Arteriovenous Malformations

Arteriovenous Malformations

An arteriovenous malformation is a condition in which the blood vessels connecting arteries (a blood vessel that carries blood away from the heart) and veins (a blood vessel that carries blood to the heart and lungs) are tangled abnormally. Due to this entanglement, the normal flow of blood is disturbed, and the oxygen circulation is also disturbed in the body. Thus arteriovenous malformation creates a shortcut that allows passing the blood directly from the arteries to the veins without passing from the thin blood vessels called capillaries. The passing of blood through the capillaries is important because the transfer of oxygen occurs from the capillaries to the organs of the body. Therefore, in the condition of arteriovenous malformation, the nearby tissues may not get enough oxygen. If this condition remains untreated, it may lead to the death of the surrounding tissues.

Generally, the symptoms of the arteriovenous malformation are based on the location of the malformation, size of the AVM, and size of the blood vessels involved in this. Some of the symptoms of AVM are:-

1. Buzzing or rushing sound
2. Facial paralysis
3. Vision problems like loss of a spot in your vision field
4. Changes in the sense of smell
5. Paralysis in one part of the body
6. Dizziness
7. Nausea and vomiting
8. Loss of consciousness
9. Bleeding
10. Speech problems
11. Dementia
12. Hallucinations
13. Seizures
14. Blue-coloured fingers and toes
15. Memory loss
16. Confusion

In the case of Spinal AVM, the patients may experience the following symptoms along with the above symptoms:

1. Weakness of muscles
2. Numbness and tingling sensation
3. Loss of coordination can cause a problem with gait
4. Pain in back
5. Weakness in lower extremities 
6. Difficulty in urination and bowel movement
7. Headache
8. Stiff neck
9. Increased light sensitivity

The arteriovenous malformation is caused by the development of a direct abnormal connection between the arteries and the veins. But, still, the exact cause behind the arteriovenous malformation is unknown. But, some researchers believe that this occurs in the womb or shortly after birth and shows the symptoms in later stages of life. There may be a role in certain genetic changes. But, in most cases, the condition is not inherited. The presence of some genetic abnormalities like Cobb syndrome and Parkes weber syndrome can also cause arteriovenous malformation.

Risk factors  

In rare cases, the family history of the arteriovenous malformation can increase the risk of causing this disease. Certain hereditary conditions like hemorrhagic telangiectasia (HHT), also known as Osler weber rendu syndrome, can increase the risk of developing arteriovenous malformation.

Disease Progression

The greatest potential risk is the case of arteriovenous malformation haemorrhage. It is so because most cases of bleeding remain unnoticed because the bleeding is not so severe that it can cause large neurological damage. But, if left unnoticed, then severe and fatal haemorrhages can also occur. That is why whenever the arteriovenous malformation is diagnosed, the patient is checked carefully for any symptoms and severity and risk of haemorrhage. The staging of the AVM is generally done through the Schöbinger Staging System. The stages include:

Stage I (Quiescence): Patients with stage I AVM have a pink-blue stain. The shunting is determined through Doppler ultrasound.

Stage II (Expansion): The symptoms of stage II are similar to stage I with additional symptoms including pulsations, enlargement, bruit, thrill, and tortuous and tense veins.

Stage III (Destruction): The symptoms of stage III are similar to stage II with additional symptoms including ulceration, skin dystrophy, necrosis and pain.

Stage IV (Decompensation): The symptoms of stage IV are similar to stage III along with cardiac failure.

Differential diagnosis

1. Arteriovenous malformations can be sometimes mistaken for infantile hemangioma. But, Arteriovenous malformation gets bigger as the baby grows, whereas infantile hemangioma grows only in the womb.
2. The major difference between the two is that the blood vessels involved are large in arteriovenous malformation, and the blood flows at a fast speed. These are present in the deeper layer of the skin. Whereas in capillary malformation, the blood vessels involved are small and are present in the upper layer of the skin.

Diagnostic Tests

The doctor can diagnose the arteriovenous malformation by reviewing the medical history of the patient and by looking at the area that is affected. 

The doctor can order the following tests to diagnose the arteriovenous malformation. These are:-

1. CT scan: It uses an X-ray to create an image of the head, brain, and spinal cord. It helps in finding the bleeding cases. 
2. MRI scan: It uses a powerful magnet and radio waves to create a detailed image of the tissues. 
3. Cerebral Angiography: this process is also called arteriography. In this process, a special dye known as a contrast agent is injected into the arteries. It highlights the structure of the arteries when viewed under X-ray.
4. Magnetic Resonance Angiography: Through magnetic resonance angiography, the doctor determines the speed and distance of flow of blood through the abnormal vessels. 
5. Brain imaging in patients with suspected AVM: The doctor recommends computed tomography angiography, cerebral magnetic resonance angiography, and transcranial doppler ultrasound in patients suspected of suffering from AVM.

The arteriovenous malformations are benign. It means these are non-cancerous. The treatment of arteriovenous malformations is mainly focused on managing the signs and symptoms and improving the lives of the patient. The treatment of the arteriovenous malformation depends upon the location of the abnormality and your overall health. 

Surgical method:

1. Embolisation: In embolisation, materials like metal coil, medical glue, or plugs are put in the centre of arteriovenous malformation. These materials are placed there with the help of the catheter. The catheter is a thin tube inserted into the blood vessels by making an incision. Placing this material there helps stop the flow of blood through the malformation.
2. Sclerotherapy: In this method, liquid medicine known as sclerosant is injected into the malformation region. This medicine destroys the vessels that cause the scar to form. This process also helps decrease and eventually stop the flow of blood through the region of malformation. 

Embolisation and Sclerotherapy are the most common surgical methods used to treat arteriovenous malformation. They cannot make the malformation disappear completely, but they can decrease the size and symptoms of the arteriovenous malformation.

Some people may find out about having a problem like arteriovenous malformation when it starts bleeding. However, immediately contact your doctor if you are experiencing symptoms like physical and muscle weakness, numbness, vomiting, seizures, constant dizziness, and any kind of change in vision. 

Complications

Some of the complications that the patient may experience in the case of arteriovenous malformation are as follows:-

1. Numbness in some parts of the body
2. Stroke
3. Problems associated with speech and movement of the body
4. Retarded growth in children
5. Haemorrhage
6. Hydrocephalus (accumulation of spinal fluid in the brain due to increased pressure on the normal spinal fluid pathway)
7. Lower quality of life after AVM (arteriovenous malformation)
8. Seizure
9. Aneurysm
10. Brain damage
11. Coma
12. Death