Ultrasound diagnosis of ulnar neuropathy: comparison of symptomatic and asymptomatic nerve thickness

Diagnostic accuracy of ultrasound and MR imaging in peroneal neuropathy: A prospective, single-center study

INTRODUCTION/AIMS

Magnetic resonance imaging (MRI) findings in peroneal neuropathy are not well documented and the prognostic value of imaging remains uncertain. Upper limits of cross-sectional area (CSA) on ultrasound (US) have been established, but uncertainty regarding generalizability remains. We aimed to describe MRI findings of the peroneal nerve in patients and healthy controls and to compare these results to US findings and clinical characteristics.

METHODS

We prospectively included patients with foot drop and electrodiagnostically confirmed peroneal neuropathy, and performed clinical follow-up, US and MRI of both peroneal nerves. We compared MRI findings to healthy controls. Two radiologists evaluated MRI features in an exploratory analysis after images were anonymized and randomized.

RESULTS

Twenty-two patients and 38 healthy controls were included. Whereas significant increased MRI CSA values were documented in patients (mean CSA 20 mm2 vs. 13 mm2 in healthy controls), intra- and interobserver variability was substantial (variability of, respectively, 7 and 9 mm2 around the mean in 95% of repeated measurements). A pathological T2 hyperintense signal of the nerve was found in 52.6% of patients (50% interobserver agreement). Increased CSA measurements (MRI/US), pathological T2 hyperintensity of the nerve and muscle edema were not predictive for recovery.

DISCUSSION

Imaging is recommended in all patients with peroneal neuropathy to exclude compressive intrinsic and extrinsic masses but we do not advise routine MRI for diagnosis or prediction of outcome in patients with peroneal neuropathy due to high observer variability. Further studies should aim at reducing MRI observer variability potentially by semi-automation.

Ultra-high-definition (22 MHz) ultrasound of the ulnar nerve: additional value and normative data

We studied 30 healthy volunteers (60 arms), categorized into three age groups with equal numbers to verify if a 22 MHz compared with a 15 MHz ultrasound transducer has additional value for studying the intraneural architecture of the ulnar nerve throughout its course. At six sites, there were no differences in cross-sectional area measurements between the two transducers. With both, the cross-sectional area was significantly larger at the medial epicondyle compared with the other sites and smaller at the mid-forearm and Guyon's canal compared with the mid-upper arm. With higher age the cross-sectional area significantly increased. Significantly more fascicles were visible distal to the medial epicondyle compared with more proximal sites, as well as in men compared with women. Finally, higher body weight was related to a significantly smaller number of fascicles being seen. A 22 MHz transducer depicts more details of the intraneural architecture than a 15 MHz transducer. Our data can be used as normative data or reference values in analysing ulnar nerve pathology.Level of evidence: II.

Evidence-based guideline: Neuromuscular ultrasound for the diagnosis of ulnar neuropathy at the elbow

INTRODUCTION/AIMS

The purpose of this literature review is to develop an evidence-based guideline for the use of neuromuscular ultrasound in the diagnosis of ulnar neuropathy at the elbow (UNE). The proposed research question was: "In patients with suspected UNE, does ulnar nerve enlargement as measured with ultrasound accurately identify those patients with UNE?"

METHODS

A systematic review and meta-analysis was performed, and studies were classified according to American Academy of Neurology criteria for rating articles for diagnostic accuracy.

RESULTS

Based on Class I evidence in four studies, it is probable that neuromuscular ultrasound measurement of the ulnar nerve at the elbow, either of diameter or cross-sectional area (CSA), is accurate for the diagnosis of UNE.

RECOMMENDATION

For patients with symptoms and signs suggestive of ulnar neuropathy, clinicians should offer ultrasonographic measurement of ulnar nerve cross-sectional area or diameter to confirm the diagnosis and localize the site of compression (Level B).

Effect of treadmill exercise on pain-related Wnt/β-catenin signaling pathway in dorsal root ganglion neurons at the early phase regeneration of the injured sciatic nerve

The purpose of this study was to determine whether treadmill walking exercise can improve mechanical allodynia through regulation of Wnt/β-catenin signaling in dorsal root ganglion (DRG) neurons at the early stage of regeneration after sciatic nerve injury (SNI). The experimental rats were divided into seven groups: the normal control, sedentary groups for 3-, 7-, and 14-day post crush (dpc), and exercise group for 3, 7, and 14 dpc. The rats in exercise groups performed treadmill walking exercise at a speed of 8 m/min for 20 min once a day according to experiment duration. For evaluating neuropathic pain-like behavior after SNI, the mechanical allodynia was examined by von Frey apparatus. And the expression levels of pain-related protein were identified in the cytoplasm or nucleus of DRG neurons using Western blot techniques. Mechanical allodynia was significantly ameliorated in the exercise group at 7 and 14 dpc. Treadmill exercise further decreased Wnt3a expression at 3, 7, and 14 dpc compared to in the sedentary group. Also, phosphorylated-low-density lipoprotein receptor 6 was decreased in exercise groups at 3 and 14 dpc. Beta-catenin was significantly decreased in exercise groups at 3 and 14 dpc compared to sedentary groups as well as treadmill exercise decreased translocation of β-catenin towards the nucleus of DRG neurons at 14 dpc. Our findings indicate that treadmill walking exercise may be an important regulator of neuropathic pain after peripheral nerve injury through delayed Wnt/β-catenin signaling pathway in DRG neurons.

Enhancing diagnostic accuracy using a side-to-side cross-sectional area ratio for the diagnosis of unilateral ulnar mononeuropathy at the elbow

INTRODUCTION

Neuromuscular ultrasonography (NMUS) is a valuable adjunct to electrodiagnostic testing for the diagnosis of entrapment neuropathy. The aim of this study was to determine whether diagnostic accuracy of NMUS could be enhanced in patients with unilateral ulnar mononeuropathy at the elbow (UNE) by utilizing side-to-side ulnar nerve cross-sectional area (CSA) ratios.

METHODS

Retrospective case-control analysis of unilateral UNE cases identified cutoff values for elbow segment ulnar nerve maximum CSA (MCSA) of the symptomatic/asymptomatic limb (M ratio), as well as side-to-side ratios comparing MCSA with ipsilateral CSA at the Guyon canal (E/G), middle forearm (E/F), and middle humerus (E/H). Diagnostic accuracy values were calculated.

RESULTS

The optimal M-ratio cut-off was 1.22 (sensitivity, 92.9%; specificity, 97.8%; accuracy, 95.4%). Optimal cutoffs for inter-E/G, -E/F, and -E/H ratios were 1.07 (sensitivity, 98%; specificity, 78%; accuracy, 87.7%), 1.11 (sensitivity, 95%; specificity, 80%; accuracy, 87.2%), and 1.18 (sensitivity, 95%; specificity, 93%; accuracy, 94%), respectively.

DISCUSSION

The M ratio and inter-E/H ratio exhibited high diagnostic accuracy for unilateral UNE. Prospective studies are needed to compare the accuracy of the new measures with a single MCSA measurement.

Ultrasound Ulnar Nerve Measurement in a Healthy Population

Introduction

Ulnar tunnel syndrome at the elbow is a common pathology. The ultrasound cross-sectional area is a well-known metric widely accepted in radiology for the description of nerve entrapment. However, the pathological cut-off value remains challenging. The objectives of this study were to (1) describe the ultrasound cross-sectional area measurement of the ulnar nerve at three locations, and (2) to evaluate the inter-observer reliability by two independent ultrasonographers.

Methods

One-hundred ulnar nerves of 50 asymptomatic individuals were scanned using B-mode and power Doppler ultrasonography. The ultrasound cross-sectional area measurements of the ulnar nerve were performed at three different levels: 2 cm proximal to the epicondyle, at the level of the epicondyle, and 2 cm distal to the epicondyle.

Results

In our healthy population, we found 21, 24 and 7% of ultrasound cross-sectional area ulnar nerve > 8 mm², respectively, at three different levels of measurement and 4, 7, and 0% US-CSA ulnar nerve > 10 mm². The intraclass correlation coefficient measured at three different site levels were good (0.7943, 0.7509) to moderate (0.5701).

Conclusions

Almost one-quarter of our healthy population had an ultrasound cross-sectional area ulnar nerve more than 8 mm² and few more than 10 mm². A cut-off of ultrasound cross-sectional area ulnar nerve measurement more than 10 mm² could be considered as pathological. No abnormal elbow ulnar nerve vascularization has been seen. This is the first step towards normal B-mode ulnar nerve values at the elbow to further detect pathological US findings as ulnar nerve entrapment.

Ultrasound in the diagnosis and management of fibular mononeuropathy

INTRODUCTION

Ultrasound (US) evaluation of peripheral nerves is a noninvasive, cost-effective approach to diagnosing focal mononeuropathies and guiding surgical management. We used the intranerve ratio to evaluate for possible cut-off values in diagnosis of fibular mononeuropathies (FNs).

METHODS

A retrospective analysis of FN confirmed by electrodiagnosis (EDx) was performed to identify intranerve ratio values between affected and unaffected limbs at the fibular head and popliteal fossa.

RESULTS

The optimal fibular head/popliteal fossa intranerve ratio to discriminate between limbs with and without disease was 1.25 (sensitivity, 51%; specificity, 71%). There was no statistically significant difference between affected vs unaffected limbs (ratio, 1.13; P = .15) nor in subgroup analyses. However, 25% of patients had structural lesions amenable to surgery.

DISCUSSION

The utility of US in diagnosis of FN is limited using intranerve ratio data, but US has a distinct advantage over EDx for identifying treatable structural lesions.

Neuromuscular ultrasound in electrically non-localizable ulnar neuropathy

INTRODUCTION

The aim of this study was to determine the value of high-resolution ultrasound (HRUS) in patients with ulnar neuropathy whose electrophysiology displayed an axonal, non-localizing pattern.

METHODS

A prospective study of patients referred to an electromyography laboratory for ulnar neuropathy was performed. Of the 56 patients with clinical and electrodiagnostic (EDx) evidence of ulnar neuropathy, 12 were identified with non-localizing electrophysiology who subsequently underwent HRUS of the ulnar nerve.

RESULTS

HRUS localized the ulnar neuropathy in all patients. In 2 patients, HRUS demonstrated structural lesions not at the elbow.

DISCUSSION

HRUS often adds complementary information to standard EDx studies, including ulnar neuropathy. Thus, HRUS should be employed in patients with a non-localizing ulnar neuropathy on EDx studies. Muscle Nerve 58: 655-659, 2018.

Investigation of the Diagnostic Value of Ultrasonography for Radial Neuropathy Located at the Spiral Groove

Objective

To determine a diagnostic cut-off value for the cross-sectional area (CSA) of the radial nerve using ultrasonography for radial neuropathy located at the spiral groove (SG).

Methods

Seventeen patients with electrodiagnostic evidence of radial neuropathy at the SG and 30 healthy controls underwent ultrasonography of the radial nerve at the SG . The CSAs at the SG were compared in the patient and control groups. The CSA at the SG between the symptomatic and asymptomatic sides (ΔSx–Asx and Sx/Asx, respectively) were analyzed to obtain the optimal cut-off value. The relationship between the electrophysiological severity of radial neuropathy and CSA was also evaluated.

Results

Among the variables examined, there were statistically significant differences in the CSA between the patient and control groups, ΔSx–Asx, and Sx/Asx at the SG. In a receiver operating characteristics analysis, the cut-off CSA was 5.75 mm² at the SG (sensitivity 52.9%, specificity 90%), 1.75 mm² for ΔSx–Asx (sensitivity 58.8%, specificity 100%), and 1.22 mm² for Sx/Asx (sensitivity 70.6%, specificity 93.3%) in diagnosing radial neuropathy at the SG. There was no significant correlation between CSA and electrophysiological severity score for either patient group.

Conclusion

The reference value obtained for CSA of the radial nerve at the SG may facilitate investigation of radial nerve pathologies at the SG.

Ulnar Nerve Cross-Sectional Area for the Diagnosis of Cubital Tunnel Syndrome: A Meta-Analysis of Ultrasonographic Measurements

OBJECTIVE

To examine the performance of sonographic cross-sectional area (CSA) measurements in the diagnosis of cubital tunnel syndrome (CuTS).

DATA SOURCES

Electronic databases, comprising PubMed and EMBASE, were searched for the pertinent literature before July 1, 2017.

STUDY SELECTION

Fourteen trials comparing the ulnar nerve CSA measurements between participants with and without CuTS were included.

DATA EXTRACTION

Study design, participants' demographic characteristics, diagnostic reference of CuTS, and methods of CSA measurement.

DATA SYNTHESIS

Among different elbow levels, the between-group difference in CSA was the largest at the medial epicondyle (6.0mm²; 95% confidence interval [CI], 4.5-7.4mm²). The pooled mean CSA in participants without CuTS was 5.5mm² (95% CI, 4.4-6.6mm²) at the arm level, 7.4mm² (95% CI, 6.7-8.1mm²) at the cubital tunnel inlet, 6.6mm² (95% CI, 5.9-7.2mm²) at the medial epicondyle, 7.3mm² (95% CI, 5.6-9.0mm²) at the cubital tunnel outlet, and 5.5mm² (95% CI, 4.7-6.3mm²) at the forearm level. The sensitivities, specificities, and diagnostic odds ratios pooled from 5 studies, using 10mm² as the cutoff point, were .85 (95% CI, .78-.90), .91 (95% CI, .86-.94), and 53.96 (95% CI, 14.84-196.14), respectively.

CONCLUSIONS

The ulnar nerve CSA measured by ultrasound imaging is useful for the diagnosis of CuTS and is most significantly different between patients and participants without CuTS at the medial epicondyle. Because the ulnar nerve CSA in healthy participants, at various locations, rarely exceeds 10mm², this value can be considered as a cutoff point for diagnosing ulnar nerve entrapment at the elbow region.

Diagnostic Cutoff Value for Ultrasonography of the Common Fibular Neuropathy at the Fibular Head

Objective

To establish the diagnostic cutoff value of ultrasonographic measurement for common fibular neuropathy (CFN) at the fibular head (FH).

Methods

Twenty patients with electrodiagnostically diagnosed CFN at the FH and 30 healthy controls were included in the study. The cross-sectional area (CSA) of sciatic nerve at mid-thigh level, common fibular nerve at popliteal fossa (PF), and common fibular (CF) nerve at FH were measured. Additionally, the difference of CF nerve CSA at the FH between symptomatic side and asymptomatic side (ΔSx–Asx), the ratio of CF nerve CSA at FH to at PF (FH/PF), and the ratio of CF nerve CSA at the FH symptomatic side to asymptomatic side (Ratio Sx–Asx) were calculated.

Results

CSA at the FH, FH/PF, ΔSx–Asx, and Ratio Sx–Asx showed significant differences between the patient and control groups. The cutoff value for diagnosing CFN at the FH was 11.7 mm² for the CSA at the FH (sensitivity 85.0%, specificity 90.0%), 1.70 mm² for the ΔSx–Asx (sensitivity 83.3%, specificity 97.0%), 1.11 for the FH/PF (sensitivity 47.1%, specificity 93.3%), and 1.24 for the Ratio Sx–Asx (sensitivity 72.2%, specificity 96.7%).

Conclusion

The ultrasonographic measurement and cutoff value could be a valuable reference in diagnosing CFN at the FH and improving diagnostic reliability and efficacy.

Cross-sectional area of the ulnar nerve after decompression at the cubital tunnel

A total of 48 patients undergoing surgical decompression of the ulnar nerve at the cubital tunnel between February 2010 and May 2013 were retrospectively studied to determine changes in the cross-sectional area of the nerve by the technique of neurosonography. The mean follow-up was 46 months. Post-operative follow-up examination of the cross-sectional area of the ulnar nerve showed a slight reduction in the mean value from 13.8 mm(2) (pre-operative) to 12.9 mm(2) (post-operative). Of the 48 patients, 36 showed a reduction in the cross-sectional area. No correlation was detected between the clinical and sonographic outcomes. Ultrasound seems to be of limited value in the post-operative assessment of patients with entrapment neuropathy of the ulnar nerve.

LEVEL OF EVIDENCE

IV.

Diagnostic cutoff value for ultrasonography in the ulnar neuropathy at the elbow

Objective

To determine the diagnostic cutoff values of ultrasonographic measurements in ulnar neuropathy at the elbow (UNE).

Methods

Twenty-five elbows of 23 patients (9 females, 16 males) diagnosed with UNE and 30 elbows of 30 healthy controls (15 females, 15 males) were included in our study. The ulnar nerve cross-sectional area (CSA) was measured at the Guyon canal, midforearm, and maximal swelling point (MS) around the elbow (the cubital tunnel inlet in healthy controls). CSA measurements of the ulnar nerve at each point, the Guyon canal-to-MS ulnar nerve area ratio (MS/G), and the midforearm-to-MS ulnar nerve ratio (MS/F) were calculated.

Results

Among the variables, only CSA at MS, MS/G, and MS/F displayed significant differences between the control and patient groups. The cutoff value for diagnosing UNE was 8.95 mm² for the CSA at MS (sensitivity 93.8%, specificity 88.3%), 1.99 for the MS/G (sensitivity 75.0%, specificity 73.3%), and 1.48 for the MS/F (sensitivity 93.8%, specificity 95.0%).

Conclusion

These findings may be helpful to diagnose UNE.