What are the causes? The cause of AVMs is not known, but it is thought that they develop as a result of a mistake in embryonic or fetal development (during a baby’s development in the womb). Arteriovenous malformations of the brain The main symptoms of brain AVMs include: seizures/epilepsybrain haemorrhage (bleeding in or around the brain)in the absence of brain haemorrhage, weakness or numbness in the bodyringing in the ears (known as pulsatile tinnitus) – this only occurs with AVMS occurring under the dura (covering of the brain). Further problem that depend on the specific position of the AVM include: muscle weakness or paralysisloss of coordinationdizzinessvisual disturbancesproblems in using or understanding languagenumbness, tingling or painmemory deficits. Vein of Galen malformation Vein of Galen malformation is a rare specific form of AVM. There are three main methods of treating AVMs of the brain: embolisation, in which particles are injected to block off the blood vessels of AVMs of the brain and dura (covering of the brain)stereotactic radiosurgery, in which radiation is used to treat small vascular malformations, mainly AVMs less than three centimetres acrossneurosurgery, in which a surgical operation is performed on the brain to disconnect an AVM of the brain or dura (covering of the brain) from the arteries that supply it and the veins that drain it. Inheritance patternsRarely, AVMs may occur in the brain and lungs as a result of a condition called hereditary haemorrhagic telangiectasia. Prenatal diagnosisThe presence of an AVM may be picked up on ultrasound scan, although this is not usually the case. Pulmonary arteriovenous malformations As in AVMs of the brain, a pulmonary AVM is present at birth and the capillaries essential for the full oxygenation of blood are not present. Consequently, the normal oxygenation is not carried out properly as the exchange process of oxygen and nutrients for carbon dioxide and other waste products does not occur. The effects of pulmonary AVMs include: breathing difficultiesshortness of breath on physical exertioncyanosis (bluish or purplish discolouration of skin or lips as a result of poor blood oxygenation)clubbing (enlargement of the tips) of the fingersaudible murmur (noise from the heart) when a stethoscope is placed over the AVMwarmth of the overlying skinoccasionally coughing up blood. Some people with a pulmonary AVM do not have symptoms. Diagnosis of a pulmonary AVM is made following tests which include, chest X-rays, chest computerised tomography (CT) scan, bubble echocardiogram (scan of the heart), perfusion lung scan (X-ray examination after injection of radioactive material), pulmonary arteriogram (motion picture X-rays) or blood tests. Treatment of pulmonary AVMs is by either surgical removal of the abnormal vessels and surrounding lung tissue or it might be possible to block the fistula with a coil when an arteriogram is carried out. If treatment is not carried out, there is a possibility of blood clots travelling from the lungs to the limbs or the brain. In which case, a stroke is a possibility. Inheritance patternsAVMs may be associated with conditions such as hereditary haemorrhagic telangiectasia, which is inherited in an autosomal dominant manner, or juvenile polyposis (a condition where there are multiple polyps in the gastrointestinal tract) with hereditary haemorrhagic telangiectasia. Prenatal diagnosisThis may be picked up on an ultrasound scan. Spinal arteriovenous malformations Spinal AVMs are very rare. They usually become apparent in adult life. They are a potentially treatable cause of myelopathy (any disease or disorder of the spinal cord). Myelopathies may cause any or all of the following symptoms: weakness of the legsdisturbance of sensation over the legs, buttocks and genital areasimpairment of bladder and/or bowel function. Spinal AVMs usually involve the lower part of the spinal cord, called the thoracic cord, which stretches from the neck to the small of the back. Improvements in spinal cord imaging with magnetic resonance imaging (MRI) have lead to quicker diagnosis. However, spinal AVMs are notoriously difficult to detect, and may require spinal catheter angiography (visualisation of the blood vessels after injection of a radiopaque substance) to be certain about the diagnosis. Treatment of spinal AVMs is often difficult, and usually its objective is to limit further damage to the spinal cord, rather than alleviate the problems already caused. The two main forms of treatment are surgical excision and embolisation via a catheter in the groin. Embolisation is becoming the mainstay of treatment as technological advances in catheters and embolic glues are made. Is there support? AVM Support UK Email: via websiteWebsite: avmsupport.co.uk AVM Support UK offers information and support to all whose lives have been affected by Arteriovenous Malformations. It hosts an online support meeting area in which registered users meet on a weekly basis. Group details last updated July 2015.