Intracranial pressure oscillations (B-waves) caused by oscillations in cerebrovascular volume.

In experiments during stepwise increases in intracranial pressure, B-waves could be provoked synchronously with pial vascular diameter oscillations. The vascular oscillations are known to be a sign of myogenic cerebrovascular regulation. An increase in their amplitude indicates vessel wall relaxation and impending failure of myogenic autoregulation. Therefore, vascular oscillations provoked during intracranial hypertension can be ascribed to a fall in transmural pressure and vessel wall tension. The resulting oscillations in the cerebral blood volume are reflected by ICP oscillations and lead to synchronous variation in ICP, the so-called "B-waves" with a frequency of 0.5 to 2 per minute.