AVM vs. AVF | Arteriovenous Malformations & Arteriovenous Fistualas
What is an AVM?
Arteriovenous malformation (AVM) is an abnormal connection between arteries and veins which can involve the brain or spine. AVMs usually occur prior to birth or early childhood, and slowly develop over time. AVMs occur in less than 1% of the population. A cause is unknown.
What are symptoms of an AVM?
An AVM may not cause signs or symptoms until it ruptures, resulting in bleeding in the brain or spine. However, about half of patients with AVMs do have symptoms prior to a rupture. Those symptoms may include:
- A whooshing/ buzzing noise in your ear (pulsatile tinnitus).
- Headache – may be in one area or the entire head.
- Weakness or numbness that gets progressively worse. You may have difficult walking.
- Visual symptoms – including blurred vision, double vision or decreased vision.
Symptoms when bleeding occurs are those similar to a stroke:
- Sudden severe headache
- Weakness, numbness, unsteadiness or paralysis
- Vision loss
- Difficulty speaking or the inability to understand what others are telling you.
How is an AVM diagnosed?
A complete physical and neurological exam is needed. Diagnostic tests may include:
- Cerebral Angiogram
- Magnetic Resonance Imaging./ Angiography (MRI or MRA)
- Head CT scan
How is an AVM treated?
Treatment options are determined by size, location, age and medical history of the patient. Imaging and medical history is reviewed prior to scheduling a consultation. This will help determine if further imaging or testing is required to determine your best treatment options.
There are several ways in which AVMs are treated. Some treatments are used together.
This procedure is completed similar to an angiogram. General anesthesia is required for this procedure. A thin tube (catheter) is placed in the femoral artery (groin area) through a small nick in the skin about the size of the tip of a pencil. The catheter is guided to the area to be studied. A dye (contrast) is then injected into the catheter while taking x-rays of the area. The contrast makes the AVM visible on the x-ray.
Once the AVM has been identified, a glue-like substance is injected into the abnormal blood vessels to stop the blood flow to the AVM. This reduces the chance of the AVM bleeding.
This is often the first choice of treatment for AVMs or is used in conjunction with a surgical procedure.
Surgical treatment is preformed by a Neurosurgeon. A section of the skull is removed to gain access to the AVM. The Neurosurgeon seals off the AVM with special clips and carefully removes it. The skull bone is reattached and the scalp is closed with stitches.
Endovascular embolization and surgical removal are often used together to treat AVM’s.
This treatment uses focused beams of radiation to destroy the AVM. The radiation causes the blood vessels to slowly clot off. This usually occurs over months and often years following the treatment. Despite the name, the does not require an open surgery.
Endovascular embolization and stereotactic radiosurgery are often used together to treat AVMs.
How do I prepare for an AVM embolization?
The AVM embolization procedure is completed under general anesthesia and an admission to the hospital for at least an overnight stay. An AVM Embolization requires a pre-operative history and physical. You should have this scheduled with your primary care physician within 30 days of your scheduled procedure. Blood work will need to be drawn within 14 days of your scheduled procedure. Blood work needed includes BUN, creatinine, platelets, hemoglobin, potassium, sodium and INR.
You will called by telephone to pre-register for your procedure.
Eating: Do not eat or drink anything after midnight on the day of your procedure. Maintain hydration – drink extra fluids 2 days prior to your procedure, unless you are on fluid restrictions from your physician.
Medication: Medications can be taken in the morning with a sip of water. Please bring a list of your medications with you to your appointment.
- If you are a diabetic and take Glucophage (Metformin) DO NOT take your morning dose. If you take insulin, ask your doctor about modifying your insulin dose for the day of the procedure.
- If you are taking blood thinners (Coumadin/Warfarin, Pradaxa/dabigatran, Aggrenox/aspirin/dipyridamole (or similar medications) ask your doctor about stopping these medications at least 5-6 days prior to your procedure. Please let us know if you are taking clopidogrel (Plavix) or prasugrel (Effient).
- If you are taking aspirin DO NOT stop this medication prior to the procedure
Allergies: If you are allergic to contrast dye, please let us know. You will need to take a prescription steroid medication methylprednisolone (Medrol) and diphenhydramine (Benedryl) prior to your procedure.
Kidney Function: If you have a history of renal insufficiency (an increased creatinine level or a decreased GFR) please let us know as you may need to be pretreated with Mucomyst (a medicine that helps to protect your kidney function). Ask your primary care physician about with holding potential nephrotoxic medications you may be taking prior to your procedure.
Smoking: No smoking 72 hours prior to your angiogram.
Driving: You will not be allowed to drive for 24-48 hours after general anesthesia or if you are taking narcotics. You will need a driver to take you home when you are discharged from the hospital.
What happens on the day of the AVM embolization?
The day of the procedure you will check in at the Pre-operative Care Center 2 hours prior to your procedure time.
A nurse and anesthesiologist will review your health history as well as your medications and allergies.
You may need blood drawn, if not already completed within 14 days of your procedure.
The interventional neuroradiologist doing the procedure will meet with you prior to the procedure to, answer any questions you may have and have you sign consent.
You will be taken, by cart, to the interventional neuroradiology suite where you will be transferred to an x-ray exam table.
Your heart rate and blood pressure will be monitored. Your groin will be shaved, prepped and draped.
A small nick is made in the skin over the femoral artery. Using x-ray guidance (fluoroscopy) a thin, small tubing (catheter) is inserted through the skin into the blood vessel and guided to the area to be examined (neck, head or spine). The contrast is then injected though the catheter to allow several sets of pictures to be taken. The “glue” (or another substance) is then injected through the catheter into the abnormal blood vessels, blocking the flow of blood to the AVM.
At the end of the embolization, the catheter is removed and pressure is applied to the groin puncture to stop any bleeding. The opening is then covered with a bandage.
Following the procedure you will go to the post-anesthesia recovery area. When the nurse feels you are ready you will be transported to your room for an overnight stay and most likely be discharged the following morning. It is not uncommon to feel groggy and fatigued following the procedure. Headaches may occur in some patients following endovascular embolization. These headaches usually resolve within several days. If needed you may be sent home with additional medication to treat headaches.
- It is important to drink plenty of fluids for the next several weeks. This will help to avoid headaches.
- Gradually increase your activity as tolerated.
- You should avoid lifting objects heavier than 10 pounds for 5 days
- Avoid bending your leg at the hip and straining.
- Support your groin site with your hand when you cough, climb stairs or change positions for the first 48 hours following your procedure.
- Keep the puncture site dry. If you have bleeding or swelling under the skin, lie down and put firm pressure slightly above the puncture site for 10 to 20 minutes.
- You may shower 24 hours after your procedure. Gently wash the site with warm water. Dry gently. If there is still a slit in the skin cover with a bandage until it closes. Your may shower. Do not take tub baths, or swim in lakes of pools until your puncture site is healed without a scab.
- You will not be allowed to drive for 48 hours after general anesthesia or if you are taking narcotics.
- Additionally, you should not drink alcoholic beverages or make critical decisions or sign important documents for 48 hours.
A follow up cerebral angiogram is recommended 6 months after your procedure. This will show how much, if any, of the AVM remains and if additional treatment is needed.
Additional follow-up may be necessary thereafter.