Effects of age, sex, and anthropometric factors on nerve conduction measures

The Scratch-Collapse Test: A Systematic Review and Statistical Analysis

BACKGROUND

The scratch-collapse test (SCT) is a provocative maneuver used to diagnose compressive neuropathies. Despite multiple studies supporting its use, the SCT remains a controversial point in the literature in regard to its exact clinical application. We performed a systematic review and statistical analysis to provide statistical data on SCT outcomes and elucidate its role in diagnosing compressive conditions.

METHODS

We performed a systematic review of the literature according to Preferred Reporting for Systematic Reviews and Meta-Analyses guidelines. We extracted data of patients with outcomes on the SCT (yes/no) and on an accepted gold standard examination (electrodiagnostic studies). These data were analyzed using a statistical software program to generate the sensitivity and specificity values of the pooled data, as well as kappa agreement statistics.

RESULTS

For patients with carpal tunnel, cubital tunnel, peroneal, and pronator compressive neuropathies, the overall sensitivity of the SCT was 38%, and the specificity was 94%, with the kappa statistic approximately 0.4. Sensitivity and specificity values were higher for cubital tunnel syndrome and peroneal compression syndrome but lower for carpal tunnel syndrome. Pronator syndrome was also examined, but the data were inadequate for analysis.

CONCLUSIONS

The SCT is a useful adjunct in the armament of diagnostic tools for the hand surgeon. Given its low sensitivity and high specificity, SCT should be used as a confirmatory test, rather than as a diagnostic screening test. More analyses are needed to identify subtler applications.

Motor point stimulation activates fewer Ia-sensory nerves than peripheral nerve stimulation in human soleus muscle

Peripheral nerve stimulation (PNS) and motor point stimulation (MPS) are noninvasive techniques used to induce muscle contraction, aiding motor function restoration in individuals with neurological disorders. Understanding sensory inputs from PNS and MPS is crucial for facilitating neuroplasticity and restoring impaired motor function. Although previous studies suggest that MPS could induce Ia-sensory inputs less than PNS, experimental evidence supporting this claim is insufficient. Here, we implemented a conditioning paradigm combining transcutaneous spinal cord stimulation (tSCS) with PNS or MPS to investigate their Ia-sensory inputs. This paradigm induces postactivation depression of spinal reflexes associated with transient decreases in neurotransmitter release from Ia-afferent terminals, allowing us to examine the Ia-sensory input amount from PNS and MPS based on the depression degree. We hypothesized that MPS would induce less postactivation depression than PNS. Thirteen individuals underwent MPS and PNS on the soleus muscle as conditioning stimuli, with tSCS applied to the skin between the spinous processes (L1-L2) as test stimuli. PNS- and MPS-conditioned spinal reflexes were recorded at five interstimulus intervals (ISIs) and four intensities. Results revealed that all PNS conditioning showed significant decreases in spinal reflex amplitudes, indicating postactivation depression. Furthermore, PNS conditioning exhibited greater depression for shorter ISIs and higher conditioning intensities. In contrast, MPS conditioning demonstrated intensity-dependent depression, but without all-conditioning depression and clear ISI dependency as seen in PNS conditioning. In addition, PNS induced significantly greater depression than MPS across most conditions. Our findings provide experimental evidence supporting the conclusion that MPS activates Ia-sensory nerves less than PNS.NEW & NOTEWORTHY Peripheral nerve stimulation (PNS) and motor point stimulation (MPS) induce neuroplasticity, but differences in their effects on Ia-sensory inputs are unclear. We investigated their Ia-sensory inputs using a conditioning paradigm with spinal reflexes. Results showed that PNS conditioning significantly inhibited spinal reflexes than MPS conditioning, indicating greater postactivation depression due to Ia-sensory nerve activation. These findings provide experimental evidence that MPS activates Ia-sensory nerves to a lesser extent than PNS, enhancing our understanding of neuroplasticity.

Reference Standard of Median Nerve Conduction Study in Korea

OBJECTIVE

To establish the reference standard of the median nerve conduction study (NCS) in Korea.

METHODS

A total of 648 median motor and 602 median sensory NCSs from 349 Korean healthy volunteers were tested and analyzed prospectively. Equipment calibration, assessment of intraand inter-rater reliability, and the NCSs per se were conducted according to a predetermined protocol. A reference standard was established from uncertainty components for the following parameters: the onset and peak latencies; the baseline-to-peak and peak-to-peak amplitudes; the area and duration of the negative wave; and the nerve conduction velocity. The effects of sex, age and stimulation intensity were analyzed.

RESULTS

Each measured value of 648 median motor and 602 median sensory nerves were obtained and presented with both mean and expanded uncertainties, as well as mean and standard deviations. The cut-off values with expanded uncertainty were determined for different age and sex groups. After adjusting for anthropometric covariates, all parameters except duration were affected by age, and sex appeared to influence both duration and area. While stimulation intensity significantly affected some parameters including latencies, the effect sizes were negligible.

CONCLUSION

We propose the median NCS reference standard using the largest Korean dataset ever available. The use of the traceable and reliable reference standard is anticipated to promote more accurate and dependable diagnosis and appropriate management of median neuropathies in Korea.

Nerve conduction features may serve as a diagnostic clue for neuronal intranuclear inclusion disease

Neuronal intranuclear inclusion disease is a neurodegenerative disorder with a wide phenotypic spectrum, including peripheral neuropathy. This study aims to characterize the nerve conduction features and proposes an electrophysiological criterion to assist the diagnosis of neuronal intranuclear inclusion disease. In this study, nerve conduction studies were performed in 50 genetically confirmed neuronal intranuclear inclusion disease patients, 200 age- and sex-matched healthy controls and 40 patients with genetically unsolved leukoencephalopathy. Abnormal electrophysiological parameters were defined as mean values plus or minus two standardized deviations of the healthy controls or failure to evoke a response on the examined nerves. Compared to controls, neuronal intranuclear inclusion disease patients had significantly slower motor and sensory nerve conduction velocities, as well as lower amplitudes of compound motor action potentials and sensory nerve action potentials in all tested nerves (P < 0.05). Forty-eight of the 50 neuronal intranuclear inclusion disease patients (96%) had at least one abnormal electrophysiological parameter, with slowing of motor nerve conduction velocities being the most prevalent characteristic. The motor nerve conduction velocities of median, ulnar, peroneal and tibial nerves were 44.2 ± 5.5, 45.3 ± 6.1, 37.3 ± 5.3 and 35.6 ± 5.1 m/s, respectively, which were 12.4-13.6 m/s slower than those of the controls. The electrophysiological features were similar between neuronal intranuclear inclusion disease patients manifesting with CNS symptoms and those with PNS-predominant presentations. Thirteen of the 14 patients (93%) who underwent nerve conduction study within the first year of symptom onset exhibited abnormal findings, indicating that clinical or subclinical peripheral neuropathy is an early disease marker of neuronal intranuclear inclusion disease. We then assessed the feasibility of using motor nerve conduction velocity as a diagnostic tool of neuronal intranuclear inclusion disease and evaluated the diagnostic performance of various combinations of nerve conduction parameters using receiver operating characteristic curve analysis. The criterion of having at least two nerves with motor nerve conduction velocity ranging from 35 to 50 m/s in median/ulnar nerves and 30-40 m/s in tibial/peroneal nerves demonstrated high sensitivity (90%) and specificity (99%), with an area under the curve of 0.95, to distinguish neuronal intranuclear inclusion disease patients from healthy controls. The criterion's diagnostic performance was validated on an independent cohort of 56 literature reported neuronal intranuclear inclusion disease cases (area under the curve = 0.93, sensitivity = 87.5%, specificity = 99.0%), and in distinguishing neuronal intranuclear inclusion disease from genetically unresolved leukoencephalopathy cases (sensitivity = 90.0%, specificity = 80.0%). In conclusion, mildly to moderately decreased motor nerve conduction velocity in multiple nerves is a significant electrophysiological hallmark assisting the diagnosis of neuronal intranuclear inclusion disease, regardless of CNS- or PNS-predominant manifestations.

Harnessing historical data to derive reference limits - A comparison of e-norms to traditionally derived reference limits

Objective

Nerve conduction studies (NCS) require valid reference limits for meaningful interpretation. We aimed to further develop the extrapolated norms (e-norms) method for obtaining NCS reference limits from historical laboratory datasets for children and adults, and to validate it against traditionally derived reference limits.

Methods

We compared reference limits obtained by applying a further developed e-norms with reference limits from healthy controls for the age strata's 9-18, 20-44 and 45-60 years old. The control data consisted of 65 healthy children and 578 healthy adults, matched with 1294 and 5628 patients respectively. Five commonly investigated nerves were chosen: The tibial and peroneal motor nerves (amplitudes, conduction velocities, F-waves), and the sural, superficial peroneal and medial plantar sensory nerves (amplitudes, conduction velocities). The datasets were matched by hospital to ensure identical equipment and protocols. The e-norms method was adapted, and reference limit calculation using both ±2 SD (original method) and ±2.5 SD (to compensate for predicted underestimation of population SD by the e-norms method) was compared to control data using ±2 SD. Percentage agreement between e-norms and the traditional method was calculated.

Results

On average, the e-norms method (mean ±2 SD) produced slightly stricter reference limits compared to the traditional method. Increasing the e-norms range to mean ±2.5 SD improved the results in children while slightly overcorrecting in the adult group. The average agreement between the two methods was 95 % (±2 SD) and 96 % (±2.5 SD).

Conclusions

The e-norms method yielded slightly stricter reference limits overall than ones obtained through traditional methods; However, much of the difference can be attributed to a few outlying plots where the raters found it difficult to apply e-norms correctly. The two methods disagreed on classification of 4-5% of cases. Our e-norms software is suited to analyze large amounts of raw NCS data; it should further reduce bias and facilitate more accurate ratings.

Significance

With small adaptations, the e-norms method adequately replicates traditionally derived reference limits, and is a viable method to produce reference limits from historical datasets.

Neurophysiological indices for split phenomena: correlation with age and sex and potential implications in amyotrophic lateral sclerosis

Background

Split phenomena (SP) are characterized by patterns of differential muscle wasting and atrophy, which are highly prevalent in amyotrophic lateral sclerosis (ALS) patients. Several neurophysiological indicators, including the split-hand index (SHI), split-leg index (SLI), and split-elbow index (SEI), have been proposed to assess SP. Nevertheless, their cutoff values and the impact of age and sex on these measures remain unclear.

Methods

We prospectively collected neurophysiological data from 300 healthy adult subjects. The following indices were measured from compound muscle action potentials (CMAPs): SHI [abductor pollicis brevis (APBcmap) x first dorsal interosseous (FDI)cmap/adductor digiti minimi (ADMcmap)], SEI (BICEPScmap/TRICEPScmap), SLI (extensor digit brevis (EDB)cmap/abductor Hallucis (AH)cmap), and the neurophysiological ratios APBcmap /ADMcmap and FDIcmap/ADMcmap. Multiple linear regression analysis was used to investigate the association between age, sex, CMAPs, and neurophysiological indicators.

Results

The median SHI was 10.4, with a median APBcmap/ADMcmap ratio of 0.9 and a median FDIcmap/ADMcmap ratio of 1.2. The median SEI was 1.6 (IQR:1.1-2.4) and the median SLI was 0.7 (IQR:0.5-1.0). Negative associations were observed between age, most of the CMAPs, and all the neurophysiological indices, except for SLI. The male subjects exhibited significantly higher CMAP values for the first dorsal interosseous (FDI), biceps, and SHI compared to the female participants.

Conclusion

Our findings highlight the importance of age- and sex-adjusted normative data for SP indices, which could enhance their diagnostic accuracy and clinical utility in patients with ALS. The SL index appears to be the most reliable indicator, as it showed no significant association with age or sex.

Sensory nerve conduction studies in infants, children and teenagers - An update

Objective

Nerve conduction studies (NCS) in children remain technically challenging and depend on the cooperation of the child. Motor NCS are not compromised by analgosedation but data for sensory NCS are lacking. Here, we ask whether sensory NCS is influenced by analgosedation. We also compare the present data with NCS studies from the 1990s regarding anthropometric acceleration of the contemporary paediatric population.

Methods

Sensory NCS of the median nerve and sural nerve were performed in 182 healthy subjects aged 1 to 18 years during general anaesthesia and in 47 of them without analgosedation.

Results

Sensory NCS was not influenced by midazolam or propofol. The sensory nerve action potential (SNAP) amplitude and the nerve conduction velocity (NCV) of the sural nerve as well as the SNAP of the median nerve show no significant age dependence in age range 1-18 years. The sensory NCV of the median nerve increased age-dependent.

Conclusions

In clinical practice, analgosedation can be used for diagnostic NCS. Sensory NCS data show no relevant secular trend over the last 30 years. Differences due to technical inconsistency predominate.

Significance

Analgosedation can improve diagnostic quality of sensory NCS in children. Additionally, we provide sensory NCS values from a large pediatric cohort.

V, Manikandan M. Arm Length-Does It Influence Late Response in a Nerve Conduction Study?

Introduction  F wave response, a late response obtained from a motor nerve, can be influenced by various external factors like gender, temperature, height, weight, and limb length, and hence it causes variation in the measured parameters. Since very few studies have studied the impact of arm length on the F wave, this study was conducted to analyze the relation between the arm length on various parameters of F wave and hence to consider the importance of it during conduct of a nerve conduction study. Methods  The study was conducted among 40 healthy individuals and 40 diabetics with neuropathy. The arm length was measured in the upper limbs in both the groups and F wave was recorded following a conventional procedure using a standardized instrument. Results  This study showed that in the upper limbs of both the groups, there existed a positive correlation for certain parameters like minimum, maximum and mean latencies, persistence, FM latency and M latency, and a negative correlation for chronodispersion. Conclusion  F wave parameters should be adjusted for arm length to improve the sensitivity and diagnostic ability of neurological testing.

Age-Related Changes in Neurologic Examination and Sensory Nerve Amplitude in the General Population: Aging of the Peripheral Nervous System

BACKGROUND AND OBJECTIVES

Chronic axonal polyneuropathy is a common disease of the peripheral nervous system with increasing prevalence with age. Typical neurologic signs are present in patients with polyneuropathy but may also occur in individuals without disease. Owing to limited knowledge on normal aging of the peripheral nervous system, it can be difficult to distinguish peripheral nerve dysfunction due to disease from variations in normal aging. Therefore, we described the changes in neurologic examination and nerve conduction studies that accompany aging in the general population.

METHODS

In this cross-sectional population-based study, we screened participants for chronic polyneuropathy in a controlled environment using standardized methods including a symptom questionnaire, neurologic examination, and nerve conduction studies (NCS). Inclusion criteria were 40 years or older and living in a suburb of Rotterdam, the Netherlands. Participants not diagnosed with chronic polyneuropathy, based on the discussion of findings in the screening by an expert team, were included to determine the effect of age (range 41-96 years) on features of neurologic examination and NCS using frequency calculations and quantile regression analysis.

RESULTS

In total, 4,179 participants (mean age 64.5 ± 12.7 years, 54.9% female) were included of whom 3,780 (90.5%) did not fulfil the criteria for polyneuropathy. In the population without polyneuropathy, the frequency of normal features at neurologic examination declined with age, most pronounced for vibration sense at the hallux (from 6.6 [SD ± 1.5] in 40-49 years to 3.6 [SD ± 3.1] in 80 years or older) and Achilles tendon reflexes (absent in 9% in 40-49 years up to 33% in 80 years or older). Superficial pain sensation and patellar tendon reflexes remained stable over time. Sural sensory nerve action potential (SNAP) amplitude declined with age from 11.2 μV in 40-49 years to 3.3 μV in 80 years or older. Nonrecordable SNAP amplitudes were found in 25.1% of the participants older than 80 years, more often in men (30.3%) than in women (21.0%).

DISCUSSION

This study showed the effect of age on features of neurologic examination and sural nerve amplitude in the general population. These findings are helpful to distinguish features suggesting polyneuropathy from variations of normal aging of the peripheral nervous system.

Morbidity Associated with Chronic Hyponatremia

This article will discuss the consequences of chronic hyponatremia. In conditions such as cancer, heart failure, liver cirrhosis, or chronic kidney disease, the presence and magnitude of hypotonic hyponatremia are considered to reflect the severity of the underlying disease and are associated with increased morbidity as well as mortality. Hyponatremia can be acute (<48 h) or chronic (>2-3 days). Chronic hyponatremia is associated with attention deficit, dizziness, tiredness, gait disturbance, falls, sarcopenia, bone fractures, osteoporosis, hypercalciuria (in the syndrome of inappropriate antidiuresis-SIADH), and kidney stones. In vitro studies have shown that cells grown in a low concentration of extracellular sodium have a greater proliferation rate and motility. Patients with chronic hyponatremia are more likely to develop cancer. We will not review the clinical consequences of respiratory arrest and osmotic demyelination syndrome (ODS) of the too-late or excessive treatment of hyponatremia.

Nerve Conduction Differences in a Large Clinical Population: The Role of Age and Sex

BACKGROUND

The normal limits of nerve conduction studies are commonly determined by testing healthy subjects. However, in comprehensive real-life nerve conduction electrodiagnostic (EDX) evaluations, multiple nerves are tested, including normal nerves, for purposes of comparison with abnormal ones.

OBJECTIVE

This study aims to evaluate the average values of normal nerve conduction studies in a large population and examined the influence of age and sex.

METHODS

EDX parameters were extracted from an electronic database of studies performed from May 2016 to February 2022. Established normal values were used to determine the classification of a nerve study as normal.

RESULTS

We identified 10,648 EDX reports with 5077 normally interpreted nerve conduction studies (47.6%) of which 57% (n = 2890) were for females. The median age of studies with no abnormalities was 45.1 years (range < 1 to 92) overall and 42.5 years (range: 0.16 -89.5 years) for males and 47.5 years (range:<1 -91.7) for females. Correlations between age and amplitude, latency, and velocity (p < 0.001) were observed in most nerves. Amplitude correlated negatively with age in adults in all nerves with a mean of -0.44 (range: -0.24 to -0.62). However, in the pediatric population (age < 18 years), amplitude as well as velocity increased significantly with age. In the adult cohort, sex differences were noted, where females had higher mean sensory nerve action potentials in ulnar, median, and radial evaluations (p < 0.001). In older patients (aged > 70 years) with normally interpreted EDX studies (845 records of 528 patients), sural responses were present in 97%.

CONCLUSIONS

This real-life study confirms that advanced aging is associated with decreased nerve conduction amplitudes, increased latency, and the slowing of conduction velocity. The findings also indicate higher sensory amplitudes and conduction velocities in females. Sural nerve responses were identified in most adults over age 70.

Precise Spiking Motifs in Neurobiological and Neuromorphic Data

Why do neurons communicate through spikes? By definition, spikes are all-or-none neural events which occur at continuous times. In other words, spikes are on one side binary, existing or not without further details, and on the other, can occur at any asynchronous time, without the need for a centralized clock. This stands in stark contrast to the analog representation of values and the discretized timing classically used in digital processing and at the base of modern-day neural networks. As neural systems almost systematically use this so-called event-based representation in the living world, a better understanding of this phenomenon remains a fundamental challenge in neurobiology in order to better interpret the profusion of recorded data. With the growing need for intelligent embedded systems, it also emerges as a new computing paradigm to enable the efficient operation of a new class of sensors and event-based computers, called neuromorphic, which could enable significant gains in computation time and energy consumption-a major societal issue in the era of the digital economy and global warming. In this review paper, we provide evidence from biology, theory and engineering that the precise timing of spikes plays a crucial role in our understanding of the efficiency of neural networks.

Clinical Relevance of Ultrasonographic and Electrophysiological Findings of the Median Nerve in Unilateral Carpal Tunnel Syndrome Patients

Few studies have compared the unaffected and affected sides in the same carpal tunnel syndrome (CTS) patients using ultrasonography and electrophysiological tests. We focused on unilateral idiopathic CTS patients to investigate whether clinical test results differ between the unaffected and affected sides. The bilateral wrist joints of 61 unilateral idiopathic CTS patients were evaluated. The median nerve cross-sectional area of ultrasound image, and latencies of the compound muscle action potential (CMAP) and sensory nerve action potential (SNAP) were measured. The values obtained were compared between the affected and unaffected sides. The diagnostic accuracies of each parameter were assessed, and cut-off values were defined. Significant differences were observed in all parameters between the affected and unaffected sides (p < 0.01). Area under the curve (AUC) values were 0.74, 0.88, and 0.73 for the cross-sectional area, CMAP distal latency, and SNAP distal latency, respectively. Cut-off values were 11.9 mm2, 5.1 ms, and 3.1 ms for the cross-sectional area, CMAP distal latency, and SNAP distal latency, respectively. The most reliable parameter that reflected clinical symptoms was the distal latency of CMAP. Cut-off values for each parameter are considered to be an index for the onset of the clinical symptoms of CTS.

Nerve Conduction Study in Healthy Elderly Subjects in Central India: A Cross-Sectional Study

Background

There are many physiological changes that accompany aging. Slowing of muscle contraction, alteration of muscle metabolism and neuromuscular junction, and reduction of nerve conduction velocity (NCV) are among these physiological changes. The present study was conducted to elucidate the effect of physiological factors like gender, height, and Body Mass Index (BMI) on motor and sensory nerve conduction study (NCS) of the upper limb and find out the normal data for healthy elderly subjects in central India.

Methods

A cross-sectional study among 382 healthy adult participants of central India aged 60 years and above. The study was carried out in the department of Physiology, Acharya Vinoba Bhave Rural Hospital, Wardha, India, from July 2017 to June 2022. An NCS was performed using the Neuron Spectrum 5 machine (Neurosoft, Ivanovo, Russia). A Microsoft Excel spreadsheet (Microsoft Corporation, Redmond, Washington, United States) was used to tabulate the information gathered. For statistical analysis, IBM SPSS Statistics for Windows, Version 22.0 (Released 2013; IBM Corp., Armonk, New York, United States) was used.

Results

All NCS parameters were greater in males as compared to females. As age advances, longer distal motor latency (DML) and F-wave minimum latency, decreasing amplitude, and slowing of conduction velocity (CV) were observed. As height increases, increasing DML and F-wave minimum latency, decreasing amplitude, and slowing of CV were observed. Higher BMI was found to be associated with lower amplitudes and slowing of CVs.

Conclusion

Age and height have a negative influence on amplitude and CV is a positive influence on DML and F-min latency. Higher BMI has a negative influence on amplitude and CV.

Sural Sensory Nerve Action Potential: A Study in Healthy Indian Subjects at Tertiary Care Center of North-West India

Objectives

This study was done to obtain the reference data for the sural SNAP amplitude and latency at distances of 14, 12, and 10 cm from the active recording electrode in Indian healthy subjects for different age groups.

Material and Methods

Two hundred forty-four healthy subjects (18-80 years) were included in this cross-sectional study. Subjects were divided into six groups according to age. Sural SNAP was recorded antidromically stimulating at three sites (14, 12, and 10 cm from the recording electrode). The quantitative variables were expressed as Mean ± SD/Median (IQR) and compared using t test/ANOVA. Transformed data for amplitude were analyzed with the use of paired t test. P < 0.05 was considered statistically significant. SPSS version 20.0 software was used for statistical analysis.

Results

Mean age of included subjects was 43.28 years. Maximum leg girth was at 14 cm. Analysis showed a significant difference in the leg girth at all three sites (P < 0.001). Sural SNAP latency at each stimulating site was compared in different age groups, no significant difference was found between groups (P = 0.19). Maximum amplitude was in the 18-30-years age group and amplitude was minimum in the 71-80-years age group (4.34 and 2.79, respectively). The difference in the amplitude recorded in the different age groups was found to be statistically different (P < 0.001). The difference in the amplitude recorded at each site was found to be statistically different (P < 0.001).

Conclusion

This is the first study with a large sample size (244 subjects) to provide age-stratified reference data for SNAP in the Indian population by using three sites of stimulation at distances of 14, 12, and 10 cm from the recording electrode. This study shows that sural SNAP amplitude varies with the age of the subject and distance from stimulation.

SUDOSCAN in Combination with the Michigan Neuropathy Screening Instrument Is an Effective Tool for Screening Diabetic Peripheral Neuropathy

BACKGROUND

Screening for diabetic peripheral neuropathy (DPN) is important to prevent severe foot complication, but the detection rate of DPN is unsatisfactory. We investigated whether SUDOSCAN combined with Michigan Neuropathy Screening Instrument (MNSI) could be an effective tool for screening for DPN in people with type 2 diabetes mellitus (T2DM) in clinical practice.

METHODS

We analysed the data for 144 people with T2DM without other cause of neuropathy. The presence of DPN was confirmed according to the Toronto Consensus criteria. Electrochemical skin conductance (ESC) of the feet was assessed using SUDOSCAN. We compared the discrimination power of following methods, MNSI only vs. SUDOSCAN only vs. MNSI plus SUDOSCAN vs. MNSI plus 10-g monofilament test.

RESULTS

Confirmed DPN was detected in 27.8% of the participants. The optimal cut-off value of feet ESC to distinguish DPN was 56 μS. We made the DPN screening scores using the corresponding odds ratios for MNSI-Questionnaire, MNSI-Physical Examination, SUDOSCAN, and 10-g monofilament test. For distinguishing the presence of DPN, the MNSI plus SUDOSCAN model showed higher areas under the receiver operating characteristic curve (AUC) than MNSI only model (0.717 vs. 0.638, P=0.011), and SUDOSCAN only model or MNSI plus 10-g monofilament test showed comparable AUC with MNSI only model.

CONCLUSION

The screening model for DPN that includes both MNSI and SUDOSCAN can detect DPN with acceptable discrimination power and it may be useful in Korean patients with T2DM.

Reference Standards for Nerve Conduction Studies of Individual Nerves of Lower Extremity With Expanded Uncertainty in Healthy Korean Adults

Objective To develop a set of reference standards for tibial motor, common peroneal motor, sural sensory, and superficial peroneal sensory nerve conduction studies (NCSs) with expanded uncertainty in a healthy Korean population.Methods Standardized procedures were conducted for individual lower extremity NCSs of 199 healthy participants in their 20s (n=100) and 50s (n=99). Mean values and expanded uncertainties for parameters were analyzed with thorough consideration of multiple uncertainty factors under the International Guide to the Expression of Uncertainty in Measurement. In addition, side-to-side differences in onset latency, amplitude, and nerve conduction velocity (NCV) were analyzed.Results Mean (reference range) for distal onset latency, baseline to negative peak amplitude, NCV of tibial motor nerve in males in their 20s were 4.3 ms (3.1–5.4 ms), 7.1 mV (3.4–10.9 mV), and 50.7 m/s (42.2–59.3 m/s), respectively; sural sensory nerve baseline to negative peak amplitude in males in their 20s was 21.7 μV (8.3–35.2 μV). Including the aforementioned data, we present a vast dataset of normative mean values and expanded uncertainties for NCSs of the leg in a healthy Korean population. Furthermore, upper limits for normal side-to-side differences for onset latency, amplitude, and NCV of each nerve are suggested.Conclusion To our knowledge, this is the first study to present the reference standards of leg NCSs with consideration for multifactorial uncertainties in an Asian population. We expect these results to help practitioners make reliable and reproducible clinical decisions.

Functional Characterization of Human Pluripotent Stem Cell-Derived Models of the Brain with Microelectrode Arrays

Human pluripotent stem cell (hPSC)-derived neuron cultures have emerged as models of electrical activity in the human brain. Microelectrode arrays (MEAs) measure changes in the extracellular electric potential of cell cultures or tissues and enable the recording of neuronal network activity. MEAs have been applied to both human subjects and hPSC-derived brain models. Here, we review the literature on the functional characterization of hPSC-derived two- and three-dimensional brain models with MEAs and examine their network function in physiological and pathological contexts. We also summarize MEA results from the human brain and compare them to the literature on MEA recordings of hPSC-derived brain models. MEA recordings have shown network activity in two-dimensional hPSC-derived brain models that is comparable to the human brain and revealed pathology-associated changes in disease models. Three-dimensional hPSC-derived models such as brain organoids possess a more relevant microenvironment, tissue architecture and potential for modeling the network activity with more complexity than two-dimensional models. hPSC-derived brain models recapitulate many aspects of network function in the human brain and provide valid disease models, but certain advancements in differentiation methods, bioengineering and available MEA technology are needed for these approaches to reach their full potential.

Variable differences of nerve conduction amplitudes versus velocities and distal latencies of healthy subjects assessed in ethnic cohorts

Variable differences of nerve conduction amplitudes vs velocities and distal latencies (DLs) of healthy subjects assessed in ethnic cohorts.

INTRODUCTION/AIMS

The variables affecting reference compound muscle (CMAP) and sensory nerve action potential (SNAP) amplitudes as compared to ones affecting conduction velocities and DLs have not been adequately evaluated in previous studies. In this report, this subject is studied in healthy subject cohorts mainly of Northern European extraction, Northern Plains Indians, and Latinos.

METHODS

Nineteen variables and 18 attributes of nerve conductions (NCs) were assessed using highly standard testing conditions and techniques. Classification and Regression Tree analyses were used to assess variable differences among amplitudes, conduction velocities, and DLs.

RESULTS

The most important variable affecting CMAP and SNAP amplitudes was age. For conduction velocities (CVs) and DLs, the variables were height, ethnic cohort, and age.

DISCUSSION

The variables affecting attributes of NCs were similar for the three ethnic cohorts evaluated. The differences of variables affecting amplitudes compared to CVs and DLs need to be taken into account in interpretation of NC results and in setting reference limits for use in medical practice, epidemiology surveys, and therapeutic trials. Scores of CMAP and SNAP amplitudes are suitable measures of sensorimotor polyneuropathy severity, whereas conduction velocities and DLs reflect physiologic/pathologic abnormality of nerve fibers.

Can tendon reflexes be elicited by both stretch and vibration in man?

AIM OF STUDY

When the biceps tendon is tapped, a contraction is elicited in the biceps muscle. This also occurs with tapping of the radial bone, and it has been suggested that vibration is a stimulus for deep tendon reflexes. We investigated whether the normal stimulus for the deep tendon reflex is a sudden stretch, a phasic vibration, or both. Furthermore, we investigated the importance of forearm position for the reflex response in controls and stroke patients.

METHODS

We investigated 50 neurological outpatients without clinical signs of neurological disorders in the arms. The biceps tendon and distal radius were tapped with the forearm in the midway (90°), supinated, and pronated positions. In 10 of these patients, the two reflexes were also investigated with quantitative electromyography (EMG) measurements in the 3 positions. Another 10 patients were investigated clinically when stretch of elbow was eliminated and 17 patients were examined when prestretching of the biceps tendon was avoided. Finally, we examined 32 patients that had experienced stroke.

RESULTS

In 94% (47/50) of patients, after a radial tap, the biceps contraction disappeared in the supinated forearm, and the median peak-to-peak amplitude of the surface EMG response (n = 10) decreased from 1.1 to 0.2 mV (p < .01). Elimination of elbow stretch as well as pressure on the biceps tendon did not change the reflex response. In 84% (27/32) of stroke patients, after a radial tap, the biceps contraction persisted in supination in the arm with hyperreflexia.

CONCLUSION

The combined clinical and EMG results are consistent with the concept that the deep tendon reflexes in man can be elicited by both stretch and phasic vibration. Clinicians should be aware that the brachioradial reflex depends on the forearm position.

Effect of aging on vagus somatosensory evoked potentials and ultrasonographic parameters of the vagus nerve

Vagus somatosensory evoked potentials (VSEP) and ultrasonography can be used to detect functional and structural changes of the vagus nerve (VN) that are hypothesized to be associated with neurodegenerative diseases. However, it has not yet been established whether age-related changes in the VN occur in the healthy population. In this pilot study we included healthy volunteers in the 26-30 and 51-55 age range who comprised the younger (n = 20) and older (n = 20) groups, respectively. VSEP were recorded separately for stimulation of the auricular branch of the left and right VN. The VN CSA was measured in the transverse plane proximal to the carotid bifurcation, at the level of the distal end of the common carotid artery. No differences were found between the younger and older groups when comparing the average VN CSA (2.01 ± 0.20 vs 2.05 ± 0.20, mm²; p = 0.570) or the CSA of the right (2.08 ± 0.19 vs 2.17 ± 0.24, mm²; p = 0.233) or left VN (1.94 ± 0.26 vs 1.93 ± 0.24, mm²; p = 0.911). The right VN was larger than the left in 95% (n = 19) of older participants and in 65% (n = 13) of younger participants (p = 0.055). In comparison with the younger group, older participants showed significantly longer VSEP latencies of all wave components for electrodes C4-F4 and Fz-F3, of P1 for electrodes C3-F3 and of N1 and P2 for electrodes Fz-F4. The results of this study indicate that older age is associated with longer VSEP latencies but not with changes in VN CSA.

Do carpal Tunnel Hands Have Different Shape Compare to Normal Hands?

Background

Given the fact that the carpal tunnel syndrome (CTS) happens as a consequence of the median nerve entrapment, besides other known factors, the shape and anthropometric characteristics of the carpal tunnel, wrist, and hand could be considered as a predisposing risk factor for idiopathic CTS. The aim of this study was to evaluate the morphology and radiologic scales in CTS hands.

Methods

In this prospective study, patients who underwent upper extremity electrodiagnostic studies were enrolled for hand morphologic and radiographic indexes. Patients were divided into CTS suffering and CTS symptom-free groups according to nerve conduction velocity (NCV) findings. A true posteroanterior radiograph of the hands was pas performed for each participant. Metacarpal length to wrist length index (carpal ratio), metacarpal length to metacarpal width index, third to first metacarpal length, hand length index, and hand volume index were measured in both groups.

Results

Significant differences were seen between the two groups regarding the body mass index (P< 0.001), metacarpal length divided by metacarpal width index (P=0.08), first metacarpal length divided by third metacarpal length (P=0.002), wrist circumference divided by distal flexor wrist crease to the tip of the third finger (P< 0.001), distal flexor wrist crease to the tip of the third finger divided by hand volume (P=0.05), and distal flexor wrist crease to the tip of the third finger divided by wrist circumference (P< 0.001). Multivariable analysis of hand indices were statically significant for the first metacarpal length divided by third metacarpal length (P=0.00), wrist circumference divided by distal flexor wrist crease to the tip of the third finger (P=0.138), and distal flexor wrist crease to the tip of the third finger divided by wrist circumference (P=0.117). However, first metacarpal length divided by third metacarpal length and third metacarpal length divided by palm height were associated with higher CTS occurrences. Receiver operating characteristic curve analysis demonstrated cutoff points which were possible to estimate only for first metacarpal length divided by third metacarpal length and wrist circumference divided by distal flexor wrist crease to the tip of the third finger.

Conclusion

Based on our findings, CTS hand is characterized by shorter fingers compared to thumb and wrist (metacarpal length to wrist length and hand length indexes), wider (metacarpal length to metacarpal width index), and bulkier (hand volume index) compared to non-CTS hands. The severity of CTS was correlated with a higher carpal ratio. In conclusion, CTS hands are bulkier with wider palms and shorter fingers compared to thumb. In this study, the thumb to the third metacarpal length was proved to be the best index for diagnosis of "CTS hand".

The determinants of complication trajectories in American Indians with type 2 diabetes

BACKGROUNDWe aimed to determine whether metabolic syndrome (MetS) affects longitudinal trajectories of diabetic complications, including neuropathy, cardiovascular autonomic neuropathy (CAN), and kidney disease in American Indians with type 2 diabetes.METHODSWe performed a prospective study where participants underwent annual metabolic phenotyping and outcome measurements. The updated National Cholesterol Education Program criteria were used to define MetS and its individual components, using BMI instead of waist circumference. Neuropathy was defined using the Michigan Neuropathy Screening Instrument index, CAN with the expiration/inspiration ratio, and kidney disease with glomerular filtration rate. Mixed-effects models were used to evaluate associations between MetS and these outcomes.RESULTSWe enrolled 141 participants: 73.1% female, a mean (±SD) age of 49.8 (12.3), and a diabetes duration of 19.6 years (9.7 years) who were followed for a mean of 3.1 years (1.7 years). MetS components were stable during follow-up except for declining obesity and cholesterol. Neuropathy (point estimate [PE]: 0.30, 95% CI: 0.24, 0.35) and kidney disease (PE: -14.2, 95% CI: -16.8, -11.4) worsened over time, but CAN did not (PE: -0.002, 95% CI: -0.006, 0.002). We found a significant interaction between the number of MetS components and time for neuropathy (PE: 0.05, 95% CI: 0.01-0.10) but not CAN (PE: -0.003, 95% CI: -0.007, 0.001) or kidney disease (PE: -0.69, 95% CI: -3.16, 1.76). Systolic blood pressure (SBP, unit = 10 mmHg) was associated with each complication: neuropathy (PE: 0.23, 95% CI: 0.07, 0.39), CAN (PE: -0.02, 95% CI: -0.03, -0.02), and kidney disease (PE: -10.2, 95% CI: -15.4, -5.1).CONCLUSIONIn participants with longstanding diabetes, neuropathy and kidney disease worsened during follow-up, despite stable to improving MetS components, suggesting that early metabolic intervention is necessary to prevent complications in such patients. Additionally, the number of MetS components was associated with an increased rate of neuropathy progression, and SBP was associated with each complication.FUNDINGThe following are funding sources: NIH T32NS0007222, NIH R24DK082841, NIH R21NS102924, NIH R01DK115687, the Intramural Program of the NIDDK, the NeuroNetwork for Emerging Therapies, the Robert and Katherine Jacobs Environmental Health Initiative, the Robert E. Nederlander Sr. Program for Alzheimer's Research, and the Sinai Medical Staff Foundation.TRIAL REGISTRATIONClinicalTrials.gov, NCT00340678.

Can Foraminal Stenosis Due to Lumbar Isthmic Spondylolisthesis Cause Axonopathy in the Lower Extremity?

This study aimed to investigate, using electrodiagnosis, whether foraminal stenosis due to isthmic spondylolisthesis (IS) causes peripheral nerve axonopathy. We retrospectively reviewed the medical records of the Yeungnam University Hospital and included 46 patients (mean age = 60.8 ± 13.7 years; male:female = 24:22) with foraminal stenosis due to IS. We classified foraminal stenosis grading based on T2 and T1 sagittal spinal magnetic resonance imaging (MRI). Patients were divided into mild (n = 18) and severe foraminal stenosis (n = 28) groups. To evaluate axonopathy in the lower extremity, results of compound motor action potential (CMAP) of the extensor digitorum brevis muscle (EDB) and abductor hallucis brevis muscle (AHB), and sensory nerve action potential (SNAP) of the sural nerve were retrieved. No statistically significant difference was observed in the amplitude of CMAP of the EDB and AHB and SNAP of the sural nerve with the severity of foraminal stenosis. However, age showed a statistically significant relationship with the amplitude of NCS in the EDB, AHB, and sural nerves (p < 0.001). The severity of foraminal stenosis due to IS showed no relationship with axonopathy beyond age-related degeneration of the lower extremities. Therefore, if there is robust axonopathy in lower extremities, physicians should consider pathologies other than foraminal stenosis due to IS.

Metabolic and Anthropometric Influences on Nerve Conduction Parameters in Patients with Peripheral Neuropathy: A Retrospective Chart Analysis

Background and Aims: Nerve conduction study (NCS) measures how fast an electrical impulse moves through the nerve and is a standard technique for diagnosing and assessing neurological diseases. Despite diabetes and obesity being a common accompaniment of peripheral neuropathy, their effects on NCS patterns have not been elucidated conclusively. Our study aimed to assess several anthropometric and metabolic factors with NCS outcomes to address this gap. Research Design and Methods: This retrospective chart analysis study was conducted on subjects who underwent NCS between 1 January 2009 and 31 December 2019 at a regional hospital. Metabolic, anthropometric, demographical and NCS data were collected from patients’ health records. Results: In total, 120 subjects presenting with sensorimotor peripheral neuropathy symptoms were included in the study. Age, HbA1c, urea and ESR variables were significantly negatively associated with nerve conduction outcomes (Spearman’s correlation rho between −0.210 and −0.456, p < 0.038). HbA1c and age consistently had the most substantial contribution to velocity and amplitude in all regression models (beta coefficients between −0.157 and 0.516, p < 0.001). Urea also significantly account for a large amount of variance in amplitude and velocity in the lower limbs. Conclusion: This study suggests that the severity of sensorimotor neuropathy is influenced by glycaemic control, age and uraemia. The interpretation of NCS results must consider these factors suggesting that improved glycaemic and uraemic control may improve nerve conduction outcomes.

Association of the role of personal variables and nonoccupational risk factors for work-related carpal tunnel syndrome

OBJECTIVES

The purpose of this study was to identify personal variables and nonoccupational risk factors for carpal tunnel syndrome and to analyse the strength of association of these factors.

METHODS

We performed a case-control study with 162 cases and 300 controls. We studied consecutive patients with an electrophysiologically confirmed diagnosis of symptomatic carpal tunnel syndrome. Univariate analysis was performed in the case group and control comparing them for presence of various risk factors. Multivariate analysis was carried out through logistic regression.

RESULTS

The mean BMI and age were greater in the case group than in the control. Multivariate analysis showed that BMI (OR = 1.05, 95% CI = 1.01-1.11) and arterial hypertension (OR = 4.63, 95% CI = 2.88-7.44) were the only factors significantly associated with carpal tunnel syndrome. The age, cigarette smoking and alcohol drinking were at the edge of significance.

CONCLUSIONS

Carpal tunnel syndrome is the most common peripheral neuropathy and has been related to occupational activities in some but not all studies. Clarifying this relationship has important implications for workers' compensation systems. Based on our findings, BMI and arterial hypertension are considered to be the most significant risk factors of carpal tunnel syndrome in our study.

Quantified Morphology of the Cervical and Subdiaphragmatic Vagus Nerves of Human, Pig, and Rat

It is necessary to understand the morphology of the vagus nerve (VN) to design and deliver effective and selective vagus nerve stimulation (VNS) because nerve morphology influences fiber responses to electrical stimulation. Specifically, nerve diameter (and thus, electrode-fiber distance), fascicle diameter, fascicular organization, and perineurium thickness all significantly affect the responses of nerve fibers to electrical signals delivered through a cuff electrode. We quantified the morphology of cervical and subdiaphragmatic VNs in humans, pigs, and rats: effective nerve diameter, number of fascicles, effective fascicle diameters, proportions of endoneurial, perineurial, and epineurial tissues, and perineurium thickness. The human and pig VNs were comparable sizes (∼2 mm cervically; ∼1.6 mm subdiaphragmatically), while the rat nerves were ten times smaller. The pig nerves had ten times more fascicles-and the fascicles were smaller-than in human nerves (47 vs. 7 fascicles cervically; 38 vs. 5 fascicles subdiaphragmatically). Comparing the cervical to the subdiaphragmatic VNs, the nerves and fascicles were larger at the cervical level for all species and there were more fascicles for pigs. Human morphology generally exhibited greater variability across samples than pigs and rats. A prior study of human somatic nerves indicated that the ratio of perineurium thickness to fascicle diameter was approximately constant across fascicle diameters. However, our data found thicker human and pig VN perineurium than those prior data: the VNs had thicker perineurium for larger fascicles and thicker perineurium normalized by fascicle diameter for smaller fascicles. Understanding these differences in VN morphology between preclinical models and the clinical target, as well as the variability across individuals of a species, is essential for designing suitable cuff electrodes and stimulation parameters and for informing translation of preclinical results to clinical application to advance the therapeutic efficacy of VNS.

The effects of anthropometric and demographic factors on conduction parameters of the ulnar nerve: Multivariate analysis

The objective of the study is to investigate the effects of age, height, gender, body mass index (BMI), waist-to-hip ratio (WHR), arm and elbow measures on ulnar nerve conduction. We enrolled 261 "disease-free" subjects. We analyzed motor conduction velocity (MCV) in across elbow (AE) and forearm tracts, and sensory conduction velocity in 4th, 5th digit-wrist tracts (U4, U5) and in dorsal ulnar cutaneous nerve (DUC). We calculated the amplitudes of sensory and motor potentials (CMAPa and SNAPa), % of CMAPa drop AE, MCV drop and distal motor latency (DML). Univariate and multivariate analyses were performed. We estimated the predictive equations. The median nerve was examined for comparison. Age was negatively correlated with all conduction parameters. Forearm and AE MCV, % of CMAPa drop, DML, U4 and U5 SCV also depended upon height. Females had higher U4 and U5 SNAPa than males. BMI showed inverse relationship with U4 and U5 SNAPa. DUC parameters depended upon BMI and arm length. Similar trends were observed for the median nerve. "Normative" ulnar conduction parameters should be adjusted for demographic and anthropometric measures to improve diagnostic sensitivity.

Risk Factors for Diabetic Peripheral Neuropathy and Cardiovascular Autonomic Neuropathy in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) Study

The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study demonstrated that intensive glucose control reduced the risk of developing diabetic peripheral neuropathy (DPN) and cardiovascular autonomic neuropathy (CAN). We evaluated multiple risk factors and phenotypes associated with DPN and CAN in this large, well-characterized cohort of participants with type 1 diabetes, followed for >23 years. DPN was defined by symptoms, signs, and nerve conduction study abnormalities in ≥2 nerves; CAN was assessed using standardized cardiovascular reflex tests. Generalized estimating equation models assessed the association of DPN and CAN with individual risk factors measured repeatedly. During DCCT/EDIC, 33% of participants developed DPN and 44% CAN. Higher mean HbA1c was the most significant risk factor for DPN, followed by older age, longer duration, greater height, macroalbuminuria, higher mean pulse rate, β-blocker use, and sustained albuminuria. The most significant risk factor for CAN was older age, followed by higher mean HbA1c, sustained albuminuria, longer duration of type 1 diabetes, higher mean pulse rate, higher mean systolic blood pressure, β-blocker use, estimated glomerular filtration rate <60 mL/min/1.73 m2, higher most recent pulse rate, and cigarette smoking. These findings identify risk factors and phenotypes of participants with diabetic neuropathy that can be used in the design of new interventional trials and for personalized approaches to neuropathy prevention.

Electrodiagnostic reference data for sensory nerve conduction studies in Saudi Arabia

Objectives:

To estimate reference data for the commonly performed sensory nerve conduction studies (NCS) using a cohort of healthy subjects from Saudi Arabia

Methods:

This is a cross-sectional study conducted between May 2015, and June 2019. Sensory nerve action potential (SNAP) amplitude, conduction velocity (CV), and peak latency (PL) were recorded. Associations between these parameters and the covariates (age, sex, height, weight, and body mass index) were tested with Pearson correlations. Reference data were then derived using the lowest percentile that could be reliably determined for SNAP amplitude and CV. Reference data were derived using the highest percentile for PL.

Results:

Upper and lower limb sensory NCS were performed in 127 and 137 participants, respectively. Age was the only covariate that required adjustment for estimation of SNAP amplitude. Therefore, a prediction model was generated for each nerve. Percentile estimation for PL and CV did not require adjustment for any of the covariates. Hence, it was derived for all the subjects pooled together.

Conclusion:

The sensory NCS reference data were comparable to the data from other countries. However, minimal differences were observed. Further studies are required with a focus on the older age group. Received 2nd August 2019. Accepted 11th December 2019.

Reference values of upper extremity nerve conduction studies in a Colombian population

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Reference values for upper extremity nerve conductions studies from a South American population.

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AANEM task force of nerve conduction reference value establishment recommendations followed.

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Results in agreement to international studies, correlated with studies in similar populations.

Objective

To establish appropriate reference values of upper extremity nerve conduction studies (NCS) at the Del Valle University Hospital, from Colombia.

Methods

Two hundred and twenty-two (N = 222) healthy volunteers were recruited. Latencies, amplitudes and conduction velocities from the Median, Ulnar, and Radial nerves were performed following recommendations from Buschbacher and Prahlow. Then, according to the American Association of Neuromuscular and Electrodiagnostic Medicine (AANEM) task force for reference value establishment, analyses of variance were run where each electrophysiological parameter from every nerve tested was used as dependent variable, to define which characteristics have to be kept for the model. Percentiles 3 and 97 from each of the parameters were derived. Finally, a multivariate quantile regression analysis model was tested.

Results

Sensory percentiles were 2.8–3.5 ms, 18.9–120.8 μV, and 40.0–50.0 m/s for the Median, 2.1–2.9 ms, 10.4–106.9 μV, and 41.0–58.0 m/s for the Ulnar, while 2.6–3.5 ms, 11.3–69.9 μV, and 39.0–54.0 m/s for the Radial nerve. The same parameters for motor function were 2.8–3.9 ms, 4.6–15.0 mV, and 49.0–68.0 m/s for the Median, while 2.3–3.5 ms, 3.9–11.5 mV and 51.0–70 m/s for the Ulnar nerve.

Conclusions

Values of latency, amplitude, and conduction velocity of sensory and motor functions from upper extremity nerves among Colombians are similar to equal parameters, obtained by comparable studies of populations alike.

Significance

This is the first study to establish reference values for upper extremity NCS carried out following the AANEM recommendations in a South American population.

Irrelevant auditory and tactile signals, but not visual signals, interact with the target onset and modulate saccade latencies

Saccadic eye movements bring events of interest to the center of the retina, enabling detailed visual analysis. This study explored whether irrelevant auditory (experiments A, B & F), visual (C & D) or tactile signals (E & F) delivered around the onset of a visual target modulates saccade latency. Participants were instructed to execute a quick saccade toward a target stepping left or right from a fixation position. We observed an interaction between auditory beeps or tactile vibrations and the oculomotor reaction that included two components: a warning effect resulting in faster saccades when the signal and the target were presented simultaneously; and a modulation effect with shorter–or longer–latencies when auditory and tactile signals were delivered before–or after–the target onset. Combining both modalities only increased the modulation effect to a limited extent, pointing to a saturation of the multisensory interaction with the motor control. Interestingly, irrelevant visual stimuli (black background or isoluminant noise strips in peripheral vision, flashed for 10 ms) increased saccade latency whether they were presented just before or after target onset. The lack of latency reduction with visual signals suggests that the modulation observed in the auditory and tactile experiments was not related to priming effects but rather to low-level audio- and tactile-visual integration. The increase in saccade latency observed with irrelevant visual stimuli is discussed in relation to saccadic inhibition. Our results demonstrate that signals conveying no information regarding where and when a visual target would appear modulate saccadic reactivity, much like in multisensory temporal binding, but only when these signals come from a different modality.

Remote Analgesic Effects Of Conventional Transcutaneous Electrical Nerve Stimulation: A Scientific And Clinical Review With A Focus On Chronic Pain

BACKGROUND

Transcutaneous electrical nerve stimulation (TENS) is a safe, noninvasive treatment for chronic pain that can be self-administered. Conventional TENS involves stimulation of peripheral sensory nerves at a strong, non-painful level. Following the original gate-control theory of pain, stimulation is typically near the target pain. As another option, remote stimulation may also be effective and offers potential advantages.

OBJECTIVE

This narrative review examines mechanisms underlying the remote analgesic effects of conventional TENS and appraises the clinical evidence.

METHODS

A literature search for English-language articles was performed on PubMed. Keywords included terms related to the location of TENS . Citations from primary references and textbooks were examined for additional articles.

RESULTS

Over 30 studies reported remote analgesic effects of conventional TENS. The evidence included studies using animal models of pain, experimental pain in humans, and clinical studies in subjects with chronic pain. Three types of remote analgesia were identified: at the contralateral homologous site, at sites distant from stimulation but innervated by overlapping spinal segments, and at unrelated extrasegmental sites.

CONCLUSION

There is scientific and clinical evidence that conventional TENS has remote analgesic effects. This may occur through modulation of pain processing at the level of the dorsal horn, in brainstem centers mediating descending inhibition, and within the pain matrix. A broadening of perspectives on how conventional TENS produces analgesia may encourage researchers, clinicians, and medical-device manufacturers to develop novel ways of using this safe, cost-effective neuromodulation technique for chronic pain.

W, Fazan VPS. Sensory and Motor Conduction Velocity in Spontaneously Hypertensive Rats: Sex and Aging Investigation

The literature is extensive on how hypertension affects the morphology and function of the central nervous system (CNS) and is being focused on multiple organ damage involving the kidneys, heart, endothelium and retina. Hypertension damage to the peripheral nervous system is less explored in the literature. We have previously shown morphometric alterations in large and small caliber myelinated fibers of nerves in the adult spontaneously hypertensive rat (SHR). However, the functional correlation of these findings has not been explored. We performed an electrophysiological investigation of hind limb nerves in SHR of both genders in different ages. Normotensive Wistar-Kyoto (WKY) rats were used as controls. Electrophysiological recordings and determination of motor (MCV) and sensory (SCV) nerve conduction velocity were performed in the same animals at four different ages: 5, 8, 20 and 40 weeks after birth. Comparisons were made between ages, genders and animal strain. We showed a continuous body weight increase in adult life in all animals studied. MCV got stable at 20-week old hypertensive animals and continued to increase in normotensive ones. The SCV was constant between the ages of 20 and 40 weeks old in female SHR and decreased in male SHR while it continued to increase in WKY animals. The electrophysiological investigation of the nerves in WKY and SHR from both genders and different ages, associated with morphological and morphometric data from the literature suggest that hypertension affects the nerve function and might corroborate the development of a peripheral neuropathy.

Perineural Platelet-Rich Plasma for Diabetic Neuropathic Pain, Could It Make a Difference?

Objective

To evaluate the clinical effect of perineural platelet-rich plasma (PRP) injection for pain and numbness alleviation in diabetic peripheral neuropathy (DPN).

Study Design

A randomized prospective clinical trial.

Setting

Pain clinic and Rheumatology and Rehabilitation Departments, Assiut University Hospital.

Methods

Sixty adult patients with type II DM accompanied by DPN of at least six months’ duration were assessed by modified Toronto Clinical Neuropathy Score (mTCNS) and randomly allocated into two groups. Group I underwent ultrasound-guided perineural PRP injection and medical treatment, and Group II received medical treatment only. Patients were followed up at months 1, 3, and 6 with regard to pain and numbness visual analog scale (VAS) and mTCNS scores.

Results

Significant improvement was recorded in pain and numbness VAS scale scores in group I vs group II (P ≤ 0.001 during the whole study period for both parameters); at the same time, mTCNS improved in group I in comparison with group II with P = 0.01, 0.001, and &lt;0.001 at months 1, 3, and 6, respectively.

Conclusions

Perineural PRP injection is an effective therapy for alleviation of diabetic neuropathy pain and numbness and enhancement of peripheral nerve function.

Facing the challenges of electrodiagnostic studies in the very elderly (>80 years) population

OBJECTIVE

Studies on electrodiagnostic (EDX) methods usually exclude the very elderly. This also holds true for studies of normal EDX values. We analyzed the outcome and diagnostic value of EDX and collected reference data in a large cohort of patients ≥80 years of age.

METHODS

Referral information, ICD-10 diagnoses and EDX data were retrieved from all patients ≥80 years of age referred for EDX studies at our department in 1995-2015. Normative data, including reference ranges, were obtained using the extrapolated norms (e-norms) method.

RESULTS

1966 unique patients (2335 examinations) were included. Only 11% were considered to have normal findings. 66% had pathological EDX findings in accordance with the indication for referral. Carpal tunnel syndrome was by far the most common diagnosis. Normative data retrieved using e-norms were similar to those of reference values from healthy subjects regarding EMG multiMUP data, but typically provided a wider normality window when applied to nerve conduction parameters.

CONCLUSIONS

EDX studies are valuable in the diagnostic work-up of very elderly patients. Using the e-norms method may be a useful alternative when obtaining reference values in this age group.

SIGNIFICANCE

Our findings provide additional insights to the challenges of evaluating very elderly patients with neuromuscular disease and underline the importance of including this growing part of the patient population in EDX research.

Study of Wrist Ratio and Wrist-to-Palm Index Radio in Individuals Suffering from Carpal Tunnel Syndrome

Background:

Carpal tunnel syndrome (CTS) is the commonest median nerve entrapment neuropathy, with preponderance in females.

Aims and Objective:

The aim of the present study was to find out wrist ratio (WR) and wrist/palm ratio (WPR) in clinically diagnosed patients of CTS.

Methodology:

One hundred individuals (fifty patients of CTS and fifty as control group) aged between 30 and 50 years were recruited for the study. Early confirmation of clinically suspected patients of CTS was done by performing electrodiagnostic tests of median and ulnar nerves. Motor and sensory conduction velocities, distal motor and sensory latencies, and F-wave latencies were performed in the recruited volunteers.

Results:

The values for mean wrist ratio in control groups were 0.694, 0.703 respectively, and in patients with carpal tunnel syndrome, it was 0.704 and 0.719 respectively in moderate and severe type. The mean wrist to palm ratio (WPR) in control group was 0.371, while in patients with CTS, it was 0.374, 0.382, 0.387, and 0.401 based on progression of severity. Both were statistically significant for the last two groups (wrist to index finger [WIF] >4.4 m/s, moderate, and WIF nonrecordable, severe). Statistically significant (P < 0.001) decrease of motor conduction velocities for median nerve was seen in the CTS group as compared to control group. Statistically significant (P < 0.001) increase in distal motor and sensory latencies was observed for both median and ulnar nerves in CTS group with more increase in distal motor latency than sensory latency. Increase in F-wave latencies of both nerves was seen in CTS group.

Conclusion:

The study results confirm selective slowing of sensory and motor conduction within wrist-to-palm segment in patients of CTS. Both WR and WPR have a progressive correlation with the severity of CTS, but statistically significant changes were seen in the groups with moderate and severe CTS. Thus, WR/WPR can act as one of the essential parameters in the diagnosis of CTS with moderate-to-severe CTS.

Asymmetric recurrent laryngeal nerve conduction velocities and dorsal cricoarytenoid muscle electromyographic characteristics in clinically normal horses

The dorsal cricoarytenoid (DCA) muscles, are a fundamental component of the athletic horse's respiratory system: as the sole abductors of the airways, they maintain the size of the rima glottis which is essential for enabling maximal air intake during intense exercise. Dysfunction of the DCA muscle leads to arytenoid collapse during exercise, resulting in poor performance. An electrodiagnostic study including electromyography of the dorsal cricoarytenoid muscles and conduction velocity testing of the innervating recurrent laryngeal nerves (RLn) was conducted in horses with normal laryngeal function. We detected reduced nerve conduction velocity of the left RLn, compared to the right, and pathologic spontaneous activity (PSA) of myoelectrical activity within the left DCA muscle in half of this horse population and the horses with the slowest nerve conduction velocities. The findings in this group of horses are consistent with left sided demyelination and axonal loss, consistent with Recurrent Laryngeal Neuropathy (RLN), a highly prevalent degenerative disorder of the RLn in horses that predominantly affects the left side. The detection of electromyographic changes compatible with RLN in clinically unaffected horses is consistent with previous studies that identified "subclinical" subjects, presenting normal laryngeal function despite neuropathologic changes within nerve and muscle confirmed histologically.

The scratch collapse test: A systematic review

The diagnosis of nerve compression relies on collecting diagnostic clues from the history, physical examination, imaging and diagnostic testing. There are several provocative tests to aid in the diagnosis of nerve compression. The 'Scratch Collapse Test' (SCT) has emerged as a new provocative test to assist in the localisation of peripheral nerve compression. This study aims to perform a systematic review of literature to assess the data on the reliability of the SCT as a diagnostic test for entrapment neuropathy. Ten articles were reviewed. Five articles had sufficient numerical data for analysis, and in these five articles, the positive predictive values and specificity were high, i.e. between 0.71 and 0.99 and 0.6 and 0.99, respectively, whereas other values were very variable, i.e. individual negative predictive values ranged from 0.15 to 0.92 and the sensitivity values ranged from 0.24 to 0.77. Another main finding was the versatility of the test in that it can be used for various nerve entrapments and to localise the exact level of compression. Literature suggests that SCT has potential to be used as a clinical diagnostic tool for entrapment neuropathy. However, wide variations in early literature suggest that SCT should not be used as a sole diagnostic tool but as an adjunct to a surgeon's diagnostic repertoire.

Pathological classification of equine recurrent laryngeal neuropathy

Recurrent Laryngeal Neuropathy (RLN) is a highly prevalent and predominantly left-sided, degenerative disorder of the recurrent laryngeal nerves (RLn) of tall horses, that causes inspiratory stridor at exercise because of intrinsic laryngeal muscle paresis. The associated laryngeal dysfunction and exercise intolerance in athletic horses commonly leads to surgical intervention, retirement or euthanasia with associated financial and welfare implications. Despite speculation, there is a lack of consensus and conflicting evidence supporting the primary classification of RLN, as either a distal ("dying back") axonopathy or as a primary myelinopathy and as either a (bilateral) mononeuropathy or a polyneuropathy; this uncertainty hinders etiological and pathophysiological research. In this review, we discuss the neuropathological changes and electrophysiological deficits reported in the RLn of affected horses, and the evidence for correct classification of the disorder. In so doing, we summarize and reveal the limitations of much historical research on RLN and propose future directions that might best help identify the etiology and pathophysiology of this enigmatic disorder.

Are the Sensory Fibers of the Ulnar Nerve Affected in Carpal Tunnel Syndrome?

PURPOSE

Distribution of paresthesia throughout the skin area without median nerve innervation is frequently seen in carpal tunnel syndrome (CTS). However, its pathophysiologic mechanisms are still unclear. We aimed to research whether a dysfunction in sensory fibers of the ulnar nerve (UN) was present or not in hands with CTS.

METHODS

Totally, upper extremity nerve conduction study recordings of 508 patients were considered. After exclusions, 331 upper extremity recordings of 277 patients were included. We compared the results of sensory conduction studies of median nerve and UN between normal hands and hands with CTS.

RESULTS

The mean distal sensory latency of the median nerve was longer, the mean conduction velocity was slower, and mean nerve action potential amplitude was higher in the hands with CTS than in normal hands (P < 0.001 for all comparisons). There was no statistically significant difference on any sensory conduction parameters of UN recorded on digit IV or digit V between the disease and control groups (P > 0.05 for all comparisons). The rates of conduction abnormalities of the UN sensory fibers were also similar in hands with CTS and in normal hands (P > 0.05 for all comparisons).

CONCLUSIONS

The hands with CTS do not have an increased rate of conduction abnormalities of UN sensory fibers compared with the normal hands in our study population. Therefore, our study did not confirm the distortion of UN sensory fibers as a mechanism underlying the spread of paresthesia throughout the skin area without median nerve innervation in CTS.

High body mass and kidney dysfunction relate to worse nerve function, even in adults without neuropathy

Polyneuropathy is a prevalent and disabling disorder. Despite extensive evaluation, the cause often remains unknown. Factors that predispose for the development of polyneuropathy need to be identified. We investigated the effect of anthropometric and metabolic factors on peripheral nerve function in 908 participants of the population-based Rotterdam Study without any symptoms or signs of polyneuropathy. Participants underwent nerve conduction studies of the sural and peroneal nerve. Data on age, height, weight, waist circumference, diabetes, lipid levels, hypertension, and kidney function were collected. Regression analyses were used to investigate determinants of nerve action potential amplitudes. The frequency of abnormal sural sensory nerve action potential (SNAP) amplitudes increased with age from 1% under 60 years to 23% over 80 years. Similarly, the frequency of abnormal peroneal nerve compound motor action potential (CMAP) amplitudes increased from 4% to 13%. High weight and body mass index were independently associated with reduced sural SNAP amplitudes and peroneal CMAP amplitudes. Participants with hypertension and kidney dysfunction were more likely to have abnormal sural SNAP amplitudes. Older age, high weight, hypertension, and moderate kidney dysfunction might thus lead to peripheral nerve dysfunction in persons yet without symptoms or signs of polyneuropathy.