Cubital tunnel syndrome: diagnosis by high-resolution ultrasonography

Gray-Scale and Power Doppler Ultrasound Findings Predictive of Cubital Tunnel Syndrome Severity

BACKGROUND

The use of ultrasound in the diagnosis of cubital tunnel syndrome (CuTS) is an attractive alternative to electrodiagnostic (EDX) studies, but its utility is binary with poor severity correlation. We hypothesize that increasing ulnar nerve cross-sectional area (CSA) and power Doppler measurement of intraneural vascularity may predict the extent of disease.

METHODS

We identified 20 elbows from patients with a history of CuTS and 20 elbows in 10 asymptomatic controls. Electrodiagnosis was performed for symptomatic patients. Gray-scale ultrasound and power Doppler ultrasound were performed to measure CSA and intraneural vascularity in all participants. Functional measures, Boston Carpal Tunnel Questionnaire (BCTQ), and Patient-Reported Outcomes Measurement Information System surveys were also completed.

RESULTS

A strong positive correlation was found between CSA and motor nerve conduction velocity (MNCV) decrease between elbow and forearm, which increased when BCTQ >2 was used as a screening criterion. Increased CSA also demonstrated a high positive predictive value (PPV) in predicting MNCV changes, but poor ability to predict axonal loss. In contrast, power Doppler ultrasound demonstrated 100% PPV and 94% negative predictive value (NPV) in predicting severe CuTS (defined as compound motor action potential [CMAP] amplitude <6 mV and electromyography [EMG] findings).

CONCLUSIONS

Cross-sectional area is a sensitive method for identifying changes in MNCV and amplitude but does not stratify disease severity, as defined by diminished CMAP amplitude and/or evidence of denervation on EMG. The presence of increased intraneural vascularity is relatively sensitive but highly specific for axonal loss. The combination of nerve CSA, BCTQ screening, and power Doppler ultrasound may provide an alternative means for CuTS assessment.

Modern Treatment of Cubital Tunnel Syndrome: Evidence and Controversy

Cubital tunnel syndrome is the second most common peripheral mononeuropathy in the upper extremity. However, the diagnosis and treatment of cubital tunnel syndrome remains controversial without a standard algorithm. Although diagnosis can often be made from the patient's history and physical examination alone, electrodiagnostic studies, ultrasound, computed tomography (CT), and magnetic resonance image (MRI) can also be useful in diagnosing the disease and selecting the most appropriate treatment option. Treatment options include conservative nonoperative techniques as well as various surgical options, including in situ decompression with or without transposition, medial epicondylectomy, and nerve transfer in advanced disease. The purpose of this review is to summarize the most up-to-date literature regarding cubital tunnel syndrome and propose a treatment algorithm to provide clarity about the challenges of treating this complex patient population.

Changes in Ultrasound Measurements of the Ulnar Nerve at Different Elbow Joint Positions in Patients with Cubital Tunnel Syndrome

Ultrasound imaging (US) is increasingly being used in the diagnosis of entrapment neuropathies. The aim of the current study was to evaluate changes in stiffness (shear modulus), cross-sectional area (CSA), and trace length (TRACE) of the ulnar nerve in patients with cubital tunnel syndrome (CuTS), with shear wave elastography (SWE). A total of 31 patients with CuTS were included. CSA, shear modulus, and TRACE examinations were performed in the SWE mode in four positions of the elbow: full extension, 45° flexion, 90° flexion, and maximum flexion. There were significant side-to-side differences in the ulnar nerve elasticity value at 45°, 90°, and maximal elbow flexion (all, p < 0.001) but not at elbow extension (p = 0.36). There were significant side-to-side differences in the ulnar nerve CSA value at each elbow position (all, p < 0.001). There were significant side-to-side differences in the ulnar nerve trace value at each elbow position (all, p < 0.001). The symptomatic ulnar nerve in patients with CuTS exhibited greater stiffness (shear modulus), CSA, and TRACE values, compared with the asymptomatic side. US examinations (shear modulus, CSA, and TRACE evaluation) of the ulnar nerve can be helpful in supporting and supplementing the diagnosis in patients with CuTS.

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).

Ultrasonographic Findings of the Ulnar Nerve Following Elbow Flexion in Patients with Cubital Tunnel Syndrome

OBJECTIVE

To evaluate the ultrasonographic findings obtained following various degrees of elbow flexion in patients with cubital tunnel syndrome (CuTS).

DESIGN

Retrospective, cross-sectional study.

SETTING

General teaching hospital, rehabilitation unit.

SUBJECTS

Electrophysiological and ultrasonographic assessments were performed on 11 elbows of healthy controls and 21 elbows of 17 patients with CuTS.

METHODS

Dynamic movement of the ulnar nerve during elbow motion was measured. To measure ulnar nerve dynamic movement during elbow motion, the distance from the medial epicondyle (ME) to the nearest surface of the ulnar nerve toward the ME was measured at the cubital tunnel inlet at elbow extension (0°), elbow flexion to 60°, and elbow flexion to 90°.

RESULTS

The distance between the ME and ulnar nerve was lower in CuTS patients than in healthy patients at all elbow flexion angles. This difference was statistically significant at 0° and 60° elbow flexion (P < 0.05). When calculating the cutoff value, the distance between the ME and ulnar nerve at full elbow extension for CuTS diagnosis was 0.53 cm (sensitivity = 71.4%, specificity = 90.7%). The distance ratio between the ME and ulnar nerve for diagnosis of ulnar neuropathy at the elbow was 24.4% (sensitivity = 76.2%, specificity = 100%).

CONCLUSION

Measurement of the distance between the ME and ulnar nerve in full elbow extension may facilitate the diagnosis of patients with CuTS. These findings may be important for CuTS diagnosis, as they were also observed in patients with mild-stage CuTS.

Sonographic Follow-Up of Patients With Cubital Tunnel Syndrome Undergoing in Situ Open Neurolysis or Endoscopic Release: The SPECTRE Study

Background:The measurement of cross-sectional area (CSA) is a diagnostic tool to detect entrapments syndrome. The aim of this study was to compare the clinical outcome in elbows undergoing endoscopic and "in situ" open cubital tunnel release for cubital tunnel syndrome (CuTS) using ultrasound-related changes in the largest CSA of the ulnar nerve. The purpose is to determine the association between clinical outcome and CSA. Methods: From May 2011 to April 2016, 60 patients with CuTS were prospectively followed and not randomly divided in two groups: 30 patients undergoing an endoscopic release (ER) and 30 patients with "in situ" open neurolysis (OR). A sonographic examination was performed by the senior authors at baseline and 3, 6, and 12 months after surgical decompression. Results: CSA values were statistically significantly lower in the ER. Hand grip strength difference with Jamar test was not statistically significant a 12 months (39 kg vs 27 kg). Static-2 point discrimination test difference was only statistically significant lower in the endoscopic group at 3, 6 and 12 months but not clinically relevant (5 mm vs 6 mm). The American Shoulder and Elbow Surgeons-Elbow questionnaire (ASES-e) function score, ASES-e Pain score, and ASES-e Satisfaction score were not statistically significant different between the two groups at 3, 6, and 12 months post operatively. Conclusions: The study confirms that in spite of lower values of CSA in the ER, there is not a statistically significant difference between the two techniques in terms of subjective outcomes. Ultrasound (US) measurements seem to have a limited value in clinical results of patients treated for entrapment neuropathy of the ulnar nerve.Type of study/LOE: Prognostic Level III.

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.

Optimal Choice of Ultrasound-Based Measurements for the Diagnosis of Ulnar Neuropathy at the Elbow: A Meta-Analysis of 1961 Examinations

OBJECTIVE. The purpose of this study was to determine the optimal ultrasound (US) measurement technique and cutoff value for the diagnosis of ulnar neuropathy at the elbow. MATERIALS AND METHODS. A systematic literature search was conducted of the PubMed, Embase, Scopus, and Web of Science databases for studies evaluating the diagnostic accuracy of US of patients with ulnar neuropathy at the elbow before April 2019. Random-effects modeling was performed to compare the sensitivity, specificity, and diagnostic odds ratio (DOR) of different US measurements, including diameter and cross-sectional area (CSA) of the nerve at the medial epicondyle or proximal and distal levels, maximal diameter, maximal CSA, and nerve ratios. Sensitivity and metaregression analyses were performed to assess the impact of clinical and imaging-based variables on the DOR of US. RESULTS. Among 820 retrieved studies, 19 studies (1961 examinations) were included. Measuring the CSA of the ulnar nerve at the medial epicondyle with a cutoff value greater than 10-10.5 mm² had higher sensitivity (80.4%, 95% CI, 75.4-84.7%) than other techniques. Nerve ratios had higher specificity (89.1%, 95% CI, 85.8-91.8%) than other measurements; however, the definition of ratios and cutoff values varied across studies. ROC analysis showed higher diagnostic performance for measuring CSA at the medial epicondyle (AUC, 0.931). The mean CSA value was a significant predictor of the DOR of US (β coefficient, 0.307 ± 0.074; p < 0.001). Every 1-mm² larger CSA was associated with a 36% increase in DOR. The diagnostic performance of US was the same in any degree of elbow flexion. CONCLUSION. Measuring CSA of the ulnar nerve at the medial epicondyle has sensitivity and diagnostic performance superior to those of other techniques for the diagnosis of ulnar neuropathy at the elbow.

Diagnostic value of ultrasonography versus electrodiagnosis in ulnar neuropathy

Purpose

Ulnar neuropathy at elbow is the second-most common compression neuropathy. The main aim of this study was to assess the diagnostic value of ultrasonography (US) as an alternative method to electrodiagnosis (EDX), which had traditionally been used as the method of choice.

Methods

This diagnostic study was conducted on 66 participants (32 patients` elbows and 34 normal elbows) referred for EDX. Both groups were reassessed by US to evaluate the consistency of the two tests. The quantitative parameters of US, such as cross-sectional area (CSA) of the ulnar nerve at three different levels around the medial epicondyle (ME) were compared between groups.

Results

Our findings demonstrated that CSA at the ME and 2 cm distal to the ME were significantly larger in the patient group than normal participants. This higher nerve size was more prominent among those who had predominant axonal loss rather than demyelinating lesions (P<0.01). Finally, we evaluated US diagnostic value with the best singular feature (2 cm distal to ME) at a cutoff of 9 mm², which revealed specificity of 80% and sensitivity 84%.

Conclusion

Based on these results we can conclude that US is a sensitive and specific method in diagnosing ulnar neuropathy at the elbow and can be used as an acceptable complementary method, in particular when EDX is not available.

The Use of Preoperative Dynamic Ultrasound to Predict Ulnar Nerve Stability Following In Situ Decompression for Cubital Tunnel Syndrome

PURPOSE

To assess the use of preoperative, dynamic ultrasound to predict ulnar nerve instability following in situ decompression for cubital tunnel syndrome.

METHODS

Prior to undergoing in situ decompression, 43 consecutive patients underwent dynamic ultrasound to assess the stability of the ulnar nerve during elbow flexion. The dynamic ultrasound findings were compared with the intraoperative assessment of nerve stability following in situ decompression.

RESULTS

The preoperative dynamic ultrasound agreed with intraoperative findings in 38 of 43 patients (88%). Physical examination of ulnar nerve stability agreed with the intraoperative findings in 5 of 43 patients (12%). For the 5 of 43 cases in which the dynamic ultrasound did not correlate with the degree of ulnar nerve stability after in situ decompression, dynamic ultrasound overestimated the degree of ulnar nerve stability in 4 cases.

CONCLUSIONS

Preoperative dynamic ultrasound can be used to accurately predict the degree of ulnar nerve instability following in situ decompression.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic II.

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.

Accuracy of Preoperative Ultrasonography for Cubital Tunnel Syndrome: A Comparison with Intraoperative Findings

Background

The aim of this study was to assess the consistency between preoperative ultrasonographic and intraoperative measurements of the ulnar nerve in patients with cubital tunnel syndrome.

Methods

Twenty-six cases who underwent anterior transposition of the ulnar nerve for cubital tunnel syndrome were enrolled prospectively. On preoperative ultrasonography, largest cross-sectional diameters of the ulnar nerve were measured at the level of medial epicondyle (ME) and 3 cm proximal (PME) and distal (DME) to the ME on the transverse scan by a single experienced radiologist. Intraoperative direct measurements of the largest diameter at the same locations were performed by a single surgeon without knowledge of the preoperative values. The consistency between ultrasonographic and intraoperative values including the largest diameter and swelling ratio were assessed.

Results

Significant differences between ultrasonographic and intraoperative values of the largest diameter were found at all levels. The mean difference was 1.29 mm for PME, 1.38 mm for ME, and 1.12 mm for DME. The mean ME-PME swelling ratio for ultrasonographic and intraoperative measurements was 1.50 and 1.39, respectively, showing significant difference. The mean ME-DME swelling ratio for ultrasonographic and intraoperative measurements was 1.53 and 1.43, respectively, showing no significant difference.

Conclusions

Ultrasonographically measured largest diameters of the ulnar nerve at any levels were smaller than the real values determined intraoperatively. The ME-DME swelling ratio of the ulnar nerve measured by ultrasonography was consistent with the intraoperative measurement.

Optimal Measurement Level and Ulnar Nerve Cross-Sectional Area Cutoff Threshold for Identifying Ulnar Neuropathy at the Elbow by MRI and Ultrasonography

PURPOSE

Imaging criteria for diagnosing compressive ulnar neuropathy at the elbow (UNE) have recently been established as the maximum ulnar nerve cross-sectional area (UNCSA) upon magnetic resonance imaging (MRI) and/or ultrasonography (US). However, the levels of maximum UNCSA and diagnostic cutoff values have not yet been established. We therefore analyzed UNCSA by MRI and US in patients with UNE and in controls.

METHODS

We measured UNCSA at 7 levels in 30 patients with UNE and 28 controls by MRI and at 15 levels in 12 patients with UNE and 24 controls by US. We compared UNCSA as determined by MRI or US and determined optimal diagnostic cutoff values based on receiver operating characteristic curve analysis.

RESULTS

The UNCSA was significantly larger in the UNE group than in controls at 3, 2, 1, and 0 cm proximal and 1, 2, and 3 cm distal to the medial epicondyle for both modalities. The UNCSA was maximal at 1 cm proximal to the medial epicondyle for MRI (16.1 ± 3.5 mm²) as well as for US (17 ± 7 mm²). A cutoff value of 11.0 mm² for MRI and US was found to be optimal for differentiating between patients with UNE and controls, with an area under the receiver operating characteristic curve of 0.95 for MRI and 0.96 for US. The UNCSA measured by MRI was not significantly different from that by US. Intra-rater and interrater reliabilities for UNCSA were all greater than 0.77. The UNCSA in the severe nerve dysfunction group of 18 patients was significantly larger than that in the mild nerve dysfunction group of 12 patients.

CONCLUSIONS

By measuring UNCSA with MRI or US at 1 cm proximal to the ME, patients with and without UNE could be discriminated at a cutoff threshold of 11.0 mm² with high sensitivity, specificity, and reliability.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic III.

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.

The cubital tunnel syndrome caused by the intraneural or extraneural ganglion cysts: Case report and review of the literature

Cubital tunnel syndrome is the second most common nerve compression syndrome in peripheral nerve compression disease. Although potential ulnar nerve entrapment can occur at multiple points along its course, such as the arcade of struthers, the medial intermuscular septum, the medial epicondyle, the cubital tunnel, and the deep flexor pronator aponeurosis, the most common site of entrapment is the cubital tunnel. However, cubital tunnel syndrome could also be caused by the occupying masses along the course of ulnar nerve, such as intraneural or extraneural ganglia. The cubital tunnel syndrome caused by intraneural or extraneural ganglion cysts has been rarely reported. In our hospital, there were 184 patients with cubital tunnel syndrome who underwent surgical treatment from January 2010 to January 2014. Of these patients, 16 had extraneural cysts and 3 had intraneural ganglion cysts. The incidence rate of cysts in the cubital tunnel was 10.33%. Electromyography was used as routine examination. Ultrasound was used only in some patients in whom elbow mass was suspected. In the surgery of the cubital tunnel syndrome combined with cyst, if any other cysts were found, we should be remove completely the cyts and decompress the ulnar nerve thoroughly with the ulnar nerve being anterior transposition. These cysts were confirmed by histopathological examination. Finally, we compared the clinical features of patients who had a medial elbow ganglion with those of patients who had only cubital tunnel syndrome. B ultrasound can significantly improve the diagnosis. All patients were followed up for 4 months to 2 years, and the curative effect was good.

US of the Peripheral Nerves of the Upper Extremity: A Landmark Approach

Ultrasonography (US) has become a first-line modality for the evaluation of the peripheral nerves of the upper extremity. The benefits of US over magnetic resonance (MR) imaging include higher soft-tissue resolution, cost effectiveness, portability, real-time and dynamic imaging, and the ability to scan an entire extremity quickly and efficiently. US can be performed on patients who are not eligible for MR imaging. Metallic implant artifacts are usually not problematic. US has been shown to have equal specificity and greater sensitivity than MR imaging in the evaluation of peripheral nerves. Any abnormal findings can be easily compared with the contralateral side. The published literature has shown that US has demonstrated clinical utility in patients with suspected peripheral nerve disease by guiding diagnostic and therapeutic decisions as well as by confirming electrodiagnostic findings. Common indications for upper extremity peripheral nerve US are the evaluation for injury due to penetrating trauma, entrapment by scar tissue, and tumor. US of the upper extremity is most commonly performed to evaluate carpal and cubital tunnel syndrome. It is important for the radiologist or sonographer to have a detailed knowledge of anatomy and specific anatomic landmarks for each nerve to efficiently and accurately perform an examination. The goal of this article is to introduce readers to the basics of US of the peripheral nerves of the upper extremity with a focus on the median, ulnar, and radial nerves. Common sites of disease and the location of important anatomic landmarks will be reviewed.

Imaging of regional pain syndromes; from syndromes to conditions using imaging?

Musculoskeletal regional pain syndromes often lead to patient referrals in general and rheumatological practice. Detailed history taking and clinical examination can in most cases reveal the cause for pain and direct the subsequent management of the conditions. Yet, when in doubt, imaging methods have to support the clinical assessment. This paper presents the underlying pathologies of the most frequently encountered regional pain syndromes and the role of musculoskeletal ultrasonography and magnetic resonance imaging in their visualization. It presents data, where available, on diagnostic accuracy and comparisons with gold standards. The article stresses the advantages and disadvantages of the analyzed imaging modalities and suggests the future research agenda.

Systematic Review of Sonographic Measurements of the Ulnar Nerve at the Elbow

A systematic review was performed to identify studies reporting summary data (mean, standard deviation) of sonographic cross-sectional measurements of the ulnar nerve at the elbow. Comparisons of measurements were performed to determine whether statistical differences existed between groups of individuals symptomatic and asymptomatic of ulnar nerve entrapment at the elbow (UNE). Across the four studies meeting the selection criteria of the search, five sample groups were identified and compared: three asymptomatic of UNE and two symptomatic of UNE. There were significant differences between measurements of people with and without UNE ( P < .0001—.041). Significant differences also existed between the two symptomatic populations ( P < .0001—.0062) and between the three asymptomatic populations ( P < .0001—.41). This systematic review demonstrates that significant differences exist between sonographic measurements of ulnar nerve dimension between people with and without UNE, confirming that these measurements are potential discriminators of UNE. The demonstration of significant differences between measurements of ulnar nerve size within sample populations with similar symptomatic status suggests that further studies are required to confirm the effect of ulnar nerve pathologies, measurement protocols, and anthropometric factors.

The Ulnar Nerve at the Elbow: An Anatomic, Sonographic, and Histology Comparison

When making sonographic measurements of peripheral nerves, either for research or clinical purposes, it is important to have established that the measurements are valid. This study compared sonographic measurements and appearances of the ulnar nerve at the elbow with anatomic measurements of the nerve and with histologic findings. The results demonstrated that the anatomic measurements were very similar to the sonographic measurements of the nerve, when the nerve was imaged postdissection. However, the in situ sonographic measurements of the nerve were discrepant with the anatomic measurements of the nerve. This discrepancy occurred because the predissection sonographic measurement did not include the echogenic border surrounding the hypoechoic nerve. Histologic correlation demonstrated that the hypoechoic structure on the sonogram probably represented the major fascicle(s) of the nerve rather than the complete nerve and that the surrounding echogenic tissue represents the epineurial connective tissues of the nerve.

Elbow US: Anatomy, Variants, and Scanning Technique

As with other musculoskeletal joints, elbow ultrasonography (US) depends on the examination technique. Deep knowledge of the relevant anatomy, such as the bone surface anatomy, tendon orientation, nerves, and vessels, is crucial for diagnosis. It is important to be aware of the primary imaging pitfalls related to US technique (anisotropy) in the evaluation of deep tendons such as the distal biceps and peripheral nerves. In this article, US scanning technique for the elbow as well as the related anatomy, primary variants, and scanning pitfalls are described. In addition, an online video tutorial of elbow US describes a possible approach to elbow evaluation. Online supplemental material is available for this article.

Ultrasound diagnosis of ulnar nerve entrapment by confirming baseline cross-sectional area measurement for normal and abnormal nerves

Background: Magnetic resonance imaging is most commonly employed, alongside electrodiagnostic studies, in the diagnosis of ulnar nerve entrapment. It is expensive, time consuming, not readily available to the general public, and limits imaging to a segment of the nerve at any given time. In contrast, high-frequency ultrasound is an inexpensive imaging modality with a flexible field of view through which the nerve can be traced. An ultrasound cross-sectional area (CSA) >0.075 cm² has previously been suggested as indicative of nerve entrapment. Objectives: To confirm the suggested CSA measurement of 0.075 cm² and discuss the difference in CSA measurement between abnormal nerves, nerves in the contra-lateral elbow of the same participant, and those of asymptomatic participants. Methods: Ultrasonography was performed on both elbows of 25 patients with confirmed unilateral ulnar nerve entrapment and on 25 healthy controls for comparison. Three CSA measurements were taken of the ulnar nerve along its course, and the mean measurement was recorded.Results: CSA measurements were significantly different between patients with ulnar nerve entrapment and healthy controls (p < 0.05). In our study, a CSA >0.070 cm² defined ulnar nerve entrapment at the elbow. Conclusion: Ultrasound CSA measurement of the ulnar nerve is accurate in the diagnosis of ulnar nerve entrapment. The range of values and varied criteria previously reported call for standardisation of the procedure and CSA measurement. We suggest that a measurement of 0.070 cm² be considered as a new baseline for the optimal diagnosis of ulnar nerve entrapment.[PDF to follow]

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.

Assessment of the utility of ultrasonography with high-frequency transducers in the diagnosis of entrapment neuropathies

The primary aim of this paper was to assess the relevance of high-frequency ultra-sound examination in qualifying patients for either surgical or conservative treatment of peripheral entrapment neuropathies. The study was conducted in a group of 55 patients aged 7–83 (mean age 43.6), including 28 males and 27 females, who in 2009–2011 were referred to an ultrasound examination due to a clinical suspicion of entrapment neuropathies. For the purposes of the analysis, the patients were divided into four groups: carpal tunnel syndrome (1), ulnar nerve entrapment (2) (cubital tunnel syndrome and Guyon's canal syndrome), posterior interosseous nerve syndrome (3) and other entrapment neuropathies (4). The cases of isolated idiopathic carpal tunnel syndrome were excluded from the analysis. All patients underwent the interview, physical examination and ultrasound examination. Ultrasound examinations were performed with Esaote MyLab 50 and MyLab 60 systems using high-frequency broadband linear transducers: 6–18 MHz. Sixty-seven percent of patients (37 persons) underwent a neurophysiological test. Nerve echostructure, its hyperemia as well as nerve cross-sectional area or, in the case of small nerves, diameter were assessed in all patients. Furthermore, the following were assessed in individual groups: notch sign in group 1, nerve instability in a dynamic ultrasound examination in group 2, nerve angulation in a dynamic ultrasound examination and tenderness on nerve compression at the site of the visualized pathology in group 3. The analyses of the collected material were performed by means of descriptive statistics. The results of clinical and surgical verification were consistent with ultrasound findings in 96.4%. The results indicate that high-frequency ultrasonography is a valuable method in qualifying patients for various types of treatment of peripheral neuropathies resulting from compression.

Does the ulnar nerve enlarge after surgical transposition?

OBJECTIVES

The purpose of this study was to test the hypothesis that symptomatic transposed ulnar nerves have a larger average cross-sectional area (CSA) than symptomatic in situ ulnar nerves.

METHODS

We conducted a retrospective review of the charts and sonograms of 68 patients who had failed ulnar nerve transposition compared to 48 patients with cubital tunnel syndrome who had not undergone surgical management. In addition, postoperative sonograms were compared with preoperative studies when available. Failure was defined as persistence or recurrence of symptoms of ulnar neuropathy postoperatively. The cross-sectional area of the nerve, subjective echogenicity, and residual sites of compression were recorded. Groups were subsequently compared by t tests.

RESULTS

The failed ulnar nerve transposition group showed a mean cross-sectional area ± SD of 17.26 ± 9.93 mm(2), whereas the control group showed a mean cross-sectional area of 13.45 ± 7.33 mm(2). This difference was statistically significant (P= .018). Nontransposed nerves were more likely to have identifiable sites of compression (P< .05). There was a trend toward postoperative enlargement in the 6 patients with available preoperative imaging (P = .17). No difference in subjective echogenicity was found in this analysis.

CONCLUSIONS

Patients with failed ulnar nerve transposition show a significantly enlarged cross-sectional area when compared to symptomatic nerves in situ. Although a specific etiology for this difference cannot be determined, the data suggest that the reference ranges for the cross-sectional area of the ulnar nerve may need to be revised for those who have undergone surgery.

Contribution of static and dynamic ultrasound in cubital tunnel syndrome

INTRODUCTION

Electroneuromyography (ENMG) is the gold standard examination in cubital tunnel syndrome (CuTS), but sheds no light on etiology. High-resolution ultrasound (HRU) analyzes the anatomic abnormalities and physical properties of the ulnar nerve (UN) and enables dynamic study. The present non-randomized prospective study compared HRU with clinical, ENMG and intraoperative findings.

MATERIAL AND METHODS

Sixty patients were included. The McGowan clinical classification as modified by Goldberg was employed, and ENMG lesions were ranked for severity. HRU screened for morphologic abnormalities of the ulnar nerve and cubital tunnel, measuring UN cross-sectional area (UNCSA) and flattening index (FI) in the cubital tunnel, in extension and flexion. UN stability was assessed.

RESULTS

Ultrasound found 2 stenoses, 29 pseudoneuromas 25 dedifferentiations. There were 16 morphologic abnormalities. Mean cubital tunnel UNCSA (in cm(2)) and FI were respectively 0.112 and 1.549 in extension and 0.117 and 1.827 in flexion. Nineteen cases of UN instability were found on HRU, versus 17 intraoperatively. Only 8 patients showed no abnormality on HRU. Pseudoneuroma or dedifferentiation on HRU correlated with clinical stage (P=0.2579 and 0.2615, respectively). Dedifferentiation was associated with severe abnormality on ENMG (P<0.5). Thirty-two stenoses, 18 pseudoneuromas and 10 epitrochlearis anconeus muscles were found intraoperatively, matching HRU abnormalities.

DISCUSSION

The present findings were comparable to those of the literature. Cubital tunnel UNCSA was elevated in case of CuTS, with cut-off at 0.112 cm(2). FI was elevated in flexion (P=0.0063). The rate of UN instability was 32%, compared to 21-60% in the literature. HRU findings matched the clinical and ENMG classifications. HRU proved to be an effective diagnostic tool for CuTS and its etiologies.

LEVEL OF EVIDENCE

IV.

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

There is still no consensus on a normal value for the cross-sectional area of the ulnar nerve at the elbow. Such data would be valuable for the ultrasound diagnosis of ulnar neuropathy. Comparison of the symptomatic and contralateral asymptomatic sides has been recommended. The aim of this study was to investigate whether or not the asymptomatic ulnar nerve could be a reference value. High-resolution ultrasonic measurements of the cross-sectional areas of the ulnar nerves at the elbow were compared with 38 contralateral asymptomatic elbows of patients with unilateral ulnar neuropathy and 38 healthy controls. There were significant differences in the cross-sectional areas at all levels between the healthy control subjects and asymptomatic side of the ulnar neuropathy patients (p < 0.05). The findings of this study suggest that there is a limitation in using the asymptomatic side for obtaining reference values in ultrasonographic studies. Each ultrasonographic laboratory should determine its own reference values.

Movement of the ulnar nerve at the elbow: a sonographic study

OBJECTIVES

The aim of this study was to measure the degree of movement of the ulnar nerve in the cubital tunnel using sonography in patients with ulnar neuropathy at the elbow compared to a healthy control group.

METHODS

We examined the ulnar nerve in the cubital tunnel using sonography with the elbow extended and then flexed in 26 patients with ulnar neuropathy and 13 control participants. The distance from the ulnar nerve to the skin, medial epicondyle, and tip of olecranon at the inlet of the cubital tunnel and the distance from the ulnar nerve to the skin and olecranon recess at the outlet of the cubital tunnel were measured when the elbow was extended and flexed, respectively. Displacement of the ulnar nerve during elbow extension and flexion between patients with ulnar neuropathy and controls was compared.

RESULTS

There was significantly greater displacement of the ulnar nerve to the medial epicondyle at the inlet of the cubital tunnel in the patients with ulnar neuropathy (mean ± SD, 4.22 ± 3.79 mm) compared to the controls (1.76 ± 1.51 mm) during elbow extension and flexion (P = .008).

CONCLUSIONS

A significantly greater degree of movement of the ulnar nerve occurs in patients with ulnar neuropathy at the elbow compared to healthy people, as determined by sonography.

Ultrasound assessment on selected peripheral nerve pathologies. Part I: Entrapment neuropathies of the upper limb - excluding carpal tunnel syndrome

Ultrasound (US) is one of the methods for imaging entrapment neuropathies, post-traumatic changes to nerves, nerve tumors and postoperative complications to nerves. This type of examination is becoming more and more popular, not only for economic reasons, but also due to its value in making accurate diagnosis. It provides a very precise assessment of peripheral nerve trunk pathology – both in terms of morphology and localization. During examination there are several options available to the specialist: the making of a dynamic assessment, observation of pain radiation through the application of precise palpation and the comparison of resultant images with the contra lateral limb. Entrapment neuropathies of the upper limb are discussed in this study, with the omission of median nerve neuropathy at the level of the carpal canal, as extensive literature on this subject exists. The following pathologies are presented: pronator teres muscle syndrome, anterior interosseus nerve neuropathy, ulnar nerve groove syndrome and cubital tunnel syndrome, Guyon's canal syndrome, radial nerve neuropathy, posterior interosseous nerve neuropathy, Wartenberg's disease, suprascapular nerve neuropathy and thoracic outlet syndrome. Peripheral nerve examination technique has been presented in previous articles presenting information about peripheral nerve anatomy [Journal of Ultrasonography 2012; 12 (49): 120–163 – Normal and sonographic anatomy of selected peripheral nerves. Part I: Sonohistology and general principles of examination, following the example of the median nerve; Part II: Peripheral nerves of the upper limb; Part III: Peripheral nerves of the lower limb]. In this article potential compression sites of particular nerves are discussed, taking into account pathomechanisms of damage, including predisposing anatomical variants (accessory muscles). The parameters of ultrasound assessment have been established – echogenicity and echostructure, thickness (edema and related increase in the cross sectional area of the nerve trunk), vascularization and the reciprocal relationship with adjacent tissue.

Ultrasonography in ulnar neuropathy at the elbow: a critical review

INTRODUCTION

Ultrasonography of the ulnar nerve has been recommended as a useful additional test in ulnar neuropathy at the elbow (UNE).

METHODS

We searched the literature and systemically reviewed all clinical trials in UNE. We also looked for articles about the normal sonoanatomy and specific causes of UNE.

RESULTS

Seven of 14 clinical trials in UNE were suitable for further analysis. Ultrasonographic ulnar nerve size measurement appears to be a test with good diagnostic accuracy. The most frequently reported abnormality was an increased cross-sectional area of the ulnar nerve at the elbow. However, several studies had methodological flaws. In addition, the ultrasonographic techniques and study designs differed among the studies. There were a few other uncontrolled studies about the underlying causes of UNE.

DISCUSSION

The role of ultrasonography in UNE seems promising but could not be firmly established. More prospective studies are needed, and we make several recommendations for further research.

Ultrasonography in patients with ulnar neuropathy at the elbow: comparison of cross-sectional area and swelling ratio with electrophysiological severity

The aim of this study was to determine the diagnostic value of ultrasonographic measurements in ulnar neuropathy at the elbow (UNE) and to assess the relationship between the measurements and the electrophysiological severity. The largest anteroposterior diameter (LAPD) and cross-sectional area (CSA) measurements of the ulnar nerve were noted at multiple levels along the arm, and the distal-to-proximal ratios were calculated. Almost all of the measurements and swelling ratios between patients and controls showed statistically significant differences. The largest CSA, distal/largest CSA ratio, CSA at the epicondyle, and proximal LAPD had larger areas under the curve than other measurements. The sensitivity and specificity in diagnosing UNE were 95% and 71% for the largest CSA, 83% and 85% for the distal/largest CSA ratio, 83% and 81% for the CSA at the epicondyle, and 93% and 43% for the proximal LAPD, respectively. There was a statistically significant correlation between the electrophysiological severity scale score (ESSS) and the largest CSA, the CSA at the epicondyle and 2 cm proximal to the epicondyle, and the LAPD at the level of the epicondyle (P < 0.05). None of the swelling ratios showed a significant correlation with the ESSS. The largest CSA measurement is the most valuable ultrasonographic measurement both for diagnosis and determining the severity of UNE.

The validity of ultrasonographic assessment in cubital tunnel syndrome: the value of a cubital-to-humeral nerve area ratio (CHR) combined with morphologic features

Diagnosis of a typical idiopathic cubital tunnel syndrome (CuTS) is straight forward but the work-up of mild forms is clinically challenging. The diagnostic value of high-resolution ultrasound (HRUS) relying solely on nerve measurements is doubtful. Additional textural analysis of the nerve may possibly overcome this drawback. Thirty-eight prospectively enrolled patients with idiopathic CuTS and 23 healthy volunteers underwent standardized HRUS. A cubital-to-humeral nerve area ratio (CHR) was calculated and the texture of the most swollen nerve segment assessed. CHR was significantly different among patients and volunteers (p<0.001) but with a marked overlap. Combination of at least partial inner fascicular masking plus a CHR>1.4 showed a positive linear coherence with idiopathic CuTS at a specificity>95% and a PPV>90%. Thus, the combined textural analysis and CHR calculation seems a powerful tool for the sonographic diagnosis of idiopathic CuTS.

Evaluation of peripheral nerves of the upper limb with ultrasonography: a comparison of ultrasonographic examination and the intra-operative findings

We prospectively studied 26 consecutive patients with clinically documented sensory or motor deficiency of a peripheral nerve due to trauma or entrapment using ultrasound, and in 19 cases surgical exploration of the nerves was undertaken. The ultrasonographic diagnoses were correlated with neurological examination and the surgical findings. Reliable visualisation of injured nerves on ultrasonography was achieved in all patients. Axonal swelling and hypoechogenity of the nerve was diagnosed in 15 cases, loss of continuity of a nerve bundle in 17, the formation of a neuroma of a stump in six, and partial laceration of a nerve with loss of the normal fascicular pattern in five. The ultrasonographic findings were confirmed at operation in those who had surgery. Ultrasound may be used for the evaluation of peripheral nerve injuries in the upper limb. High-resolution ultrasound can show the exact location, extent and type of lesion, yielding important information that might not be obtainable by other diagnostic aids.