Simple laboratory experiments to replicate some of the stresses on vertebro-basilar arterial walls. An investigation of possible mechanisms of traumatic subarachnoid haemorrhage.

The hypothesis that reversed blood flow in transiently occluded vertebral arteries may be responsible for some cases of massive traumatic subarachnoid haemorrhage has been investigated in vitro. Simple laboratory tests were performed on 25 vertebro-basilar arterial systems, and succeeded in producing either longitudinal tears in normally structured vertebral arteries, or tears at the origin of the posterior inferior cerebellar arteries. The results indicated that under such conditions, with systolic blood pressure in the physiological range, reversed blood flow had different characteristics and stressed the arterial wall to the point where it yielded.