Cerebral autoregulation and autonomic nervous system: A narrative review

Abstract

Cerebral autoregulation (CA) is the process through which the brain maintains a sufficient cerebral blood flow (CBF) despite varying cerebral perfusion pressure (CPP). When systemic BP varies, the cerebral vasculature's inherent CA protection mechanism works to maintain CBF stability. The autonomic nervous system (ANS), among other physiological pathways, may impact CA disturbances. Cholinergic and adrenergic nerve fibers innervate the cerebral vascular system. Several reasons, such as the complexity of the ANS and cerebrovascular interactions, measurement flaws, differences in methods used to evaluate the ANS concerning CBF, and experimental strategies that can or cannot shed light on the sympathetic control of CBF, the role of the ANS in regulating CBF is hotly debated. To comprehend the mechanisms underlying the reported crosstalk between the controls of the heart and the cerebrovascular system, one needs to define more precisely the frequency bands to compute spectral CA markers and develop models more in line with physiology to describe the behavior of CA; it may be helpful to study the involvement of the autonomic nervous system (ANS) on CA. The review investigates how the ANS affects CA, which could significantly impact diagnosing and treating pathological diseases.