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Purpose: Chemotherapy-induced peripheral neuropathy (CIPN) is an adverse event of cancer treatment that can affect sensory, motor, or autonomic nerves. Assessment of autonomic neuropathy is challenging, with limited available tools. Accordingly, it is not routinely assessed in chemotherapy-treated patients. In this study, we aimed to examine whether electrochemical skin conductance (ESC) via Sudoscan, a potential measure of autonomic function, associates with subjective and objective measures of CIPN severity and autonomic neuropathy. Methods: A cross-sectional assessment of patients who completed neurotoxic chemotherapy 3–24 months prior was undertaken using CIPN patient-reported outcomes (EORTC-QLQ-CIPN20), clinically graded scale (NCI-CTCAE), neurological examination score (TNSc), autonomic outcome measure (SAS), and Sudoscan. Differences in CIPN severity between participants with or without ESC dysfunction were investigated. Linear regression analyses were used to identify whether ESC values could predict CIPN severity. Results: A total of 130 participants were assessed, with 93 participants classified with CIPN according to the clinically graded scale (NCI-CTCAE/grade ≥ 1), while 49% demonstrated hands or feet ESC dysfunction (n = 46). Participants with ESC dysfunction did not significantly differ from those with no dysfunction on multiple CIPN severity measures (clinical-grade, patient-report, neurological examination), and no differences on the autonomic outcome measure (SAS) (all p > 0.0063). Linear regression analyses showed that CIPN could not be predicted by ESC values. Conclusions: The inability of ESC values via Sudoscan to predict clinically-graded and patient-reported CIPN or autonomic dysfunction questions its clinical utility for chemotherapy-treated patients. The understanding of autonomic neuropathy with chemotherapy treatment remains limited and must be addressed to improve quality of life in cancer survivors. [ABSTRACT FROM AUTHOR]

• Electrochemical skin conductance is a new method to quantify sudomotor function. • ALS patients had a decreased palmar and plantar sudomotor function. • Abnormal sudomotor function is part of the ALS disease spectrum. Amyotrophic lateral sclerosis (ALS) is now recognized as a multisystem neurodegenerative disorder, comprising autonomic dysfunction. We aimed to assess sudomotor function in ALS by measuring the electrochemical skin conductance (ESC). Thirty-one ALS patients [median age of 62 years (1st-3rd interquartile range – IQR, 56–72), male 71%] were prospectively compared with 29 healthy controls, matched for age and sex. We analysed ESC results from hands and feet, bilaterally. A total of 120 ESC recordings were obtained. Hands and feet ESC measurements were significantly lower in patients compared with controls [64 μS (1st-3rd IQR, 57–58) versus 78 μS (1st-3rd IQR, 70.5–84), p < 0.001 and 76 μS (1st-3rd IQR, 68–83) versus 81 μS (1st-3rd IQR, 78–86), p = 0.008, respectively]. In ALS group, no differences were observed between spinal and bulbar-onset forms for hands and feet results (p > 0.05). Hands and feet ESC measurements did not correlate also with disease duration, total ALSFRS-R scale, or ALSFRS-R progression rate (all p > 0.05). ESC is a non-invasive, fast and quantitative method suitable for assessing sudomotor function. ALS patients revealed a decreased function in upper and lower extremities. Sudomotor dysfunction is part of the ALS manifestations. [ABSTRACT FROM AUTHOR]

Background Intradialytic hypotension (IDH), a common complication in haemodialysis (HD) patients, is associated with multiple risk factors including cardiac dysfunction and alterations of the peripheral autonomic nervous system. To what extent dysautonomia may contribute to the occurrence of IDH remains elusive. We sought to investigate the clinical utility of Sudocan®, a device that quantifies dysautonomia, in the prediction of IDH. Methods We conducted a prospective monocentric study in adult HD patients from July 2019 to February 2020. Dysautonomia was assessed by the measurements of hand and foot electrochemical skin conductance (ESC) using Sudocan®, before HD. The primary endpoint was the incidence of IDH (The National Kidney Foundation/Kidney-Dialysis Outcome Quality Initiative definition), according to the presence of a pathological hand and/or foot ESC value, during the 3-month study period. Results A total of 176 HD patients (64 ± 14 years old) were enrolled. Mean pre-dialysis HD hand and foot ESC was 45 ± 20 and 54 ± 22 µS, respectively. About 35% and 40% of patients had a pathological ESC at the hand and foot, respectively. IDH occurred in 46 patients. Logistic regression showed that pathologic pre-dialysis HD hand ESC was associated with an increased risk of IDH [odds ratio = 2.56, 95% CI (1.04–6.67), P = 0.04]. The cumulative risk incidence of IHD during the study was 5.65 [95% CI (2.04–15.71), P = 0.001] and 3.71 [95% CI (1.41–9.76), P = 0.008], with a pathological hand and foot ESC, respectively. Conclusions A pathological hand ESC, as assessed by a non-invasive Sudoscan® test, is associated with an increased risk of IDH. [ABSTRACT FROM AUTHOR]

• The most common misdiagnosis of transthyretin familial amyloid polyneuropathy (TTR-FAP) is CIDP. • Sudoscan is a rapid quantitative sudomotor test, assessing autonomic function. • Sudoscan has good sensitivity and specificity to distinguish CIDP from TTR-FAP. Transthyretin familial amyloid polyneuropathy (TTR-FAP) is an aggressive hereditary neuropathy characterized by sensory and autonomic dysfunction. There are numerous reports of TTR-FAP misdiagnosed and treated as chronic inflammatory demyelinating polyneuropathy (CIDP), leading to delayed diagnosis, risk of iatrogenic adverse events and increased socio-economic costs. Quantitative sudomotor function measured by electrochemical skin conductance (ESC) appears to be a sensitive test in TTR-FAP. We aimed to evaluate the performance of ESC in differentiating TTR-FAP from CIDP. Thirty-eight patients with genetically confirmed hereditary TTR amyloidosis and 26 with definite CIDP according to the EFNS/PNS guidelines and negative TTR-FAP genetic testing were involved in this study. We compared the ESC for feet and hands measured by Sudoscan for each patient. ESC (µS) was significantly lower in TTR-FAP for both hands (72 vs 45, p < 0.0001) and feet (77 vs 35, p < 0.0001). Feet ESC < 64 µS had a 89% sensitivity and a 96% specificity to differentiate between CIDP and TTR-FAP. Sudoscan is a fast, non-invasive and easy to perform test, able to distinguish CIDP and TTR-FAP patients with good sensitivity and specificity. Sudoscan can be helpful in distinguishing between CIDP and TTR-FAP. [ABSTRACT FROM AUTHOR]

Purpose: Currently available techniques for the evaluation of small fiber neuropathy and related sudomotor function remain suboptimal. Electrochemical skin conductance (ESC) has recently been introduced as a simple noninvasive and fast method for the detection of sudomotor dysfunction. The purpose of this review is to synthesize and appraise research using ESC measurements for sudomotor evaluation in adults.Methods: Electronic databases including MEDLINE and Google Scholar were searched (up to March 13, 2017). The search strategy included the following terms: "electrochemical skin conductance," "Sudoscan," and "EZSCAN." Evidence was graded according to defined quality indicators including (1) level of evidence; (2) use of established tests as reference tests (e.g., quantitative sudomotor axon test [QSART], sympathetic skin responses [SSR], thermoregulatory sweat test [TST], and skin biopsies to assess sudomotor and epidermal small fibers); (3) use of consecutive/non-consecutive subjects; and (4) study design (prospective/retrospective).Results: A total of 24 studies met the inclusion criteria. These were classified into preclinical, normative, comparative/diagnostic, or interventional. ESC measurement properties, diagnostic accuracy, and similarities to and differences from established tests were examined.Conclusions: ESC measurements expand the arsenal of available tests for the evaluation of sudomotor dysfunction. The advantages and disadvantages of ESC versus established tests for evaluating sudomotor/small fiber function reviewed herein should be used as evidence to inform future guidelines on the assessment of sudomotor function. [ABSTRACT FROM AUTHOR]

Summary Objectives Myasthenia gravis (MG) is an autoimmune disease associated with antibodies against the nicotinic muscle acetylcholine receptor (AChR) at the neuromuscular junction. Dysautonomia has been previously described in MG. Electrochemical skin conductance (ESC), assessed by Sudoscan®, is a non-invasive method that allows evaluation of sudomotor function. Since sweat glands are innervated by sudomotor, postganglionic, cholinergic sympathetic C-fibers, we hypothesized that ESC could be a reliable method for assessing autonomic dysfunction in MG. Methods ESC measurements were prospectively assessed in patients with generalized MG and in healthy controls. Patients with diabetes mellitus, anticholinergic medication or electrophysiological findings of peripheral neuropathy were excluded. Data regarding demographic and disease features were collected. Presence of autonomic symptoms in patients with MG was assessed by Compass-31. For statistical analysis we performed student t -test and Chi2 test for comparison between both groups. Results We included 24 patients (mean age of 46.4 ± 10.6, 75% women, mean disease duration 12.5 years, 62.5% positive for AChR antibodies) and 37 controls. We found no difference in either foot (P = 0.13) or hand (P = 0.83) ESC measurements between patients and controls, even after correcting for age. Conclusion We could not prove the presence of autonomic sympathetic dysfunction in our cohort of MG patients when assessed by Sudoscan®. In addition, Compass-31 was not a useful questionnaire in this clinical context. [ABSTRACT FROM AUTHOR]

The diagnosis and follow-up of peripheral neuropathies involving small-diameter nerve fibers require specific examinations beyond conventional nerve conduction studies which only concern large-diameter nerve fibers. Among these tests, some are dedicated to the investigation of cutaneous innervation by the autonomic nervous system, mainly by unmyelinated sympathetic C fibers. To this end, various laboratory tests have been proposed, but the measurement of electrochemical skin conductance (ESC) by Sudoscan® is increasingly becoming the most widely used technique, because it allows a quick and simple assessment of the sudomotor function of the limb extremities. This technique is based on the principles of reverse iontophoresis and chronoamperometry and since its introduction in 2010, has been the source of nearly 200 publications. In the clinical field, most of these publications concern the evaluation of diabetic polyneuropathy, for which the value of Sudoscan® no longer needs to be demonstrated. However, there is also evidence for a role for Sudoscan® in the testing of the autonomic nervous system in various peripheral neuropathies of other origins or diseases primarily affecting the central nervous system. In this article, a comprehensive review of the literature on the clinical value of Sudoscan® outside of diabetes is presented, detailing ESC changes in neuropathies associated with various clinical conditions, such as hereditary amyloidosis or other genetic pathologies, chemotherapy neurotoxicity, dysimmune or infectious disorders, fibromyalgia, parkinsonism or other neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

Peripheral neuropathies may involve the small diameter nerve fibers of the autonomic nervous system. In the presence of clinical signs compatible with dysautonomia, it is very difficult to affirm that these signs are really linked to an alteration in postganglionic autonomic innervation, and not to a lesion of the central nervous system or to a direct damage to the tissues and innervated organs. Also, in the context of the investigation of peripheral neuropathies, there is an interest in performing objective and quantitative assessment of distal autonomic innervation. The corresponding autonomic tests are mainly based on the exploration of sudomotor or vasomotor disorders of the limb extremities. In this article, we provide an overview of the various tests available for the study of the autonomic nervous system in clinical practice, including vasomotor reactivity tests, in particular based on laser Doppler techniques, and sudomotor tests, based on axon-reflexes produced by iontophoresis of cholinergic drugs or on the simpler measurement of electrochemical skin conductance by the Sudoscan® device. [ABSTRACT FROM AUTHOR]

Autonomic nervous system (ANS) involvement has been studied in systemic lupus erythematosus, rheumatoid arthritis, systemic sclerosis, Sjogren's syndrome, and ankylosing spondylitis but still has not been studied in psoriatic arthritis (PsA). The aim of this study was to investigate the prevalence and the nature of autonomic neuropathy in patients with PsA. Sixteen patients of PsA and 15 age and sex matched control subjects were studied prospectively using a battery of noninvasive tests. Cardiovascular autonomic neuropathy (CAN) was diagnosed by applying four cardiovascular reflex tests, and peripheral sympathetic autonomic function was assessed by Sudoscan. Patients with PsA had significantly higher heart rate response to standing ( p = 0.01), blood pressure response to standing ( p = 0.02), and Sudoscan ( p = 0.01) when compared with healthy controls. Fifty percent ( n = 8) of the patients with PsA had at least two or more abnormal CAN parasympathetic dysfunction; of these, 18.75 % ( n = 3) of the patients had abnormal parasympathetic and sympathetic dysfunction, 68.7 % ( n = 11) and 25 % ( n = 4) of the patients had at least one abnormal parasympathetic and sympathetic parameters, respectively, and 37.5 % ( n = 6) of the patients had moderate sudomotor dysfunction. About 18.7 % ( n = 3) of our parasympathetic dysfunction patients had autonomic symptoms. None of healthy volunteers had abnormal ANS dysfunction. Heart rate response significantly correlated with erythrocyte sedimentation rate ( p < 0.05) and C-reactive protein ( p < 0.05) levels. In conclusion, cardiovascular autonomic and peripheral sympathetic neuropathy occurs in PsA. Parasympathetic function is more commonly found to be abnormal than sympathetic function. There is no correlation of peripheral sympathetic dysfunction with cardiovascular autonomic neuropathy. [ABSTRACT FROM AUTHOR]

Coronavirus disease-19 (COVID-19) is a predominantly respiratory syndrome. Growing reports about a SARS-CoV-2 neurological involvement, including autonomic dysfunction (AD), have been reported, mostly in critically-ill patients, or in the long-COVID syndrome. In this observational, cross-sectional study, we investigated the prevalence of AD in 20 non-critically-ill COVID-19 patients (COVID+ group) in the acute phase of the disease through a composite instrumental evaluation consisting of Sudoscan, automated pupillometry, heart rate variability (HRV), and pulse transit time (PTT). All the parameters were compared to a control group of 20 healthy volunteers (COVID− group). COVID+ group presented higher values of pupillary dilatation velocities, and baseline pupil diameter than COVID− subjects. Moreover, COVID+ patients presented a higher incidence of feet sudomotor dysfunction than COVID− group. No significant differences emerged in HRV and PTT parameters between groups. In this study we observed the occurrence of autonomic dysfunction in the early stage of the disease. [ABSTRACT FROM AUTHOR]