What is a stroke and how is it treated? (Part 2)Sunday, May 16, 2021
Dr Ernest Madu & Dr Paul Edwards
A few weeks ago, we looked at stroke and how it presents. This week we will review the diagnosis and management of strokes.
Like heart attacks, the treatment of stroke has undergone much change over the past decades. Currently, there is emphasis on rapid recognition of symptoms and going to the emergency room when a stroke is suspected. For some types of strokes, it is possible to give treatment that can improve symptoms and reduce disability.
As we had discussed previously strokes are divided into ischemic strokes in which blood vessels to the brain become obstructed and haemorrhagic strokes in which there is bleeding into brain tissue. Both processes result in death of brain tissue with loss of function of the area of the brain that has died. Like the situation in heart attacks, an ischemic stroke offers the possibility for saving brain tissue if the area of blockage can be opened. This possibility is time dependent, the longer the vessel is obstructed the more tissue that is supplied by the vessel dies until the total area is dead. A haemorrhagic stroke (bleeding in the brain) in a patient who is otherwise stable does not offer the same possibility to save brain tissue and is treated differently.
The initial test that is performed in a patient who presents with a stroke is a plain CT scan of the brain. It is interesting to note that the primary reason to do the CT scan is not to see the changes in the area of the stroke as these changes can take hours to be evident on CT scanning. The point of the scan is to exclude bleeding in the brain or any other abnormality that may result in stroke symptoms such as tumor, etc. Once bleeding and other causes are excluded with a normal or negative CT scan, the patient is diagnosed as ischemic stroke and the patient can be evaluated for treatment to potentially save brain tissue. The aim should be to perform a CT scan quickly, in the United States the American Heart Association recommends a target of within 25 minutes of emergency room arrival and interpretation within 45 minutes.
Magnetic resonance imaging (MRI) can diagnose strokes with greater accuracy and changes suggestive of ischemic stroke are noted at a higher frequency and earlier when compared to a CT scan of the brain. It is generally not as easily available as CT scanning and requires more preparation and takes longer to perform. It is therefore not as useful in the early management of stroke. Other tests that are performed routinely in stroke patients include testing for diabetes and cholesterol abnormalities, ultrasound evaluation of the vessels in the neck to look for cholesterol deposition and ultrasound evaluation of the heart to look for any cardiac reasons for stroke.
As noted previously, in ischemic strokes there is the potential to save brain tissue and thus prevent or limit disability. Success in doing this is very time dependent. An important part of stroke treatment is community awareness of stroke symptoms and the need to be quickly taken to an emergency room for treatment.
In more developed countries, most big cities have stroke centres where potential stroke patients are preferentially taken. These stroke centres have systems to ensure the rapid evaluation and testing of patients and have the ability to offer modalities to open obstructed blood vessels in the brain. In our health care context, this may not be easily achieved but this is certainly a goal to which we should aim. In contrast to patients who are having chest pain suggestive of a heart attack, we do not recommend that patients take aspirin at home for stroke symptoms as bleeding in the brain has not yet been excluded.
On arrival in the emergency room, ideally the patient will be evaluated within minutes and a CT scan ordered and performed. If there is no evidence of bleeding on a CT scan, the patient has symptoms that suggest a clinically significant stroke and the patient is within four hours of the start of symptoms consideration can be given to thrombolytic therapy. This is a drug (Alteplase) which is given intravenously to break up clots in the vessels of the brain. Studies have shown that early administration of this drug can reduce the size of the stroke and reduce the amount of disability after a stroke. The drug does have the uncommon side effect of bleeding and patients must be selected carefully prior to administration. Aside from giving drugs to open clotted vessels, some centres can perform angiography (assessment of the blood flow to the brain) and then use small balloons to open occluded vessels. This is an invasive procedure which requires trained personnel and special machines. This can be performed in patients who have not responded to thrombolytic therapy or it can be done as the initial management. Success with this procedure has been demonstrated in patients who have delayed presentation to the hospital.
For the patient who has had a bleed in the brain, they are initially treated conservatively unless they have large areas of bleeding that are compromising brain function, that is, compressing healthy tissue. In this scenario, emergency surgery can be performed to evacuate the blood but this is done relatively rarely. Depending on the location and type of bleeding, studies may be done to look for aneurysm of the blood vessels in the brain. These aneurysms are enlarged sections of blood vessels with weak walls which are prone to rupture. Often, these can be treated either surgically or by invasive procedures and prevent future stroke. Aside from addressing the stroke itself, treatment in hospital is geared towards trying to prevent extension of the area of stroke, to identifying and treating underlying causes.
An important component of hospital stroke care is the initiation of rehabilitation. Many patients who present with deficits secondary to stroke will have improvement over time. In some patients this can be significant and nearly complete. Physical and occupational therapy are important in maximising functional recovery after a stroke. In patients in whom speech and language are affected speech therapy can also be useful. In many patients these therapies continue at specialist rehabilitation institutes or as an outpatient from home.
After Stroke Prevention
Once a patient has had a stroke it become extremely important to try to prevent recurrence. For ischemic strokes both aspirin and statin (cholesterol drug therapy) have been shown to reduce the chance of a second stroke. Hypertension and diabetes should be treated if present, and the patient should be encouraged to exercise. If an aneurysm in the brain is the cause of bleeding, this can often be treated surgically or through special procedures again reducing the chance of a second stroke. If underlying causes are found, for example, irregular heart rhythm, clotting in the heart, significant obstruction to blood flow in the vessels of the neck, abnormalities of the blood that promote clotting, these should be addressed. A patient that has had a stroke is often at risk for cardiovascular disease and disease in other blood vessels so that the measures that we suggest for heart health and a healthy lifestyle should be followed.
Dr Ernest Madu, MD, FACC and Dr Paul Edwards, MD, FACC are Consultant Cardiologists at Heart Institute of the Caribbean (HIC) and HIC Heart Hospital. Correspondence to email@example.com or call 876-906-2107
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