B-waves revisited

Abstract

Abstract Reduced intracranial compliance is a key manifestation common to a number of pathological conditions of the brain. It is encountered in, but not limited to, traumatic brain injury, cerebral edema, and hydrocephalus. There are no clinically accepted methods to measure intracranial compliance available to date. Intracranial pressure (ICP) waveform analysis is seeing a revival driven by advances in our understanding of cerebrospinal fluid and pressure dynamics. Its translation to widespread clinical use is dependent on the possibility to derive relevant metrics such as intracranial compliance reliably and non-invasively. The B-wave is one of the features of the ICP waveform, reflecting vasogenic activity of cerebral autoregulation. B-waves were originally defined to occupy the 0.5 to 2 cycles per minute frequency range. Recently renamed and redefined as slow waves with an extended range of 0.33 to 3 cycles per minute, specific changes in their pattern of occurrence are considered to be indicative of reduced intracranial compliance. With the still unmet need for a clinically acceptable method for acquiring intracranial compliance, and the revival of ICP waveform analysis, B-waves are moving back into the research focus. Herein we provide a concise review of the literature on B-waves, including a critical assessment of non-invasive methods for obtaining B-wave surrogates.