Heart Rate Variability in evaluation of autonomic dysfunction in idiopathic REM-sleep behaviour disorder

INTRODUCTION

Nearly 80% of people diagnosed with idiopathic REM sleep behaviour disorder (iRBD) via video-polysomnography (v-PSG) are expected to be in the prodromal stage of an alpha-synucleinopathy. Signs of autonomic dysfunction can appear earlier than motor or cognitive alpha-synucleinopathy symptoms. Heart Rate Variability (HRV) can potentially be an objective measurement of autonomic dysfunction, and furthermore can be obtained directly from v-PSG.

OBJECTIVES

The aim of this study was to evaluate dysautonomia in iRBD subjects using HRV obtained during different sleep stages and wakefulness from v-PSG.

MATERIAL AND METHODS

Subjects positively screened by an RBD screening questionnaire (RBD-SQ) underwent v-PSG to diagnose RBD. HRV obtained from v-PSG recordings was correlated to dysautonomia evaluated from a Non-Motor Symptoms Scale (NMSS) questionnaire. Optimal cut-off values of HRV parameters to predict dysautonomia were calculated using receiver operating characteristics (ROC) - area under the curve (AUC) analysis. The effect of confounder variables was predicted with binomial logistic regression and multiple regression analyses.

RESULTS

Out of 72 positively screened subjects, 29 subjects were diagnosed as iRBD (mean age 66 ± 7.7 years) by v-PSG. Eighty-three per cent of the iRBD subjects in our cohort were at the time of diagnosis classified as having possible or probable prodromal Parkinson's Disease (pPD) compared to zero subjects being positively screened in the control group. The iRBD-positive subjects showed significant inverse correlations of NMSS score, particularly to log low-frequency (LF) component of HRV during wakefulness: r = -0.59 (p = 0.001). Based on ROC analysis and correlation between NMSS score, log LF during wakefulness (AUC 0.74, cut-off 4.69, sensitivity 91.7%, specificity 64.7%, p = 0.028) was considered as the most accurate predictor of dysautonomia in the iRBD group. Apnoea-hypopnoea index (AHI) negatively predicted dysautonomia in the iRBD group. None of the HRV components was able to predict the presence of iRBD in the full cohort. Age, gender, and PSG variables were significant confounders of HRV prediction.

CONCLUSIONS

The presented study did not confirm the possibility of using HRV from v-PSG records of patients with iRBD to predict dysautonomia expressed by questionnaire methods. This is probably due to several confounding factors capable of influencing HRV in such a cohort.

A Pilot Study of Autonomic Function Screening Tests for Differentiating Complex Regional Pain Syndrome Type II and Traumatic Neuropathic Pain

Background and Objectives: One of the most challenging tasks in a clinical setting is to differentiate between complex regional pain syndrome (CRPS) type II and traumatic neuropathic pain (NeP). CRPS is characterized by several dysautonomic manifestations, such as edema, hyper/hypohidrosis, skin color change, and tachycardia. This study compared the outcomes of autonomic function screening tests in patients with CRPS type II and traumatic NeP for diagnostic differentiation. Materials and Methods: CRPS type II was diagnosed according to the Budapest research criteria, while NeP was diagnosed according to the updated grading system suggested by the International Association for the Study of Pain Special Interest Group on Neuropathic Pain in 2016. Twenty patients with CRPS type II and twenty-five with traumatic NeP were investigated. Results: Twelve patients with CRPS type II presented abnormal results for the quantitative sudomotor axon reflex test (QSART). Abnormal QSART results were more common in the CRPS type II group. Conclusions: Analysis of QSART combined with other ancillary tests can help in the differential diagnosis of CRPS type II and traumatic NeP if factors influencing abnormal QSART are sufficiently controlled.

Experiences of living with postural tachycardia syndrome

OBJECTIVE

Postural tachycardia syndrome (PoTS) is a disorder of the autonomic nervous system which involves a range of symptoms, worsened when adopting an orthostatic (upright) position. Symptoms can include tachycardia, dizziness, fainting, nausea as well as many others which, as is typical of a syndrome, vary from person to person. Although research is increasing into this condition, the unifying experiences of managing it on a daily basis have not been extensively investigated. This study aimed to capture participants' experiences of living with PoTS.

METHOD

A longitudinal digital ethnographic approach was employed. Eight participants recorded daily video diaries discussing their experiences of PoTS and its impact for 17 days. Interpretative phenomenological analysis was utilised to analyse the data and identify connections across participants' accounts.

RESULTS

Four superordinate themes emerged: 'loss of control and lack of agency over body', 'identity changes', 'lack of understanding from others' and 'adapting to cope with PoTS'.

DISCUSSION

The findings demonstrated the complex and widespread impact these participants experience from their PoTS symptoms, including the consequent emotional difficulties that result from managing this condition. An overall lack of understanding about PoTS by others was emphasised, suggesting the requirement for better education and support services for this condition.

Corona With Lyme: A Long COVID Case Study

The longevity of the coronavirus disease 2019 (COVID-19) pandemic has necessitated continued discussion about the long-term impacts of SARS-CoV-2 infection. Many who develop an acute COVID-19 infection will later face a constellation of enduring symptoms of varying severity, otherwise known as long COVID. As the pandemic reaches its inevitable endemicity, the long COVID patient population will undoubtedly grow and require improved recognition and management. The case presented describes the three-year arc of a previously healthy 26-year-old female medical student from initial infection and induction of long COVID symptomology to near-total remission of the disease. In doing so, the course of this unique post-viral illness and the trials and errors of myriad treatment options will be chronologized, thereby contributing to the continued demand for understanding this mystifying disease.

Longitudinal analysis of the Non-Motor Symptoms Scale in Parkinson's Disease (NMSS): An exploratory network analysis approach

Introduction

Parkinson's disease (PD) is a multisystem neurodegenerative disorder characterized by motor and non-motor symptoms. In particular, non-motor symptoms have become increasingly relevant to disease progression. This study aimed to reveal which non-motor symptoms have the highest impact on the complex interacting system of various non-motor symptoms and to determine the progression of these interactions over time.

Methods

We performed exploratory network analyses of 499 patients with PD from the Cohort of Patients with Parkinson's Disease in Spain study, who had Non-Motor Symptoms Scale in Parkinson's Disease ratings obtained at baseline and a 2-year follow-up. Patients were aged between 30 and 75 years and had no dementia. The strength centrality measures were determined using the extended Bayesian information criterion and the least absolute shrinkage and selection operator. A network comparison test was conducted for the longitudinal analyses.

Results

Our study revealed that the depressive symptoms anhedonia and feeling sad had the strongest impact on the overall pattern of non-motor symptoms in PD. Although several non-motor symptoms increase in intensity over time, their complex interacting networks remain stable.

Conclusion

Our results suggest that anhedonia and feeling sad are influential non-motor symptoms in the network and, thus, are promising targets for interventions as they are closely linked to other non-motor symptoms.

A case of dysautonomia after COVID-19 infection in a patient with poorly controlled type I diabetes

COVID-19 has been linked to dysautonomia in the current literature, as has uncontrolled diabetes. Here, we present a case report of severe dysautonomia following a COVID-19 infection in a patient with pre-existing poorly controlled type-1 diabetes. This patient exhibited symptoms consistent with both postural orthostatic tachycardia syndrome (POTS), as well as orthostatic hypotension. His symptoms became so severe that he was unable to come to a standing position without experiencing syncope. Extensive workup was completed to identify an alternative cause of his dysautonomia with inconclusive results. Dysautonomia can have devastating consequences in regard to physical, social, and psychological health. Counseling individuals with poorly controlled diabetes about the importance of maintaining tight blood glucose control and avoiding COVID-19 infection should be primary interventions when treating patients with this DM1. Early detection and management of diabetes mellitus, COVID-19, and of possible resultant dysautonomia through medical interventions, as well as lifestyle changes, are extremely important measures to avoid development of dangerous and potentially life-threatening consequences.

Effect of using a structured pacing protocol on post-exertional symptom exacerbation and health status in a longitudinal cohort with the post-COVID-19 syndrome

Post-exertional symptom exacerbation (PESE) is a characteristic symptom of post-COVID syndrome (PCS). This prospective study investigated the effect of a 6-week structured World Health Organization (WHO) Borg CR-10 5-phase pacing protocol on PESE episodes and quality of life in a cohort of individuals with long-standing PCS (average duration of symptoms was 17 months). Participants received weekly telephone calls with a clinician to complete the Leeds PESE questionnaire (LPQ) and identify the appropriate phase of the pacing protocol. EQ-5D 5L was completed at the intervention's beginning and end to measure overall health. Thirty-one participants completed the 6-week protocol, with a statistically and clinically significant reduction in the average number of PESE episodes (from 3.4 episodes in Week 1 to 1.1 in Week 6), with an average decrease of 16% (95% CI: 9%-24%; p < 0.001) each week, and reduction across all three exertional triggers (physical, cognitive, and emotional). Physical activity levels showed moderate improvements during the intervention period. Mean EQ-5D 5L scores improved from 51.4 to 60.6 points (paired difference of 9.2 points, 95% CI: 3.2-15.2 points; p = 0.004). A structured pacing protocol significantly reduces PESE episodes and improves overall health in PCS.

Short Communication: Stellate Ganglion Blockade for Persistent Olfactory and Gustatory Symptoms Post-COVID-19

One hundred ninety-five patients presenting with post-COVID symptomology, including parosmia and dysgeusia, underwent reversible stellate ganglion blockade. Stellate ganglion blockade was performed at an outpatient facility, and patients were evaluated via survey at seven days post-injection. Of the 195 participants, ages ranged from 18-69 years of age with the breakdown of sexes being females n = 157 and males n = 38. The most significant finding was a reported improvement in olfaction post-injection in 87.4% of subjects. The effectiveness of this novel treatment for post-COVID is promising and warrants further investigation.

Long COVID: mechanisms, risk factors and recovery

NEW FINDINGS

What is the topic of this review? The emerging condition of long COVID, its epidemiology, pathophysiological impacts on patients of different backgrounds, physiological mechanisms emerging as explanations of the condition, and treatment strategies being trialled. The review leads from a Physiological Society online conference on this topic. What advances does it highlight? Progress in understanding the pathophysiology and cellular mechanisms underlying Long COVID and potential therapeutic and management strategies.

ABSTRACT

Long COVID, the prolonged illness and fatigue suffered by a small proportion of those infected with SARS-CoV-2, is placing an increasing burden on individuals and society. A Physiological Society virtual meeting in February 2022 brought clinicians and researchers together to discuss the current understanding of long COVID mechanisms, risk factors and recovery. This review highlights the themes arising from that meeting. It considers the nature of long COVID, exploring its links with other post-viral illnesses such as myalgic encephalomyelitis/chronic fatigue syndrome, and highlights how long COVID research can help us better support those suffering from all post-viral syndromes. Long COVID research started particularly swiftly in populations routinely monitoring their physical performance - namely the military and elite athletes. The review highlights how the high degree of diagnosis, intervention and monitoring of success in these active populations can suggest management strategies for the wider population. We then consider how a key component of performance monitoring in active populations, cardiopulmonary exercise training, has revealed long COVID-related changes in physiology - including alterations in peripheral muscle function, ventilatory inefficiency and autonomic dysfunction. The nature and impact of dysautonomia are further discussed in relation to postural orthostatic tachycardia syndrome, fatigue and treatment strategies that aim to combat sympathetic overactivation by stimulating the vagus nerve. We then interrogate the mechanisms that underlie long COVID symptoms, with a focus on impaired oxygen delivery due to micro-clotting and disruption of cellular energy metabolism, before considering treatment strategies that indirectly or directly tackle these mechanisms. These include remote inspiratory muscle training and integrated care pathways that combine rehabilitation and drug interventions with research into long COVID healthcare access across different populations. Overall, this review showcases how physiological research reveals the changes that occur in long COVID and how different therapeutic strategies are being developed and tested to combat this condition.

Suspected COVID-19 mRNA Vaccine-Induced Postural Orthostatic Tachycardia Syndrome

We present a case of a 15-year-old South Asian male who developed suspected postural orthostatic tachycardia syndrome (POTS) two weeks after receiving the Pfizer-BioNTech coronavirus disease 2019 (COVID-19) vaccine booster, which was successfully managed with low-dose fludrocortisone and ivabradine. Clinicians should be aware of the Pfizer-BioNTech COVID-19 vaccine being implicated with the onset of POTS.

[The successful use of Cytoflavin in the patient with postaveny syndrome]

A clinical observation of the use of Cytoflavin according to a two-stage scheme (10.0 ml intravenously drip per 200 ml of 0.9% sodium chloride solution for 10 days, followed by a transition to a tablet form of 2 tablets 2 times/day for 25 days) in a patient with postcovid syndrome with pronounced vegetative and neurocognitive disorders. The effectiveness of therapy was confirmed by an improvement in heart rate variability and a decrease in the severity of depression, anxiety (on the HADS scale) and the level of autonomic dysfunction (on the COMPASS-31 scale). The significant changes in levels of fatigue (on a scale MFI) is not marked. The obtained results can serve as a basis for further research.

Integrated Dynamic Autonomic and Cardiovascular Regulation during Postural Transitions in Older Adults Living with Frailty: A Systematic Review Protocol

Older adults often experience episodes of a sudden drop in blood pressure when standing, known as orthostatic hypotension (OH). OH is associated with an increased risk of life-threatening health problems, falls, and death. Although OH has been studied in older adults, the integrated dynamic autonomic and cardiovascular regulation during postural transitions in older adults with frailty remains scarce and poorly understood. The primary aim of this systematic review is to determine the association between how active (e.g., lie-to-stand) and passive (head-up tilt) postural transitions affect the dynamic integrated autonomic and cardiovascular regulatory responses, comparing older adults with different levels of frailty (non-frail, pre-frail, or frail). A second aim is to perform a meta-analysis to compare autonomic and cardiovascular responses during active postural transitions in non-frail, pre-frail, and frail older adults. The systematic review will be outlined according to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols. The meta-analysis will generate estimates of the comparative autonomic and cardiovascular responses after active postural transitions in adults who are non-frail, pre-frail, and frail. This systematic review will provide critical information on how integrated dynamic autonomic and cardiovascular regulation occurs during postural transitions in older adults with different frailty statuses.

Autonomic Nerve Involvement in Post-Acute Sequelae of SARS-CoV-2 Syndrome (PASC)

The novel SARS-CoV-2 virus and resulting COVID-19 global pandemic emerged in 2019 and continues into 2022. While mortality from COVID-19 is slowly declining, a subset of patients have developed chronic, debilitating symptoms following complete recovery from acute infection with COVID-19. Termed as post-acute sequelae of SARS-CoV-2 syndrome (PASC), the underlying pathophysiology of PASC is still not well understood. Given the similarity between the clinical phenotypes of PASC and postural orthostatic tachycardia syndrome (POTS), it has been postulated that dysautonomia may play a role in the pathophysiology of PASC. However, there have been only a few studies that have examined autonomic function in PASC. In this retrospective study, we performed an analysis of autonomic nerve function testing in PASC patients and compared the results with those of POTS patients and healthy controls. Our results suggest that a significant number of PASC patients have abnormal autonomic function tests, and their clinical features are indistinguishable from POTS.

Pupillometric findings in ATTRv patients and carriers: results from a single-centre experience

INTRODUCTION

Hereditary transthyretin amyloidosis (ATTRv) is a treatable multisystemic disease with great phenotypic heterogeneity. Among extra-neurological features, pupillary abnormalities have been reported, either related to amyloid deposition in the eye or to a progressive autonomic neuropathy.

OBJECTIVE

To evaluate the role of automated pupillometry, a non-invasive and rapid test able to provide objective and reproducible data on pupil size and reactivity, as a marker of disease severity in late-onset ATTRv patients.

PATIENTS AND METHODS

We performed automated pupillometry on a cohort of ATTRv patients and pre-symptomatic TTR mutation carriers and compared results to healthy controls. An exhaustive clinical and instrumental evaluation was performed on all enrolled subjects.

RESULTS

A statistically significant difference in most pupillometry parameters was found in ATTRv patients as compared to both carriers and healthy controls. Moreover, in ATTRv patients, we found a significant correlation between many pupillometry findings and disease duration, as well as widely accepted clinical scales and investigations (NIS, Sudoscan from feet, and Norfolk QoL-DN questionnaire).

CONCLUSIONS

We suggest pupillometry may play a role as a reliable and non-invasive biomarker to evaluate ATTRv disease severity and monitor its progression.

Autonomic symptoms in migraine: Results of a prospective longitudinal study

Objective

To assess the prevalence and burden of autonomic symptoms in migraine, and determine the relationship with migraine frequency.

Background

Autonomic symptoms in migraine have been theorized to occur in the setting of inter-ictal sympathetic hypoactivity and hyper-sensitivity. There is limited data prospectively assessing cranial and extra-cranial autonomic symptoms with a validated instrument, or longitudinal data on the relationship between migraine disease activity and autonomic symptoms.

Methods

Patients attending a single tertiary academic center were recruited into a prospective cohort study between September 2020 and June 2022. In addition to standard clinical care, they completed several surveys including the Composite Autonomic Symptom Scale (COMPASS-31) questionnaire, a validated survey of autonomic symptoms.

Results

A total of 43 patients (66.7% female, median age 42, IQR 17) were included in the final analysis. There was a baseline 20 monthly headache days (MHD) (IQR 21.7), and 65.1% of the population had chronic migraine by ICHD-3 criteria. A significantly elevated weighted COMPASS-31 score was reported in 60.5% of respondents (mean 30.3, SD 13.3) at baseline. After 12 months treatment, significant improvements were reported in migraine frequency (median MHD 20-8.7) and disability (median Migraine Disability Assessment Score 67-48), but not in autonomic symptoms (mean score 30.3, SD 11.2).

Conclusion

Autonomic symptoms were frequently reported in patients with migraine. However, they did not correlate with headache frequency or reversion to episodic frequency. Further study is required to elucidate specific approaches and treatments for autonomic symptoms, and further evaluate the underlying pathophysiological mechanisms.

Characterization of autonomic symptom burden in long COVID: A global survey of 2,314 adults

BACKGROUND

Autonomic dysfunction is a known complication of post-acute sequelae of SARS-CoV-2 (PASC)/long COVID, however prevalence and severity are unknown.

OBJECTIVE

To assess the frequency, severity, and risk factors of autonomic dysfunction in PASC, and to determine whether severity of acute SARS-CoV-2 infection is associated with severity of autonomic dysfunction.

DESIGN

Cross-sectional online survey of adults with PASC recruited through long COVID support groups between October 2020 and August 2021.

PARTICIPANTS

2,413 adults ages 18-64 years with PASC including patients who had a confirmed positive test for COVID-19 (test-confirmed) and participants who were diagnosed with COVID-19 based on clinical symptoms alone.

MAIN MEASURES

The main outcome measure was the Composite Autonomic Symptom 31 (COMPASS-31) total score, used to assess global autonomic dysfunction. Test-confirmed hospitalized vs. test-confirmed non-hospitalized participants were compared to determine if the severity of acute SARS-CoV-2 infection was associated with the severity autonomic dysfunction.

KEY RESULTS

Sixty-six percent of PASC patients had a COMPASS-31 score >20, suggestive of moderate to severe autonomic dysfunction. COMPASS-31 scores did not differ between test-confirmed hospitalized and test-confirmed non-hospitalized participants [28.95 (15.62, 46.60) vs. 26.4 (13.75, 42.10); p = 0.06].

CONCLUSIONS

Evidence of moderate to severe autonomic dysfunction was seen in 66% of PASC patients in our study, independent of hospitalization status, suggesting that autonomic dysfunction is highly prevalent in the PASC population and independent of the severity of acute COVID-19 illness.

Dysautonomia in Children with Post-Acute Sequelae of Coronavirus 2019 Disease and/or Vaccination

Long-term health problems such as fatigue, palpitations, syncope, and dizziness are well-known in patients after COVID-19 (post-acute sequelae of coronavirus (PASC)). More recently, comparable problems have been noticed after the SARS-CoV-2 vaccination (post-VAC). The pathophysiology of these problems is not well-understood. Methods: In 38 children and young adults, we tested if these health problems were related to dysautonomia in an active standing test (Group 1: 19 patients after COVID-19; Group 2: 12 patients with a breakthrough infection despite a vaccination; and Group 3: 7 patients after a vaccination without COVID-19). The data were compared with a control group of 47 healthy age-matched patients, as recently published. Results: All patients had a normal left ventricular function as measured by echocardiography. Significantly elevated diastolic blood pressure in all patient groups indicated a regulatory cardiovascular problem. Compared with the healthy control group, the patient groups showed significantly elevated heart rates whilst lying and standing, with significantly higher heart rate increases. The stress index was significantly enhanced in all patient groups whilst lying and standing. Significantly decreased pNN20 values, mostly whilst standing, indicated a lower vagus activity in all patient groups. The respiratory rates were significantly elevated in Groups 1 and 2. Conclusion: The uniform increase in the heart rates and stress indices, together with low pNN20 values, indicated dysautonomia in children with health problems after COVID-19 disease and/or vaccination. A total of 8 patients fulfilled the criteria of postural orthostatic tachycardia syndrome and 9 patients of an inappropriate sinus tachycardia, who were successfully treated with omega-3 fatty acid supplementation and pharmacotherapy.

Central Effects of Ivermectin in Alleviation of Covid-19-induced Dysauto-nomia

Covid-19 may be associated with various neurological disorders, including dysautonomia, a dysfunction of the autonomic nervous system (ANS). In Covid-19, hypoxia, immunoinflammatory abnormality, and deregulation of the renin-angiotensin system (RAS) may increase sympathetic discharge with dysautonomia development. Direct SARS-CoV-2 cytopathic effects and associated inflammatory reaction may lead to neuroinflammation, affecting different parts of the central nervous system (CNS), including the autonomic center in the hypothalamus, causing dysautonomia. High circulating AngII, hypoxia, oxidative stress, high pro-inflammatory cytokines, and emotional stress can also provoke autonomic deregulation and high sympathetic outflow with the development of the sympathetic storm. During SARS-CoV-2 infection with neuro-invasion, GABA-ergic neurons and nicotinic acetylcholine receptor (nAChR) are inhibited in the hypothalamic pre-sympathetic neurons leading to sympathetic storm and dysautonomia. Different therapeutic modalities are applied to treat SARS-CoV-2 infection, like antiviral and anti-inflammatory drugs. Ivermectin (IVM) is a robust repurposed drug widely used to prevent and manage mild-moderate Covid-19. IVM activates both GABA-ergic neurons and nAChRs to mitigate SARS-CoV-2 infection- induced dysautonomia. Therefore, in this brief report, we try to identify the potential role of IVM in managing Covid-19-induced dysautonomia.

Kleine-Levin syndrome: report of a case with marked dysautonomic features

Kleine-Levin syndrome is a rare neurologic disorder of unknown etiopathogenesis, characterized by abrupt onset and remission of attacks of hypersomnia and cognitive dysfunctions. Psychiatric symptoms are frequently present, ranging from disinhibited sexual behavior and eating disorders to hallucinations, anxiety, mood alterations, and derealization. A vast range of attack-related dysautonomic signs and symptoms are reported but remain poorly described. We describe a patient with Kleine-Levin syndrome with sleep attacks dominated by marked dysautonomic features. We briefly review similar clinical cases and suggest that the hypothalamus may play a central role in the genesis of autonomic dysfunction in Kleine-Levin syndrome.

CITATION

Fiamingo G, Esposto R, Dal Fabbro B, Terzaghi M. Kleine-Levin syndrome: report of a case with marked dysautonomic features. J Clin Sleep Med. 2022;18(9):2313-2316.

Cardiovascular Autonomic Assessment in Guillain-Barré Syndrome: A Longitudinal Study

BACKGROUND

Severe dysautonomia is typically seen during acute phase of Guillain-Barré syndrome (GBS).

OBJECTIVE

To investigate the relationship of cardiovascular autonomic dysfunction with motor recovery in GBS.

MATERIALS AND METHODS

Consecutive GBS patients presented to our hospital were recruited. Clinical assessment was evaluated with the Medical Research Council (MRC) sum score and GBS disability score (GDS). All patients had series of autonomic testing on admission and after treatment at 6 and 24 weeks. Both computation-dependent tests (heart rate variability [HRV] and baroreflex sensitivity [BRS]) and autonomic maneuvers were performed. Age- and gender-matched healthy controls (HC) were recruited. The data obtained at admission, 6 weeks and 24 weeks were compared within groups for statistical difference.

RESULTS

Six patients (4 men; mean age 39.5 ± 14.3 years) were recruited over one year. Five had GBS and one Miller Fisher syndrome. The mean MRC sum score and GDS on admission were 52.3 ± 4.3 and 3.5 ± 0.8 respectively. During admission, time-domain average RR interval (AVNN) and BRS were significantly poorer among cases compared to HC. Active standing 30:15 ratio and cold pressor test at admission were also significantly abnormal when compared with HC. All the autonomic parameters had normalized by 6 weeks and these were significant for the high frequency-HRV, BRS, and active standing 30:15 ratio. For MRC and GDS, there were significant improvements in the scoring over a period of 24 weeks.

CONCLUSIONS

Dysautonomia in GBS improved gradually and in keeping with motor and disability recovery.

Neurological manifestations of hereditary transthyretin amyloidosis: a focus on diagnostic delays

BACKGROUND

The recent availability of disease-modifying therapies for hereditary transthyretin amyloid (ATTRv) amyloidosis warrants urgency for earlier diagnosis and timely identification of active disease state among genetic carriers.

METHODS

We reviewed clinical neurological data of all patients with ATTRv amyloidosis with initial visits at our amyloidosis centre between January 2016 and December 2018. We abstracted the signs and symptoms of neurological manifestations, as well as rates and patterns of diagnostic testing.

RESULTS

Of 92 patients with 19 different transthyretin (TTR) mutations, 66 and 36% had symptoms attributed to large-fibre and small-fibre neuropathy, respectively, compared to 75 and 66% with corresponding examination findings. Thirty-six patients with V122I ATTR mutation had asymptomatic polyneuropathy identified on neurological examination, eight without concurrent cardiac disease. Seventy-three percent of patients had symptoms of carpal tunnel syndrome (CTS), while 26% had dysautonomia. The average delays between the onset of symptoms of large fibre neuropathy (LFN) or CTS to ATTRv amyloidosis diagnosis were 2.9 and 6.7 years, respectively.

DISCUSSION

Our study found higher rates of polyneuropathy by examination than patient-reported symptoms, especially among those with V122I TTR amyloidosis, signalling asymptomatic polyneuropathy. Our findings suggest the need for routine neurological examinations and other testing for genetic carriers to achieve earlier identification of active disease state.

Dysautonomia in COVID-19 Patients: A Narrative Review on Clinical Course, Diagnostic and Therapeutic Strategies

Introduction

On March 11, 2020, the World Health Organization sounded the COVID-19 pandemic alarm. While efforts in the first few months focused on reducing the mortality of infected patients, there is increasing data on the effects of long-term infection (Post-COVID-19 condition). Among the different symptoms described after acute infection, those derived from autonomic dysfunction are especially frequent and limiting.

Objective

To conduct a narrative review synthesizing current evidence of the signs and symptoms of dysautonomia in patients diagnosed with COVID-19, together with a compilation of available treatment guidelines.

Results

Autonomic dysfunction associated with SARS-CoV-2 infection occurs at different temporal stages. Some of the proposed pathophysiological mechanisms include direct tissue damage, immune dysregulation, hormonal disturbances, elevated cytokine levels, and persistent low-grade infection. Acute autonomic dysfunction has a direct impact on the mortality risk, given its repercussions on the respiratory, cardiovascular, and neurological systems. Iatrogenic autonomic dysfunction is a side effect caused by the drugs used and/or admission to the intensive care unit. Finally, late dysautonomia occurs in 2.5% of patients with Post-COVID-19 condition. While orthostatic hypotension and neurally-mediated syncope should be considered, postural orthostatic tachycardia syndrome (POTS) appears to be the most common autonomic phenotype among these patients. A review of diagnostic and treatment guidelines focused on each type of dysautonomic condition was done.

Conclusion

Symptoms deriving from autonomic dysfunction involvement are common in those affected by COVID-19. These symptoms have a great impact on the quality of life both in the short and medium to long term. A better understanding of the pathophysiological mechanisms of Post-COVID manifestations that affect the autonomic nervous system, and targeted therapeutic management could help reduce the sequelae of COVID-19, especially if we act in the earliest phases of the disease.

Post-Ganglionic Sympathetic Neurons can Directly Sense Raised Extracellular Na+ via SCN7a/Nax

The relationship between dietary NaCl intake and high blood pressure is well-established, and occurs primarily through activation of the sympathetic nervous system. Nax, a Na+-sensitive Na+ channel, plays a pivotal role in driving sympathetic excitability, which is thought to originate from central regions controlling neural outflow. We investigated whether post-ganglionic sympathetic neurons from different ganglia innervating cardiac and vasculature tissue can also directly sense extracellular Na+. Using whole-cell patch clamp recordings we demonstrate that sympathetic neurons from three sympathetic ganglia (superior cervical, stellate and superior mesenteric/coeliac) respond to elevated extracellular NaCl concentration. In sympathetic stellate ganglia neurons, we established that the effect of NaCl was dose-dependent and independent of osmolarity, Cl- and membrane Ca2+ flux, and critically dependent on extracellular Na+ concentration. We show that Nax is expressed in sympathetic stellate ganglia neurons at a transcript and protein level using single-cell RNA-sequencing and immunohistochemistry respectively. Additionally, the response to NaCl was prevented by siRNA-mediated knockdown of Nax, but not by inhibition of other membrane Na+ pathways. Together, these results demonstrate that post-ganglionic sympathetic neurons are direct sensors of extracellular Na+ via Nax, which could contribute to sympathetic driven hypertension.