Stroke

Stroke (also known as Brain Attack) occurs when blood supply to the  brain is affected due to either blockage or leakage (or both blockage and leakage)  of a blood vessel responsible for supplying or draining blood to and from  the brain, thereby, causing brain damage leading to difficulty in movements, sensation, speaking, vision etc. or at times to death.

Types of stroke

Ischemic Stroke:In India about 70-75% of all strokes are ischemic, in which blood flow to the brain is blocked by blood clots or fatty deposits (also known as plaque) in blood vessel linings.

Hemorrhagic Stroke:It occurs when a blood vessel leaks in the brain. Blood accumulates and compresses the surrounding brain tissue. This is also called ‘Brain hemorrhage.

Intracerebral hemorrhage: It is the most common type of hemorrhagic stroke. It occurs when an artery in the brain leaks, flooding the surrounding tissue with blood.

Subarachnoid hemorrhage: It is bleeding in the area between the brain and its covering consisting of layers of tissue. 

Transient ischemic attack (TIA) is a "warning stroke" or a "mini-stroke" that results in no lasting damage. Recognizing and treating TIAs immediately can reduce your risk of a major stroke.

References:

• www.cdc.gov
• www.nhs.uk
• www.nlm.nih.gov
• www.nhlbi.nih.gov
• www.stroke.org

The content of this module has been validated by Dr Kameshwar Prasad, Head, Department of Neurology on 26th March 2015.

Stroke can affect any movement, senses, speech, behavior, thoughts, memory, and emotions. The body may become paralyzed or weak.

The five most common symptoms of stroke are

• Weakness or Numbness of the face, arm, or leg.
• Confusion or trouble speaking or understanding others.
• Difficulty in vision
• Difficulty in walking or loss of balance or coordination.
• Severe headache with unknown cause.

Reference:

• www.cdc.gov

Presence of following risk factors place people at increased risk for developing stroke. 

A.Non-modifiable 

• Family history
• Old age
• Male sex

B.Modifiable

• High blood pressure
• Diabetes
• High cholesterol
• Heart disease
• Smoking (as it injures the blood vessels and speeds up the hardening of the arteries)
• Consuming excessive alcohol (as it increases the blood pressure)
• Low socioeconomic status 

Reference:

• www.cdc.gov

Strokes is primarily a clinical diagnosis, supported by  brain imaging.

CT scans and MRI

Two common methods used for brain imaging are a computer tomography (CT) scan and magnetic resonance imaging (MRI) scan.

A CT scan is like an X-ray, but uses multiple images to build up a more detailed, three-dimensional (3D) picture of the brain. 

An MRI scan uses a strong magnetic field and radio waves to produce a detailed picture of the inside of  the body.

Swallowing test:

A swallow test is essential for a person who has had a stroke. When a person cannot swallow properly, there is a risk that food and drink may get into the windpipe and then into the lungs (called aspiration), which can lead to chest infections and pneumonia.

Certain other tests carried out generally to diagnose stroke are as follows: Ultrasound (carotid ultrasonography)

An ultrasound scan uses high frequency sound waves to produce an image of the inside of the body. Doctor may use a wand-like probe (transducer) to send high-frequency sound waves into neck. These pass through the tissue, creating images on a screen that will show if there is any narrowing or clotting in the arteries leading to brain.

This type of ultrasound scan is sometimes also known as a "Doppler Scan" or a "Duplex Scan". 

Brain Angiography

This is done to take images of the blood vessels of the brain. This can be done using CT (CT angiography), MRA (MR angiography) or injecting dye called catheter angiography.

This gives a more detailed view of arteries than can be obtained using ultrasound, CT angiography or MR angiography.

Echocardiogram

In some cases an echocardiogram may be used to produce images of the heart using an ultrasound probe placed on the chest (transthoracic echocardiogram). In addition, transoesophageal echocardiography (TOE) may also be used. This involves an ultrasonic probe which is passed down the food pipe (esophagus), usually under sedation. Because it's directly behind the heart, it produces a clear image of blood clots and other abnormalities that may not get picked up by the transthoracic echocardiogram.

References:

• www.nhs.uk

All patients need good supportive care in a stroke unit, looked after by physicians, nurses, physiotherapists, Speech therapists, Occupational therapists with help from Radiologists, Neurosurgeons and others with interest in stroke.

Ischemic stroke

Blockage of a blood vessel, the root cause of ischemic stroke, can be cleared by injection of ‘clot-busters’ like t-PA into the patient’s forearm veins, but this is successful only in one third of patients who receive this injection within three hours of start of stroke. ‘Blood thinner’ (like aspirin) and treatment in stroke unit can be used in most patients. Some patients develop life-threatening swelling of the brain, and require surgery (called hemi craniectomy) to save their lives. In well equipped centres, clots can be mechanically removed with a device from inside of the arteries after angiography. Besides these, risk factors, fever, high blood pressure and high pressure within the  head need to be brought under control. 

Brain Haemorrhage  Intra-cerebral haemorrhage

Leakage of the vessels stops soon on its own because blood clot seals the puncture site, but in one-third patients some leakage continues for 24 hours. Control of blood pressure is important to prevent continued leakage. Many patients require surgery for removal of the large blood clot causing life-threatening increase in pressure inside the skull. Rest of the treatment is similar to that of ischemic stroke. 

Subarachnoid haemorrhage

Often, this is due to a sac like bulge from a blood vessel (called an aneurysm), which has a tendency of life-threatening re-bleeding, which requires surgery or angiography with coiling to prevent re-bleeding. 

• Patient should be closely monitored for signs of increased pressure on the brain, such as restlessness, confusion, difficulty in following commands, and headache. Other measures should be taken to keep the patient away from straining due to excessive coughing, vomiting, lifting weights and straining at stool.
• In some cases, medicines may be given to control blood pressure, brain swelling, blood sugar levels, fever and seizures.
• Surgery, if needed, may include surgical removal of blood clot, also aneurysm clipping, coil embolization and arteriovenous malformation (AVM) repair. 

Reference:

• www.nhlbi.nih.gov
• www.ncbi.nlm.nih.gov

There are complications that can arise as a result of stroke, many of which are life threatening.Some of these complications are as follows:

Dysphagia:

The damage caused by a stroke can interrupt normal swallowing reflex, making it possible for small particles of food to enter respiratory tract (windpipe). Problems with swallowing are known as dysphagia. Dysphagia can lead to damage to lungs, which can trigger a lung infection (pneumonia).

Hydrocephalus:

Hydrocephalus is a condition that occurs when there is too much cerebrospinal fluid in the cavities (ventricles) of the brain. About 10% of people who experience a hemorrhagic stroke will develop hydrocephalus.

Deep vein thrombosis (DVT):

Some people with the stroke might  experience a further blood clot in their leg, known as deep vein thrombosis (DVT). This normally occurs in people who have lost some or all of the movement in their leg, as immobility will slow the blood flow in their veins, increasing blood pressure and the chances of a blood clot.

Reference: www.nhs.uk Warning symptoms/’mini stroke’

A. Ischemic stroke: Some patients (about 15 to 20%) develop transient ischemic attack ‘TIAs’ before the stroke. The symptoms of TIAs are short lasting and consist usually of weakness, difficulty of vision, speech problem or sensory disturbance.  Patients having TIAs need to see a physician at the earliest possible opportunity for detection and control of risk factors including carotid narrowing.

B.Sudden severe headache of the kind never experienced before in life can be a symptom of  ‘a warning leak’ of subarachnoid hemorrhage. Patients with this symptom need urgent CT scan of head to diagnose subarachnoid hemorrhage.  

Stroke is a condition for which the statement ‘Prevention is better than cure’ is perfect and holds good. It is said that attending to ‘four and four’ is key to the prevention of stroke. Four lifestyle factors which help in prevention are avoiding tobacco use (smoking or chewing), alcohol excess, taking balanced diet (low salt, high vegetable and fruit content) and maintaining adequate physical activity (minimum 30 minutes brisk walking for five days in a week). Four medical conditions to keep under control are high blood pressure, high blood sugar, high body fat (cholesterol or weight control) and heart diseases. If adequate attention is paid to the above four lifestyle factors and four medical conditions, risk of stroke can be mitigated to a great extent. Heart disease, particularly with irregular heartbeat may require a blood thinner to prevent stroke. Warning symptoms or mini stroke may require investigation for blood vessel narrowing at neck level and if present, appropriate treatment along with a blood thinner; and control of risk factors. Warning leaks may require angiography and appropriate treatment to prevent subarachnoid haemorrhage.