Tag: dysautonomia

Post-COVID-19 Syndrome: A Novel Diagnosis

Abstract:

Patients with post-COVID-19 syndrome have reported a wide array of symptoms that include autonomic dysfunction. It is hypothesized that this may be secondary to interruption of baroreflex pathways in the carotid arteries or nucleus tractus solitarius, however, confirming studies have yet to be performed. A limited number of studies have highlighted the presence of an exaggerated baroreflex response in patients with a post-COVID-19 syndrome that mirror other chronic autonomic dysfunction-related conditions.

Source: Kalia R, Kalia R, Musih J, Cubelo M, Popat J. Post-COVID-19 Syndrome: A Novel Diagnosis. Cureus. 2022 Aug 22;14(8):e28266. doi: 10.7759/cureus.28266. PMID: 36158335; PMCID: PMC9491485. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9491485/ (Full text)

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Post-COVID Syndrome: A Common Neuroimmune Ground?

Abstract:

A Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating chronic disease of unknown aetiology under growing interest now in view of the increasingly recognized post-COVID syndrome as a new entity with similar clinical presentation.

We performed the first cross-sectional study of ME/CFS in community population in Russia and then described and compared some clinical and pathophysiological characteristics of ME/CFS and post-COVID syndrome as neuroimmune disorders.

Of the cohort of 76 individuals who suggested themselves suffering from ME/CFS 56 subsequently were confirmed as having CFS/ME according to ≥1 of the 4 most commonly used case definition.

Of the cohort of 14 individuals with post-COVID-19 syndrome 14 met diagnostic criteria for ME/CFS. The prevalence of clinically expressed and subclinical anxiety and depression in ME / CFS and post-COVID ME/CFS did not differ significantly from that in healthy individuals.

Severity of anxiety / depressive symptoms did not correlate with the severity of fatigue neigther in ME / CFS nor in post-COVID ME/CFS, but the positive correlation was found between the severity of fatigue and 20 other symptoms of ME / CFS related to the domains of “post-exertional exhaustion”, “immune dysfunction”, “sleep disturbances”, “dysfunction of the autonomic nervous system”, “neurological sensory / motor disorders” and “pain syndromes”.

Immunological abnormalities were identified in 12/12 patients with ME / CFS according to the results of laboratory testing.

The prevalence of postural orthostatic tachycardia assessed by the active standing test was 37.5% in ME / CFS and 75.0% in post-COVID ME/CFS (the latter was higher than in healthy controls, p = 0.02).  There was a more pronounced increase in heart rate starting from the 6th minute of the test in post-COVID ME/CFS compared with the control group.

Assessment of the functional characteristics of microcirculation by laser doppler flowmetry revealed obvious and very similar changes in ME/CFS and post-COVID ME/CFS compared to the healthy controls.  The identified pattern corresponded to the hyperemic form of microcirculation disorders, usually observed in acute inflammatory processes or in deficiency of systemic vasoconstriction influences.

Source: Ryabkova, V.A.; Gavrilova, N.Y.; Fedotkina, T.V.; Churilov, L.P.; Shoenfeld, Y. Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Post-COVID Syndrome: A Common Neuroimmune Ground?. Preprints 2022, 2022090289 (doi: 10.20944/preprints202209.0289.v1) https://www.preprints.org/manuscript/202209.0289/v1 (Full study available as PDF file)

Circadian skin temperature rhythm and dysautonomia in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: the role of endothelin-1 in the vascular dysregulation

Abstract:

Purpose: There is accumulating evidence of autonomic dysfunction in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS); however, little is known about its association with circadian rhythms and endothelial dysfunction. This study aimed to explore the relationship between autonomic responses using an orthostatic test, skin temperature circadian variations, and circulating endothelial biomarkers in ME/CFS.

Methods: Sixty-seven adult female ME/CFS patients and 48 matched healthy controls were enrolled. Demographic and clinical characteristics suggestive of autonomic disturbances were assessed using validated self-reported outcome measures. Postural changes in blood pressure [BP], heart rate [HR], and wrist temperature (WT) were recorded during the orthostatic test. Actigraphy during one week was used to determine the 24-hour profile of peripheral temperature and motor activity. Circulating endothelial biomarkers were also measured as indicators of endothelial functioning.

Results: ME/CFS patients showed higher BP and HR values than healthy controls at rest (p < 0.05 for both), and also higher amplitude of the circadian activity rhythm (p < 0.01). Circulating levels of endothelin-1 (ET-1) and vascular cell adhesion molecule-1 (VCAM-1) were significantly higher in ME/CFS (p < 0.05). In ME/CFS, ET-1 levels were associated with the stability and amplitude of the temperature rhythm, (p < 0.01), and also with the self-reported questionnaires (p < 0.001).

Conclusions: ME/CFS patients exhibited alterations in circadian rhythms and hemodynamic measures that are associated with endothelial dysfunction, supporting previous evidence of dysautonomia in ME/CFS. Future investigation in this area is needed to assess vascular tone abnormalities and dysautonomia which may provide therapeutic targets for ME/CFS.

Source: Trinitat Cambras, Maria Fernanda Zerón-Rugerio, Antoni Díez-Noguera et al. Circadian skin temperature rhythm and dysautonomia in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: the role of endothelin-1 in the vascular dysregulation, 21 September 2022, PREPRINT (Version 1) available at Research Square https://doi.org/10.21203/rs.3.rs-2044838/v1 (Full text)

Local anesthetics as a therapeutic tool for post COVID-19 patients: A case report

Abstract:

Background: Post COVID-19 syndrome (PC-19S) appears to be independent of acute illness severity and humoral response. The involvement of the autonomic nervous system (ANS), expressed by dysautonomia, has been hypothesized as a contributor. Several studies have associated the therapeutic effects of local anesthetics (LA) to their action on the ANS. To the best of our knowledge, this is the first report of therapeutic injections with LA linked to clinical improvement in a patient with PC-19S.

Patient concerns and diagnoses: This was a 54-year-old-man with postCOVID-19 symptoms lasting 14 weeks, including fatigue, breathlessness, diarrhea, muscle pain, and emotional lability.

Interventions and outcome: Injections of 0.5% procaine in the stellate ganglion (SG) and sphenopalatine ganglion (SPG), and in clinically relevant points in the scalp, thorax, and abdomen were performed 3 times over 3 months. The patient reported progressive improvement and was asymptomatic upon completing the treatment. Prescribed medications were discontinued. The 36-Item Short Form Health Survey (SF-36) score showed significant improvement across all SF-36-domains.

Conclusion: Subanesthetic doses of LA injected in clinically relevant points led to rapid and complete symptom resolution in this patient with PC-19S. Targeted LA injections may have therapeutic benefits in PC-19S and in other chronic diseases linked to stress and inflammation.

Source: Vinyes D, Muñoz-Sellart M, Caballero TG. Local anesthetics as a therapeutic tool for post COVID-19 patients: A case report. Medicine (Baltimore). 2022 Jul 15;101(28):e29358. doi: 10.1097/MD.0000000000029358. PMID: 35839020. https://journals.lww.com/md-journal/Fulltext/2022/07150/Local_anesthetics_as_a_therapeutic_tool_for_post.33.aspx (Full text)

Chronic Fatigue Exhibits Heterogeneous Autoimmunity Characteristics Which Reflect Etiology

Abstract:

Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is considered to be associated with post-viral complications and mental stress, but the role of autoimmunity also remains promising. A comparison of autoimmune profiles in chronic fatigue of different origin may bring insights on the pathogenesis of this disease.

Thirty-three patients with CFS/ME were divided into three subgroups. The first group included Herpesviridae carriers (group V), the second group included stress-related causes of chronic fatigue (distress, group D), and the third group included idiopathic CFS/ME (group I). Were evaluated thirty-six neural and visceral autoantigens with the ELISA ELI-test (Biomarker, Russia) and compared to 20 healthy donors, either without any fatigue (group H), or “healthy but tired” (group HTd) with episodes of fatigue related to job burnout not fitting the CFS/ME criteria.

β2-glycoprotein-I autoantibodies were increased in CFS/ME patients, but not in healthy participants, that alludes the link between CFS/ME and antiphospholipid syndrome (APS) earlier suspected by Berg et al. (1999). In CFS/ME patients, an increase in levels of autoantibodies towards the non-specific components of tissue debris (double-stranded DNA, collagen) was shown. Both CFS and HTd subgroups had elevated level of autoantibodies against serotonin receptors, glial fibrillary acidic protein and protein S100. Only group V showed an elevation in the autoantibodies towards voltage-gated calcium channels, and only group D had elevated levels of dopamine-, glutamate- and GABA-receptor autoantibodies, as well as NF200-protein autoantibodies.

Therefore, increased autoimmune reactions to the multiple neural antigens and to adrenal medullar antigen, but not to other tissue-specific somatic ones were revealed. An increase in autoantibody levels towards some neural and non-tissue-specific antigens strongly correlated with a CFS/ME diagnosis. Autoimmune reactions were described in all subtypes of the clinically significant chronic fatigue. Visceral complaints in CFS/ME patients may be secondary to the neuroendocrine involvement and autoimmune dysautonomia. CFS may be closely interrelated with antiphospholipid syndrome, that requires further study.

Source: Danilenko OV, Gavrilova NY, Churilov LP. Chronic Fatigue Exhibits Heterogeneous Autoimmunity Characteristics Which Reflect Etiology. Pathophysiology. 2022 May 25;29(2):187-199. doi: 10.3390/pathophysiology29020016. PMID: 35736644.  https://www.mdpi.com/1873-149X/29/2/16/htm (Full text)

Impaired Cardiac Autonomic Control in Women With Fibromyalgia Is Independent of Their Physical Fitness

Abstract:

Background/objective: Evidence has suggested abnormal cardiac autonomic responses to exercise in patients with fibromyalgia (FM). However, it is not clear whether the dysautonomia represents a reduced physical fitness rather directly related to FM pathogenesis. Thus, we aimed to verify the cardiac autonomic responses before, during, and after a maximal incremental exercise in women with FM and whether these hypothesized alterations would be dependent with their physical fitness.

Methods: This is a cross-sectional study with 23 FM women and 17 healthy women. The participants performed a maximal incremental cycling test to determine their maximal workload (Wmax) and were further matched by their Wmax (14 FM patients, Wmax: 128.6 ± 16.2 W; and 14 healthy women, Wmax: 131.9 ± 15.9 W). Beat-to-beat heart rate (HR) was continuously monitored to calculate HR variability indexes at rest, chronotropic reserve during exercise, and HR recovery.

Results: Heart rate variability indexes related to vagal modulation were significantly lower in FM patients than in healthy women (p < 0.05). The chronotropic reserve and the HR recovery at 30, 120, 180, 300, and 600 seconds after exercise were all lower in FM patients compared with those of healthy women (p < 0.05). Similar findings were found when analysis was performed using the matched physical fitness subgroup.

Conclusions: The documented cardiac autonomic abnormalities at rest, during, and after exercise in FM patients persist even when physical fitness status is taken in account. Thus, strategies to attenuate the dysautonomia in FM patients must be considered.

Source: Schamne JC, Ressetti JC, Lima-Silva AE, Okuno NM. Impaired Cardiac Autonomic Control in Women With Fibromyalgia Is Independent of Their Physical Fitness. J Clin Rheumatol. 2021 Sep 1;27(6S):S278-S283. doi: 10.1097/RHU.0000000000001518. PMID: 32826659. https://pubmed.ncbi.nlm.nih.gov/32826659/

Impaired Vagal Activity in Long-COVID-19 Patients

Abstract:

Long-COVID-19 refers to the signs and symptoms that continue or develop after the “acute COVID-19” phase. These patients have an increased risk of multiorgan dysfunction, readmission, and mortality. In Long-COVID-19 patients, it is possible to detect a persistent increase in D-Dimer, NT-ProBNP, and autonomic nervous system dysfunction.

To verify the dysautonomia hypothesis in Long-COVID-19 patients, we studied heart rate variability using 12-lead 24-h ECG monitoring in 30 Long-COVID-19 patients and 20 No-COVID patients. Power spectral analysis of heart rate variability was lower in Long-COVID-19 patients both for total power (7.46 ± 0.5 vs. 8.08 ± 0.6; p &lt; 0.0001; Cohens-d = 1.12) and for the VLF (6.84 ± 0.8 vs. 7.66 ± 0.6; p &lt; 0.0001; Cohens-d = 1.16) and HF (4.65 ± 0.9 vs. 5.33 ± 0.9; p = 0.015; Cohens-d = 0.76) components. The LF/HF ratio was significantly higher in Long-COVID-19 patients (1.46 ± 0.27 vs. 1.23 ± 0.13; p = 0.001; Cohens-d = 1.09). On multivariable analysis, Long-COVID-19 is significantly correlated with D-dimer (standardized β-coefficient = 0.259), NT-ProBNP (standardized β-coefficient = 0.281), HF component of spectral analysis (standardized β-coefficient = 0.696), and LF/HF ratio (standardized β-coefficient = 0.820).

Dysautonomia may explain the persistent symptoms in Long COVID-19 patients. The persistence of a procoagulative state and an elevated myocardial strain could explain vagal impairment in these patients. In Long-COVID-19 patients, impaired vagal activity, persistent increases of NT-ProBNP, and a prothrombotic state require careful monitoring and appropriate intervention.

Source: Acanfora D, Nolano M, Acanfora C, Colella C, Provitera V, Caporaso G, Rodolico GR, Bortone AS, Galasso G, Casucci G. Impaired Vagal Activity in Long-COVID-19 Patients. Viruses. 2022 May 13;14(5):1035. doi: 10.3390/v14051035. PMID: 35632776; PMCID: PMC9147759. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9147759/ (Full text)

Autonomic dysfunction in long-COVID syndrome: a neurophysiological and neurosonology study

Dear Sirs,

A significant proportion of patients infected from SARS-CoV-2 experience new, recurring, or ongoing symptoms usually 3 months after infection that may last for weeks or months and comprise the so-called Long-COVID Syndrome (LCS). Most frequent neurological symptoms include fatigue, memory/attention deficits, sleep disorders, myalgias and hyposmia []. The occurrence of LCS is not associated with the severity of foregoing acute COVID-19 nor have specific predisposing factors been identified so far. LCS shares common features with two other diseases, Fibromyalgia (FM) and Chronic Fatigue Syndrome (CFS): young women are predominantly affected, the etiology is unknown, although a previous viral infection is suspected, and both conditions have symptoms similar to those of LCS. Autonomic Nervous System (ANS) maladaptation has been proposed as a possible pathogenetic underlying mechanism. [, ]

Hence, a case–control study was conducted to investigate if ANS dysfunction may contribute to LCS. Consecutive, adult patients, with history of laboratory-confirmed COVID-19 without hospitalization, presenting with persistent LCS symptoms for > 3 months from COVID-19 onset, including fatigue, cognitive impairment (brain fog), orthostatic dizziness, palpitations, breathlessness or gastrointestinal symptoms, were evaluated at a referral center in Athens, Greece (“Attikon” University Hospital) between September 2021 and December 2021. LCS patients with cardiovascular complications or diabetes were excluded. Controls included colleagues, nursing staff and volunteers without history of SARS-COV-2 infection, cardiovascular diseases, diabetes and ANS disorders. Evaluation of ANS function was performed by Sympathetic Skin Response (SSR) to investigate the Sympathetic Nervous System (SNS), and the cross-sectional area (CSA) of the Vagus Nerve (VN) was assessed by ultrasound to investigate the Parasympathetic Nervous System (PNS) []. A detailed description of the methods is available in the online-only supplement. The study was approved by the Institutional Research Bioethics. Informed consent was obtained by all participants. Statistical analysis was performed using the Statistical Package for Social Science (SPSS Inc., version 24.0 for Windows; IBM, Armonk, NY, USA). Descriptive statistics are given as the mean and standard deviation, frequency, and percentage. Statistical comparisons between different groups were performed using the chi-square test (or exact test) for binary outcomes, and Student’s t test or Mann–Whitney U test for continuous variables as appropriate.

Read the full article HERE.

Source: Papadopoulou M, Bakola E, Papapostolou A, Stefanou MI, Gaga M, Zouvelou V, Michopoulos I, Tsivgoulis G. Autonomic dysfunction in long-COVID syndrome: a neurophysiological and neurosonology study. J Neurol. 2022 May 10:1–2. doi: 10.1007/s00415-022-11172-1. Epub ahead of print. PMID: 35536408; PMCID: PMC9086662. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9086662/ (Full text)

Autonomic dysfunction and post-COVID-19 syndrome: A still elusive link

Editorial:

Infection from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is causing the long-lasting pandemic coronavirus disease 2019 (COVID-19), with dramatic clinical, social, and economic implications. Importantly, evolving experience consistently shows that, in addition to issues related to the acute phase, patients who recover from COVID-19 may present a wide variety of bothersome symptoms, which may be debilitating and significantly impair their quality of life. This condition, when it persists beyond 12 weeks after recovery, is defined as “post–COVID-19” or “long COVID-19” syndrome.

Some of the symptoms, including tachycardia/palpitations, chest pain, fatigue, and dyspnea with reduced effort tolerance, suggest a possible cardiovascular cause, whereas others (eg, muscle and/or joint pain, headache, memory loss, nausea, mood disturbances) suggest involvement of other systems. Symptoms may occur independently of the severity of COVID-19, although patients with more severe symptoms in the acute phase experience a higher rate of symptom persistence during follow-up. , 

Importantly, careful diagnostic assessment usually fails to identify specific causes of post–COVID-19 syndrome. However, it has been suggested that at least some post–COVID-19 symptoms, including those of potential cardiovascular origin, might be related to abnormalities of the autonomic nervous system (ANS). The pathophysiological mechanisms responsible for ANS impairment remain speculative and might include direct damage of the ANS (ganglia and/or nerve terminations) by the virus, a toxic effect of inflammatory cytokines released during the acute infection, and an immune-mediated response triggered by some viral component(s). ,  Independent of the mechanism, the possibility of ANS involvement in SARS-CoV-2 infection is supported by the frequent occurrence of neurologic symptoms (eg, anosmia, dysgeusia) as well as the sporadic occurrence of clinical conditions typically related to ANS dysfunction (eg, orthostatic hypotension, orthostatic tachycardia) in post–COVID-19 syndrome. Furthermore, patients with COVID-19, compared to healthy subjects, have been found to show reduced heart rate variability (HRV) parameters 20 weeks after recovery from the illness. However, a pathogenetic relationship between dysautonomia and post–COVID-19 syndrome remains to be demonstrated. Establishing such a relationship would be of importance because it might help guide the management of this clinical condition.

The study by Ladlow et al in this issue of Heart Rhythm Journal is welcome because it attempts to clarify whether any association exists between dysautonomia and symptoms, as well as objective evidence of exercise intolerance, in patients with post–COVID-19 syndrome. In their study, Ladlow et al enrolled 205 patients referred to a post–COVID-19 clinic who fulfilled specific eligibility criteria (hospitalization and desaturation ≤95% on a Harvard step test or chest pain with electrocardiographic [ECG] changes during acute illness and life-limiting symptoms persisting for >12 weeks). All patients underwent bicycle cardiopulmonary exercise testing (CPET) and were divided into 1 of 2 groups according to evidence or no evidence of dysautonomia.

Dysautonomia was diagnosed based on 3 heart rate (HR) parameters that Jouven et al found to be associated with total mortality and sudden death in a population of asymptomatic subjects: (1) resting HR >75 bpm; (2) increase in HR during exercise <89 bpm; and (3) HR reduction <25 bpm during the first minute of recovery from peak exercise. HRV was also assessed by calculating the root mean square of the squared differences of adjacent RR intervals (RMSSD) on a 1-minute 12-lead ECG at rest and on 30-second ECGs during the first 3 minutes of recovery after peak exercise.

Patients were studied 183 ± 77 days (∼6 months) from COVID-19 disease, and dysautonomia was found in 51 patients (25%). Per definition, these patients had higher HR at rest (95 ± 12 bpm vs 81 ± 12 bpm; P <.001) and lower HR increase during CPET (75 ± 12 bpm vs 96 ± 13 bpm; P <.001) and HR recovery after peak exercise (17 ± 4 bpm vs 31 ± 17 bpm; P <.001) compared to those without dysautonomia.

Patients with dysautonomia were older, had a higher body mass index (BMI) (P = .013) and waist circumference (WC) (P = .003), and had a lower basal RMSSD (P <.001). Furthermore, at rest, dysautonomic patients showed a higher breathing rate (P = .006) and lower forced vital capacity (P = .031), forced expiratory volume in 1 second (P = .036), and ventilatory efficiency (Ve/Vco 2) (P = .036).

When assessing symptoms that showed prevalence >25%, a significant association with dysautonomia was found for low mood (P = .007), headache (P = .026), and poor attention (P = .047). However, other symptoms, including some of potential cardiovascular origin (eg, shortness of breath, fatigue), showed no significant association with dysautonomia.

Patients with dysautonomia, however, showed a lower performance on CPET. In particular, HR at peak exercise (170 ± 13 bpm vs 177 ± 15 bpm; P = .003), maximal work rate (219 ± 37 W vs 253 ± 52 W; P <.001), and maximal oxygen consumption (V⋅O2) (30.6 ± 5.5 mL/kg/min vs 35.8 ± 7.6 mL/kg/min; P <.001) all were significantly lower in patients with dysautonomia than in those without dysautonomia, suggesting a role of ANS dysfunction in their physical limitation.

Ladlow et al should be congratulated for performing this large study on post–COVID-19 syndrome. However, possible alternative interpretations of the data suggest caution in deriving definitive conclusions from their results.

Although the study shows the lack of significant relationship between dysautonomia and most post–COVID-19 symptoms, including, in particular, some symptoms of possible cardiovascular origin, the method applied to identify patients with an impairment of ANS function presents some limitations. Both higher HR at rest and lower HR recovery after exercise suggest an imbalance of sympathovagal tone toward adrenergic predominance in their patients with dysautonomia. However, rather than reflecting a primary impairment of the ANS, these findings simply might have been related to differences between the 2 groups with regard to some basal clinical characteristics, including higher BMI/WC, lower efficiency in respiratory function, and lower mood in dysautonomic patients. In addition, the lower increase in HR during maximal exercise in patients with dysautonomia might have been a mere consequence of their having a higher HR at rest and, given their older age, a lower maximal theoretical HR for age. The percent of predicted maximal HR for age achieved during CPET, in fact, did not differ between the 2 groups. The possibility that the differences in HR behavior might have not been related to a primary abnormality of the ANS is also suggested by the fact that, despite the basal difference, RMSSD values were similar during exercise recovery in the 2 groups of patients, suggesting a similar ANS response to exercise interruption in the 2 groups.

Future studies should clarify whether different results regarding the relationship between ANS dysfunction and post–COVID-19 symptoms might be obtained using more comprehensive and better validated methods for the diagnosis of ANS dysfunction, such as standard tests of autonomic function and HRV assessed from its multiple (short-term and long-term) components.

Of note, although the results of CPET in the study by Ladlow et al suggest lower performance by patients classified with dysautonomia, exercise tolerance was largely normal in these subjects, who achieved >100% of the predicted maximal oxygen consumption and an average maximal work rate of 219 W, with only small differences compared to patients without dysautonomia, possibly explained, again, and at least in part, by some demographic (age) and clinical (BMI, respiratory function) differences.

In conclusion, the study by Ladlow et al provides interesting data on the clinical characteristics and objective physical performance of patients with post–COVID-19 syndrome. However, the role of ANS in determining symptoms (particularly those of potential cardiovascular origin) and physical limitation in these patients still has not been fully elucidated by their data, making necessary further studies applying more comprehensive and valuable methods for the assessment of ANS function.

Source: Lanza GA. Autonomic dysfunction and post-COVID-19 syndrome: A still elusive link. Heart Rhythm. 2022 Apr;19(4):621-622. doi: 10.1016/j.hrthm.2021.12.027. Epub 2021 Dec 28. PMID: 34968741; PMCID: PMC8712711. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8712711/ (Full study)

Small fiber neuropathy underlying dysautonomia in COVID-19 and in post-SARS-CoV-2 vaccination and long-COVID syndromes

Letter:

We eagerly read the excellent editorial by Gemignani and the corresponding original article by Abrams et al. about the suspected involvement of small fibers (small fiber neuropathy [SFN]) in acute severe, acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and in long-coronavirus disease (COVID) syndrome.1, 2 It was speculated that at least some of the clinical manifestations of long-COVID syndrome could be attributed to involvement of small nerve fibers by the viral infection. The authors believe that studies are needed that investigate the role of autonomic dysfunction in long-COVID syndrome and the prevalence of SFN by means of the 13-item SFN symptom inventory questionnaire. The papers are appealing but raise some concerns that require discussion.

I do not agree with the notion that long-COVID syndrome is the same as post-COVID syndrome.1 Acute COVID-19 usually lasts one to 4 wk. Subacute COVID-19 lasts 5 to 12 wk. When clinical manifestations of COVID-19 persist beyond 12 wk, the condition is termed post-COVID syndrome. Both subacute COVID-19 and post-COVID syndrome are included under the overarching term long-COVID-syndrome. Differentiating long-COVID syndrome from post-COVID-syndrome is crucial for their management and for assessing long-term outcomes.

An issue not addressed in the paper is Guillain-Barre syndrome (GBS) due to an infection with SARS-CoV-2.3 There is ample evidence that the immune response to the virus can trigger autoimmune reactions, including those that are involved in the development of GBS. There is evidence accumulating that mRNA- and vector-based anti-SARS-CoV-2 vaccines can trigger the development of GBS.4 GBS can affect not only motor and sensory fibers, but also peripheral autonomic fibers, particularly in the GBS subtype of acute motor and sensory axonal neuropathy (AMSAN). There is a subtype of GBS that may exclusively affect autonomic fibers and present with pure dysautonomia.5 Because GBS may be mild, it can go unrecognized; because patients often have a long recovery time, autonomic manifestations in long COVID syndrome could be explained by incomplete recovery from autonomic involvement in abortive GBS.

Not addressed in the articles is the involvement of the central autonomic nervous system (ANS). There are several reports demonstrating that a SARS-CoV-2 infection can be complicated by hypophysitis.6 Furthermore, patients with a pre-existing pituitary micro- or macro-adenoma have an increased risk of pituitary apoplexy during SARS-CoV-2 infection.7 Accordingly, the hypophysial-pituitary-adrenergic axis can be impaired,8 thus leading to autonomic dysfunction.

Autonomic dysfunction may not always be recognized by those involved in the management of COVID-19 patients. Thus, patients with SARS-CoV-2 infection are often not investigated sufficiently for their symptoms of autonomic dysfunction, such as insomnia, fatigue, cognitive impairment, hypersensitivity to light, blurred vision, dry eyes or mouth, drooling, palpitations, syncope, orthostatic dizziness, hot flashes, dysphagia, bowel or bladder dysfunction, sexual dysfunction, changes in skin, hair, and nails, or abnormalities of sweating. Studies that may be performed to assess ANS involvement are a contrast-enhanced magnetic resonance imaging (MRI) of the pituitary gland, determination of releasing factors, pituitary stimulating hormones, and hormones of peripheral endocrine organs, and diagnostic testing for involvement of the peripheral ANS. Several of the latter tests are not widely available and their sensitivity and specificity may be low if portions of the peripheral ANS are tested that are not affected.

Not addressed was the role of anti-COVID-19 drugs in the development of SFN. There is increasing evidence that some of the compounds administered to infected patients are neurotoxic and can be responsible for polyneuropathy. Some of these compounds, such as lopinavir, ritonavir, daptomycin, and linezolid, may also damage autonomic fibers.

I agree that there is a need to investigate the involvement of the central and peripheral ANS in some patients with acute SARS-CoV-2 infections or long-COVID syndrome. Such patients should be investigated not only by use of questionnaires and the Quantitative Sudomotor Axon Reflex Test (QSART) but particularly by quantitative sensory testing (QST), micro-neurography of C-fibers of the superficial peroneal nerve, sensory stimulation tests, the deep breathing test, the Valsalva maneuver, tilt testing, cerebral blood flow velocity measurements, pain-related evoked potentials (PREP), laser speckle contact analysis (LASCA), laser Doppler flowmetry, laser Doppler imaging, contact heat-evoked potentials (CHEP), corneal confocal microscopy (CCM), and proximal or distal skin biopsy stained with protein gene product (PGP) 9.5. Furthermore, hormone levels should be determined and autopsy of COVID-19 patients should include histological investigations of central and peripheral autonomic pathways.

Source: Finsterer J. Small fiber neuropathy underlying dysautonomia in COVID-19 and in post-SARS-CoV-2 vaccination and long-COVID syndromes. Muscle Nerve. 2022 Apr 6. doi: 10.1002/mus.27554. Epub ahead of print. PMID: 35385125.  https://onlinelibrary.wiley.com/doi/10.1002/mus.27554 (Full text)