A new haemodynamic factor in cerebral AVM. Aspiration from the venous system demonstrated in two cases of pedonculo-Galen AVM successfully cured by occlusion of the superior longitudinal sinus.

Using a Doppler Mark 500 of ATL we measured the systolic and diastolic velocity of the red cells into the main arteries of the neck (diastolic rate cm/sec) thus approaching the flow in two cases of upper brain stem AVM with a unique drainage into the superior longitudinal sinus through an enlarged vein of Galen and a falcine sinus. Because of the desperate clinical condition of the children it was decided to stop the high blood flow by closing the aspiration coming from the low pressure of the venous system above and below the site of union between the malformation and the superior longitudinal sinus. An intra-operative and post-operative measurement of the diastolic rate showed a radical effect of the closure of the superior longitudinal sinus. The demonstration of this aspirative factor has allowed us to classify an AVM as a haemodynamic push-pull malformation.