Study of the Week: Reduced Cerebral Blood Flow in Severe Myalgic Encephalomyelitis

Welcome to study of the week, a new series from Patient Worthy. In this segment, we select a study we posted about from the previous week that we think is of particular interest or importance and go more in-depth. In this story we will talk about the details of the study and explain why it’s important, who will be impacted, and more.

If you read our short form research stories and find yourself wanting to learn more, you’ve come to the right place.


This week’s study is…

Reductions in Cerebral Blood Flow Can Be Provoked by Sitting in Severe Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients

We previously published a story about this research in a story titled “Sitting Position Linked to Reduced Cerebral Blood Flow in Patients with Myalgic Encephalomyelitis,” which can be found here. The study was originally published in the scientific journal Healthcare. You can view the full text of it here.

What Happened?

This research draws on findings from a previous large scale study which found that patients living with myalgic encephalomyelitis (also known as chronic fatigue syndrome) frequently display orthostatic intolerance, which means that symptoms worsen when the patient moves from a reclined position to an upright position (sitting, standing, etc.). One characteristic of this intolerance was reduced cerebral blood flow, which was found in 90 percent of patients. Symptoms are reduced when the patient resumes their reclined position. This was measured and detected using a standard, head-up tilt test.

This new study aimed to see if reduced cerebral blood flow was present in the most severe patients when they moved to a sitting position, which is a less pronounced orthostatic stress than the tilt test. From an initial pool of 801 patients, a total of 100 patients were evaluated. These patients were identified as having severe myalgic encephalomyelitis and most displayed other symptoms of orthostatic intolerance, such as nausea, dizziness, and syncope. A sitting test was selected partially because these patients’ ability to stand is very limited and a tilt test would produce significant symptom exacerbation (post-exertional malaise).

The patients sat for one hour before being transferred to a special research table, where cerebral blood flow, blood pressure, and heart rate were measured. Patients were then moved to a supine (lying) position for fifteen minutes and then had these measurements taken again. Compared to healthy controls, patients displayed a notably lower rate of cerebral blood flow (474 mL/min vs 627 mL/min) when seated. Blood flow in patients when seated declined by 24.5 percent in patients versus the supine position. It should be noted that this decline was primarily in patients who displayed prior symptoms of orthostatic intolerance (who saw a reduction of 26.9 percent); those that did not only saw a reduction of 2.7 percent.

About Myalgic Encephalomyelitis (ME)

Myalgic encephalomyelitis, also known as chronic fatigue syndrome, is a rare condition which is most characterized by long term fatigue and other symptoms which severely impact a person’s ability to fulfill daily tasks. The exact cause of the syndrome is poorly understood. Risk factors may include family history, low physical fitness, old age, mental health problems, and allergies. Women are also more likely to get myalgic encephalomyelitis than men. The characteristic symptom is severe, persistent fatigue that has no definitive cause and is not resolved with rest; other symptoms include difficulty sleeping, worsening of symptoms following exercise, night sweats, sensitivities to certain foods, noise, or odors, muscle and joint pain, headaches, irritable bowel syndrome, and sore throat. Symptoms may appear gradually or suddenly, and in severe cases can leave a patient bedridden. Some treatments may include energy management strategies such as pacing and changes in diet. To learn more about myalgic encephalomyelitis, click here.

Why Does it Matter?

The study demonstrated that sitting could result in major reductions in cerebral blood flow in the most severe myalgic encephalomyelitis patients, who are likely to have orthostatic intolerance. This means that a sitting test is sufficient to detect orthostatic intolerance in severe cases of myalgic encephalomyelitis. The findings also reveal that sitting should be regarded as a serious orthostatic stressor for these patients. A sitting test should be conducted in the future for this patient group as many are unable to tolerate the standard tilt test, which has the potential to inflict significant post-exertional malaise.

Though the findings from this research do not constitute a new method of diagnosing the disease on its own, the presence of cerebral flow reductions in the absence of abnormalities in blood pressure or heart rate could serve as a potential indicator of severe myalgic encephalomyelitis in those who are undiagnosed, particularly if the patient presents with other symptoms such as severe fatigue.

Check back the Monday of each week for the next installment in this series.


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