Cerebrovascular Anastomosis

The goal of cerebrovascular anastomosis surgery is to revascularize or restore blood flow to the brain. The analog of a coronary bypass in the heart is a cerebral bypass in the brain. To reroute blood flow around a damaged or obstructed artery, surgery is performed to link a blood vessel from outside the brain to a vessel inside the brain. Bypass surgery aims to restore the brain's blood flow and fend against strokes.

 

What is Cerebrovascular Anastomosis?

The right and left carotid arteries, as well as the right and left vertebral arteries, are the four major arteries that supply blood to the brain with nutrients and oxygen. Blood flow problems make it harder for the brain to function. A shortage of blood flow causes transient ischemic attacks (TIA), strokes, and ultimately the death of brain cells, a condition known as cerebrovascular insufficiency. In a cerebrovascular anastomosis, the surgeon redirects blood flow around an obstructed or damaged artery to enhance or restore blood flow to an area of the brain that is oxygen-deprived (ischemic). Depending on the location of the blockage, the underlying ailment being treated, and the size of the brain area to be revascularized, a cerebrovascular anastomosis can be carried out in a variety of ways.

 

Cerebrovascular Anastomosis Types

There are two distinct bypass methods:

• The first form makes use of a vascular graft, which is a segment of an artery or vein taken from another part of the body. Blood flow is redirected (bypassed) through the graft due to connections made above and below the blocked artery. The saphenous vein in the leg and the radial or ulnar arteries in the arm are frequently used as grafts. Harvesting the graft requires a different incision. The graft is then tunneled under the skin in front of the ear to the scalp, with one end attached to the external carotid artery (ECA) in the neck. The graft is attached to a cerebral artery through a hole that is made in the skull. When a large (high-flow) artery is compromised or needs to be removed to treat a tumor or aneurysm, this procedure is frequently used.
• The alternative procedure uses a healthy donor artery that runs through the scalp or face rather than a vascular graft. An artery on the surface of the brain is linked to the donor artery after the donor artery is separated from its natural position at one end and redirected to the inside of the skull. The obstructed or damaged vessel is now addressed by using the scalp artery to supply blood to the brain. This method is typically used when a smaller (low-flow) artery has narrowed and is incapable of delivering enough blood to the brain.

The most common type of bypass is the STA-MCA (superficial temporal artery to middle cerebral artery) bypass. The superficial temporal artery (STA) normally provides blood to the face and scalp. You can feel the pulse of the STA in front of your ear. The middle cerebral artery (MCA) normally provides blood to the frontal, temporal and parietal lobes of the brain. Blood flow through the MCA is often reduced when narrowing of the internal carotid artery occurs. An STA-MCA bypass restores blood flow to the brain by rerouting the STA (donor’s vessel) from the scalp, passing through a hole in the skull, and joining the MCA (recipient’s vessel) above the obstruction. Another channel, like the occipital artery, may be used if the STA is insufficient or inappropriate.

To connect the vascular graft or scalp donor artery from the outside of the skull to the cerebral artery inside the skull, both kinds of bypass surgeries involve drilling a hole in the skull. This procedure is therefore also known as an extracranial-intracranial bypass (EC-IC bypass).

 

Cerebrovascular Anastomosis Indications

A cerebrovascular anastomosis may be appropriate for you if you have:

• An atherosclerotic plaque, tumor, or aneurysm that cannot be treated with endovascular surgery or other methods.
• Medications fail to treat stroke or TIA symptoms.
• Angiograms, CTAs, and MRAs that demonstrate artery stenosis or occlusion
• Studies on cerebral blood flow (such as CT perfusion, PET, and SPECT) suggest that artery stenosis is the root cause of insufficient brain blood flow

Cerebrovascular anastomosis may be beneficial in improving blood flow and lowering the risk of stroke in:

• Moyamoya disease. The internal carotid arteries near the base of the brain can narrow due to Moyamoya disease, which can result in numerous strokes or hemorrhages. The brain develops collateral blood vessels to provide oxygen-rich blood to areas of the brain that aren't receiving it to cover for the constricted arteries. A bypass can stop more strokes from occurring by restoring blood supply to the brain.
• Aneurysm. An aneurysm is an arterial wall bulging or ballooning. Surgical clipping or endovascular coiling cannot be used to treat all large, fusiform, or dissecting aneurysms. For the aneurysm to be successfully treated in such circumstances, the parent artery must be sacrificed and the blood flow must be bypassed.
• Skull base tumor. A tumor may develop and surround or infiltrate an artery where the major blood vessels enter the skull. It could be necessary to sacrifice the encased artery and stop the blood flow to remove the tumor.
• Carotid artery stenosis. A narrowing or obstruction of the carotid artery in the neck brought on by the buildup of atherosclerotic plaque in the vessel wall is known as carotid artery stenosis.
• Intracranial arterial stenosis. A constriction or obstruction of an artery inside the skull that delivers blood to various parts of the brain is known as intracranial arterial stenosis.

 

Who Performs Cerebrovascular Anastomosis?

A neurosurgeon performs a cerebrovascular anastomosis. Cerebrovascular surgery is a specialty area for many neurosurgeons. Inquire about your surgeon's training, particularly if your situation is complicated.

 

Cerebrovascular Anastomosis Preparation

Your doctor might request additional tests to help design the bypass operation, such as:

• Examination of suitable graft sites in the arms and legs using angiography or ultrasonography.
• Brain angiography to assess the occlusion and determine the optimum locations to connect the graft.
• By blocking one artery temporarily or permanently, the balloon test occlusion can determine whether doing so won't have a substantial impact on your brain's blood supply. A balloon is inserted into an artery using a catheter during an angiography. Your condition is evaluated when the balloon is temporarily inflated to block blood flow. Your foot flexion and extension, language, memory, and facial expression are all evaluated every few minutes for signs of impairment. If your collateral blood vessels are healthy, the other arteries will supply adequate blood to your brain to prevent any changes in how it functions. Usually, the balloon is left in position for 30 minutes before being deflated and taken away. Lack of collateral connections can result in inadequate blood flow to the brain, which might cause speaking difficulties or arm weakness. If this happens, the balloon is removed and deflated right away. Within a few seconds of being removed, blood flow is restored and the weakness disappears.

You will be given a surgery date if the results of the pre-surgical tests are positive. You will fill out papers to provide the surgeon with information about your medical history, including any allergies, medications, adverse reactions to anesthesia, and past surgeries, and sign consent forms in the doctor's office. Before surgery, you must undergo a thorough history and physical examination by your primary care physician or in the hospital's pre-admission testing office. Usually, an electrocardiogram (ECG), blood test, and chest X-ray are required. With your healthcare practitioner, go over every medicine you use, including prescription, over-the-counter, and herbal supplements. On the day of surgery, several drugs need to be stopped or continued.

One week before surgery, stop using all non-steroidal anti-inflammatory drugs. One week before surgery and two weeks following it, abstain from smoking, chewing tobacco, and consuming alcohol as these behaviors might lead to issues with bleeding. If you have a history of other medical or heart concerns, you might additionally require approval from your primary care doctor or cardiologist. The night before surgery, after midnight, no food or drink is allowed.

Before surgery, you could be instructed to wash your skin and hair with a good soap. Infections at surgical sites are decreased and microorganisms are killed. (Avoid getting CHG soap in the nose, genital area, eyes, or ears.) Before surgery, avoid eating or drinking after midnight (unless the hospital tells you otherwise).

 

The Surgery Day

• No candy, gum, or food is allowed. Take your prescribed medications with a little sip of water.
• Use antimicrobial soap while showering. Wear loose-fitting, recently washed clothing.
• Wear closed-back, flat-heeled footwear.
• Aspirin 325 mg should be taken to thin the blood.
• Remove any jewelry, nail polish, contacts, hairpins, makeup, and body piercings.
• All jewelry and valuables should be left at home.
• Bring a list of the medications you take, along with the recommended doses and times of the day.
• Bring a list of any drug or food allergies.

You have to reach the hospital early to finish the required paperwork and pre-procedure exams. Arrive two hours before your planned operation time. You will speak with an anesthesiologist who will go over the risks and effects of anesthesia. Both an arterial line and an intravenous (IV) line will be inserted into your arm.

 

Cerebrovascular Anastomosis Procedure

Depending on the kind of bypass operation used, several things happen during surgery. The commonly used STA-MCA bypass is described below. The operation, which has 8 steps, often takes three hours.

• Prepare the patient. On the operating table, you will be lying on your back while receiving an anesthetic. Once you're unconscious, your head is put in a 3-pin skull-fixation device that fixes to the table and holds your head in place while the surgery is performed. The scalp is cleaned with an antiseptic and the hair close to the incision is shaved.
• Make a skin incision. The superficial temporal artery (STA) is found and marked on the head with a pen by the surgeon using Doppler ultrasound. The artery is cut through the skin.
• Prepare the donor artery. Carefully separating an STA branch from the underlying muscle. The muscle is dissected and folded back to show the bone after the STA has been released.
• Perform a craniotomy. The skull is then drilled with tiny burr holes. The burr holes allow a unique, jigsaw-like saw to enter. A bone window's outline is cut by the surgeon. To reveal the dura, the brain's protective covering, the bone flap is raised and removed. To reveal the brain, the dura is folded back and opened.
• Prepare the recipient artery. Under a microscope, the surgeon carefully identifies a middle cerebral artery (MCA) branch that can be bypassed. The recipient vessel's size must be a suitable match with the donor vessel's diameter.
• Attach donor and recipient arteries. To stop the blood flow, temporary clips are put across the donor and recipient vessels. The distal STA is cut and the end is prepared for anastomosis. The doctor then produces an opening in the side of the MCA vessel and stitches the two blood vessels.
• Verify blood flow through the bypass. The surgeon removes the temporary clips once the vessels are linked and checks to make sure there are no leaks. A Doppler ultrasonography or specialized fluorescent dye is used to confirm that the anastomosis is working properly.
• Close the craniotomy. Sutures are used to shut the dura. The bone flap is restored, but a hole is made bigger to let the bypass vessel pass through without kinking or being under strain. With the help of titanium plates and screws, the bone flap is attached to the skull. Reattaching the muscles and skin requires sutures. The incision is covered with a dressing.

 

What Happens after Cerebrovascular Anastomosis?

The recovery area is where you'll awaken. Due to the breathing support tube used during surgery, you can experience a sore throat. The ventilator (breathing tube) typically stays in place until you have completely recovered from the anesthetic. You will be taken to the neurology unit for observation once you are awake. As part of the neurological examination, you will frequently be told to move your arms, fingers, toes, and legs. After surgery, nausea and headache are possible; these symptoms can be managed with medications. Patients are advised to get out of bed, take multiple daily walks, and eat and drink as they are able.

Every few hours, the nurse will use a Doppler ultrasound scan to monitor the pulse at the location of your incision to make sure the new blood vessel link between your arteries is functioning properly. At some point after surgery, a CT scan will be done to ensure there have been no issues (especially postoperative bleeding). You'll be discharged from the hospital and given discharge instructions in one to two days. For the first 24 to 48 hours, make sure you have assistance at home. For two weeks following surgery or up until your follow-up visit, adhere to the surgeon's home care instructions. Typically, you can anticipate:

Restrictions

• Never lift anything more than five pounds.
• No laborious activities, such as housework, yard work, or sexual activity.
• Avoid consuming alcohol. Blood thinning and bleeding risk are both increased. Additionally, avoid combining alcohol and painkillers.
• Avoid using nicotine-containing vape, dip, or chew products. It might delay healing.
• Drive, go back to work, or take a flight only after your surgeon gives the all-clear.

Wound Care

• The day following surgery, you are allowed to take a shower and wash your hair with baby shampoo. Every day, gently cleanse the incision site with soap and water. Avoid scrubbing or letting the water hit your incision aggressively. Clean off.
• Do not pick or rub at the skin glue if it covers your incision.
• Avoid immersing or soaking the incision in a tub, bath, or pool. Avoid using any lotion or ointment, including hair styling products, on the incision.
• Your head may make odd noises (popping, crackling, or ringing). This is typical healing as the fluid and air are reabsorbed.
• Wait six weeks before coloring your hair. When cutting your hair, be careful around the incision.

Medications

• Following surgery, headaches are typical. Take acetaminophen if necessary.
• As advised by your surgeon, take your pain medications. As your discomfort lessens, cut back on the quantity and frequency. Don't take the painkiller if you don't need it.
• Constipation can result from narcotics. Consume foods high in fiber and drink plenty of water. Laxatives and stool softeners can aid with bowel movement. Over-the-counter medications include Colace and Senokot.
• Drugs to prevent seizures may be prescribed. Some people experience adverse reactions including sleepiness, balance issues, or rashes. If any of these take place, contact your doctor.

Activity

• Every 3 to 4 hours, get up and take a 5- to 10-minute walk. As you are able, gradually increase your walking.
• Eye or facial bruising and swelling could happen. It won't go away for a few weeks.
• To lessen pain and swelling, elevate your head at night and apply ice 3–4 times daily for 15-20 minutes.

 

Cerebrovascular Anastomosis Recovery

Ten to fourteen days following surgery, you will have a visit with a nurse practitioner to have your sutures removed and have your recovery status checked before you leave the hospital. You can make plans with your primary care physician to have your stitches removed there if you don't live close by.

Your neurosurgeon will schedule a follow-up visit for 2 to 4 weeks following surgery. 3 to 6 months after surgery, follow-up imaging studies are typically planned to ensure that the bypass graft and arteries are receiving enough blood flow.

When using eyeglasses, caution is needed. If the glasses fit too firmly over your ears in the temple region, there is a chance of injuring the graft. To soften the space between your wound and your glasses, use gauze.

Patients undergoing cerebrovascular anastomosis surgery will regularly take an antiplatelet drug (such as aspirin). Anti-platelets thin the blood, allowing better blood flow and avoiding the formation of clots in the bypass graft. Coated aspirin should be taken with meals if a patient has stomach issues. Doctors advise cerebrovascular anastomosis patients not to use birth control since they raise their risk of blood clot issues.

 

Cerebrovascular Anastomosis Risks

Risks are inherent in all surgeries. Any surgery might have general complications, such as bleeding, infection, blood clots, and anesthesia-related side effects. Following are some possible issues specific to cerebrovascular anastomosis:

• Stroke. The manipulation and a brief closure of the arteries in the brain can result in a stroke. It can also happen as a result of graft failure or inadequate blood flow through the newly linked arteries.
• Seizures. Any brain operation carries the risk of seizures. Following your procedure, you will be prescribed anti-seizure medication for several days. A potential but uncommon condition called hyper-perfusion damage can also result in seizures. An increase in blood flow to parts of the brain that were previously receiving relatively little might cause swelling and bleeding in the brain. Headache, pain in the face or eyes, or other neurological impairments are signs of hyper-perfusion damage.
• Graft occlusion. Blood clots that grow inside the donor’s vessel and stop the blood flow cause graft occlusion. Because blood flow measurements are taken at the time of surgery to ensure graft patency, this is uncommon.

 

Cerebrovascular Anastomosis Results

Restoring blood supply to the brain and lowering the risk of stroke are the basic goals of cerebrovascular anastomosis surgery. The type of graft utilized and the underlying condition being addressed both affect how well a bypass works.

According to research, cerebrovascular anastomosis for Moyamoya disease increases blood flow to low-perfused parts of the brain, reducing the risk of an ischemic stroke. Current research is examining how well bypass works to prevent hemorrhagic stroke. Since the tiny, delicate moyamoya veins that were once required to perfuse the brain are no longer present, some believe that the danger of hemorrhage may be reduced. However, only 25-65% of individuals have a reduction in moyamoya vessels.

The outcomes of cerebrovascular anastomosis surgery for aneurysms and tumors depend greatly on the location of the lesion and the type of bypass graft. Consult your surgeon about the possible results.

It is debatable if cerebrovascular anastomosis surgery works to reduce the risk of ischemic stroke in cases with carotid artery stenosis. Several clinical trials have looked at the function of cerebrovascular anastomosis surgery for atherosclerotic carotid artery stenosis, but none of them have been able to prove that it is superior to standard medical care. However, cerebrovascular anastomosis surgery may be a possibility for some stroke patients who have hemodynamic ischemia, inadequate collateral circulation, and a significant risk of recurrent stroke.

Although carotid artery or cerebrovascular illness is not cured by cerebrovascular anastomosis, it does increase the blood supply to the brain. Your outcomes and long-term success will partly depend on taking your medications as prescribed and leading a healthy lifestyle, which includes quitting smoking, eating well, lowering your cholesterol, maintaining a healthy weight, managing your blood pressure, managing your diabetes, and exercising.

 

Conclusion

When conducted to treat an ischemic cerebrovascular disorder of the carotid or middle cerebral arteries, which includes the treatment or prevention of strokes, cerebrovascular anastomosis surgery is not a covered procedure. No evidence has been provided to support the claim that this treatment, which skips narrowed artery segments, increases the blood flow to the brain and lowers the chance of suffering a stroke. Therefore, when cerebrovascular anastomosis surgery is carried out to treat the ischemic cerebrovascular disease of the carotid or middle cerebral arteries, it is not regarded as reasonable and required within the meaning of the Act.