol and fatty material build up in the brain arteries. This causes severe narrowing and frequently results in acute blockage (cerebral thrombosis) when it ruptures or when clots build up.  

It is less common in the West, accounting for 8-12% of stroke in the US. In Asians, the incidence is much higher, with up to 67% of strokes of this type in Chinese patients.  

The long-term mortality and recurrent stroke risk are significantly higher in this group of patients. It is a progressive disease, with a significant increase in the risk of blockage. About 10% to 20% of patients will come down with another stroke in a year, despite adequate medical therapy.  

The long-term mortality rate is unfavourable, with a 3.5-year cumulative mortality rate of 20.8%.  

The annual risk of recurrent stroke is 10.9% if there’s no narrowing, 17.1% in the presence of IAS and 24.3% if there is IAS with extracranial carotid (narrowing of the carotid artery in the neck) narrowing.  

Related story:Imaging options 

Note: Dr Alex Tang is a consultant vascular & interventional radiologist. This information is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. 

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