Stroke; a journal of cerebral circulation
-
Chronobiological analyses of stroke onset may throw some light on the mechanisms that trigger stroke. Observations may generate new hypotheses for identifying significant causal relationships. ⋯ We found that young adults and women are frequently stricken by brain infarction during weekends and holidays and that the circadian distribution of the onset of brain infarction among young adults is different from that of middle-aged people. These observations suggest that there may be stroke-triggering activities that are associated with lifestyle.
-
Increased resistance in the venous drainage of intracranial arteriovenous malformations (AVMs) may contribute to their increased risk of hemorrhage. Venous drainage impairment may result from naturally occurring stenoses/occlusions, or if draining veins (DVs) undergo occlusion before feeding arteries during surgical removal, or after surgery in the presence of "occlusive hyperemia." We employed a detailed biomathematical AVM model using electrical network analysis to investigate theoretically the hemodynamic consequences and the risk of AVM rupture due to venous drainage impairment. ⋯ On theoretical grounds, venous drainage impairment was predictive of AVM nidus rupture and was strongly dependent on AVM morphology (presence of intranidal fistulas and their spatial relation to DVs) and hemodynamics. Specifically, stenosis/occlusion of a high-flow DV induces a rapid redistribution of blood into the weak plexiform vessels of the opposing region of the nidus, causing a hemodynamic overload and an increased risk of rupture. These findings should be carefully considered among all factors affecting the natural history of intracranial AVMs and the mechanisms implicated in their spontaneous rupture. They may also provide a theoretical rationale for some of the hemorrhagic complications that occur during and after surgical treatment.