Given the task definition and input, reply with output. Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.

Abstract: It is postulated that the repetitive thrust of a sensitized blood vessel, at the peak of systole, against a taut pia-arachnoid fiber may produce or accentuate vasospasm.
Cerebral vasospasm: a theoretical relationship between systolic thrust and pia-arachnoid fibers.