Hypertension does not cause spontaneous hemorrhage of intracranial arteriovenous malformations

The authors measured blood pressure changes non-invasively in 56 conscious, unpremedicated patients with cerebral arteriovenous malformations (AVMs) during preparation for proton beam therapy. The procedure requires six injections of local anesthetic and application of a stereotactic frame by fixation into the outer table of the skull, and has been used during the past 20 yr to treat over 1,000 patients with cerebral AVMs. No effort was made to control blood pressure. Blood pressure increased during administration of the local anesthetic and application of the frame. Maximum systolic and mean arterial pressures averaged 160 +/- 17 and 118 +/- 7 mmHg (mean +/- SD), respectively. This represented an average increase of 44 mmHg (38%) in systolic pressure and 32 mmHg (37%) in mean blood pressure at some point during the procedure (P less than 0.01 compared with pretreatment control pressures). Systolic pressure increased more than 60 mmHg in 21% of patients. Nevertheless, none of these 56 patients nor any of the more than 1,000 patients treated in similar fashion suffered a clinically evident AVM hemorrhage during the procedure. Since the treatment protocol has not changed materially during the past 20 yr, the authors assume that most patients treated in this fashion developed a similar degree of hypertension and conclude from this large clinical experience that moderate arterial hypertension does not precipitate spontaneous hemorrhage of intracranial AVMs.