Electrodiagnostic methods to verify Guillain-Barré syndrome subtypes in Istanbul: A prospective multicenter study.

BACKGROUND AND AIMS: This study aimed to identify the clinical characteristics and electrodiagnostic subtypes of Guillain-Barré syndrome (GBS) in Istanbul. METHODS: Patients with GBS were prospectively recruited between April 2019 and March 2022 and two electrodiagnostic examinations were performed on each patient. The criteria of Ho et al., Hadden et al., Rajabally et al., and Uncini et al. were compared for the differentiation of demyelinating and axonal subtypes, and their relations with anti-ganglioside antibodies were analyzed. RESULTS: One hundred seventy-seven patients were included, 69 before the coronavirus disease 2019 pandemic (April 2019-February 2020) and 108 during the pandemic (March 2020-March 2022), without substantial changes in monthly frequencies. As compared with the criteria of Uncini et al., demyelinating GBS subtype diagnosis was more frequent according to the Ho et al. and Hadden et al. criteria (95/162, 58.6% vs. 110/174, 63.2% and 121/174, 69.5%, respectively), and less frequent according to Rajabally et al.'s criteria (76/174, 43.7%). Fourteen patients' diagnoses made using Rajabally et al.'s criteria were shifted to the other subtype with the second electrodiagnostic examination. Of the 106 analyzed patients, 22 had immunoglobulin G anti-ganglioside antibodies (14 with the axonal subtype). They had less frequent sensory symptoms (54.5% vs. 83.1%, p = 0.009), a more frequent history of previous gastroenteritis (54.5% vs. 22.9%, p = 0.007), and a more severe disease as compared with those without antibodies. INTERPRETATION: Serial electrodiagnostic examinations are more helpful for accurate subtype diagnosis of GBS because of the dynamic pathophysiology of the disease. We observed no significant increase in GBS frequency during the pandemic in this metropolis.

Training factors that influence electrodiagnostic medicine knowledge.

INTRODUCTION/AIMS: Self-assessment examinations (SAEs) help trainees assess their progress in education. SAEs also provide feedback to training programs as to how factors in training influence examination performance. This study's goal was to examine the relationship between the number of months of training in electrodiagnostic (EDx) medicine, the number of EDx studies during training, and scores on the American Association of Neuromuscular and Electrodiagnostic Medicine SAE. METHODS: This was a retrospective study of the 2023 AANEM-SAE results. In addition to the examination score, participants were asked approximately how many EDx studies they performed in training and how many months of training they had completed. Analysis included correlation of the examination scores with months of training as well as number of EDx studies. In addition, a multivariate linear regression model was developed. RESULTS: A total of 756 participants completed the proctored examination in May 2023. Examination score was moderately and positively correlated with the number of months of training (Pearson r = .5; p < .001) as well as the number of EDx studies during training (Pearson r = .55; p < .001). Scores steadily improved with additional months of training, but leveled off after 300-400 EDx studies. Regression analysis indicated that higher numbers of EDx studies were correlated with a higher examination score even after accounting for the number of months of study. DISCUSSION: We believe that a greater number of months of training is associated with better performance on the AANEM-SAE and that greatest improvement in examination performance occurs during the first 300-400 EDx studies.

An electrophysiological prognostic diagnosis for facial palsy.

Two electrophysiological tests for facial palsy-electroneurography (ENoG) and nerve excitability test (NET)-were reviewed. ENoG has advantages over NET in that it reflects the percentage of degenerated facial nerve fibers and can provide an accurate prognosis. However, as disadvantages, ENoG requires large, expensive equipment, and such supramaximal electrical stimulation can be quite painful for patients. NET is less painful due to weak stimulation with just enough current to meet the threshold, and the required equipment is compact and inexpensive to procure. However, it is impossible to calculate the percentage of degenerated nerve fibers, and NET is inferior to ENoG in terms of accurate prognostic prediction for facial palsy. The appropriate timing for both ENoG and NET is 7 to 10 days after the onset. While ENoG has proven more popular than NET because of its accuracy for prognostic prediction, we should not predict the prognosis of facial palsy based solely on the results of electrophyisiolgical examinations; a comprehensive evaluation including the facial muscle grading system is essential.

A Three months Electrodiagnostic Follow-Up of Patients Suspected of having Ulnar Nerve Involvement at Elbow Level with Normal Conventional Electrodiagnostic Study at First Evaluation.

Background: Compression of ulnar nerve at the elbow is the second most common peripheral neuropathy of the upper extremity. Objective: Due to the lack of the gold diagnostic standard for ulnar nerve involvement at elbow level (UNE) and the lack of sufficient study in this field, we decided to evaluate patients with symptoms of this disease who have normal conventional electrodiagnostic study (EDX) in first evaluation. Materials and Methods: In this cross-sectional study, 18 persons were selected from patients who were referred to the clinic of Physical Medicine and Rehabilitation. If conventional EDX was normal, compound nerve action potential (CNAP) test (peak latency and amplitude) was carried out. Patients with normal conventional EDX but abnormal ulnar CNAP included to our study. After 3 months, if they had not been treated for ulnar neuropathy, they were reexamined by conventional EDX plus ulnar CNAP measurement. Results: In total, 18 patients (11 females, 7 males) aged 28-58 years old (mean = 40.11) were analyzed in this study. After 3 months, 14 patients (77.8%) demonstrated parameter changes consistent with UNE in conventional EDX. Conclusion: Based on the results of this study, ulnar CNAP has diagnostic value in patients with symptoms of UNE who have normal routine EDX. Therefore, ulnar CNAP should be taken into account for early diagnosis of ulnar neuropathy when routine electrodiagnostic tests are normal.

The supraclavicular nerve.

INTRODUCTION/AIMS: The aim of this study was to describe a new method for studying the supraclavicular nerve (SCN) conduction and to report four cases with SCN lesions. METHODS: The SCN was antidromically recorded with a pair of self-adhesive electrodes located in the middle of the clavicle. Stimulation (<5 mA) was delivered 7 cm proximally with a bar electrode. To facilitate recording, it was explained to the participant that they would feel a very faint electrical sensation locally and an electrical tingle upward (ear) or downward (shoulder/clavicle). Each participant was asked to say when the tingling moved downward. RESULTS: In normal subjects, median values were 16 µV (range: 9-33) for sensory nerve action potential (SNAP) amplitude; 1.2 ms (range: 1-1.5) for onset latency; and 1.25 (range: 1-1.7) for side-to-side amplitude ratio. In the four patients, the SCN SNAP was absent on the pathological side and normal on the healthy side. All four patients complained of unilateral neuropathic hypoesthesia on the anterior aspect of the neck, chest, and shoulder that occurred after radical neck surgery for thyroid or larynx cancer (x3) and first rib resection (x1). DISCUSSION: A comparison with previous reports shows that this simple method provides similar or highest SNAP amplitudes. SCN lesions are rare, and rarely referred for electrodiagnosis, and often overlooked. However, the SCN conduction study, which causes very slight inconvenience (low-intensity stimulation), allows a better understanding of the origin of the complaints and permits the patient to benefit of more suitable treatment.

Neurophysiological features in spinocerebellar ataxia type 2: Prospects for novel biomarkers.

Electrophysiological biomarkers are useful to assess the degeneration and progression of the nervous system in pre-ataxic and ataxic stages of the Spinocerebellar Ataxia Type 2 (SCA2). These biomarkers are essentially defined by their clinical significance, discriminating patients and/or preclinical subjects from healthy controls in cross-sectional studies, their significant changes over time in longitudinal studies, and their correlation with the cytosine-guanine-adenine (CAG) repeat expansion and/or clinical ataxia scores, time of evolution and time to ataxia onset. We classified electrophysiological biomarkers into three main types: (1) preclinical, (2) disease progression and (3) genetic damage. We review the data that identify sural nerve potential amplitude, maximum saccadic velocity, sleep efficiency, rapid eye movement (REM) sleep percentage, K-complex density, REM sleep without atonia percentage, corticomuscular coherence, central motor conduction time, visual P300 latency, and antisaccadic error correction latency as reliable preclinical, progression and/or genetic damage biomarkers of SCA2. These electrophysiological biomarkers will facilitate the conduction of clinical trials that test the efficacy of emerging treatments in SCA2.

Focal Peripheral Neuropathies Observed in Patients Diagnosed With COVID-19: A Case Series.

ABSTRACT: A growing number of studies have documented a wide variety of neurological manifestations associated with the novel SARS-CoV-2 (COVID-19). Of the available literature, cranial neuropathies and central nervous system disorders, such as encephalopathy and ischemic strokes, remain the predominant discussion. Limited investigations exist examining peripheral neuropathies of those with COVID-19. This case series discusses eight patients who tested positive for COVID-19 and presented with localized weakness after a prolonged course of mechanical ventilation (>21 days). We retrospectively reviewed all patients' charts who received electrodiagnostic evaluation between March and November 2020 in the outpatient clinic or in the acute care hospital at the JFK Medical Center/JFK Johnson Rehabilitation Institute and Saint Peter's University Hospital of New Jersey. A total of eight COVID-19-positive patients were identified to have a clinical presentation of localized weakness after a prolonged course of mechanical ventilation. All patients were subsequently found to have a focal peripheral neuropathy of varying severity that was confirmed by electrodiagnostic testing. Patient demographics, clinical, and electrodiagnostic findings were documented. The findings of local weakness and focal peripheral neuropathies after diagnosis of COVID-19 raise significant questions regarding underlying pathophysiology and overall prognosis associated with COVID-19.

Prognosis prediction changes based on the timing of electroneurography after facial paralysis.

BACKGROUND: The process of determining the prognosis and subsequent facial nerve decompression has become an important factor in determining the patient's quality of life. AIM: In this study, the prognosis of facial paralysis was verified in detail based on the timing of electroneurography (ENOG) and nerve conduction study (NCS). MATERIALS AND METHODS: The ENOG and NCS of 368 facial palsy patients were analyzed. House-Brackmann (HB) scale after 6 months was used as an outcome. For the ENOG, nasalis muscle/levator labii superioris alaeque nasi (NL), and orbicularis oculi (OO) muscle were used and NCS performed using temporal, zygomatic, and buccal branches. RESULTS: ENOG at the OO performed 4-6 d after onset was ≤10% (p = .002, 10.0-fold) and showed unfavorable results (when the standard was ≥30%). In addition, the ENOG at the NL performed 13-15 d after onset was ≤10% (p = .001, 10.5-fold) and showed unfavorable results (when the standard was ≥30%). CONCLUSIONS: The results indicated that ENOG at the OO performed 4-6 d after onset and ENOG at the NL performed 13-15 d after onset had more prognostic value for the outcomes of acute peripheral facial palsy.

Electrodiagnosis of Guillain-Barre syndrome in the International GBS Outcome Study: Differences in methods and reference values.

OBJECTIVE: To describe the heterogeneity of electrodiagnostic (EDx) studies in Guillain-Barré syndrome (GBS) patients collected as part of the International GBS Outcome Study (IGOS). METHODS: Prospectively collected clinical and EDx data were available in 957 IGOS patients from 115 centers. Only the first EDx study was included in the current analysis. RESULTS: Median timing of the EDx study was 7 days (interquartile range 4-11) from symptom onset. Methodology varied between centers, countries and regions. Reference values from the responding 103 centers were derived locally in 49%, from publications in 37% and from a combination of these in the remaining 15%. Amplitude measurement in the EDx studies (baseline-to-peak or peak-to-peak) differed from the way this was done in the reference values, in 22% of motor and 39% of sensory conduction. There was marked variability in both motor and sensory reference values, although only a few outliers accounted for this. CONCLUSIONS: Our study showed extensive variation in the clinical practice of EDx in GBS patients among IGOS centers across the regions. SIGNIFICANCE: Besides EDx variation in GBS patients participating in IGOS, this diversity is likely to be present in other neuromuscular disorders and centers. This underlines the need for standardization of EDx in future multinational GBS studies.

Expert consensus on the combined investigation of carpal tunnel syndrome with electrodiagnostic tests and neuromuscular ultrasound.

Expert consensus was sought to guide clinicians on the use of electrodiagnostic tests (EDX) and neuromuscular ultrasound (NMUS) in the investigation of suspected carpal tunnel syndrome (CTS). Consensus was achieved using the Delphi method via three consecutive anonymised surveys of 15 experts and was defined as rating agreement ≥ 80%. The panel agreed that combining EDX and NMUS is more informative than using each modality alone. NMUS adds value in patients with clinically suspected CTS with non-localizing or normal EDX, atypical EDX, failed CTS surgery, polyneuropathy, and CTS suspected to be secondary to structural pathology. The median nerve cross-sectional area should be measured at the site of maximal nerve enlargement, and the nerve should be scanned from mid-forearm to the palm. The group also identified those situations where the wrist-to-forearm area ratio and longitudinal scans of the median nerve should also be obtained. EDX should always be performed to quantify CTS severity and in individuals over age 70. This document is an initial step to guide clinicians on the combined investigation of CTS using EDX and NMUS, to be updated regularly with the emergence of new research.

Utility of shear wave elastography and high-definition color for diagnosing carpal tunnel syndrome.

OBJECTIVE: The diagnostic values of measuring median nerve (MN) stiffness and vascularity with shear wave elastography (SWE) and high-definition (HD) color were investigated in carpal tunnel syndrome (CTS). METHODS: Seventy patients (123 wrists) with CTS and thirty-five healthy volunteers (70 wrists) were enrolled. Based on nerve conduction studies (NCS), the patients were subdivided into NCS-negative, mild-to-moderate, and severe CTS groups. MN and abductor pollicis brevis (APB) SWE and MN HD color were performed on a longitudinal plane. RESULTS: The mild-to-moderate and severe CTS groups showed increased MN stiffness at the wrist and MN stiffness ratio (wrist-to forearm) compared with the control (p < 0.001). The NCS-negative CTS group showed increased MN stiffness at the wrist (p = 0.022) and MN stiffness ratio (p = 0.032) compared with the control. The severe CTS group showed increased MN stiffness at the wrist compared with the mild-to-moderate CTS group (p = 0.034). The cutoff-values in diagnosing NCS-confirmed CTS were 50.12 kPa for MN stiffness at the wrist, 1.91 for MN stiffness ratio, and grade 1 for HD color. CONCLUSIONS: SWE and HD color are good supportive tools in diagnosing and assessing severity in CTS. SIGNIFICANCE: SWE and HD color demonstrated that MN in CTS was associated with increased stiffness and hypervascularity.

Evaluation of the Electroglottographic Signal Variability in Organic and Functional Dysphonia.

OBJECTIVES: To confirm the data reported in our previous studies on the analysis of the variability of the electroglottographic signal in the pathological voice; to evaluate possible differences in variability between organic and functional pathologies; to identify any distinctive/typical EGG patterns for these pathologies. METHODS: One hundred twenty-five subjects were enrolled (36 euphonic and 89 pathological: 24 functional dysphonia, 21 bilateral vocal nodules, 23 unilateral polyps and 21 unilateral cysts). All subjects were studied with videolaryngostroboscopy, spectrographic analysis of voice and electroglottography (EGG). The EGG signal variability was then investigated using amplitude-speed combined analysis, by means of a proprietary software algorithm. Amplitude and Speed variation were expressed as a new parameter, the Variability Index (VI), calculated both for the whole EGG signal recorded (VI-tot) and in each phase of the glottic cycle (VI-Q, absolute value; VI-Q%, percentage value). RESULTS: In the comparison of VI values between pathological and normal groups, VI-tot and VI-Q2% (which corresponds to the final phase of vocal fold contact) were significantly greater in pathological subjects (P= 0.002). The comparison of VI values among subgroups of the various pathologies showed a difference for VI-tot (P< 0.0001) and VI-Q2% (P= 0.001); this difference was more marked in the cysts than in the functional dysphonia. The cut-off values of VI-tot and VI-Q2% were 0.191 and 18.17%, respectively (sensitivity and specificity 65.2% and 66.7% for VI-tot and 84.3% and 77.8% for VI-Q2%). CONCLUSIONS: The variability of the EGG signal investigated through the combined analysis of the amplitude and the speed of vibration using a proprietary algorithm software has proved useful not only to distinguish the normal voice from the pathological voice, but also to characterize which phases are more altered in the various voice pathologies studied, both functional and organic. Furthermore, the analysis of the VI parameter allowed to propose cut-off values characterized by a good sensitivity and specificity to discriminate dysphonia from the euphonic voice. Larger groups of patients will be needed to confirm these results.

Accuracy of the Scratch Collapse Test for Carpal Tunnel Syndrome in Comparison With Electrodiagnostic Studies.

Background: The scratch collapse test (SCT) is a clinical examination maneuver that has been previously reported as a reliable and reproducible test to diagnose carpal tunnel syndrome (CTS). The initial study by Cheng et al in 2008 showed a simple test with high sensitivity. However, subsequent attempts to reproduce those findings have resulted in lower accuracy. Our goal was to evaluate the use of the SCT for patients presenting with symptoms of pain, numbness, or weakness in an upper extremity. Methods: Forty patients were referred to the electrodiagnostic (EDX) lab for evaluation of an upper extremity. One blinded examiner who was familiar with the maneuver performed the SCT on all 40 patients. Another physician or technician performed the nerve conduction study and electromyography. Patient history and accompanying physical examination findings were not revealed to the SCT examiner. Results: The relationship between the SCT performed by a blinded examiner and the EDX performed by blinded examiners was nonsignificant (P = .676) and showed a sensitivity of 0.48, specificity of 0.59, positive predictive value of 0.61, and negative predictive value of 0.45. Conclusion: Based on this study and previous findings by other authors, we would advise against the use of the SCT in CTS for important patient-care decisions, such as surgical decision-making, until future research is done. It is possible that the SCT, in combination with other physical examination maneuvers, could increase diagnostic accuracy and enhance patient management.

Neuromuscular Ultrasound: Indications in the Electrodiagnostic Laboratory.

ABSTRACT: Accurate assessment of neuromuscular disorders is critical to facilitate timely treatment and achieve the best outcomes. Historically, electrodiagnostic studies have filled this role, but recently, neuromuscular ultrasound is being used in the electrodiagnostic laboratory. This review discusses the uses of neuromuscular ultrasound in the electrodiagnostic laboratory that have strong evidence, emphasizing those that could be adopted in a typical electrodiagnostic laboratory with a reasonable level of equipment and training. The evidence currently supports using neuromuscular ultrasound to diagnose carpal tunnel syndrome and ulnar neuropathies at the elbow and as a supplementary test when electrodiagnostic studies are suspected to be falsely negative or in axonal nonlocalizing lesions. Neuromuscular ultrasound can identify the causes of focal mononeuropathies, which can change treatment in specific cases. It is sensitive at identifying fasciculations and providing complementary evidence of autoimmune demyelinating polyneuropathies. It is particularly helpful in assessing nerves after trauma. Neuromuscular ultrasound is likely to prove even more useful in the electrodiagnostic laboratory as the technology continues to advance.

Prevalence and predictive factors for bilateral carpal tunnel syndrome by electrodiagnosis: A retrospective study.

INTRODUCTION: Carpal tunnel syndrome (CTS) is the most common compressive neuropathy. Patients who have unilateral symptoms are frequently found to have bilateral CTS by electrodiagnostic (EDx) study. We aimed to (a) study the prevalence and identify the predictive factors for bilateral CTS diagnosed by EDx; and (b) develop a model to predict bilateral CTS. METHODS: The retrospective clinical and EDx data of patients with CTS were collected and analyzed using the Chi-squared test and multiple logistic regression analysis. A model was fitted, and the best cutoff point determined. Calibration and discrimination performance of the model were performed. RESULTS: A total of 327 patients with a mean age of 50.0 years were enrolled. Most were women (82.6%), and the most common presenting symptom was hand numbness (93.6%). The median duration of symptoms was 60 days. The prevalence of bilateral CTS was 80.7%. In the multivariate analysis, the predictive factors for bilateral CTS were the presence of bilateral symptoms (AOR 6.7 [95%CI 3.1-14.3]), thenar muscle weakness (AOR 3.9 [95%CI 1.3-11.6]), and age ≥ 45 years (AOR 2.5 [95%CI 1.3-4.6]). The logistic regression model was fitted, and the best cutoff point determined. The area under the receiver operating curve (AUC) was 0.76. The respective optimism-corrected C index and Somers' D was 0.762 and 0.524. CONCLUSION: The prevalence of bilateral CTS was 80.7%. Our findings suggest bilateral CTS was predicted with adequate diagnostic accuracy by bilateral symptoms, age ≥ 45 years, and thenar muscle weakness.

Evaluation and resolution of many challenges of neural spike sorting: a new sorter.

We evaluate existing spike sorters and present a new one that resolves many sorting challenges. The new sorter, called "full binary pursuit" or FBP, comprises multiple steps. First, it thresholds and clusters to identify the waveforms of all unique neurons in the recording. Second, it uses greedy binary pursuit to optimally assign all the spike events in the original voltages to separable neurons. Third, it resolves spike events that are described more accurately as the superposition of spikes from two other neurons. Fourth, it resolves situations where the recorded neurons drift in amplitude or across electrode contacts during a long recording session. Comparison with other sorters on ground-truth data sets reveals many of the failure modes of spike sorting. We examine overall spike sorter performance in ground-truth data sets and suggest postsorting analyses that can improve the veracity of neural analyses by minimizing the intrusion of failure modes into analysis and interpretation of neural data. Our analysis reveals the tradeoff between the number of channels a sorter can process, speed of sorting, and some of the failure modes of spike sorting. FBP works best on data from 32 channels or fewer. It trades speed and number of channels for avoidance of specific failure modes that would be challenges for some use cases. We conclude that all spike sorting algorithms studied have advantages and shortcomings, and the appropriate use of a spike sorter requires a detailed assessment of the data being sorted and the experimental goals for analyses.NEW & NOTEWORTHY Electrophysiological recordings from multiple neurons across multiple channels pose great difficulty for spike sorting of single neurons. We propose methods that improve the ability to determine the number of individual neurons present in a recording and resolve near-simultaneous spike events from single neurons. We use ground-truth data sets to demonstrate the pros and cons of several current sorting algorithms and suggest strategies for determining the accuracy of spike sorting when ground-truth data are not available.

Acute carpal tunnel syndrome: Clinical, electromyographic, and ultrasound features in 25 patients.

BACKGROUND: The acute presentation of carpal tunnel syndrome (CTS) is rare. When symptoms start acutely with no obvious causes, ultrasound (US) imaging may provide clues to the etiology. OBJECTIVE: This study describes the clinical, electromyographic, and US findings in 25 patients presenting with acute CTS (ACTS). METHODS: In this analysis, of the patients referred for electrodiagnostic confirmation of CTS over the past decade, 25 had an acute onset of symptoms. All patients underwent EMG/NCV and US of the median nerve at the carpal tunnel and forearm. RESULTS: Of the 25 cases with ACTS, 5 (20%) had bilateral involvement leading to the total hands studied to 30. In 14 (56%) patients, an inciting event was identified as a possible cause of ACTS. In 11 (44%) patients without an antecedent event, 7 (64%) had a persistent median artery (PMA) detected by US. Electrodiagnostic studies showed prolonged distal motor latency with normal motor conduction velocity proximal to the carpal tunnel in 24 (80%) of 30 hands, 6 (20%) hands showed absent compound muscle action potentials over the abductor pollicis brevis (APB), and 22 (73%) hands had absent sensory potentials. Denervation changes were seen in the APB in 13 (43%) hands, and motor unit potentials were absent in 6 (20%) hands. Sixteen (64%) patients underwent a carpal tunnel release for severe symptoms. CONCLUSION: CTS may present acutely without a clinically identifiable cause. US complements electrodiagnostic studies and is particularly useful when electrodiagnostic tests are non-diagnostic (due to absent compound muscle and sensory action potentials). US may also provide clues to the underlying cause.

An open-source application for the standardized burst identification from the integrated muscle sympathetic neurogram.

Muscle sympathetic nerve activity (MSNA) can be acquired from humans using the technique of microneurography. The resulting integrated neurogram displays pulse-synchronous bursts of sympathetic activity, which undergoes processing for standard MSNA metrics including burst frequency, height, area, incidence, total activity, and latency. The procedure for detecting bursts of MSNA and calculating burst metrics is tedious and differs widely among laboratories worldwide. We sought to develop an open-source, cross-platform web application that provides a standardized approach for burst identification and a tool to increase research reproducibility for those measuring MSNA. We compared the performance of this web application against a manual scoring approach under conditions of rest, chemoreflex activation (n = 9, 20-min isocapnic hypoxia), and metaboreflex activation (n = 13, 2-min isometric handgrip exercise and 4-min postexercise circulatory occlusion). The intraclass correlation coefficient (ICC) indicated good to strong agreement between scoring approaches for burst frequency (ICC = 0.92-0.99), incidence (ICC = 0.94-0.99), height (ICC = 0.76-0.88), total activity (ICC = 0.85-0.99), and latency (ICC = 0.97-0.99). Agreement with burst area was poor to moderate (ICC = 0.04-0.67) but changes in burst area were similar with chemoreflex and metaboreflex activation. Scoring using the web application was highly efficient and provided data visualization tools that expedited data processing and the analysis of MSNA. We recommend the open-source web application be adopted by the community for the analysis of MSNA.NEW & NOTEWORTHY The basic analysis of muscle sympathetic nerve activity (MSNA) requires the identification of pulse-synchronous bursts from the integrated neurogram before standard MSNA metrics can be quantified. This process is a time-consuming task requiring an experienced microneurographer to visually identify and manually label bursts. We developed an open-source, cross-platform application permitting a standardized approach for sympathetic burst identification and present the performance of this application against a manual scorer under basal conditions and during sympathoexcitatory stresses.

Machine learning-based approach for disease severity classification of carpal tunnel syndrome.

Identifying the severity of carpal tunnel syndrome (CTS) is essential to providing appropriate therapeutic interventions. We developed and validated machine-learning (ML) models for classifying CTS severity. Here, 1037 CTS hands with 11 variables each were retrospectively analyzed. CTS was confirmed using electrodiagnosis, and its severity was classified into three grades: mild, moderate, and severe. The dataset was randomly split into a training (70%) and test (30%) set. A total of 507 mild, 276 moderate, and 254 severe CTS hands were included. Extreme gradient boosting (XGB) showed the highest external validation accuracy in the multi-class classification at 76.6% (95% confidence interval [CI] 71.2-81.5). XGB also had an optimal model training accuracy of 76.1%. Random forest (RF) and k-nearest neighbors had the second-highest external validation accuracy of 75.6% (95% CI 70.0-80.5). For the RF and XGB models, the numeric rating scale of pain was the most important variable, and body mass index was the second most important. The one-versus-rest classification yielded improved external validation accuracies for each severity grade compared with the multi-class classification (mild, 83.6%; moderate, 78.8%; severe, 90.9%). The CTS severity classification based on the ML model was validated and is readily applicable to aiding clinical evaluations.

Machine learning powered tools for automated analysis of muscle sympathetic nerve activity recordings.

Automated analysis and quantification of physiological signals in clinical practice and medical research can reduce manual labor, increase efficiency, and provide more objective, reproducible results. To build a novel platform for the analysis of muscle sympathetic nerve activity (MSNA), we employed state-of-the-art data processing and machine learning applications. Data processing methods for integrated MSNA recordings were developed to evaluate signals regarding the overall quality of the signal, the validity of individual signal peaks regarding the potential to be MSNA bursts and the timing of their occurrence. An overall probability score was derived from this flexible platform to evaluate each individual signal peak automatically. Overall, three deep neural networks were designed and trained to validate individual signal peaks randomly sampled from recordings representing only electrical noise and valid microneurography recordings. A novel data processing method for the whole signal was developed to differentiate between periods of valid MSNA signal recordings and periods in which the signal was not available or lost due to involuntary movement of the recording electrode. A probabilistic model for timing of the signal bursts was implemented as part of the system. Machine Learning algorithms and data processing tools were implemented to replicate the complex decision-making process of manual MSNA analysis. Validation of manual MSNA analysis including intra- and inter-rater validity and a comparison with automated MSNA tools is required. The developed toolbox for automated MSNA analysis can be extended in a flexible way to include algorithms based on other datasets.