An AVM is a tangle of abnormal arteries and veins which has a propensity to bleed. While it can occur anywhere, brain and spinal AVMs are the ones which can put a patient at substantial risk.
Due to the brain and its blood vessels being formed together during embryological development, abnormal blood vessel formation tends to be associated with abnormal brain tissue. Thus, AVMs tend to be associated with abnormal tissue thereby allowing their removal without damaging healthy brain tissue.
Dural AVMs are found in the dura (covering) of the brain. These are “acquired” which means they are triggered by trauma. AVMs may develop after a head or spine trauma, and these are referred to as AV fistulas.