Cerebral Circulation during Arteriovenous Malformation Operation

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Abstract
The circulatory changes in the cortex around a cerebral arteriovenous malformation (AVM) were studied in 18 patients. The AVMs had rapid circulation times with early draining veins on angiography. Local cortical blood flow (ICoBF) was measured with cortically applied thermister/Peltier stack arrays. The AVMs had a more pronounced effect on ICoBF at a 2- to 4-cm distance from the AVM margin than in the adjacent cortex. Mean preexcision ICoBF was 62.9 ± 6.7 (SE) ml/100 g/minute (i.e., similar to normal controls) near the AVM margin and 43.0 ± 4.2 ml/100 g/minute far (i.e., >2 cm) from the AVM. CO2 reactivity (COR) before excision was 1.1 ± 0.3 ml/100 g/minute/torr of CO2 (i.e., similar to normal controls) at near sites and 0.6 ± 0.3 ml/100 g/minute/torr of CO2 at far sites. The mean postexcision near ICoBF remained stable at 55.8 ± 5.1 ml/100 g/minute at near sites, but the far ICoBF significantly increased (P < 0.05) to 57.2 ± 6.8 ml/100 g/minute. The cortical feeding artery pressure was substantially below the normal cortical artery pressure in 50% of the cases studied. Pressure in these arteries normalized after occlusion and AVM excision, resulting in a rapid increase in cortical artery perfusion pressure. Draining red vein pressure, which was elevated before AVM excision, also dropped after excision, contributing to the increase in perfusion pressure. Two patients who developed the normal perfusion pressure breakthrough syndrome (PBS) after operation had low ICoBF and disturbed COR before AVM excision and marked increase of ICoBF after excision. Factors that contribute to the development of PBS include: (a) low ICoBF around an AVM; (b) impaired COR; (c) low cortical artery pressure before AVM excision; (d) normalization in cortical artery pressure after AVM removal; and (e) substantial increase in ICoBF after AVM removal. Maintenance of a low systemic arterial blood pressure during the early postoperative period is essential in reducing the risk of severe cerebral edema.

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