Full title: Cerebral blood flow is reduced in ME/CFS during head-up tilt testing even in the absence of hypotension or tachycardia: a quantitative, controlled study using Doppler echography https://www.sciencedirect.com/science/article/pii/S2467981X20300044 Patients were classified as having CFS, chronic fatigue, or no chronic fatigue as defined by Fukuda and colleagues(Fukuda et al. , 1994) and as having ME or no ME as defined by Carruthers and colleagues(Carruthers et al. , 2011). Hmmmm..... It may be that the definition and diagnosis of orthostatic intolerance needs to be revised.