|
We've known for many years that people with myalgic encephalomyelitis (ME) experience a reduction in cerebral blood flow (CBF) when upright, even in the absence of postural orthostatic tachycardia syndrome (POTS) or orthostatic hypotension. We also know that orthostatic intolerance symptoms worsen in post-exertional malaise (PEM).
In this proof-of-concept study, we asked: what happens to CBF in response to an exercise stressor in a person with ME compared to a healthy control subject?
Measuring CBF takes expensive equipment. Trying to measure CBF in any position or movement besides sitting or lying down is practically a non-starter. It is also not something a person can do and interpret for themselves.
Enter the Lumia™ in-ear device. It's a reliable measure of blood flow to the head, which correlates with CBF. But can it show us anything about PEM?
That's what we aimed to find out in this project, which was recently published in the Cardiopulmonary Physical Therapy Journal.
Here's what we learned:
- The person we tested with ME had a significant drop in blood flow to the head during PEM: 17% while supine and 23% while standing. The healthy person did not have a decline.
- We observed the characteristic functional decline of PEM, with a 34% decrease in workload at the ventilatory anaerobic threshold between tests during a two-day cardiopulmonary exercise test. There was no decrease in the healthy person.
- We observed chronotropic incompetence during PEM, characterized by a 10% decrease in peak heart rate. There was an increase in the healthy subject.
- Orthostatic intolerance worsened during PEM, including symptoms of dizziness, cognitive issues, and tingling. The healthy person had no symptoms.
- Recovery time was 12 days for the person with ME, compared to less than 1 day for the healthy person.
This work lays the foundation for a larger study into the role of cerebral hypoperfusion in PEM and the utility of wearable diagnostics in ME diagnosis, care, and research.
| 
