In some patients, early identification and treatment of an ongoing stroke is possible, and the reestablishment of blood supply to the affected brain can improve the outlook for the patient.
STROKE is a medical emergency. Whilst heart attacks are frequently dramatic and obvious, strokes may be silent or present subtly. The signs and symptoms of stroke vary depending on the location, the extent of damage, and the cause of the disorder. When a person presents with the symptoms associated with a stroke, it is advisable to rush him or her to the nearest hospital as soon as possible. Time is critical. Every second counts.
When someone presents with suspicion of stroke, an urgent CT (computer tomography) scan or MRI (magnetic resonance imaging) is routinely performed to establish the nature and categorise the stroke, ie, ischaemic (blockage to a blood vessel supplying parts of the brain) or haemorrhagic (bleeding) type. A MR angiogram, if available, will further determine if there is any significant major arterial branch narrowing/blockage inside and outside the brain. A colour Doppler ultrasound and Transcranial Doppler (TCD) are other feasible options in certain centres.
If the studies show an ischaemic stroke, the patient is placed on medical treatment. This involves anti-thrombotic therapy (treatment aimed at preventing the formation or growth of a clot), which is the mainstay of treatment.
Many anti-platelet agents can be prescribed, ie, aspirin, ticlid, or clopriglorel to prevent or to cut down the risk and progression of stroke. Concurrent management of vascular risk factors such as high blood pressure, diabetes, high cholesterol and so on as well as stroke rehabilitation and physiotherapy are also necessary.
In certain centres, and in a suitable patient, the physician or neurologist may advise using a clot buster to reverse the stroke. This is called thrombolysis. A special drug, ie, rTPA, is administrated through a vein to unclog the blockage. This is a very expensive drug and carries definite risks of major complications. Thrombolysis can only be performed in the absence of bleeding. IV infusion can only be done if the stroke is less than three hours (from the onset of symptoms) old.
There are many stringent criteria for the selection of patients undergoing this treatment. You are advised to consult your doctors with regard to the nature and risks of the treatment. In general, there is a significant risk of a secondary bleed (30%) into the stroke area and this may be life-threatening.
If a major arterial branch is blocked, and the patient presents within three to six hours after a stroke, the clot buster may be administrated through a tiny tube (catheter) placed directly into the obstructed brain artery (intra-arterial thrombolysis).
This is an invasive procedure and carries a definite risk. Similarly, it has stringent selection criteria, and may not be suitable for all patients. Its availability is also extremely limited as it requires a highly trained interventional radiologist and a properly equipped interventional laboratory to perform the treatment. You are advised to consult your doctor prior to the treatment.
Apart from thrombolysis using a clot buster, are there any other options in stroke salvage? Generally, when an occlusion or narrowing of the brain artery is detected, there are a few options available:
The treatments are aimed at reopening the occlusion and reversing the ischaemic salvageable areas. A favourable prognosis is associated with early reestablishment of flow to the affected brain.
Balloon angioplasty and stenting
Narrowing of the brain arteries is commonly encountered in stroke victims. About 30% of our patients are detected to have this condition, called intracranial atherosclerotic stenosis. There is also a possibility of stroke from narrowed neck arteries (carotid arteries).
The incidence of carotid artery narrowing is far less common in the Asian population compared to Caucasians. Whilst both these intra and extra-cranial arterial narrowings can be addressed with balloon dilatation (angioplasty) and stenting (a wire mesh tube is placed in a damaged artery to support the arterial walls and keep them open), the procedure is only reserved for patients with significant narrowing (more than 70%).
The intracranial stenting is only performed in patients who have failed maximal medical therapy, ie, those who come back with recurrent transient ischaemic attacks (TIA) or stroke despite optimal anti-platelet therapy and management of risk factors.
In the procedure, a tiny tube (catheter) is inserted through the groin artery. This is guided by a wire and is brought up into the narrowed neck or brain arteries under the control of a dedicated screening machine, ie, a digital subtraction angiography system.
A tiny metal scaffolding device or tube (stent) is then inserted across the narrowing to keep the artery open. This will reestablish blood circulation to the affected brain, preventing further damage and salvaging the remaining viable neurons.
A special protection system (filter device) may be used in stenting of the carotid arteries to prevent dislodged plaques or debris from floating into the brain.
After stenting, the patient is required to be on anti-platelet medication for life and must have optimal control of compounding risk factors such as high blood pressure, high cholesterol and diabetes.
This technique has been proven to be highly effective in salvaging patients with stroke in progression or those with a large area of ischaemic brain, as well as reducing the risk of another stroke from 17% to 3.5% per treated arterial territory.
Whilst the clinical result is frequently encouraging in improving the outcome, converting a disabling stroke to a better neurological status, there is also a small risk (10%) of deterioration of the stroke or death during the procedure.
This procedure is only carried out if the benefits outweigh the risks. In general, the neurological improvement is very encouraging and the majority of patients have a good outcome if the stenting is successfully performed.
The procedure’s success rate is in the range of 85%. This is because in some patients, the arteries are too tortuous and windy to allow the inserting of a balloon and stent into the brain. This is the major prohibiting factor in the development of intracranial stenting compared with coronary (heart) intervention.
New dedicated neuro stents are still works in progress and are expected to be commercially available in a couple of years.
In essence, strokes are preventable and are potentially salvageable if they are detected early and treated promptly.
Routine screening for neck and brain artery narrowing is beneficial for those with high vascular risks and with strong family history.
Both thrombolysis and stenting are effective in treating strokes in properly selected patients. The treatments are aimed at reopening the occlusion and reversing the ischaemic salvageable areas of the brain adjacent to irreversible infarction (death of tissue).
A favourable prognosis is associated with early reestablishment of flow to the affected brain.
Note: Dr Alex Tang is a consultant vascular and interventional radiologist. He’s a council member of the College of Radiology, Academy of Medicine of Malaysia. For more information on stroke, visit www.radiologymalaysia.org. This information is for educational and communication purposes only and 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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