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Updated: Jul 13, 2026

Double Direct Injection of Blood into the Cisterna Magna as a Model of Subarachnoid Hemorrhage
Published on: August 30, 2020
Circumstances, activities, and events precipitating aneurysmal subarachnoid hemorrhage
Masayuki Matsuda1, Kazuyoshi Watanabe, Akira Saito
1Department of Neurosurgery, Shiga University of Medical Science, Ohtsu, Japan.
Abstract:
Medical records of 513 patients with aneurysmal subarachnoid hemorrhage were reviewed to analyze the factors precipitating aneurysmal rupture. There was no seasonal difference in incidence. A significantly higher incidence was observed during 6:00 AM to 9:00 AM and 6:00 PM to 9:00 PM when engaging in daily routines such as defecation/micturition, brushing teeth/washing face/dressing, eating/drinking, and taking a bath. These activities are associated with a Valsalva maneuver that results in sudden pressure changes across the aneurysmal wall precipitating aneurysmal rupture. Aneurysmal rupture occurred most frequently during talking, chatting, watching television, or staying home without any strenuous physical activity. Considering the time spent, the highest incidence rate was found during defecation/micturition. There was no significant difference between men and women or between younger and older age groups regarding activities or events preceding aneurysmal rupture. Hypertension was the most common pre-existing medical problem. The main results are the same as those of the previous study except for aging of the patients.
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