Haemodynamic changes in arteriovenous malformations induced by superselective embolization: transcranial Doppler evaluation

To reduce the intraoperative and postoperative complications in patients who suffer intracerebral arteriovenous malformations (AVM's), the slow reduction of the shunt flow to a brain perfusion flow has been tried by the use of several methods: microsurgical techniques, selective and superselective embolization, intraoperative embolization, staged operation. The risk of re-bleeding and intraoperative oedema increases in AVM's with two or more feeders. Our policy was to exclude such AVM's by primary superselective embolization. If there was only a small residual angioma, we tried to remove this by microsurgical techniques. The haemodynamics in AVM's could be examined by measuring the blood flow velocities in the feeding arteries and in the other parts of the circle of Willis by transcranial Doppler sonography (TCD). Signs of haemodynamic effective embolization could be measured by the reduction of flow velocities. After exclusion of an AVM the velocities in the brain and feeding arteries decreased to below normal values in the first days after the operation. In the feeding arteries this was due to the fact that the arteries were enlarged so that the velocity must be decreased when there was normal volume flow. The combination of superselective angiography and microsurgical resection of the residual angioma seemed to be the best way to treat AVM's which are fed by more than two arteries and which are 3 or more cm in diameter. TCD investigations were used to measure the haemodynamic changes before and after angioma superselective embolization and microsurgical operation.