Presence and removal of arteriovenous malformation: Impact of regional cerebral blood flow, as assessed with xenon/CT.

In 26 patients with supratentorial AVMs and 1 patient with a dural arteriovenous fistula, the regional cerebral blood flow (rCBF) was assessed by means of xenon-enhanced computed tomography (Xe/CT) before and after complete resective surgery. Each assessment comprised an acetazolamide challenge in order to check the cerebrovascular reserve capacity. While scanning through the AVM was purposely avoided, a single brain slice at the level of the basal ganglia was examined. Five regions of interest (ROIs) in gray matter of the AVM-bearing hemisphere were compared to the contralateral ROIs and categorized into 7 CBF groups. Interhemispherical differences exceeding 20% of the contralateral value in either direction were considered to the significant. AVM-related (AVM-R) and AVM-non-related (AVM-NR) ROIs were looked at separately. Before surgery, all possible rCBF patterns were found, including a normal rCBF as well as a reduced or an increased rCBF, either in AVM-R, AVM-NR, or both. After AVM removal, a rCBF increase in AVM-R is relatively rare, whereas a rCBF decrease is twice as frequent. A rCBF drop to a level of impaired reserve capacity correlates with the occurrence of post-operative neurological deficit.