Arteriovenous malformations (AVMs) are groups of blood vessels in your body that form in the wrong way. In AVMs, arteries and veins are abnormally tangled. This causes irregular connections between the arteries and veins.

AVMs can form anywhere in the body. But they most often occur in the spinal cord or brain. They often occur as the body develops before birth or shortly after. Those that form in the brain or close to the spinal cord are called neurological AVMs. These are most likely to have long-term effects. They may reduce the amount of oxygen getting to the brain and spinal cord. AVMs can also sometimes put pressure on nearby tissues.

Many people with an AVM don't know they have one because they may not have any symptoms or problems. Instead, AVMs are often found when doctors are treating some other unrelated health concern. Or one of the blood vessels in an AVM may rupture, revealing the problem. Sometimes AVMs are found only after death, during an autopsy.

No one knows why AVMs form. Some experts believe that the risk of developing AVMs could be genetic.

Many people with AVMs will never have any problems. If symptoms don't appear by age 50, they tend to remain stable. They are less likely to cause symptoms later in life.

Symptoms may occur as a result of pregnancy. Being pregnant may put pressure on blood vessels.

Symptoms of an AVM depend on where it is located. You may have:

• Buzzing or a rushing sound in your ears.
• Headache, although no specific type of headache has been identified.
• Backache.
• Seizures.
• Loss of sensation in part of your body.
• Muscle weakness.
• Changes in vision.
• Facial paralysis.
• Drooping eyelids.
• Problems speaking.
• Changes in your sense of smell.
• Problems with motion.
• Dizziness.
• Loss of consciousness.

Doctors will ask about a person's past health and symptoms. They will also do a physical exam. They may talk with family and friends about a person's symptoms if the person is unconscious.

The final diagnosis is often made based on areas of blood flow shown by imaging tests, including:

• Cerebral angiogram.
• MRI scan and magnetic resonance angiography.
• CT scan and CT angiography.
• Vascular ultrasound.

A treatment plan is developed based on the size and location of the AVM. Treatments may include:

• Medicine for symptoms.
• Plugging off the malformed blood vessels (embolization).
• Surgery (best when AVMs are small and located in superficial areas of the brain or spinal cord).
• Radiation therapy (radiosurgery).

Talk with your doctor about the risks and benefits of your treatment options.

The main concern with AVMs is that they may cause uncontrolled bleeding (hemorrhage). A small percentage of AVMs bleed. This can cause severe effects that may even result in death.

Other complications of AVMs are:

• Stroke.
• Numbness in part of the body.
• Problems with speech or movement.
• Spinal fluid buildup in the brain (hydrocephalus).
• Lower quality of life.

AVMs happen before birth or shortly after. Their cause is unknown. So you can't prevent them. The best approach is to respond quickly to symptoms.

Some people find out about an AVM only when it bleeds. This causes stroke in some people.

Call 911 if you have:

• A seizure.
• Numbness.
• Vomiting.
• Physical weakness.

• Arteriovenous malformations (AVMs) are groups of blood vessels in your body that form in the wrong way.
• AVMs often develop before birth or shortly after. The cause may be genetic.
• Most people with AVMs will never have any problems.
• If a person does have symptoms, it will depend on where the AVM is located. Symptoms may include headache, backache, seizures, or dizziness.
• Imaging tests, such as an MRI or a CT scan, can often find an AVM.
• Treatment options may include medicines or surgery.

Tips to help you get the most from a visit to your doctor:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your doctor tells you.
• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you.
• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if you do not take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your doctor if you have questions, especially after office hours or on weekends.