Unblocking Brain Arteries: How Carotid Surgery Prevents Strokes
What is Carotid Artery Disease?
One of the common causes of stroke or transient ischaemic attack (TIA) is the narrowing of the carotid artery, which supplies blood to the brain.
A carotid and vertebral artery carry blood to the brain on each side of the neck. Like the arteries to the heart or legs, the carotid artery can become narrowed (stenosis) or blocked with a build-up of fatty material (plaques). These plaques cause hardening of the arteries (atherosclerosis).
The common place for this to happen is where the carotid artery branches into two and becomes the internal carotid artery, which takes blood to the brain, and the external carotid artery, which takes blood to the face.
Plaques attract blood clots and can also burst (rupture), resulting in debris that can break off (emboli) and flow in the arteries into the brain. This debris can block the small arteries, resulting in reduced blood flow to that part of the brain. This phenomenon can cause a stroke or TIA.
What are the common Symptoms?
If you have had weakness or numbness on one side of an arm or leg, we look for narrowing in the opposite carotid artery. This is because the left part of the brain controls the right side of your body, and the right controls the left.
How is the diagnosis made?
An ultrasound (Duplex) scan is performed on your neck. This is a painless procedure, where a tiny probe covered in jelly is passed over the side of your neck to build up a picture of the arteries. We can then see if there is any narrowing (stenosis) of the artery. Sometimes, the Duplex scan may be repeated if the pictures are not clear.
A few patients may need further tests. A CT scan done with an injection of contrast (dye) into your vein will allow pictures of the neck
arteries to be taken. This involves lying on a table while the X-rays are taken. Some patients may need to have an Arch Angiogram. This usually involves a local anesthetic injection into the groin and the passage of a tube into the arteries below the neck. A contrast is injected, and pictures are taken to look at the narrowing of the arteries.
When is the Treatment Required?
Arteries with mild stenosis (less than 50 percent narrowing of the artery) usually do not need surgery.
Arteries with moderate stenosis (50-69 percent narrowing) and severe stenosis (greater than 70 percent narrowing) have a high risk of causing further TIA and stroke, and there are procedures to reduce this risk.
If the artery is blocked, there is no blood flow and no additional procedures to unblock this. The other arteries in the neck supply blood to the brain.
What is a Carotid Endarterectomy (Surgery of the carotid artery)?
This operation clears the narrowing in the carotid artery, and research has shown that if you have severe stenosis, surgery can halve the risk of stroke in the next five years. When the surgery has to be performed is dependent on the patient’s clinical condition.
The operation can be done either under local or general anesthetic. The vascular surgeon and anesthetist will decide this.
What are the Risks?
It is crucial to understand that the operation is being done to prevent further strokes or TIA, not to reverse the effects of a stroke that has already happened.
There is a small risk of stroke during and immediately after surgery (3 percent). This may be higher with early surgery, but early surgery prevents more strokes overall. Therefore, Carotid Endarterectomy is only recommended for people with significant narrowing of the artery (greater than 50 percent), where the risk of having another stroke if left alone is far greater than the risks with surgery.
This is complex surgery, not only because we are stopping the blood flow to the brain but also because there are essential nerves that lie close to the carotid artery. Permanent damage to these nerves is not common (2-3 percent), but there can be some temporary effects if the nerve is stretched while the artery is operated on. This can affect the voice (hoarse), the tongue (moves to the same side), the corner of the mouth (unable to pull down), or sometimes swallowing can be difficult. Many patients will experience some numbness around the wound and the earlobe. This is not serious, but men who shave need to take care.
Bruising in the neck is expected because of the surgery but gets better with time. Sometimes, blood collects inside the wound, which may cause the neck to swell. In some patients (5 percent), this may need to be removed in theatre as a second operation.
The wound is usually red and tender after surgery, but this will improve rapidly. Wound infection (ongoing redness and soreness) is uncommon but requires prompt treatment and assessment.
All major operations carry general risks, including a one to two percent risk of a heart attack.
Who will perform the surgery?
A Vascular Surgeon
What are the Alternatives?
Alternatives include medical treatment (tablets). This reduces your stroke risk, but surgery (along with the tablets) minimizes the risk much more.
Carotid artery stenting is another treatment modality. The safety and efficacy of stenting are under review.
How can I help myself?
It is important to maintain a healthy lifestyle => eat a healthy diet, avoid smoking, exercise, and have regular blood pressure checks to reduce the risk of narrowing in your arteries.
Dr.Karthikeyan Sivagnanam
M.B.B.S,M.S (General Surgery) ,DNB (Vascular & Endo Vascular Surgery)