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, by C (Linda) MC van Campen, Freek WA Verheugt, Peter C Rowe, Frans C Visser in Clinical Neurophysiology Practice Vol 5, 2020, pp 50-58 [https://doi.org/10.1016/j.cnp.2020.01.003]
- Extracranial Doppler technique to measure cerebral blood flow is feasible during head-up tilt testing.
- Cerebral blood flow in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients is reduced during head-up tilt testing compared to healthy volunteers.
- Using a lower limit of normal of the cerebral blood flow reduction during head-up tilt testing of 13%, 90 percent of ME/CFS patients showed an abnormal cerebral blood flow reduction.
- Reduction in cerebral blood flow is correlated with symptoms of orthostatic intolerance.
The underlying hypothesis in orthostatic intolerance (OI) syndromes is that symptoms are associated with cerebral blood flow (CBF) reduction. Indirect CBF measurements (transcranial Doppler flow velocities), provide inconsistent support of this hypothesis. The aim of the study was to measure CBF during a 30 min head-up tilt test (HUT), using
Doppler flow imaging of carotid and vertebral arteries, in individuals with chronic fatigue syndrome/myalgic encephalomyelitis (ME/CFS), a condition with a high prevalence of OI.
429 ME/CFS patients were studied: 247 had a normal heart rate (HR) and blood pressure (BP) response to HUT, 62 had delayed orthostatic hypotension (dOH), and 120 had postural orthostatic tachycardia syndrome (POTS). We also studied 44 healthy controls (HC). CBF measurements were made at mid-tilt and end-tilt. Before mid-tilt, we
administered a verbal questionnaire to ascertain for 15 OI symptoms.
End-tilt CBF reduction was 7% in HC versus 26% in the overall ME/CFS group, 24% in patients with a normal HR/BP response, 28% in those with dOH, and 29% in POTS patients (all P<.0005). Using a lower limit of normal of 2SD of CBF reduction in HC (13% reduction), 82% of patients with normal HR/BP response, 98% with dOH and 100% with POTS showed an abnormal CBF reduction. There was a linear correlation of summed OI
symptoms with the degree of CBF reduction at mid-tilt (P<.0005).
During HUT, extracranial Doppler measurements demonstrate that CBF is reduced in ME/CFS patients with POTS, dOH, and even in those without HR/BP abnormalities.
This study shows that orthostatic intolerance symptoms are related to CBF reduction, and that the majority of ME/CFS patients (90%) show an abnormal cerebral flow reduction during orthostatic stress testing. This may have implications for the diagnosis and treatment of ME/CFS patients.