ME/CFS Evidence Browser — Classified Studies on Myalgic Encephalomyelitis

241–260 of 360 studies

E2 ModerateCohortPEM not requiredCase-Control

Pathogenesis and management of delayed orthostatic hypotension in patients with chronic fatigue syndrome.

De Lorenzo, F, Hargreaves, J, Kakkar, V V·Clinical autonomic research : official journal of the Clinical Autonomic Research Society·1997

Some ME/CFS patients experience dizziness or fainting when standing up, a condition called orthostatic hypotension. This study tested whether salt supplements could help 22 ME/CFS patients with this symptom. After 8 weeks, salt helped 11 patients feel better, but 10 patients' symptoms returned—and those 10 had lower levels of a hormone called renin that helps regulate blood pressure.

Autonomic Nervous System

E2 ModerateCohortPEM not requiredCross-Sectional

Comparison of heart rate variability in patients with chronic fatigue syndrome and controls.

Yataco, A, Talo, H, Rowe, P et al.·Clinical autonomic research : official journal of the Clinical Autonomic Research Society·1997

Researchers tested whether ME/CFS patients have problems with their autonomic nervous system (the system that automatically controls heart rate, blood pressure, and other vital functions). They measured heart rate variability—natural variations in heart rate—in ME/CFS patients and healthy controls while lying down and standing up. They found that the heart rate patterns were similar between the two groups both at rest and when standing, suggesting that basic autonomic function may not be obviously different in ME/CFS.

Autonomic Nervous System

E2 ModerateCohortPEM not requiredCross-Sectional

Does the chronic fatigue syndrome involve the autonomic nervous system?

Freeman, R, Komaroff, A L·The American journal of medicine·1997

This study tested whether ME/CFS patients have problems with their autonomic nervous system—the part of the nervous system that controls automatic functions like heart rate and blood pressure. Researchers found that ME/CFS patients had abnormal heart rate and blood pressure responses during standing and tilting tests, and their nervous system wasn't regulating these responses properly. The findings suggest that either deconditioning from reduced activity, a viral infection damaging the nervous system, or both could explain why many ME/CFS patients feel dizzy or faint when standing up.

Autonomic Nervous System

E2 ModerateCohortPEM unclearCross-Sectional

An investigation of sympathetic hypersensitivity in chronic fatigue syndrome.

Sendrowski, D P, Buker, E A, Gee, S S·Optometry and vision science : official publication of the American Academy of Optometry·1997

Researchers tested whether ME/CFS patients have unusually sensitive nerves that control pupil size, similar to what is seen in fibromyalgia. They applied eye drops to 29 ME/CFS patients and 33 healthy controls and measured how much the pupils dilated. The results showed no significant difference between the two groups, suggesting that ME/CFS patients do not have this type of nerve sensitivity.

Autonomic Nervous System

E2 ModerateCohortPEM not requiredCase-Control

The relationship between neurally mediated hypotension and the chronic fatigue syndrome.

Bou-Holaigah, I, Rowe, P C, Kan, J et al.·JAMA·1995

Researchers tested whether ME/CFS patients have an abnormal blood pressure response when standing upright. They tilted 23 ME/CFS patients and 14 healthy controls on a special table and monitored their vital signs. Nearly all ME/CFS patients showed an abnormal response, and about 9 patients felt much better after taking medications to treat low blood pressure.

Autonomic Nervous System

E2 ModerateCohortPEM not requiredCross-Sectional

Vagal tone is reduced during paced breathing in patients with the chronic fatigue syndrome.

Sisto, S A, Tapp, W, Drastal, S et al.·Clinical autonomic research : official journal of the Clinical Autonomic Research Society·1995

This study looked at how the vagus nerve—which helps control heart rate and relaxation—works differently in people with ME/CFS compared to healthy people. Researchers had women with ME/CFS and healthy women breathe at different controlled rates while measuring their heart rate patterns. They found that people with ME/CFS had weaker vagal nerve activity overall, suggesting their nervous system may not be able to relax and recover as effectively as healthy people's.

Autonomic Nervous System

E2 ModerateCohortPEM not requiredCross-Sectional

Sympathetic overactivity in subjects complaining of unexplained fatigue.

Pagani, M, Lucini, D, Mela, G S et al.·Clinical science (London, England : 1979)·1994

This study examined how the nervous system controls heart rate in people with unexplained fatigue compared to healthy people. Using heart rate recordings, researchers found that fatigue patients showed an imbalance in their autonomic nervous system—specifically, the part that triggers the "fight or flight" response was overactive while the calming part was underactive, even at rest.

Autonomic Nervous System

E3 PreliminaryReviewPEM not requiredReview-Narrative

Cerebral Blood Flow in Orthostatic Intolerance.

Khan, Muhammad Shahzeb, Miller, Amanda J, Ejaz, Arooba et al.·Journal of the American Heart Association·2025

When you stand up, your body normally adjusts blood flow to keep your brain supplied with oxygen. Some people have problems with this adjustment, causing dizziness, fatigue, or fainting—a condition called orthostatic intolerance. This review explains that many ME/CFS and long COVID patients have reduced blood flow to the brain when standing, even though their heart rate and blood pressure look normal on standard tests. The authors review different tools doctors can use to actually measure brain blood flow, rather than just relying on heart rate and blood pressure readings.

Autonomic Nervous System

E3 PreliminaryPEM unclear

Inspiratory muscle training improves autonomic function in myalgic encephalomyelitis/chronic fatigue syndrome and post-acute sequelae of SARS-CoV-2: A pilot study.

Edgell, Heather, Pereira, Tania J, Kerr, Kathleen et al.·Respiratory physiology & neurobiology·2025

This study tested whether a simple breathing exercise program could help people with ME/CFS and Long COVID feel better. For 8 weeks, participants practiced strengthening their breathing muscles. People in all groups—including those with ME/CFS and Long COVID—showed improvements in how far they could walk, their heart rate, sleep quality, and how their nervous system functioned. Those with ME/CFS also noticed less pain and better blood vessel function.

SleepAutonomic Nervous System

E3 PreliminaryPEM unclear

Static and Kinetic Disequilibrium are Central Neural Signs in Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome-Therapeutic Effect of Repetitive Transcranial Magnetic Stimulation.

Miwa, Kunihisa·Journal of integrative neuroscience·2025

This study found that nearly half of ME/CFS patients experience balance problems—either when standing still (static disequilibrium) or when walking (kinetic disequilibrium). These balance issues were linked to difficulty standing upright and limitations in daily activities. When researchers used a brain stimulation treatment called repetitive transcranial magnetic stimulation (rTMS) on specific brain regions, most patients' balance problems improved, suggesting the root cause is in the central nervous system rather than the inner ear alone.

Autonomic Nervous System

E3 PreliminaryMechanismPEM unclearObservational

Effects of recumbent isometric yoga on the orthostatic cardiovascular response of patients with myalgic encephalomyelitis/chronic fatigue syndrome.

Oka, Takakazu, Lkhagvasuren, Battuvshin·BioPsychoSocial medicine·2025

This small study looked at whether a gentle yoga practice done while lying down could help ME/CFS patients who experience dizziness or fast heartbeats when standing up (a condition called POTS). Ten women with ME/CFS practiced this special yoga for 12 weeks, and the researchers measured their blood pressure and heart rate before and after standing. The two patients who had POTS at the start showed improvement and had normal responses after the yoga practice.

Autonomic Nervous System

E3 PreliminaryCohortPEM unclearCase-Control

Improvement in Upper Limb and Systemic Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) Symptoms After Surgical Treatment of Neurogenic Thoracic Outlet Syndrome.

Christoforou, Maritsa E, Lum, Ying Wei, Sroge, Sally C et al.·Cureus·2025

This case study describes a 19-year-old woman with ME/CFS who also had a condition called thoracic outlet syndrome (TOS), where nerves in the upper chest become compressed. After surgery to relieve this compression on both sides of her body, she experienced not only relief from arm numbness and tingling, but also surprising improvements in migraines, brain fog, dizziness, and vision problems. This suggests that some ME/CFS patients might benefit from being evaluated for TOS, as treating it could potentially help with multiple symptoms.

Autonomic Nervous SystemCognitive Impairment

E3 PreliminaryCohortPEM unclearCase-Control

Beneficial effects of intermittent intravenous saline infusion in dysautonomic patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: a case-series.

Sjögren, Per, Huhmar, Helena, Bertilson, Bo C et al.·Frontiers in neurology·2025

This small study tested whether giving patients with ME/CFS regular salt water infusions through an IV could help with symptoms like dizziness and rapid heartbeat when standing up. Twenty-two patients received these infusions every three weeks for 9 weeks, and most reported feeling better, with improvements in symptom scores, quality of life, and ability to work. While the results were encouraging, this was a preliminary study without a control group, so more research is needed to confirm whether this treatment actually works.

Autonomic Nervous System

E3 PreliminaryReviewPEM unclearReview-Narrative

[Modern approaches to diagnosis and treatment of postinfectious asthenic syndrome in children].

Nemkova, S A·Zhurnal nevrologii i psikhiatrii imeni S.S. Korsakova·2025

This review article discusses postinfectious asthenic syndrome—a condition causing severe tiredness and weakness that develops after infections like colds, flu, and COVID-19 in children and teenagers. The authors examine how this condition develops, its symptoms, and how a medication called Mexidol may help reduce fatigue and improve thinking, mood, and nervous system problems that often accompany it.

Autonomic Nervous SystemCognitive Impairment

E3 PreliminaryMechanismPEM unclearObservational

Pyridostigmine improves hand grip strength in patients with myalgic encephalomyelitis/chronic fatigue syndrome.

Schlömer, Ella, Stein, Elisa, Kedor, Claudia et al.·Frontiers in neuroscience·2025

This small study tested whether a medication called pyridostigmine could help ME/CFS patients recover hand grip strength after exertion. Twenty patients with ME/CFS showed significant muscle weakness and fatigue. When given pyridostigmine, their hand strength improved by about 2.6 kg after one hour, compared to a loss of 4.65 kg without the medication. The medication also appeared to help with blood pressure responses when standing up.

Autonomic Nervous System

E3 PreliminaryCohortPEM not requiredCase-Control

Monitoring of cardiorespiratory vagal desynchrony using novel biomarkers derived from smartwatch electrocardiograms in a patient recovering from long COVID: case report.

Kranck, Gustaf, Ståhlberg, Marcus, Andersson, Ulf et al.·European heart journal. Case reports·2025

Researchers tracked one long COVID patient over time using a smartwatch to record heart activity while he was sitting and standing. They noticed that when his fatigue improved, his heart's electrical patterns also normalized, suggesting smartwatch recordings could help monitor autonomic dysfunction (when the nervous system struggles to control heart rate and blood pressure). This simple at-home method may offer a practical way for patients to track their own recovery.

Autonomic Nervous System

E3 PreliminaryMechanismPEM unclearCross-Sectional

Autonomic phenotyping, brain blood flow control, and cognitive-motor-integration in Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome: A pilot study.

Badhwar, Smriti, Pereira, Tania J, Kerr, Kathleen et al.·Autonomic neuroscience : basic & clinical·2025

This study compared how the nervous systems of ME/CFS patients, Long COVID patients, and healthy people respond to physical stress tests like breathing different air mixtures and tilting upright. The researchers found that ME/CFS and Long COVID patients had different patterns of problems: ME/CFS patients showed difficulty controlling blood flow to the brain during one test, which was linked to coordination problems, while Long COVID patients had lower oxygen levels when upright and their nervous systems didn't adapt as well.

Autonomic Nervous SystemCognitive Impairment

E3 PreliminaryReviewPEM not requiredReview-Narrative

Cardiac Geometry and Function in Patients with Reflex Syncope.

Coseriu, Giorgia, Schiop-Tentea, Patricia, Apetrei, Csilla-Andrea et al.·Journal of clinical medicine·2024

This review examines how the size and function of the heart relate to fainting episodes in people with reflex syncope. Researchers found that people with smaller hearts and very forceful heartbeats are more prone to fainting, and this pattern is also seen in some people with chronic fatigue syndrome. Understanding these heart differences may help doctors predict who will faint again and choose better treatments.

Autonomic Nervous System

E3 PreliminaryReviewPEM unclearReview-Narrative

Dysautonomia following Lyme disease: a key component of post-treatment Lyme disease syndrome?

Adler, Brittany L, Chung, Tae, Rowe, Peter C et al.·Frontiers in neurology·2024

This review examines how Lyme disease can damage the autonomic nervous system—the part of your nervous system that controls automatic body functions like heart rate, blood pressure, and digestion. The authors argue that this autonomic dysfunction may explain why some people with Lyme disease develop persistent, widespread symptoms similar to those seen in ME/CFS and long COVID. They review existing evidence and propose possible mechanisms for how the Lyme disease bacteria might cause these ongoing problems.

Autonomic Nervous System

E3 PreliminaryReviewPEM not requiredReview-Narrative

The interplay between Sars-Cov-2 infection related cardiovascular diseases and depression. Common mechanisms, shared symptoms.

Gonjilashvili, Ana, Tatishvili, Sophio·American heart journal plus : cardiology research and practice·2024

This review examines how COVID-19 can affect both the heart and mental health, and why these problems often occur together. The authors explain that inflammation, unhealthy lifestyle changes, and communication between organs may all play a role. They note that long COVID shares many symptoms with heart and brain problems—like fatigue, brain fog, dizziness, chest pain, and depression—which is why patients need care from multiple medical specialists.

Autonomic Nervous SystemCognitive Impairment

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Pathogenesis and management of delayed orthostatic hypotension in patients with chronic fatigue syndrome.

Comparison of heart rate variability in patients with chronic fatigue syndrome and controls.

Does the chronic fatigue syndrome involve the autonomic nervous system?

An investigation of sympathetic hypersensitivity in chronic fatigue syndrome.

The relationship between neurally mediated hypotension and the chronic fatigue syndrome.

Vagal tone is reduced during paced breathing in patients with the chronic fatigue syndrome.

Sympathetic overactivity in subjects complaining of unexplained fatigue.

Cerebral Blood Flow in Orthostatic Intolerance.

Inspiratory muscle training improves autonomic function in myalgic encephalomyelitis/chronic fatigue syndrome and post-acute sequelae of SARS-CoV-2: A pilot study.

Static and Kinetic Disequilibrium are Central Neural Signs in Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome-Therapeutic Effect of Repetitive Transcranial Magnetic Stimulation.

Effects of recumbent isometric yoga on the orthostatic cardiovascular response of patients with myalgic encephalomyelitis/chronic fatigue syndrome.

Improvement in Upper Limb and Systemic Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) Symptoms After Surgical Treatment of Neurogenic Thoracic Outlet Syndrome.

Beneficial effects of intermittent intravenous saline infusion in dysautonomic patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: a case-series.

[Modern approaches to diagnosis and treatment of postinfectious asthenic syndrome in children].

Pyridostigmine improves hand grip strength in patients with myalgic encephalomyelitis/chronic fatigue syndrome.

Monitoring of cardiorespiratory vagal desynchrony using novel biomarkers derived from smartwatch electrocardiograms in a patient recovering from long COVID: case report.

Autonomic phenotyping, brain blood flow control, and cognitive-motor-integration in Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome: A pilot study.

Cardiac Geometry and Function in Patients with Reflex Syncope.

Dysautonomia following Lyme disease: a key component of post-treatment Lyme disease syndrome?

The interplay between Sars-Cov-2 infection related cardiovascular diseases and depression. Common mechanisms, shared symptoms.

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