parasympathetic activation – American ME and CFS Society

Autonomic dysregulation in long-term patients suffering from Post-COVID-19 Syndrome assessed by heart rate variability

Abstract:

Post-COVID-19 Syndrome (PCS) is a condition with multiple symptoms partly related to dysregulation of the autonomic nerve system. Assessment of heart rate variability (HRV) using 24 h Holter-ECG may serve as a surrogate to characterize cardiac autonomic activity. A prospective study including 103 PCS patients (time after infection = 252 days, age = 49.0 ± 11.3 years, 45.7% women) was performed and patients underwent detailed clinical screening, cardiopulmonary exercise testing, and 24 h Holter monitoring.

Data of PCS patients was compared to 103 CAD patients and a healthy control group (n = 90). After correction for age and sex, frequency-related variables differed in PCS patients compared to controls including LF/HFpower, LF/HFnu, and LF/HF ratio (24 h; p ≤ 0.001). By contrast, these variables were largely comparable between PCS and CAD patients, while sympathetic activation was highest in PCS patients during the 24 h period.

Overall, PCS patients showed disturbed diurnal adjustment of HRV, with impaired parasympathetic activity at night. Patients hospitalized during acute infection showed an even more pronounced overactivation of sympathetic activity compared to patients who underwent ambulant care.

Our data demonstrate persistent HRV alterations in PCS patients with long-term symptom duration, suggesting a sustained impairment of sympathovagal balance. Moreover, sympathetic overstimulation and diminished parasympathetic response in long-term PCS patients are comparable to findings in CAD patients. Whether HRV variables have a prognostic value in PCS and/or might serve as biomarkers indicating a successful interventional approach warrants further longitudinal studies.

Source: Mooren FC, Böckelmann I, Waranski M, Kotewitsch M, Teschler M, Schäfer H, Schmitz B. Autonomic dysregulation in long-term patients suffering from Post-COVID-19 Syndrome assessed by heart rate variability. Sci Rep. 2023 Sep 22;13(1):15814. doi: 10.1038/s41598-023-42615-y. PMID: 37739977; PMCID: PMC10516975. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10516975/ (Full text)

Childhood trauma as a risk factor for a dysfunctional heart rate variability in patients with CFS/ME

Background: Myalgic encephalomyelitis, also called Chronic Fatigue Syndrome or ME/CFS, is a severe and complex multisystemic disease with a heterogenous combination of symptoms. Studies have shown decreased heart rate variability (HRV) in this population. Moreover, there is a growing body of evidence showing high levels of childhood trauma (CHT) among ME/CFS patients. Traumatic experiences in childhood are linked to a decreased HRV. Specially, emotional traumatization impacts HRV. The present study investigates HRV in the context of CHT in a ME/CFS population.

Methods 37 patients diagnosed with ME/CFS participated in this study. Demographic-, clinical data, the degree of disability, and RMSSD parameters of HRV were extracted from patient records. HRV data was gathered over 30 minutes whilst in supine position. CHT was administered using the Childhood Trauma Questionnaire-Short Form. Disability was assessed using the Bell Disability Scale. Multiple regression analyses were conducted using the CHT total scores and emotional abuse and emotional neglect subscales in relation to HRV.

Results Variables / Research Materials Data / Observations Results • Fig.5 HRV in the Monitoring compare the interaction between VNS Sympathic Frequency (LF 0.04-0.15) and Parasympathic Frequency (HF 0.15-0.50) in four stages: Orthostatic Schellong Test, start of the Monitoring in lying down position, Middle section after 15 Minutes and after 30 Minutes. • Box-Plot Data shows the most fluctuation of Sympathic in the middle section. The highest scores and fluctuation which appear of Parasympathic activity is in the beginning of the measurement.

Conclusion • In sum, the results of the study suggest that CHT is more prevalent in ME/CFS populations. However, an effect of childhood trauma on HRV function and disability could not be demonstrated in this sample. The findings indicate that the underlying pathophysiologic mechanism of CHT in ME/CFS are more complex and not expressed in HRV. Future studies should include additional aspects and examine the impact of childhood trauma by looking at other biological systems affected in ME/CFS.

Works Cited • Cohen, J. (1988) Statistical power analysis for the behavioral sciences, New York second edition.

Source: Ziaja, Christof, Young, Susanne, Sadre Chirazi – Stark, Michael.Childhood trauma as a risk factor for a dysfunctional heart rate variability in patients with CFS/ME. 2023/05/24 DOI:10.13140/RG.2.2.17700.65929 https://www.researchgate.net/publication/370987476_Childhood_trauma_as_a_risk_factor_for_a_dysfunctional_heart_rate_variability_in_patients_with_CFSME

Parasympathetic autonomic dysfunction is more often evidenced than sympathetic autonomic dysfunction in fluctuating and polymorphic symptoms of “long-COVID” patients

Abstract:

Several disabling symptoms potentially related to dysautonomia have been reported in “long-COVID” patients. Unfortunately, these symptoms are often nonspecific, and autonomic nervous system explorations are rarely performed in these patients. This study aimed to evaluate prospectively a cohort of long-COVID patients presenting severe disabling and non-relapsing symptoms of potential dysautonomia and to identify sensitive tests.

Autonomic function was assessed by clinical examination, the Schirmer test; sudomotor evaluation, orthostatic blood pressure (BP) variation, 24-h ambulatory BP monitoring for sympathetic evaluation, and heart rate variation during orthostatism, deep breathing and Valsalva maneuvers for parasympathetic evaluation. Test results were considered abnormal if they reached the lower thresholds defined in publications and in our department. We also compared mean values for autonomic function tests between patients and age-matched controls.

Sixteen patients (median age 37 years [31–43 years], 15 women) were included in this study and referred 14.5 months (median) [12.0–16.5 months] after initial infection. Nine had at least one positive SARS-CoV-2 RT-PCR or serology result. Symptoms after SARS-CoV-2 infection were severe, fluctuating and disabling with effort intolerance. Six patients (37.5%) had one or several abnormal test results, affecting the parasympathetic cardiac function in five of them (31%). Mean Valsalva score was significantly lower in patients than in controls.

In this cohort of severely disabled long-COVID patients, 37.5% of them had at least one abnormal test result showing a possible contribution of dysautonomia to these nonspecific symptoms. Interestingly, mean values of the Valsalva test were significantly lower in patients than in control subjects, suggesting that normal values thresholds might not be appropriate in this population.

Source: Zanin, A., Amah, G., Chakroun, S. et al. Parasympathetic autonomic dysfunction is more often evidenced than sympathetic autonomic dysfunction in fluctuating and polymorphic symptoms of “long-COVID” patients. Sci Rep 13, 8251 (2023). https://doi.org/10.1038/s41598-023-35086-8 https://www.nature.com/articles/s41598-023-35086-8 (Full text)

Cardiac Autonomic Function in Long COVID-19 Using Heart Rate Variability: An Observational Cross-Sectional Study

Abstract:

Background: Heart rate variability is a non-invasive, measurable, and established autonomic nervous system test. Long-term COVID-19 sequelae are unclear; however, acute symptoms have been studied.

Objectives: To determine autonomic cardiac differences between long COVID-19 patients and healthy controls and evaluate associations among symptoms, comorbidities, and laboratory findings.

Methods: This single-center study included long COVID-19 patients and healthy controls. The heart rate variability (HRV), a quantitative marker of autonomic activity, was monitored for 24 h using an ambulatory electrocardiogram system. HRV indices were compared between case and control groups. Symptom frequency and inflammatory markers were evaluated. A significant statistical level of 5% (p-value 0.05) was adopted.

Results: A total of 47 long COVID-19 patients were compared to 42 healthy controls. Patients averaged 43.8 (SD14.8) years old, and 60.3% were female. In total, 52.5% of patients had moderate illness. Post-exercise dyspnea was most common (71.6%), and 53.2% lacked comorbidities. CNP, D-dimer, and CRP levels were elevated (p-values of 0.0098, 0.0023, and 0.0015, respectively). The control group had greater SDNN24 and SDANNI (OR = 0.98 (0.97 to 0.99; p = 0.01)). Increased low-frequency (LF) indices in COVID-19 patients (OR = 1.002 (1.0001 to 1.004; p = 0.030)) and high-frequency (HF) indices in the control group (OR = 0.987 (0.98 to 0.995; p = 0.001)) were also associated.

Conclusions: Patients with long COVID-19 had lower HF values than healthy individuals. These variations are associated with increased parasympathetic activity, which may be related to long COVID-19 symptoms and inflammatory laboratory findings.

Source: Menezes Junior ADS, Schröder AA, Botelho SM, Resende AL. Cardiac Autonomic Function in Long COVID-19 Using Heart Rate Variability: An Observational Cross-Sectional Study. J Clin Med. 2022 Dec 22;12(1):100. doi: 10.3390/jcm12010100. PMID: 36614901; PMCID: PMC9821736. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9821736/ (Full text)

Autonomic Nervous System Regulation Effects of Epipharyngeal Abrasive Therapy for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Associated With Chronic Epipharyngitis

Abstract:

Objective: To evaluate the autonomic nerve stimulation effect of epipharyngeal abrasive therapy (EAT) on myalgic encephalomyelitis/chronic fatigue syndrome (CFS) associated with chronic epipharyngitis. Heart rate variability analysis was performed. The study was conducted by analyzing heart rate variability.

Subjects and methods: A total of 29 patients with chronic epipharyngitis who underwent EAT from July 2017 to April 2018 were classified into two groups: 11 patients in the CFS group and 18 patients in the control group without CFS. The patients were classified as phase 1 during bed rest, phase 2 during nasal endoscopy, phase 3 during nasal abrasion, and phase 4 during oral abrasion. Electrocardiographic recordings were made, and autonomic function was compared and evaluated by measuring heart rate, coefficient of variation on R-R interval (CVRR), coefficient of component variance high frequency (ccvHF), and low frequency/ccvHF ratio (L/H) for each of the four phases. The Shapiro-Wilk test was performed to confirm the normality of the two groups, and the parametric test was selected. A repeated measures analysis of variance was performed to assess changes over time between the four events in the two groups. Multiple comparisons were corrected by the Bonferroni method. Comparisons between resting data and three events within each group were performed by paired t-test.

Results: The CFS group had an increased baseline heart rate compared to the control group, and the CFS group had a greater increase in parasympathetic activity and a decrease in heart rate with nasal abrasion. Oral abrasion elicited a pharyngeal reflex and increased heart rate and both sympathetic and parasympathetic activity.

Conclusion: The CFS group was in a state of dysautonomia due to autonomic overstimulation, with an elevated baseline heart rate. The CFS group was considered to be in a state of impaired autonomic homeostasis, with an increased likelihood that overstimulation would induce a pathological vagal reflex and the Reilly phenomenon would develop. The direct effects of EAT on the autonomic nervous system were considered to be vagus nerve stimulation and the regulation of autonomic function by opposing stimulation input to sympathetic and parasympathetic nerves. As an indirect effect, bleeding from the epipharyngeal mucosa due to abrasion was thought to restore the function of the cerebral venous and lymphatic excretory systems and the autonomic nerve center.

Source: Hirobumi I. Autonomic Nervous System Regulation Effects of Epipharyngeal Abrasive Therapy for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Associated With Chronic Epipharyngitis. Cureus. 2023 Jan 14;15(1):e33777. doi: 10.7759/cureus.33777. PMID: 36655156; PMCID: PMC9840732. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9840732/ (Full text)

Investigating the possible mechanisms of autonomic dysfunction post-COVID-19

Abstract:

Patients with long COVID suffer from many neurological manifestations that persist for 3 months following infection by SARS-CoV-2. Autonomic dysfunction (AD) or dysautonomia is one complication of long COVID that causes patients to experience fatigue, dizziness, syncope, dyspnea, orthostatic intolerance, nausea, vomiting, and heart palpitations. The pathophysiology behind AD onset post-COVID is largely unknown. As such, this review aims to highlight the potential mechanisms by which AD occurs in patients with long COVID.

The first proposed mechanism includes the direct invasion of the hypothalamus or the medulla by SARS-CoV-2. Entry to these autonomic centers may occur through the neuronal or hematogenous routes. However, evidence so far indicates that neurological manifestations such as AD are caused indirectly.

Another mechanism is autoimmunity whereby autoantibodies against different receptors and glycoproteins expressed on cellular membranes are produced. Additionally, persistent inflammation and hypoxia can work separately or together to promote sympathetic overactivation in a bidirectional interaction. Renin-angiotensin system imbalance can also drive AD in long COVID through the downregulation of relevant receptors and formation of autoantibodies. Understanding the pathophysiology of AD post-COVID-19 may help provide early diagnosis and better therapy for patients.

Source: Jammoul M, Naddour J, Madi A, Reslan MA, Hatoum F, Zeineddine J, Abou-Kheir W, Lawand N. Investigating the possible mechanisms of autonomic dysfunction post-COVID-19. Auton Neurosci. 2022 Dec 24;245:103071. doi: 10.1016/j.autneu.2022.103071. Epub ahead of print. PMID: 36580747; PMCID: PMC9789535. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9789535/ (Full text)

Reduced Parasympathetic Reactivation during Recovery from Exercise in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Although autonomic nervous system (ANS) dysfunction in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) has been proposed, conflicting evidence makes it difficult to draw firm conclusions regarding ANS activity at rest in ME/CFS patients. Although severe exercise intolerance is one of the core features of ME/CFS, little attempts have been made to study ANS responses to physical exercise. Therefore, impairments in ANS activation at rest and following exercise were examined using a case-control study in 20 ME/CFS patients and 20 healthy people.

Different autonomous variables, including cardiac, respiratory, and electrodermal responses were assessed at rest and following an acute exercise bout. At rest, parameters in the time-domain represented normal autonomic function in ME/CFS, while frequency-domain parameters indicated the possible presence of diminished (para)sympathetic activation. Reduced parasympathetic reactivation during recovery from exercise was observed in ME/CFS.

This is the first study showing reduced parasympathetic reactivation during recovery from physical exercise in ME/CFS. Delayed HR recovery and/or a reduced HRV as seen in ME/CFS have been associated with poor disease prognosis, high risk for adverse cardiac events, and morbidity in other pathologies, implying that future studies should examine whether this is also the case in ME/CFS and how to safely improve HR recovery in this population.

Source: Van Oosterwijck J, Marusic U, De Wandele I, Meeus M, Paul L, Lambrecht L, Moorkens G, Danneels L, Nijs J. Reduced Parasympathetic Reactivation during Recovery from Exercise in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. J Clin Med. 2021 Sep 30;10(19):4527. doi: 10.3390/jcm10194527. PMID: 34640544; PMCID: PMC8509376. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8509376/ (Full text)

The Role of Autonomic Function in Exercise-induced Endogenous Analgesia: A Case-control Study in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Healthy People

Abstract:

Background: Patients with myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) are unable to activate brain-orchestrated endogenous analgesia (or descending inhibition) in response to exercise. This physiological impairment is currently regarded as one factor explaining post-exertional malaise in these patients. Autonomic dysfunction is also a feature of ME/CFS.

Objectives: This study aims to examine the role of the autonomic nervous system in exercise-induced analgesia in healthy people and those with ME/CFS, by studying the recovery of autonomic parameters following aerobic exercise and the relation to changes in self-reported pain intensity.

Study design: A controlled experimental study.

Setting: The study was conducted at the Human Physiology lab of a University.

Methods: Twenty women with ME/CFS- and 20 healthy, sedentary controls performed a submaximal bicycle exercise test known as the Aerobic Power Index with continuous cardiorespiratory monitoring. Before and after the exercise, measures of autonomic function (i.e., heart rate variability, blood pressure, and respiration rate) were performed continuously for 10 minutes and self-reported pain levels were registered. The relation between autonomous parameters and self-reported pain parameters was examined using correlation analysis.

Results: Some relationships of moderate strength between autonomic and pain measures were found. The change (post-exercise minus pre-exercise score) in pain severity was correlated (r = .580, P = .007) with the change in diastolic blood pressure in the healthy group. In the ME/CFS group, positive correlations between the changes in pain severity and low frequency (r = .552, P = .014), and between the changes in bodily pain and diastolic blood pressure (r = .472, P = .036), were seen. In addition, in ME/CHFS the change in headache severity was inversely correlated (r = -.480, P = .038) with the change in high frequency heart rate variability.

Limitations: Based on the cross-sectional design of the study, no firm conclusions can be drawn on the causality of the relations.

Conclusions: Reduced parasympathetic reactivation during recovery from exercise is associated with the dysfunctional exercise-induced analgesia in ME/CFS. Poor recovery of diastolic blood pressure in response to exercise, with blood pressure remaining elevated, is associated with reductions of pain following exercise in ME/CFS, suggesting a role for the arterial baroreceptors in explaining dysfunctional exercise-induced analgesia in ME/CFS patients.

Source: Oosterwijck JV, Marusic U, De Wandele I, Paul L, Meeus M, Moorkens G, Lambrecht L, Danneels L, Nijs J. The Role of Autonomic Function in Exercise-induced Endogenous Analgesia: A Case-control Study in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Healthy People. Pain Physician. 2017 Mar;20(3):E389-E399. PMID: 28339438. https://www.painphysicianjournal.com/linkout?issn=&vol=20&page=E389 (Full text)

Reduced Parasympathetic Reactivation during Recovery from Exercise in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Parasympathetic activity is reduced during slow-wave sleep, but not resting wakefulness, in patients with chronic fatigue syndrome

Abstract:

STUDY OBJECTIVES: Physiological dearousal characterized by an increase in parasympathetic nervous system activity is important for good-quality sleep. Previous research shows that nocturnal parasympathetic activity (reflected by heart rate variability [HRV]) is diminished in individuals with chronic fatigue syndrome (CFS), suggesting hypervigilant sleep. This study investigated differences in nocturnal autonomic activity across sleep stages and explored the association of parasympathetic activity with sleep quality and self-reported physical and psychological wellbeing in individuals with CFS.

METHODS: Twenty-four patients with medically diagnosed CFS, and 24 matched healthy control individuals participated. Electroencephalography and HRV were recorded during sleep in participants’ homes using a minimally invasive ambulatory device. Questionnaires were used to measure self-reported wellbeing and sleep quality.

RESULTS: Sleep architecture in patients with CFS differed from that of control participants in slower sleep onset, more awakenings, and a larger proportion of time spent in slow-wave sleep (SWS). Linear mixed-model analyses controlling for age revealed that HRV reflecting parasympathetic activity (normalized high frequency power) was reduced in patients with CFS compared to control participants, particularly during deeper stages of sleep. Poorer self-reported wellbeing and sleep quality was associated with reduced parasympathetic signaling during deeper sleep, but not during wake before sleep, rapid eye movement sleep, or with the proportion of time spent in SWS.

CONCLUSIONS: Autonomic hypervigilance during the deeper, recuperative stages of sleep is associated with poor quality sleep and self-reported wellbeing. Causal links need to be confirmed but provide potential intervention opportunities for the core symptom of unrefreshing sleep in CFS.

Source: Fatt SJ, Beilharz JE, Joubert M, Wilson C, Lloyd AR, Vollmer-Conna U, Cvejic E. Parasympathetic activity is reduced during slow-wave sleep, but not resting wakefulness, in patients with chronic fatigue syndrome. J Clin Sleep Med. 2020 Jan 15;16(1):19-28. doi: 10.5664/jcsm.8114. Epub 2019 Nov 27. https://www.ncbi.nlm.nih.gov/pubmed/31957647