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

The relationship between diffusion tensor imaging and the clinical classification of cubital tunnel syndrome

The purpose of the study was to investigate the relationship between diffusion tensor imaging (DTI) and the clinical classification of cubital tunnel syndrome (CuTS). Ten patients with CuTS (7 men and 3 women; mean age: 52.7 years) and 5 patients without ulnar neuropathy (2 men and 3 women; mean age: 38.0 years) were enrolled in this retrospective study. Fifteen patients were clinically classified into three groups: "Normal", "1 and 2A", and "2B and 3" by an orthopedic surgeon using the modified McGowan stages. DTI was acquired using a 3.0-T MRI. Fractional anisotropy (FA) of the ulnar nerve was measured in slices covering 20 mm proximal to 20 mm distal to ulnar sulcus. Median FA values in each group were compared by Kruskal-Wallis and Steel-Dwass test (P < 0.05). Five patients with CuTS were classified as "1 and 2A" and five patients as "2B and 3". The FA values, proximal 12 mm to the ulnar sulcus were 0.486 ± 0.117, 0.425 ± 0.166 and 0.298 ± 0.0386 in the "Normal", "1 and 2A" and "2B and 3" groups, respectively. The FA values of patients classified as "Normal" were significantly higher than those classified as "2B and 3" (P = 0.0326 in Steel-Dwass test). FA proximal to the ulnar sulcus might be associated to the modified McGowan stages for the clinical classification of CuTS.

Nerve enlargement in patients with Noonan syndrome: A retrospective cohort study

Noonan syndrome (NS) is an autosomal dominant condition characterized by facial dysmorphism, congenital heart disease, development delay, growth retardation and lymphatic disease. It is caused by germline pathogenic variants in genes encoding proteins in the Ras/mitogen-activated protein kinase signaling pathway. Nerve enlargement is not generally considered as a feature of NS, although some cases have been reported. High-resolution nerve ultrasound enables detailed anatomical assessment of peripheral nerves and can show enlarged nerves. This retrospective cohort study aims to describe the sonographic findings of patients with NS performed during a 1-year time period. Data on the degree of enlargement, the relation to increasing age, pain in extremities, genotype on the gene level and clinical features were collected. Twenty-nine of 93 patients visiting the NS Center of Expertise of the Radboud University Medical Center Nijmegen underwent high-resolution ultrasound. In 24 patients (83%) nerve enlargement was found. Most of them experienced pain. We observed a weak correlation with increasing age and the degree of nerve enlargement but no association with pain, genotype at the gene level or clinical features. This study shows that patients with NS have a high predisposition for sonographic nerve enlargement and that the majority experience pain.

Ultrasound Measurements of the Ulnar Nerve at the Medial Epicondyle Correlate With Electrodiagnostic Studies

BACKGROUND

Cubital tunnel syndrome is the second most common compressive neuropathy in the upper extremity and is commonly evaluated with electrodiagnostic studies (EDS). Ultrasound (US) has emerged as a potentially more efficient alternative to EDS. The purpose of this study is to evaluate whether measurements of the cross-sectional area (CSA) of the ulnar nerve at the elbow correlate with EDS results.

METHODS

This study was a prospective analysis of patients who presented with signs and symptoms consistent of cubital tunnel syndrome, who received USs of the ulnar nerve at the elbow and nerve conduction tests. Pearson correlation coefficients were used to evaluate the correlation between ulnar nerve CSA and electrodiagnostic data. t Tests were used to evaluate statistical differences between the mean ulnar nerve CSA of patients with positive or negative nerve conduction study results. Youden Index was used to calculate the optimal cut-off point for US CSA based on maximal sensitivity and specificity. Statistical significance was based on a two-sided P less than .05.

RESULTS

The association between increasing US CSA at the medial epicondyle with slowing of the conduction velocity of the ulnar motor nerve across the elbow was statistically significant (r = -0.35, P = .02). Patients with positive EDS tests had significantly larger nerve size than those with negative tests (all Ps < .03). A cut-off point of greater than or equal to 11 mm2 had a sensitivity of 70.83% and specificity of 66.67%.

CONCLUSIONS

Larger ulnar nerve CSAs correlate with slowing of the conduction velocity on EDSs, and those with positive EDSs have larger nerve sizes than those with negative tests.

The elastography of distal ulnar nerve branches in cyclists

INTRODUCTION

Forced elbow flexion and pressure during bicycling result in ulnar nerve traction and pressure exerted in Guyon's canal or the nerve's distal branches. The compression of the nerves causes a change in their stiffness related to edema and eventually gradual fibrosis.

PURPOSE

This study aimed to evaluate the elastography of terminal branches of the ulnar nerve in cyclists.

STUDY DESIGN

Cross-sectional study.

METHODS

Thirty cyclists, 32 healthy individuals, and 32 volunteers with ulnar nerve entrapment neuropathies participated in the study. Each participant underwent a nerve examination of the cubital tunnel, Guyon's canal and the deep and superficial branches of the ulnar nerve using shear wave elastography. The cyclist group was tested before and after a 2-hour-long workout.

RESULTS

Before cycling workouts, the ulnar nerve stiffness in the cubital tunnel and Guyon's canal remained below pathological estimates. Cycling workouts altered nerve stiffness in the cubital tunnel only. Notably, the stiffness of the ulnar terminal branches in cyclists was increased even before training. The mean deep branch stiffness was 50.85 ± 7.60 kPa versus 20.43 ± 5.95 kPa (p < 0.001) in the cyclist and healthy groups, respectively, and the mean superficial branch stiffness was 44 ± 12.45 kPa versus 24.55 ± 8.05 kPa (p < 0.001), respectively. Cycling contributed to a further shift in all observed values.

DISCUSSION

These observations indicate the existence of persistent anatomical changes in the distal ulnar branches in resting cyclists that result in increased stiffness of these nerves. The severity of these changes remains, however, to be determined.

CONCLUSIONS

These data show elastography values of the ulnar terminal branches in healthy individuals and cyclists where despite lack of clinical symptoms that they seem to be elevated twice above the healthy range.

Diagnosis of Ulnar Neuropathy at the Elbow Using Ultrasound - A Comparison to Electrophysiologic Studies

PURPOSE

Given the relatively high false negative rate of electrodiagnostic studies (EDX) in patients with clinically diagnosed ulnar neuropathy at the elbow (UNE), we sought to determine whether an alternative objective test could more effectively detect UNE. Additionally, we proposed to determine the relationship between the cross-sectional area (CSA) of the ulnar nerve on ultrasound (US), EDX, and clinical symptoms.

METHODS

This was a retrospective study of patients presenting with symptomatic UNE. The performance characteristics of EDX versus ultrasound were calculated using the clinical diagnosis of UNE as the reference standard. Standard EDX studies and US of the ulnar nerve were analyzed. Maximal CSA of the ulnar nerve and EDX severity were analyzed for patients with each combination of US-positive/negative and EDX-positive/negative findings.

RESULTS

Analysis was performed on 89 patients and 115 nerves with signs and symptoms of cubital tunnel syndrome. In total, 56 (49%) nerves were diagnosed as mild UNE, 32 (28%) nerves were diagnosed as moderate UNE, 17 (15%) nerves were diagnosed as severe UNE, and 10 (8%) nerves were negative for UNE by EDX. Maximal-maximal CSA was highly correlated with disease severity as determined by nerve conduction studies/electromyography. Compared with EDX+/US+, patients with EDX-/US+ showed higher rates of ulnar sensory loss and elbow tenderness with similar rates of positive Tinel and intrinsic muscle atrophy. In this sample of patients with clinically diagnosed UNE, 91.3% of the patients demonstrated positive EDX studies, whereas 94.8% had a positive US.

CONCLUSIONS

Ultrasound is an alternative to EDX that could be incorporated clinically in the diagnosis and management of UNE. Ultrasound was able to consistently detect clinically positive cubital tunnel syndrome demonstrating its utility as a confirmatory or supplemental test to the clinical assessment if one is required. Ultrasound additionally may be able to better identify patients with early stages of UNE with negative EDX findings.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic IV.

Shoulder and Elbow Injuries in Adult Overhead Throwers: Imaging Review

Overhead throwing, particularly in baseball, subjects the shoulder and elbow to various unique injuries. Capsular contracture following repetitive external rotation shifts the humeral head posterosuperiorly, predisposing to glenohumeral internal rotation deficit (GIRD), Bennett, posterosuperior internal impingement (PSI), and superior labrum anterior-posterior (SLAP) lesions. GIRD represents loss of internal rotation at the expense of external rotation. Bennett lesion represents ossification of the posteroinferior glenohumeral ligament due to repetitive traction. PSI manifests with humeral head cysts and "kissing" tears of the posterosuperior cuff and labrum. Scapular dysfunction contributes to symptoms of PSI and predisposes to labral or rotator cuff disease. "Peel-back" or SLAP lesions occur when torsional forces detach the biceps-labral anchor from the glenoid. Finally, disorders of the anterior capsule, latissimus dorsi, teres major, and subscapularis are well recognized in overhead throwers. At the elbow, injuries typically involve the medial-sided structures. The ulnar collateral ligament (UCL) is the primary static restraint to valgus stress and can be thickened, attenuated, ossified, and/or partially or completely torn. Medial epicondylitis can occur with tendinosis, partial tear, or complete rupture of the flexor-pronator mass and can accompany UCL tears and ulnar neuropathy. Posteromedial impingement (PMI) and valgus extension overload syndrome are related entities that follow abundant valgus forces during late cocking or acceleration, and deceleration. These valgus stresses wedge the olecranon into the olecranon fossa, leading to PMI, osteophytes, and intra-articular bodies. Other osseous manifestations include olecranon stress fracture and cortical thickening of the humeral shaft. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Cubital Tunnel Syndrome: Does a Consensus Exist for Diagnosis?

PURPOSE

Cubital tunnel syndrome (CuTS) is the second most common compressive neuropathy of the upper extremity. We aimed to determine a consensus among experts using the Delphi method for clinical criteria that could be validated further for the diagnosis of CuTS.

METHODS

The Delphi method was used for establishing a consensus among a group of expert panelists, comprising 12 hand and upper-extremity surgeons, who ranked the diagnostic clinical importance of 55 items related to CuTS on a scale from 1 (least important) to 10 (most important). The average and SDs of each item were calculated, and Cronbach α was used to assess homogeneity among the panelist-ranked items.

RESULTS

All panelists answered the 55-item questionnaire. A Cronbach α value of 0.963 was obtained on the first iteration. The top criteria that were considered most clinically relevant to the diagnosis of CuTS among the group were determined based on the most highly ranked and correlated items among the expert panelist group. The criteria based on which there was agreement were as follows: (1) paresthesias in ulnar nerve distribution, (2) symptoms precipitated by increased elbow flexion/positive elbow flexion tests, (3) positive Tinel sign at the medial elbow, (4) atrophy/weakness/ late findings (eg, claw hand of the ring/small finger and Wartenberg or Froment sign) of ulnar nerve-innervated muscles of the hand, (5) loss of two-point discrimination in ulnar nerve distribution, and (6) similar symptoms on the involved side after successful treatment on the contralateral side.

CONCLUSIONS

Our study demonstrated a consensus among an expert panelist group of hand and upper-extremity surgeons on potential diagnostic criteria for CuTS. This consensus on diagnostic criteria may help clinicians readily diagnose CuTS in a standardized form; however, further weighting and validation are necessary prior to the development of a formal diagnostic scale.

CLINICAL RELEVANCE

This study is the first step in producing a consensus on how to diagnose CuTS.

Ulnar nerve thickness at the elbow on longitudinal ultrasound view in control subjects

INTRODUCTION

Ulnar mononeuropathy at the elbow is the second most frequent neuropathy in humans. Diagnosis is based on clinical and electrophysiological criteria and, more recently, also on ultrasound. Cross-sectional ultrasound is currently the most valued, although longitudinal ultrasound allows assessment of the entire affected trajectory of the nerve in a single view, but always in a straight line with no changes in direction, as in the extended elbow. The main aim of this work is to propose normative values ​​for longitudinal ultrasound of the ulnar nerve at the elbow.

METHODS

The neurological exploration of upper extremity, and electrophysiological and ultrasound parameters at the elbow of ulnar nerve were evaluated in 76 limbs from 38 asymptomatic subjects.

RESULTS

The diameters of the nerve as well as the distal and proximal areas were larger at the proximal region of the ulnar groove, and even more so in older individuals. In most of these elderly subjects, we found a small, non-significant slowdown in motor conduction velocity at the elbow with respect to the forearm (less than 5 m/s).

CONCLUSIONS

We observed a good correlation between the longitudinal and cross-sectional ultrasounds of the ulnar nerve at the elbow. Longitudinal ultrasound proved to be sensitive, reliable, simple and rapid, but its greatest contribution was allowing the visualization of the entire nerve trajectory in an integrated way, providing an image with good definition of the outline, proportions and intraneural characteristics of the nerve.

ACR Appropriateness Criteria® Chronic Elbow Pain

Chronic elbow pain can be osseous, soft tissue, cartilaginous, and nerve related in etiology. Imaging plays an important role in differentiating between these causes of chronic elbow pain. This document provides recommendations for imaging of chronic elbow pain in adult patients. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Morphological Changes of Medial Epicondyle-Olecranon Ligament and Ulnar Nerve in the Cubital Tunnel Syndrome: An Ultrasonic Study

Objective

Few studies have performed detailed ultrasound measurements of medial epicondyle‐olecranon (MEO) ligament that cause the entrapment of ulnar nerve. This study aims to comprehensively evaluate dynamic ultrasonographic characteristics of MEO ligament and ulnar nerve for clinical diagnosis and accurate treatment of cubital tunnel syndrome (CuTS).

Methods

Thirty CuTS patients (CuTS group) and sixteen healthy volunteers (control group) who underwent ultrasound scanning from October 2016 to October 2020 were retrospectively collected, with 30 elbows in each group. Primary outcomes were thickness at six points, length and width of MEO ligament. Secondary outcomes were thickness of ulnar nerve under MEO ligament at seven parts and the cross‐sectional area (CSA) of ulnar nerve at proximal end of MEO ligament (P_0 mm). The thickness of MEO ligament and ulnar nerve in different points of each group was compared by one‐way ANOVA analysis with Bonferroni post hoc test, other outcomes were compared between two elbow positions or two groups using independent‐samples t test.

Results

Thickness of MEO ligament in CuTS group at epicondyle end, midpoint in transverse view, olecranon end, proximal end, midpoint in axial view, and distal end was 0.67 ± 0.31, 0.37 ± 0.18, 0.89 ± 0.35, 0.39 ± 0.21, 0.51 ± 0.38, 0.36 ± 0.25 at elbow extension, 0.68 ± 0.34, 0.38 ± 0.27, 0.77 ± 0.39, 0.32 ± 0.20, 0.48 ± 0.22, 0.32 ± 0.12 (mm) at elbow flexion, respectively. Compared with control group, they were significantly thickened except for proximal end at elbow flexion. MEO ligament thickness at epicondyle end and olecranon end was significantly larger than midpoint in two groups. No significant difference was found in length and width of MEO ligament among different comparisons. Ulnar nerve thickness at 5 mm proximal to MEO ligament (P_5 mm, 3.25 ± 0.66 mm) was significantly increased than midpoint of MEO ligament (Mid), distal end of MEO ligament (D_0 mm), 5 mm (D_5 mm), 10 mm (D_10 mm) distal to MEO ligament at extension in CuTS group. Compared with control group, ulnar nerve thickness at P_5 mm in CuTS group was significantly increased at extension position, at D_5 mm and D_10 mm was significantly decreased at flexion position. CSA of ulnar nerve at extension position (14.44 ± 4.65 mm²) was significantly larger than flexion position (11.83 ± 3.66 mm²) in CuTS group, and CuTS group was significantly larger than control group at two positions.

Conclusions

MEO ligament in CuTS patients was thickened, which compressed ulnar nerve and caused its proximal end swelling. Ultrasonic image of MEO ligament thickness was a significant indicator for CuTS and can guide surgeons in selecting the appropriate treatment.

Diagnosing ulnar neuropathy at the elbow on MRI: importance of the longitudinal extent of the hyperintense ulnar nerve

OBJECTIVE

To evaluate the usefulness of the longitudinal extent (LE) of high ulnar nerve signal intensity (SI) for the diagnosis of ulnar neuropathy at the elbow (UNE).

MATERIALS AND METHODS

This retrospective study included 68 patients who underwent elbow MRI. Twenty-seven and 41 patients were enrolled in the UNE and control groups, respectively. Qualitative and quantitative analyses of the SI and size of the ulnar nerve at the cubital tunnel, proximal, and distal to the cubital tunnel were performed. Cross-sectional area (CSA) and nerve-to-muscle contrast ratio (NMCR) were measured at each level. The LE of the hyperintense ulnar nerve was evaluated using axial and coronal images. The presence of space-occupying lesions (SOLs), subluxation, and muscle denervation were recorded. Univariate and multivariate analyses were performed to identify independent predictive factors.

RESULTS

Ulnar nerve hyperintensity at and distal to the cubital tunnel, presence of compression, SOL, muscle denervation, LE of hyperintense ulnar nerve, NMCR, and CSA at and distal to the cubital tunnel significantly differed between the two groups. Multivariate logistic regression analysis showed that the LE of the hyperintense ulnar nerve and CSA at the cubital tunnel were independent predictive factors for UNE (p < 0.05).

CONCLUSION

LE of the hyperintense ulnar nerve could be a useful predictive factor for UNE.

How to Report: Elbow MRI

The elbow is the least common of the main joints examined with magnetic resonance imaging (MRI), thus radiologists may be less familiar with writing these reports. This article addresses the main pathologies encountered in and around the elbow, emphasizing the specific features that need reporting and providing examples of terminology to use when describing these abnormalities.

Ulnar nerve morphology on magnetic resonance imaging predicts nerve recovery after surgery for cubital tunnel syndrome

Magnetic resonance imaging (MRI) can evaluate nerve morphology in cubital tunnel syndrome (CuTS), but its value in predicting surgical outcome is unclear. The purpose of this study was to determine whether ulnar nerve morphology on MRI correlated with outcome after CuTS surgery. We reviewed 40 patients who had preoperative MRI and electrodiagnostic (EDX) examinations for CuTS and outcome evaluation 6 months and 2 years postoperatively. Using MRI, ulnar nerve cross-sectional area (UNCSA), changes in signal intensity, and any space-occupying lesion were evaluated. Other factors assessed were age, symptom duration and severity, type-2 diabetes and EDX parameters. Factors associated with unfavorable surgical outcome were identified. At 6 months postoperatively, 12 patients (30%) had excellent, 19 (47.5%) good, 8 (20%) fair and 1 (2.5%) poor results on modified Wilson-Krout criteria. On univariate analysis, unfavorable outcomes were associated with increased UNCSA, space-occupying lesion, and decreased motor nerve conduction velocity (mNCV), and on multivariate analysis with increased UNCSA 1 cm distal from the epicondyle only (model 1) or increased UNCSA 1 cm proximal from the epicondyle and decreased mNCV (model 2). At 2 years, 15 patients (37.5%) had excellent, 21 (52.5%) good, 3 (7.5%) fair and 1 (2.5%) poor results, and no factors correlated with unfavorable outcome. Increased UNCSA on MRI was associated with unfavorable outcome at 6 months but not at 2 years. This study suggests that morphologic ulnar nerve changes can predict delayed nerve recovery after surgery for CuTS.

Post-Operative Assessment of Ulnar Nerve Tension Using Shear-Wave Elastography

BACKGROUND

Ulnar nerve compression at the elbow level is the second-most common entrapment neuropathy. The aim of this study was to use shear-wave elastography for the quantification of ulnar nerve elasticity in patients after ulnar nerve decompression with anterior transposition and in the contralateral non-operative side.

METHOD

Eleven patients with confirmed diagnosis and ulnar nerve decompression with anterior transposition were included and examinations were performed on an Aixplorer^TM ultrasound system (Supersonic Imagine, Aix-en-Provence, France).

RESULTS

We observed significant differences at 0-degree (p < 0.001), 45-degree (p < 0.05), 90-degree (p < 0.01) and 120-degree (p < 0.001) elbow flexion in the shear elastic modulus of the ulnar nerve in the operative and non-operative sides. There were no statistically significant differences between the elasticity values of the ulnar nerve after transposition at 0-degree elbow flexion and in the non-operative side at 120-degree elbow flexion (p = 0.39), or in the ulnar nerve after transposition at 120-degree elbow flexion and in the non-operative side at 0-degree elbow flexion (p = 0.09).

CONCLUSION

Shear-wave elastography has the potential to be used postoperatively as a method for assessing nerve tension noninvasively by the estimation of mechanical properties, such as the shear elastic modulus.

The ultrasonographic assessment of the morphologic changes in the ulnar nerve at the cubital tunnel in Japanese volunteers: relationship between dynamic ulnar nerve instability and clinical symptoms

Background

We investigated the differences in the prevalence of ulnar nerve instability (UNI) by hand dominance and evaluated the relationship between UNI and morphologic changes in the ulnar nerve and the clinical findings and upper limb function.

Methods

This study examined 153 healthy participants (n = 306 elbows; 44 men, 112 women; mean age 65.4 years) who underwent ultrasonography to assess the ulnar nerve cross-sectional area (UNCSA) at three points of the bilateral cubital tunnel at 30° of elbow flexion. Participants were divided into three groups based on the ultrasonography findings of UNI: no instability (type N), subluxation (type S), and dislocation (type D). For the dominant and nondominant sides, we assessed the relationship between the UNCSA and clinical factors, including the age, gender, height, weight, body mass index, fat mass, grip strength, key pinch strength, UNCSA, and Patient-Rated Elbow Evaluation score.

Results

We identified 75 cases without instability in both elbows and 78 cases with some instability. The prevalence of UNI was 51%. No significant difference was found between hand dominance and the prevalence of UNI. The UNCSA at 1 cm proximal to the medial epicondyle on the bilateral sides in type S was the most increased among three types.

Conclusion

UNI was identified in almost half of the participants, with no marked difference found in the hand dominance. The UNCSA at 1 cm proximal to the medial epicondyle was significantly increased the most in type S. UNI does not appear to be associated with elbow symptoms in the general population.

Comparison of electrodiagnosis, neurosonography and MR neurography in localization of ulnar neuropathy at the elbow

INTRODUCTION

In patients with ulnar neuropathy at the elbow (UNE) the precise determination of the site of lesion is important for subsequent differential diagnostic considerations and therapeutic management. Due to a paucity of comparable data, to better define the role of different diagnostic tests, we performed the first prospective study comparing the diagnostic accuracy of short segment nerve stimulation, nerve ultrasonography, MR neurography (MRN), and diffusion tensor imaging (DTI) in patients with UNE.

METHODS

UNE was clinically diagnosed in 17 patients with 18 affected elbows. For all 18 affected elbows in patients and 20 elbows in 10 healthy volunteers, measurements of all different diagnostic tests were performed at six anatomical positions across the elbow with measuring points from distal (D4) to proximal (P6) in relation to the medial epicondyle (P0). Additional qualitative assessment regarding structural changes of surrounding nerve anatomy was conducted.

RESULTS

The difference between affected arms of patients and healthy control arms were most frequently the largest at measure intervals D2 to P0 and P0 to P2 for electrophysiological testing, or measure points P0 and P2 for all other devices, respectively. At both levels P0 and at P2, T2 contrast-to-noise ratio (CNR) of MRN and mean diffusivity (MD) of DTI-based MRN showed best accuracies.

DISCUSSION

This study revealed differences in diagnostic performance of tests concerning a specific location of UNE, with better results for T2 contrast to noise ratio (CNR) in MRN and mean diffusivity of DTI-based MRN. Additional testing with MRN and nerve ultrasonography is recommended to uncover anatomical changes.

Ultrasound-Assisted Precise In Situ Decompression for Cubital Tunnel Syndrome

Objective

To explore the effect of locating the ulnar nerve compression sites and guiding the small incision so as to decompress the ulnar nerve in situ on the elbow by high‐frequency ultrasound before operation.

Methods

A retrospective analysis was conducted on 56 patients who underwent ultrasound‐assisted in situ decompression for cubital tunnel syndrome from May 2018 to August 2019. The patients' average age was 51.13 ± 7.35 years, mean duration of symptoms was 6.51 ± 1.96 months, and mean postoperative follow‐up was 6.07 ± 0.82 months. Nine patients had Dellon's stage mild, 39 had stage moderate, and eight had stage severe. Ultrasound and electromyography were completed in all patients before operation. The presence of ulnar nerve compressive lesion, the specific location, and the reason and extent of compression were determined by ultrasound. A small incision in situ surgery was given to decompress the ulnar nerve according to the pre‐defined compressive sites.

Results

All patients underwent in situ decompression. The compression sites around the elbow were as follows: two in the arcade of Struthers, one in the medial intermuscular septum, four in the anconeus epitrochlearis muscle, five beside the cyst of the proximal flexor carpi ulnaris (FCU), and the remaining 44 cases were all from the compression between Osborne's ligament to the two heads of the FCU. The compression localizations diagnosed by ultrasound were confirmed by operations. Preoperative ultrasound confirmed no ulnar nerve subluxation in all cases. The postoperative outcomes were satisfactory. There was no recurrence or aggravation of symptoms in this group of patients according to the modified Bishop scoring system; results showed that 43 cases were excellent, 10 were good, and three were fair.

Conclusions

High‐frequency ultrasound can accurately and comprehensively evaluate the ulnar nerve compression and the surrounding tissues, thus providing significant guidance for the precise minimally invasive treatment of ulnar nerve compression.

MRI of the ulnar nerve pre- and post-transposition: imaging features and rater agreement

OBJECTIVE

Determine the rater agreement of MRI features of the ulnar nerve pre- and post-transposition and association with recurrent symptoms.

MATERIALS AND METHODS

This IRB-approved retrospective cohort analysis examined 23 subjects who underwent elbow MRI pre- and post-ulnar nerve transposition from 1999 to 2018, 10 of whom developed recurrent symptoms. Pre- and post-transposition MRIs were evaluated by two blinded radiologists for ulnar nerve cross-sectional area, signal intensity, fascicular architecture, caliber change, and perineural scar. Inter-rater agreement was estimated using intraclass correlation coefficients (ICCs) for continuous variables and Gwet's agreement coefficient (AC) for categorical variables. Binary logistic regression modeling probed associations between imaging markers and symptom recurrence.

RESULTS

The ulnar nerve, post-operatively, demonstrated statistically significant increases in size (p < 0.001), signal intensity (p = 0.021), and abrupt caliber change (p = 0.024). None of the imaging features, except for higher signal intensity of the nerve pre-transposition as demonstrated by one rater, were predictive of symptom recurrence. Inter-rater agreement for cross-sectional area measurements of the ulnar nerve at the cubital tunnel was excellent (ICCs of 0.91 and 0.83). Substantial-to-excellent inter-rater agreement was observed pre-operatively for nerve signal intensity, caliber change, and fascicular architecture. Post-operatively, agreement on nerve signal intensity and perineural scar was excellent (ACs of 0.90 and 0.88), but only slight for caliber change (0.15).

CONCLUSION

Inter-rater agreement for qualitative and quantitative assessment of the ulnar nerve was generally robust. Post-transposition, the ulnar nerve was generally larger and more T2-hyperintense, but MRI features were not predictive of recurrent ulnar neuropathy, except for perhaps the signal intensity of the nerve pre-transposition.

The external elbow measure as surrogate of the anatomical width of cubital groove and possible risk factor of ulnar neuropathy at the elbow

Introduction: There are no studies on elbow anthropometry in ulnar neuropathy at the elbow (UNE). We aimed to test the interrater agreement of external elbow measurements with caliper, the matching of external width of cubital groove (WCG) measures with those obtained through conventional radiography (XR) and ultrasonography (US). The final aim was to evaluate the differences of anthropometric elbow and body measures between UNE cases and controls with multicenter prospective study.Materials and methods: After common training of five observers for external elbow and body anthropometric measurements, we assessed the interrater agreement of measures in a single blind measurement session in 16 healthy volunteers. Then we verified if external WCG measures in eight and four of the above 16 subjects matched with those obtained with US and XR. Finally, we enrolled 40 consecutive idiopathic UNE cases in four electromyographic labs matched for sex and age with 40 controls to evaluate the differences of anthropometric measures.Results: There was high interrater agreement of all anthropometric body and elbow measures (Kendal's and interclass correlation coefficients between 0.84 and >0.9). We found high relations between WCG caliper measures and those obtained with US and XR (r > 0.9). WCG was smaller in cases than in controls (13.2 vs.15.7 mm, p < 0.001). There were no differences in body anthropometric measures (BMI and waist-to-hip ratio).Conclusion: The external measurement of WCG is reliable and reproducible and may be risk factor of UNE. Future studies should be performed in lager samples evaluating the relations with lifestyle and occupational factors.

MR imaging of the postsurgical cubital tunnel: an imaging review of the cubital tunnel, cubital tunnel syndrome, and associated surgical techniques

Ulnar nerve compression at the elbow, specifically the cubital tunnel, is the second most common upper extremity compression neuropathy. Many patients presenting with compression symptoms will subsequently undergo surgical intervention. We review the open surgical treatment of cubital tunnel syndrome and review the expected postoperative imaging appearance of those treatments on magnetic resonance imaging (MR), including: simple or in situ decompression, medial epicondylectomy, and anterior transposition, including subcutaneous, intramuscular, and submuscular variants. We discuss the relevant anatomy of the presurgical cubital tunnel and common sites and causes of ulnar nerve compression at and about the cubital tunnel. The imaging appearance of the preoperative and postoperative ulnar nerve and postoperative complications are reviewed.

Indications for neuromuscular ultrasound: Expert opinion and review of the literature

Over the last two decades, dozens of applications have emerged for ultrasonography in neuromuscular disorders. We wanted to measure its impact on practice in laboratories where the technique is in frequent use. After identifying experts in neuromuscular ultrasound and electrodiagnosis, we assessed their use of ultrasonography for different indications and their expectations for its future evolution. We then identified the earliest papers to provide convincing evidence of the utility of ultrasound for particular indications and analyzed the relationship of their date of publication with expert usage. We found that experts use ultrasonography often for inflammatory, hereditary, traumatic, compressive and neoplastic neuropathies, and somewhat less often for neuronopathies and myopathies. Usage significantly correlated with the timing of key publications in the field. We review these findings and the extensive evidence supporting the value of neuromuscular ultrasound. Advancement of the field of clinical neurophysiology depends on widespread translation of these findings.