Assessment of cerebral autoregulation in stroke: A systematic review and meta-analysis of studies at rest

Abstract

Dynamic cerebral autoregulation (dCA) has been shown to be impaired in cerebrovascular diseases, but there is a lack of consistency across different studies and the different metrics that have been proposed for assessment. We performed a systematic review and meta-analyses involving assessment of dCA in ischemic and hemorrhagic stroke. Thirty-three articles describing assessment of dCA with transfer function analysis (TFA) were included, with meta-analyses performed for derived parameters of gain, phase and autoregulation index (ARI). A total of 1233 patients were pooled from 12 studies on acute ischemic stroke (AIS) and two studies on intracerebral hemorrhage (ICH). In comparison with controls, TFA phase of AIS was significantly reduced (nine studies), in both hemispheres ( P < 0.0001). TFA gain provided inconsistent results, with reduced values in relation to controls, for both hemispheres. The ARI (six studies) was reduced compared to controls, in both hemispheres ( P < 0.005). In ICH, gain showed higher values compared to controls for the unaffected ( P = 0.01), but not for the affected hemisphere. Meta-analyses in AIS have demonstrated that phase and the ARI index can show highly significant differences in comparison with healthy controls, while ICH have been limited by the scarcity of studies and the diversity of units adopted for gain.

Cerebral Autoregulation and Neurovascular Coupling after Craniospinal Irradiation in Long-Term Survivors of Malignant Pediatric Brain Tumors of the Posterior Fossa

“…16 The parameter gain of the TFA is a less sensitive and less consistent parameter than the phase shift. 18 In our study, the DCA parameter gain was comparable in both groups and both vascular territories.…”

The critical closing pressure contribution to dynamic cerebral autoregulation in humans: influence of arterial partial pressure of CO2

“…In TFA of the dynamic relationship between MAP and CBFV, theoretical considerations would indicate that each harmonic of the gain and phase frequency responses behaves as a statistical independent quantity, which could offer the possibility of overcoming the dimensional limitations of other indices. However, despite an extensive literature on the application of TFA to physiological and clinical studies, segmentation of the spectral range where dynamic CA is active, from DC to approximately 0.2 Hz (Panerai et al 2019), into averages over the very low and low frequency ranges (Zhang et al 1998;Claassen et al 2016) has not led to consistent metrics that could be treated as independent indicators in different physiological conditions, or reflecting specific pathophysiological alterations in different cerebrovascular conditions (Panerai, 2008;Tzeng et al 2012;Intharakham et al 2019). To our knowledge, the demonstration that SRV CrCP makes a significant contribution to the dynamic CA response, and can explain the differences in SRV MCA due to hypercapnia, is the first evidence that it should be possible to quantify the phenomenon of dynamic CA in more than a single dimension.…”

Comparison of static and dynamic cerebral autoregulation under anesthesia influence in a controlled animal model

“…The clinical need to measure CA is well established but disagreement about the consistency between measurement methods exists [11][12][13]. CA measurement methods are commonly separated into two groups: static and dynamic CA [14].…”