Ulnar nerve motor conduction to the abductor digiti minimi

Deriving reference values for nerve conduction studies from existing data using mixture model clustering

OBJECTIVE

to obtain locally valid reference values (RVs) from existing nerve conduction study (NCS) data.

METHODS

we used age, sex, height and limb temperature-based mixture model clustering (MMC) to identify normal and abnormal measurements on NCS data from two university hospitals. We compared MMC-derived RVs to published data; examined the effect of using different variables; validated MMC-derived RVs using independent data from 26 healthy control subjects and investigated their clinical applicability for the diagnosis of polyneuropathy.

RESULTS

MMC-derived RVs were similar to published RVs. Clustering can be achieved using only sex and age as variables. MMC is likely to yield reliable results with fewer abnormal than normal measurements and when the total number of measurements is at least 300. Measurements from healthy controls fell within the 95% MMC-derived prediction interval in 97.4% of cases.

CONCLUSIONS

MMC can be used to obtain RVs from existing data, providing a locally valid, accurate reflection of the (ab)normality of an NCS result.

SIGNIFICANCE

MMC can be used to generate locally valid RVs for any test for which sufficient data are available.¹.

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.

The needle electromyography findings in the neurophysiological classification of ulnar neuropathy at the elbow

Background/aim

Although ulnar neuropathy at the elbow (UNE) is the second most common entrapment mononeuropathy, there are few reports on its neurophysiological classification. In this study, we tried to find out the role of needle electromyography (EMG) in the neurophysiological classification of UNE.

Materials and methods

UNE patients who met the clinical and neurophysiological diagnostic criteria and healthy individuals were included in this study. Reference values of nerve conduction studies were obtained from healthy individuals. Needle EMG was performed to all UNE patients. According to the neurophysiological classification proposed by Padua, UNE patients were classified as mild, moderate, and severe.

Results

Thirty-one controls and thirty-five UNE patients were included in the study. There was mild UNE in 23 patients, moderate UNE in 8, and severe UNE in 4. Abnormal needle EMG findings were present in all patients with moderate and severe UNE and in 12 patients with mild UNE.

Conclusion

Abnormal needle EMG findings are seen in most of the UNE patients. Therefore, it is not practical to use needle EMG findings in the neurophysiological classification. Needle EMG abnormalities may also be present in patients with mild UNE due to axonal degeneration or motor conduction block.

Electrodiagnostic reference data for motor nerve conduction studies in Saudi Arabia

OBJECTIVE

To determine nerve conduction studies (NCS) reference data for motor nerves and F-waves in the upper and lower limbs of healthy subjects in Saudi Arabia.

METHODS

This is a cross-sectional study conducted between May 2015 and June 2019. Healthy subjects without neurological or systemic diseases were recruited. Motor NCS were performed following a standard protocol. Pearson correlations were employed between NCS parameters and age, gender, height, weight, and body mass index. Reference data were generated using the percentile method.

RESULTS

A total of 127 subjects were recruited for the upper limb studies and 137 for the lower limb studies. Quantile regression models were generated to estimate compound muscle action potential amplitude (adjusted for age), as well as F-wave minimal latency (adjusted for height). The estimated reference limits of distal motor latency (ms) and conduction velocity (m/s) for the different nerves were, respectively, 3.7 and 50 for the median nerve, 3.3 and 50 for the ulnar nerve, 5.8 and 40 for the tibial nerve, and 5.0 and 40 for the fibular nerve.

CONCLUSION

The reference data for motor NCS parameters and F-wave minimal latency are generally comparable with those of Western countries. However, minimal differences were observed. The underrepresentation of the older age group warrants future studies. The reference data for motor NCS parameters and F-wave minimal latency are generally comparable with those of Western countries. However, minimal differences were observed. The underrepresentation of the older age group warrants future studies.

Upper extremity neuropathies

This chapter covers the electrodiagnostic (EDX) evaluation of upper extremity nerves and the brachial plexus. Carpal tunnel syndrome is the most common peripheral nerve disorder of the upper extremity. A number of techniques are used but there is no gold standard approach for its diagnosis. Needle EMG aids in the differentiation of proximal and distal median neuropathies. Ulnar neuropathy at the elbow and ulnar neuropathy at or distal to the wrist can be distinguished by EDX techniques. Radial neuropathy at the spiral groove has a specific EDX pattern. EDX assessment of proximal upper extremity nerve lesions such as brachial plexopathy is a valuable tool for exploring the diagnosis and differential diagnosis of this complex disorder.

Ratio and difference of the cross-sectional area of median nerve to ulnar nerve in diagnosing carpal tunnel syndrome: a case control study

Background

To evaluate the diagnostic accuracy of the median-to-ulnar nerve ratio (MUR) and the median-to-ulnar nerve difference (MUD) in patients with carpal tunnel syndrome (CTS).

Methods

In this study, 32 patients with CTS and 32 healthy volunteers were evaluated. All participants received a series of tests and ultrasound examination for the evaluation of the following criteria: cross-sectional area of the median nerve at the pisiform level (CSA-P), swelling ratio (SR), MUR, MUD, and flattening ratio (FR).

Results

CSA-P, SR, MUR, and MUD were all significantly larger in the patients with CTS than in the healthy volunteers. The areas under the receiver operator characteristic curves of MUD, MUR, CSA-P, and SR were 0.78, 0.75, 0.70, and 0.61 respectively. MUD had higher sensitivity (84%) than MUR, CSA-P, and SR (sensitivity: 63, 63, and 53%, respectively).

Conclusions

By using the ulnar nerve area at the pisiform level as an internal control parameter, the MUD and MUR methods showed higher diagnostic accuracy than SR in patients with CTS. Further application of these methods in research and clinical settings is recommended.

Trial registration

Clinicaltrial.gov NCT03033173. Registered 18 January 2017. Retrospectively registered.

Effect of shoulder and elbow position on ulnar nerve conduction

INTRODUCTION

The aims of this study were to determine the effect of shoulder and elbow position on ulnar nerve conduction studies (NCS), and the length of reserve that asymptomatic individuals have in their ulnar nerves.

METHODS

Healthy subjects (n = 22) underwent ulnar NCS in 4 positions of shoulder abduction and elbow flexion.

RESULTS

The mean increase in nerve conduction velocity (NCV) from the slack position of shoulder adducted and elbow extended to the stretch position of shoulder abducted and elbow flexed was 2.9 m/s (P < 0.01). Using this difference, the mean length of reserve in the ulnar nerve along the limb was found to be 28.3 (SD=13.8) mm. Shoulder abduction increased the mean NCV 0.8 m/s (P = 0.03) independent of elbow flexion.

CONCLUSIONS

This study demonstrates an ulnar nerve reserve in healthy patients that is taken up with shoulder abduction and elbow flexion and suggests shoulder position should be standardized during ulnar NCS. Muscle Nerve, 2019.

Association Between Gender, Body Mass Index, and Ulnar Nerve Entrapment at the Elbow: A Retrospective Study

INTRODUCTION

Entrapment of the ulnar nerve is the second most common compression neuropathy in the upper extremity, but the etiology is multifactorial and still not clearly understood. The authors aimed to determine whether gender and body mass index (BMI) are risk factors for ulnar nerve entrapment (UNE) at the elbow.

METHODS

Results of electrodiagnostic studies performed on patients with UNE between January 2008 and February 2013 were examined retrospectively. Patients with BMI ≤22 were considered slender, those with a BMI between 22 and 29, normal, and those with a BMI >29, overweight. The authors compared the data for patients with and without UNE.

RESULTS

A total of 622 subjects were studied; 295 were UNE cases (154 men, 141 women) and 327 were controls (110 men, 217 women). There was no difference between control and UNE groups in terms of BMI. In univariate analysis, age and gender are independent risk factors for UNE, but when included in a stepwise Cox regression model, only gender was a significant factor. Male gender was found to be a risk factor for UNE.

CONCLUSIONS

Male gender is a risk factor for developing UNE, but age and BMI are not significant risk factors. Further studies which examine BMI and gender differences with data about occupational risk factors are required.

Somatic neural alterations in non-diabetic obesity: a cross-sectional study

BACKGROUND

Reports on alterations in somatic neural functions due to non-diabetic obesity, a major risk factor for diabetes, are few and still a matter of debate. Nevertheless, to our knowledge, reports lack any comments on the type of somatic nerve fibers affected in non-diabetic obesity. Therefore, this study aimed to find out the alteration in somatic neural functions in non-diabetic obese persons if any.

METHODS

The study was conducted on 30 adult non-diabetic obese persons (mean age 32.07 ± 7.25 years) with BMI > 30 Kg/m2 (mean BMI 30.02 ± 2.89 Kg/m2) and 29 age- and sex-matched normal weight controls (mean age 30.48 ± 8.01 years) with BMI: 18-24Kg/m2 (mean BMI 21.87 ± 2.40 Kg/m2). Nerve conduction study (NCS) variables of median, tibial and sural nerves were assessed in each subject using standard protocol. The data were compared by Mann Whitney 'U' test.

RESULTS

In comparison to normal weight persons, obese had lower compound muscle action potential (CMAP) amplitudes of right median [9.09(7.62-10.20) Vs 10.75(8.71-12.2) mV, p = 0.025] and bilateral tibial nerves [Right: 8.5(7.04-11.18) Vs 12.1(10.55-15) mV, p < 0.001 and left 9.08(6.58-11.65) Vs 13.05(10.2-15.6) mV, p = 0.002]. Furthermore, obese persons had prolonged CMAP durations of right and left median [10.5(9.62-12) Vs 10(8.4-10.3) ms, p = 0.02 and 10.85(10-11.88) Vs 10(9-10.57) ms, p = 0.019] and right tibial [10(9-11) 8.5(7.92-10) ms, p = 0.032] nerves. Sensory NCS (sural nerve) also showed diminished sensory nerve action potential (SNAP) amplitude [16(12.08-18.21) vs 22.8(18.3-31.08) μV, p < 0.001] and prolonged duration. However, onset latencies and conduction velocities for all nerves were comparable between the groups.

CONCLUSION

This study documents subclinical peripheral nerve damage in non-diabetic obese with abnormal NCS parameters; shorter amplitudes and prolonged CMAP and SNAP durations. The reduced amplitudes of mixed and sensory nerves might be due to decreased axonal number stimulation or actual decrease in number of axonal fibers, or defect at NMJ in non-diabetic obese. Prolonged durations but normal onset latencies and conduction velocities strongly suggest involvement of slow conducting fibers.

Interrater Repeatability of Motor Nerve Conduction Velocity of the Ulnar Nerve

OBJECTIVE

The purpose of this study was to obtain data on interrater repeatability of the motor nerve conduction velocity (NCV) of the ulnar nerve of different segments, ulnar distal motor latency (DML), and compound muscle action potential (CMAP) amplitudes.

DESIGN

Twenty-four healthy volunteers were examined in consecutive order. Ulnar motor NCV of different segments, ulnar DML, and CMAP amplitudes were determined. Based on a randomization list of various combinations and sequences, 1 of 3 examiners performed the first measurement. A second examiner repeated the evaluation within half an hour.

RESULTS

There were no significant differences between the first and second measurements for all parameters. For the ulnar motor NCV of the different segments, the intraclass correlation coefficient (ICC) ranged from 0.38 to 0.51, and the coefficient of repeatability (CR) ranged from 8.0 to 11.6 m/s. For the ulnar DML, the ICC was 0.44, and the CR was 0.49 millisecond. For the CMAP amplitudes at the different stimulation sites, the ICC ranged from 0.53 to 0.76, and the CR ranged from 1.5 to 2.3 mV.

CONCLUSIONS

A moderate amount of interrater variability of the ulnar motor NCV must be taken into account. Compared with the CMAP amplitudes, the interrater repeatability of the ulnar motor NCV is poorer.

Ulnar motor study to first dorsal interosseous: Best reference electrode position and normative data

INTRODUCTION

Reference electrode position affects nerve conduction study results. This study was undertaken to determine the optimal reference electrode position for ulnar motor recording from the first dorsal interosseous (FDI) muscle and to develop normative data.

METHODS

Fifty-one subjects were tested using reference electrode positions on the thumb, index, and little fingers. Latencies were compared with a needle recording from the FDI. Analysis was performed to determine the surface placement that most closely matched the needle recording latency. A normative database was then derived on 100 healthy subjects.

RESULTS

Placing the reference electrode on the thumb yielded results closest to the "gold standard" needle recording latency. The 97th percentile (upper limit of normal) for latency was 4.0 ms. The 3rd percentile values (lower limit of normal) for amplitude were 9.0 mV for men and 9.3 mV for women.

CONCLUSIONS

The reference position on the thumb yields latencies that most closely approximate needle recording. Normative data are presented.

Ulnar nerve at the elbow - normative nerve conduction study

Introduction

A goal of our work was to perform nerve conduction studies (NCSs) of the ulnar nerve focused on the nerve conduction across the elbow on a sufficiently large cohort of healthy subjects in order to generate reliable reference data.

Methods

We examined the ulnar nerve in a position with the elbow flexion of 90^o from horizontal. Motor response was recorded from the abductor digiti minimi muscle (ADM) and the first dorsal interosseous muscle (FDI).

Results

In our sample of 227 healthy volunteers we have examined 380 upper arms with the following results: amplitude (Amp)-CMAP(wrist) for ADM 9.6 ± 2.3 mV, MNCV at the forearm 60.4 ± 5.2 m/s, MNCV across the elbow 57.1 ± 5.9 m/s.

Discussion

Our study showed that motor NCSs of the ulnar nerve above elbow (AE) and below elbow (BE) in a sufficiently large cohort using methodology recommended by AANEM gave results well comparable for registration from FDI and ADM.

Conduction in ulnar nerve bundles that innervate the proximal and distal muscles: a clinical trial

Background

This study aims to investigate and compare the conduction parameters of nerve bundles in the ulnar nerve that innervates the forearm muscles and hand muscles; routine electromyography study merely evaluates the nerve segment of distal (hand) muscles.

Methods

An electrophysiological evaluation, consisting of velocities, amplitudes, and durations of ulnar nerve bundles to 2 forearm muscles and the hypothenar muscles was performed on the same humeral segment.

Results

The velocities and durations of the compound muscle action potential (CMAP) of the ulnar nerve bundle to the proximal muscles were greater than to distal muscles, but the amplitudes were smaller.

Conclusions

Bundles in the ulnar nerve of proximal muscles have larger neuronal bodies and thicker nerve fibers than those in the same nerve in distal muscles, and their conduction velocities are higher. The CMAPs of proximal muscles also have smaller amplitudes and greater durations. These findings can be attributed to the desynchronization that is caused by a wider range of distribution in nerve fiber diameters.

Conduction parameters of nerve fibers with different diameters in the same peripheral nerve can be estimated.

Assessment of recovery from burn-related neuropathy by electrodiagnostic testing

The purpose of this study was to investigate the recovery of burn-related neuropathies by electrodiagnostic testing. Burn patients who presented to an American Burn Association verified burn center were interviewed and examined for clinical evidence of peripheral neuropathies by a physiatrist. Patients whom consented to participate were tested for electrodiagnostic evidence of peripheral neuropathy. Repeated studies were performed to assess for evidence of recovery. A total of 370 patients were screened. Thirty-six (9.73%) patients had clinical evidence of neuropathy. Eighteen male patients with a mean TBSA burn of 42% had nerve conduction studies performed. Etiologies of the injuries included eight flame, eight electrical, and three others. Seventy-three nerve conduction studies were performed and 58 of the tests were abnormal. The most commonly affected nerve was the median sensory (10). For patients with repeated tests, the mean time between tests was 169 days (SD, 140 days). There was a significant difference between the initial and follow-up test (McNemar's change test P=.009). In subset analysis of motor and sensory abnormalities, there was no significant difference (P=.07). The most common neuropathy identified in this cohort was the median sensory. Overall, there was improvement in the nerve conduction abnormalities examined. This study suggests that the prognosis for recovery after burn-related neuropathy is good.

The effect of long-distance bicycling on ulnar and median nerves: an electrophysiologic evaluation of cyclist palsy

BACKGROUND

Distal ulnar neuropathies have been identified in cyclists because of prolonged grip pressures on handlebars. The so-called cyclist palsy has been postulated to be an entrapment neuropathy of the ulnar nerve in the Guyon canal of the wrist. Previous studies utilizing nerve conduction studies have typically been either case reports or small case series.

HYPOTHESIS

Electrophysiologic changes will be present in the ulnar and median nerves after a long-distance multiday cycling event.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

A total of 28 adult hands from 14 subjects underwent median and ulnar motor and sensory nerve conductions, which were performed on both hands before and after a 6-day, 420-mile bike tour. A ride questionnaire was also administered after the ride, evaluating the experience level of the cyclist, equipment issues, hand position, and symptoms during the ride.

RESULTS

Distal motor latencies of the deep branch of the ulnar nerve to the first dorsal interosseous were significantly prolonged after the long-distance cycling event. The median motor and sensory studies as well as the ulnar sensory and motor studies of the abductor digiti minimi did not change significantly. Electrophysiologic and symptomatic worsening of carpal tunnel syndrome was observed in 3 hands, with the onset of carpal tunnel syndrome in 1 hand after the ride.

CONCLUSION

Long-distance cycling may promote physiologic changes in the deep branch of the ulnar nerve and exacerbate symptoms of carpal tunnel syndrome.

Effect of body mass index on ulnar nerve conduction velocity, ulnar neuropathy at the elbow, and carpal tunnel syndrome

Both high and low body mass index (BMI) have been reported as risk factors for ulnar neuropathy at the elbow (UNE), and a high BMI as a risk factor for carpal tunnel syndrome (CTS). To determine whether the extremes of BMI are risk factors for UNE or CTS, and whether BMI affects calculation of median and ulnar motor nerve conduction velocity (NCV), we retrospectively analyzed the electrodiagnostic records of control patients, UNE patients, and CTS patients. The BMI was calculated for 50 patients with a sole diagnosis of UNE and compared to the BMI of 50 patients with CTS and 50 control subjects. The mean BMIs were 25.9 +/- 4.4, 30.1 +/- 5.5, and 28.3 +/- 5.6 for the UNE, CTS, and controls, respectively. By one-way analysis of variance, the difference in BMI between the UNE patients and the normal patients was significant (P < 0.01). In the control groups, increasing BMI directly correlated with increasing ulnar motor NCV across the elbow but not with forearm NCV. Across-elbow (AE) ulnar motor NCV may be falsely increased in patients with a high BMI, probably due to distance measurement factors. Not only do relatively slender individuals have comparatively slower AE ulnar NCVs, they are also at increased risk for developing UNE. Patients with a high BMI are at increased risk for CTS.

Clinical, electrodiagnostic, and sonographic studies in ulnar neuropathy at the elbow

The aim of this study was to determine possible correlations between the clinical characteristics, electrophysiological features, and sonographic ulnar-nerve diameter in patients with ulnar neuropathy at the elbow (UNE). We prospectively performed clinical, electrodiagnostic, and sonographic studies in 102 patients having either purely sensory signs (35%) or sensorimotor signs (65%) of UNE. Nerve conduction studies had a sensitivity of 78%, and the addition of sonography increased this to 98%. The diagnostic value of both tests was not different among cases with and without motor deficit. Motor studies with recording from the abductor digiti minimi and first dorsal interosseous muscles were equally sensitive for the detection of conduction block or velocity slowing across the elbow, but the combination yielded more positive cases than when only one study was performed. There were modest negative correlations between the electrodiagnostic parameters and the sonographic ulnar-nerve diameter. Electrodiagnostically and sonographically, there were no significant differences between clinically pure sensory and mixed sensorimotor cases of UNE, except for electrodiagnostic findings suggesting loss of motor axons in cases with motor signs. Almost half the patients with only sensory signs had electromyographic evidence of motor axonal loss. We conclude that, although UNE is clinically heterogeneous, the electrophysiological and sonographic findings are fairly consistent despite the clinical manifestations.

Influence of age and height on nerve conduction

Previous studies demonstrated age- and height-related slowing of nerve conduction velocity (NCV) and reduction in nerve response amplitude. Unfortunately, many studies examined discontinuous populations, preventing regression analysis. The correlation coefficients of available studies vary widely, preventing clear conclusions. We retrospectively examined 3969 clinically normal subjects ranging in age from 20 to 95 years from a total of 22,420 electrodiagnostic studies done between 1986 and 1998. The correlation of NCV with height was stronger than with age. Regression equations using both factors account for 12--27% of the variance. Responses were seen in the majority of patients aged 70 years and older, but the percentage of normals who had no response increased with advancing age. Age was strongly inversely correlated with the amplitudes of both sensory and motor responses, accounting for 7--16% of the variance. Regression equations using both height and age improved this correlation, accounting for 7--22% of the variance. Therefore, both height and age must be taken into consideration when normal values are developed.

What is the best way to assess focal slowing of the ulnar nerve?

OBJECTIVE

The study assessed the influence of the length of the across elbow (AE) segment of the ulnar nerve on the true and false positive rates of velocity measurements of the AE segment. Using a short AE length will increase effects of the measurement error (ME), and using a long distance will 'dilute' the slowing due to the focal lesion; it is not known which length is optimal to detect focal slowing.

METHODS

A simulation was performed to assess diagnostic yield for AE lengths of 50, 100 and 150 mm, taking into account ME, variation in true velocity, and severity of the lesion. ME of latencies and distances were first determined in a healthy subject.

RESULTS

ME proved lower than in a published study. Diagnostic yield was consistently better for an AE length of 50 mm than for 100 or 150 mm. The optimum length is therefore near 50 mm. Yield increased with severity of the lesion, smaller ME, and when interindividual variation in true velocity was small. Judging AE on its own had a slightly better yield than comparing AE velocity to forearm velocity, except for populations with a larger than normal spread in true conduction variability.

CONCLUSIONS

The best balance between effects of ME and 'dilution' to detect focal nerve slowing is obtained at nerve lengths of about 50 mm. The need to incorporate all possible compression sites necessitates the use of a suboptimal length of about 80 mm.