Arteriovenous Malformations (AVM)
EMBOLIZATION OF VASCULAR LESIONS
There re many abnormalities of the blood vessels that affect the brain, head, neck, and spine. These include arteriovenous malformations (abnormal vessels forming a connection between the arteries and veins of the brain, spinal cord, or surrounding structures), dural arteriovenous fistulas (direct connections between the arteries and one of the large draining veins contained in the covering of the brain, without any abnormal vessels in between), traumatic vascular lesions (holes in vessels with bleeding or an expanding clot, fistulas between the arteries and veins of the head and neck, or tears in the lining of the vessels), carotid-cavernous fistulas (direct connections between the carotid artery and a surrounding vein [cavernous sinus] behind the eye), spinal vascular malformations (abnormal vessels forming abnormal connections between the arteries and veins of the spinal cord, its coverings, the bones or the spine, and/or the surrounding structures), and extracranial vascular malformations (abnormal vessels forming abnormal connections between the arteries and veins of the structures of the head and neck). These lesions can be very difficult to treat. When surgery is planned, a catheter can be placed into an artery (usually in the leg, similar to an angiogram of the heart) and a smaller catheter is then threaded through to the artery or arteries supplying the lesion. Material is then injected to block off the blood supply to the lesion; this is called embolization. There are many different materials available, depending on the location and size of the vessels to be blocked off. Sometimes, embolization is performed before radiation therapy for an arteriovenous malformation. In other instances, surgery is not possible and embolization is performed to cure the lesion. In these cases, a catheter may also be placed into the veins draining the lesion for embolization of the veins. In the case of carotid-cavernous fistulas, traumatic arteriovenous fistulas, and certain holes in the walls of major vessels, material may be injected to try to plug the hole or the fistula. Occasionally, a stent (a metal tube designed to hold a vessel open) may be used as well. In some cases, it may be necessary to block a major artery (such as a carotid artery) to treat the problem. If this is necessary, a small balloon attached to a catheter is placed in the vessel and blown up to stop the blood flow temporarily (test occlusion). The patient is examined constantly to see if they tolerate this or develop any symptoms (such as those of a stroke).
It there are no symptoms, the artery is blocked by injection of material (permanent occlusion). Depending on the circumstances, the patient may be able to go home the next day or may be kept for observation.
Figure 1: AP angiograms demonstrate a large arteriovenous malformation of the left parietal region. The film on the left demonstrates the feeding arteries from the middle cerebral artery system with a large draining vein medially to the sagittal sinus. The film on the right demonstrates several large feeding vessels from the posterior cerebral artery on the left side.
Figure 2: The AVM of the patient shown in Figure 1 after endovascular embolization using N-butyl-cyanoacryalate glue for part of the AVM. As can be seen, the AP angiogram on the carotid circulation (left) shows a greatly diminished arterial to venous shunt.
As well, the film of the right demonstrates decreased filling from the posterior cerebral supply to the AVM.
Figure 3: AP angiograms following surgical resection of the large AVM of the patient shown in Figures 1 and 2. Preoperative embolization made the operation safer with a minimum of blood loss at the time of operation. As can be seen on the carotid injection (left film), there is no arterial to venous shunting. The vertebral injection (right film) shows no AV shunting. The patient made an excellent recovery from surgery with no neurologic deficits.
Treatment of Brain Aneurysms
A brain aneurysm, also called a cerebral or intracranial aneurysm, is an abnormal bulging outward of one of the arteries in the brain. It is estimated that up to one in 15 people in the United States will develop a
brain aneurysm during their lifetime.
Brain aneurysms are often discovered when they rupture, causing a subarachnoid hemorrhage, or bleeding into the brain and the space closely surrounding the brain called the subarachnoid space. Subarachnoid hemorrhage from a ruptured brain aneurysm can lead to a hemorrhagic stroke, brain damage, and death.
The main goals of treatment once an aneurysm has ruptured are to stop the bleeding, to prevent potential permanent damage to the brain, and to reduce the risk of recurrence. Unruptured brain aneurysms are sometimes treated to prevent rupture.
Surgery or minimally-invasive endovascular coiling techniques can be used in the treatment of brain aneurysms. It is important to note, however, that not all aneurysms are treated at the time of diagnosis or are amendable by either forms of treatment. Patients need to consult a neurovascular specialist to determine if they are candidates for either treatment.
Diagnosis of Brain Aneurysms
Diagnosis of a ruptured cerebral aneurysm is commonly made by finding signs of subarachnoid hemorrhage on a CT scan. The CT scan is a computerized test that rapidly X-rays the body in cross-sections as the body is moved through a large, circular machine. If the CT scan is negative but a ruptured aneurysm is still suspected, a lumbar puncture is performed to detect blood in the cerebrospinal fluid that surrounds the brain and the spinal cord.
To determine the exact size and shape of an aneurysm (ruptured or unruptured), neuroradiologists use either cerebral angiography or tomographic angiography.
Cerebral angiography, the traditional method, involves introducing a catheter (small plastic tube) into an artery, usually in the leg, and steering it through the blood vessels of the body to the artery involved with the aneurysm. A special dye, called a contrast agent, is injected into the patient’s artery, and its distribution is shown on X-ray projections. This method may not detect some aneurysms due to overlapping structures or spasm.
Computed Tomographic Angiography (CTA) is an alternative to the traditional method and can be performed without the need for arterial catheterization. This test combines a regular CT scan with a contrast dye injected into a vein. Once the dye is injected into a vein, it travels to the brain arteries, and images are created using a CT scan. These images show exactly how blood flows into the brain arteries.
Minimally-Invasive TreatmentCoil Embolization or Endovascular Coiling
Endovascular therapy is a minimally invasive procedure that accesses the treatment area from within the blood vessel. In the case of aneurysms, this treatment is called coil embolization, or “coiling”. In contrast to surgery, endovascular coiling does not require open surgery. Instead, physicians use real-time X-ray technology, called fluoroscopic imaging, to visualize the patient’s vascular system and treat the disease from inside the blood vessel.
Endovascular treatment of brain aneurysms involves insertion of a catheter (small plastic tube) into the femoral artery in the patient’s leg and navigating it through the vascular system, into the head and then into the aneurysm. Tiny platinum coils are threaded through the catheter and deployed into the aneurysm, blocking blood flow into the aneurysm and preventing rupture. The coils are made of platinum so that they are visible via X-ray and flexible enough to conform to the aneurysm shape. This endovascular coiling, or filling, of the aneurysm is called embolization and can be performed under general anesthesia or light sedation. More than 125,000 patients worldwide have been treated with detachable platinum coils.
To get to the aneurysm, surgeons must first remove a section of the skull, a procedure commonly known as a craniotomy. The surgeon then spreads the brain tissue apart and places a tiny metal clip across the neck of the vessel to stop blood flow into the aneurysm. After clipping the aneurysm, the bone is secured in its original place, and the wound is closed.
Endovascular Coiling v. Surgical Clipping
Treatment of Ruptured Aneurysms
Until recently, most of the studies regarding surgical clipping and endovascular treatment of brain aneurysms were either small-scale studies or were retrospective studies that relied on analyzing historical case records. The only multi-center prospective randomized clinical trial – considered the gold-standard in study design – comparing surgical clipping and endovascular coiling of ruptured aneurysm is the International Subarachnoid Aneurysm Trial (ISAT).
The study found that, in patients equally suited for both treatment options, endovascular coiling treatment produces substantially better patient outcomes than surgery in terms of survival free of disability at one year. The relative risk of death or significant disability at one year for patients treated with coils was 22.6 percent lower than in surgically-treated patients.
The study results were so compelling that the trial was halted early after enrolling 2,143 of the planned 2,500 patients because the trial steering committee determined it was no longer ethical to randomize patients to be treated with neurosurgical clipping. However, long-term follow-up will be essential to assess the durability of the substantial early advantage of endovascular coiling over conventional neurosurgical clipping for the treatment of brain aneurysms. It is important to note that patients enrolled in the ISAT were evaluated by both a neurosurgeon as well as an endovascular coiling specialist, and both physicians had to collaborate and agree that the aneurysm was treatable by either technique. This study provides compelling evidence that, if medically possible, all patients with ruptured brain aneurysms should receive an endovascular consultation as part of the protocol for the treatment of brain aneurysms.
Treatment of Unruptured Aneurysms
Although no multi-center randomized clinical trial comparing endovascular coiling and surgical treatment of unruptured aneurysms has yet been conducted, retrospective analysis has found that endovascular coiling is associated with less risk of negative outcomes, shorter hospital stays and shorter recovery times compared with surgery.
Studies have shown that:
Carotid Stenting – Extracranial (Brachiocephalic) Angioplasty
EXTRACRANIAL (BRACHIOCEPHALIC) ANGIOPLASTY
Extracranial (brachiocephalic) atherosclerosis is a hardening of the arteries that supply blood to the head and neck (carotid and vertebral arteries), thus causing narrowing and eventually blockage of these vessels. Atherosclerosis of the carotid arteries often cause transient ischemic attacks (TIAs or ministrokes) because pieces of the material that forms the blockage (plaque) and blood clots that form on the plaque break off and are carried into the head where they can block vessels supplying blood the brain. If the blockage produced by this material is small and breaks up quickly, a TIA occurs. If there is blockage of a larger vessel or the blockage doesn’t break up right away, a stroke results. Blockage of the vertebral arteries usually causes symptoms because of decreased blood flow to part of the brain, not because of pieces of plaque and clot breaking off. The symptoms of blockage of these vessels may get better and worse, or they may suddenly appear if a stroke occurs.
Extracranial atherosclerosis should be treated when it is found. If there are reasons why medical therapy or surgery is not recommended (such as a severe narrowing (especially in a location that cannot be safely reached by the surgeon), poor health, or previous radiation therapy to the neck), angioplasty and possibly stenting may be recommended. A catheter is placed into an artery (usually in the leg, similar to an angiogram of the heart) and threaded up to the vessel with the blockage. A small catheter with a balloon on the tip is inserted at the site of the blockage and inflated to open the vessel; occasionally a stent (a metal tube designed to keep the vessel open) is placed. Blood thinners are given during the procedure and for a short time after to prevent blood clots as it starts to heal. Patients can usually go home later the same day or the next day.
Carotid angioplasty with stenting (CAS):
What to expect:
Carotid Angioplasty and Stenting – before and after angiography
Intracranial Angioplasty for Stroke Prevention
Blockages in blood vessels in the head (intracranial) are usually caused by hardening of the arteries (atherosclerosis); treatment with medicines is not as effective in keeping the vessel open as it is elsewhere in the body. If the blockage gets too severe, not enough blood will get to that part of the brain, and a stroke may occur. Intracranial angioplasty is a method of opening narrowed or blocked blood vessels (arteries) in the head to increase blood flow and decrease the chance of a stroke. A catheter is placed into an artery (usually in the leg, similar to an angiogram of the heart) and threaded up to the vessel with the blockage. A very small catheter with a balloon on the tip is put across the blockage and inflated to open the vessel; sometimes a stent (a metal tube designed to keep the vessel open) is placed. Blood thinners are given during the procedure and for a short time after to keep the vessel open as it starts to heal. Patients can usually go home the next day.
Figure 4. This is a 63-year-old man who experienced vertebrobasilar TIAs despite therapeutic doses of warfarin. (A) The lateral projection of the right vertebral artery injection of the angiogram revealed a severe proximal basilar artery stenosis (arrow). Imaging (B) immediately after angioplasty revealed a small intimal tear which was (C) healed at 3 months with minimal residual stenosis.
Figure 5. This 44-year-old man presented with persistent severe vertebrobasilar TIAs with gait unsteadiness, blackout spells, and visual disturbances despite oral anticoagulation. The cerebral angiogram revealed a high-grade left vertebral artery stenosis (arrows, A and B) with (C) the right-sided vertebral artery ending in PICA and no visible posterior communicating arteries. He underwent angioplasty of the left vertebral artery stenosis (arrow, E) and a right-sided OA (arrow) to (D) PICA revascularization procedure. His vertebrobasilar TIAs resolved. TIAs, transient ischemic attacks; PICA, posterior inferior cerebellar artery; OA, occipital artery.
Treatment of Vasospasm after Aneurysm Bleeding
Vasospasm (narrowing) of the vessels that supply the brain can occur after a bleed from an aneurysm in the head (subarachnoid hemorrhage). The spasm can be severe enough to prevent enough blood from reaching the brain, causing a stroke. This is usually initially treated by medical therapy, including giving medication to increase the blood pressure and giving intravenous fluids. If this does not work, then other treatments can be used. A catheter is placed into an artery (usually in the leg, similar to an angiogram of the heart) and threaded up the artery or arteries that are affected. Medication can be injected through the catheter to dilate the arteries. A tiny catheter with a soft balloon on the tip can be threaded through the catheter and gently inflated to stretch the narrow spots in the arteries (angioplasty). More than one artery may need to be treated and, in severe cases, the procedure may need to be repeated.
Angiograms are performed by interventional radiologists (IR). Angiography is an X-ray exam of the arteries and veins to diagnose blockages and other blood vessel problems. A cerebral angiogram is an X-ray of the blood vessels in your brain.
During an angiogram, the doctor inserts a thin tube (catheter) into the artery through a small nick in the skin (usually femoral artery) about the size of the tip of a pencil. A substance called a contrast agent (X-ray dye) is injected to make the blood vessels visible on the X-ray. You do not feel the catheter going through your body; you may feel a flushing sensation as the dye is injected, this will only last a few seconds.
Your browser may not support display of this image.You will be asked to lie very still while your doctor gets the pictures he needs. At times you will be asked to hold your breath while a picture is being taken; this does not last longer than a few seconds.
Your doctor can treat a blocked blood vessel or a bulge (aneurysm) without surgery; this will be scheduled for another time as you may receive’ general anesthesia to ensure you do not move during this procedure. Techniques called angioplasty (balloon catheter), stent (a metal tube placed in the blocked area), and thrombolysis (clot-busting medication), and many more are all tools your doctor has for treatment. If this is the case you will be admitted over night to the ICU for observation.
Preparation for your angiogram:
It is very important that you bring a complete list of your medications with you each time you go to the hospital or doctor’s office. You will be asked to have nothing to eat or drink from 12 midnight the night before your angiogram. Your doctor’s office will instruct you on your medications before your angiogram. It is VERY important to let them know if you are taking Coumadin/Warfarin (or any other blood thinners) and to receive special instructions regarding these medications. You will be asked to arrive one or one-and-a-half hours before your procedure depending on the facility.
You will be asked if you are allergic to any medications of foods; it is important that you tell your doctor if you are allergic to anything.
You must have someone drive you home as it is not safe to drive after receiving medication that helps you relax. You will be asked to rest after discharge with heavy lifting or driving for 24 hours. You will be asked to increase your fluid intake (water is best) to help flush the dye from your system. A Band-Aid will be placed on your groin which you should remove after 24 hours. Your doctor will tell you when you can return to work.
As we are accessing an artery there is a chance of bleeding from the artery. You may have some bruising around the insertion site. This is not uncommon, if you have a large amount of bruising or a hard area (blood collection under the skin, hematoma) you need to contact you doctor or seek immediate medical attention. While the risk of stroke is low (.5%), it is not zero. Infection, while uncommon, can occur; you should inform your doctor if you show any signs of infection.
It is important that you return to our office for your follow up appointment so we can check your groin (area of catheter insertion) and answer any questions you may have. It is always a good idea to write down your questions so you won’t forget and to have another person come with you to your visit.