Sonographic incidence of ulnar nerve (sub)luxation and its associated clinical and electrodiagnostic characteristics

Round table discussion: the management of idiopathic cubital tunnel syndrome

Idiopathic cubital tunnel syndrome is the second most common neuropathy in the upper limb. Best evidence regarding the surgical management of this condition has evolved from anterior or submuscular transposition as the former reference standard, to in situ simple release. Differences of opinion remain regarding the timing of surgery, type of surgery and adjunctive surgery. Four surgeons with Level 5 expertise were asked to answer specific questions regarding this condition.

Ultrasonographic evaluation of ulnar nerve morphology in patients with ulnar nerve instability

INTRODUCTION/AIMS

Ulnar nerve instability (UNI) in the retroepicondylar groove is described as nerve subluxation or dislocation. In this study, considering that instability may cause chronic ulnar nerve damage by increasing the friction risk, we aimed to examine the effects of UNI on nerve morphology ultrasonographically.

METHODS

Asymptomatic patients with clinical suspicion of UNI were referred for further clinical and ultrasonographic examination. Based on ulnar nerve mobility on ultrasound, the patients were first divided into two groups: stable and unstable. The unstable group was further divided into two subgroups: subluxation and dislocation. The cross-sectional area (CSA) of the nerve was measured in three regions relative to the medial epicondyle (ME).

RESULTS

In the ultrasonographic evaluation, UNI was identified in 59.1% (52) of the 88 elbows. UNI was bilateral in 50% (22) of the 44 patients. Mean CSA was not significantly different between groups. A statistically significant difference in ulnar nerve mobility was found between the group with CSA of <10 versus ≥10 mm2 (p = .027). Nerve instability was found in 85.7% of elbows with an ulnar nerve CSA value of ≥10 mm2 at the ME level.

DISCUSSION

The probability of developing neuropathy in patients with UNI may be higher than in those with normal nerve mobility. Further prospective studies are required to elucidate whether asymptomatic individuals with UNI and increased CSA may be at risk for developing symptomatic ulnar neuropathy at the elbow.

Ulnar neuropathy

Ulnar neuropathy at the elbow is the second most common compressive neuropathy. Less common, although similarly disabling, are ulnar neuropathies above the elbow, at the forearm, and the wrist, which can present with different combinations of intrinsic hand muscle weakness and sensory loss. Electrodiagnostic studies are moderately sensitive in diagnosing ulnar neuropathy, although their ability to localize the site of nerve injury is often limited. Nerve imaging with ultrasound can provide greater localization of ulnar injury and identification of specific anatomical pathology causing nerve entrapment. Specifically, imaging can now reliably distinguish ulnar nerve entrapment under the humero-ulnar arcade (cubital tunnel) from nerve injury at the retro-epicondylar groove. Both these pathologies have historically been diagnosed as either "ulnar neuropathy at the elbow," which is non-specific, or "cubital tunnel syndrome," which is often erroneous. Natural history studies are few and limited, although many cases of mild-moderate ulnar neuropathy at the elbow appear to remit spontaneously. Conservative management, perineural steroid injections, and surgical release have all been studied in treating ulnar neuropathy at the elbow. Despite this, questions remain about the most appropriate management for many patients, which is reflected in the absence of management guidelines.

The role of imaging in focal neuropathies

Electrodiagnostic testing (EDX) has been the diagnostic tool of choice in peripheral nerve disease for many years, but in recent years, peripheral nerve imaging has been used ever more frequently in daily clinical practice. Nerve ultrasound and magnetic resonance (MR) neurography are able to visualize nerve structures reliably. These techniques can aid in localizing nerve pathology and can reveal significant anatomical abnormalities underlying nerve pathology that may have been otherwise undetected by EDX. As such, nerve ultrasound and MR neurography can significantly improve diagnostic accuracy and can have a significant effect on treatment strategy. In this chapter, the basic principles and recent developments of these techniques will be discussed, as well as their potential application in several types of peripheral nerve disease, such as carpal tunnel syndrome (CTS), ulnar neuropathy at the elbow (UNE), radial neuropathy, brachial and lumbosacral plexopathy, neuralgic amyotrophy (NA), fibular, tibial, sciatic, femoral neuropathy, meralgia paresthetica, peripheral nerve trauma, tumors, and inflammatory neuropathies.

Physical Examination Versus Ultrasonography for Detection of Ulnar Nerve Subluxation in Professional Baseball Pitchers

Background

Despite the importance of accurately detecting ulnar nerve subluxation in vulnerable athletes, few studies have compared the performance of physical examination and ultrasound in this population.

Purpose/Hypothesis

The purpose of this study was to compare the diagnostic validity of physical examination versus ultrasound in detecting ulnar nerve subluxation at the cubital tunnel of the elbow in professional baseball pitchers. It was hypothesized that ultrasound would more sensitively detect ulnar nerve subluxation.

Study Design

Cohort study (diagnosis); Level of evidence, 2.

Methods

Physical and sonographic examinations for ulnar nerve subluxation were performed on 186 elbows of 95 consecutive male professional baseball pitchers (age, 17-30 years) as a routine part of their spring training assessments. Provocative maneuvers consisting of the Tinel and elbow flexion-compression tests were evaluated over the cubital tunnel. The validity of physical examination for detecting ulnar nerve subluxation at the elbow was determined using ultrasonographic examination for comparison.

Results

Ulnar nerve subluxation was detected by physical examination in 58 (31.2%) elbows and by ultrasonography in 61 (32.8%) elbows. Of the 58 elbows with positive physical examination, 47 were positive on ultrasound. Using a positive ultrasound as a reference, the accuracy of the physical examination was 86.6%, with 77% sensitivity and 91.2% specificity. The positive and negative predictive values of physical examination were 81% and 89.1%, respectively. There was no relationship between nerve instability and positive provocative tests overall, in dominant versus nondominant arms, or in right versus left arms (P > .05 for all).

Conclusion

Physical examination had moderate sensitivity and high specificity for detecting ulnar nerve subluxation at the cubital tunnel of the elbow when compared with ultrasound. These findings suggest that when detecting the presence of a subluxating ulnar nerve is most important, it may be advisable to obtain an ultrasound evaluation instead of relying on a physical examination; however, physical examination alone may be appropriate for ruling out subluxation.

Hearing and Seeing Nerve/Tendon Snapping: A Systematic Review on Dynamic Ultrasound Examination

Nerve/tendon snapping can occur due to their sudden displacement during the movement of an adjacent joint, and the clinical condition can really be painful. It can actually be challenging to determine the specific anatomic structure causing the snapping in various body regions. In this sense, ultrasound examination, with all its advantages (especially providing dynamic imaging), appears to be quite promising. To date, there are no comprehensive reviews reporting on the use of dynamic ultrasound examination in the diagnosis of nerve/tendon snapping. Accordingly, this article aims to provide a substantial discussion as to how US examination would contribute to 'seeing' and 'hearing' these pathologies' different maneuvers/movements.

In Situ Stabilization of the Ulnar Nerve as an Alternative to Transposition in Traumatic Ulnar Nerve Instability: A Case Report

CASE

We present the case of a 25-year-old male sports climber treated with in situ ulnar nerve stabilization for ulnar nerve instability (UNI) by using 2 fascial flaps.

CONCLUSION

Symptomatic UNI has traditionally been managed with subcutaneous or submuscular ulnar nerve transposition. Transposition is relatively invasive and when performed subcutaneously, embeds the ulnar nerve in an exposed location, which may render it prone to mechanical injury in physically active patients. In situ stabilization may be a less invasive alternative to transposition in select patients involved in sports such as rock climbing.

Diagnostic Considerations in Compressive Neuropathies

Peripheral nerve compression of the upper extremity is a common pathology often necessitating surgical intervention, much is known, but much more is left to understand. For the more common pathologies, carpal tunnel syndrome, cubital tunnel syndrome, and ulnar tunnel syndrome, research and clinical efforts directed toward standardization and reduction of resource use have been attempted with varied success. Diagnosis of many of these syndromes is largely based on a proper history and physical examination. Electrodiagnostic studies continue to have value, but proportionally less than previous decades. In addition, emerging technologies, including magnetic resonance neurography, novel ultrasound evaluation techniques, and ultrasound-guided diagnostic injections, are beginning to demonstrate their ability to add value to the diagnostic algorithm, particularly when less common compressive neuropathies are present and/or the diagnosis is in question.

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.

Sonographic normal values for the cross-sectional area of the ulnar nerve: a systematic review and meta-analysis

PURPOSE

Nerve size is a commonly used sonographic parameter when assessing suspected entrapment of the ulnar nerve. We aimed to create a robust set of normal values, based on a critical review of published normal values.

METHODS

We performed a systematic evaluation of studies on normal ulnar nerve sizes, identified in PubMed, Embase, and Cochrane databases. Using meta-analyses, we determined pooled mean cross-sectional area (CSA) values for different anatomical locations of the ulnar nerve throughout the arm. Subgroup analyses were performed for gender, probe frequency, in- or exclusion of diabetic patients, position of the elbow and Asian versus other populations.

RESULTS

We identified 90 studies of which 77 studies were included for further analyses after quality review, resulting in data from 5772 arms of 3472 participants. Subgroup analyses show lower CSA values at at the wrist crease and proximal to the wrist crease when using low frequency probes (< 15 MHz) and at the wrist crease, proximal to the wrist crease, proximal forearm and the distal upper arm in Asians. CSA values were lower when in flexed position compared to extended position for the cubital tunnel inlet only. No difference was found for gender.

CONCLUSIONS

Our systematic review provides a comprehensive set of normal values at sites along the entire length of the ulnar nerve. This provides a foundation for clinical practise and upon which future studies could be more systematically compared.

Neuromuscular Ultrasound: Indications in the Electrodiagnostic Laboratory

ABSTRACT

Accurate assessment of neuromuscular disorders is critical to facilitate timely treatment and achieve the best outcomes. Historically, electrodiagnostic studies have filled this role, but recently, neuromuscular ultrasound is being used in the electrodiagnostic laboratory. This review discusses the uses of neuromuscular ultrasound in the electrodiagnostic laboratory that have strong evidence, emphasizing those that could be adopted in a typical electrodiagnostic laboratory with a reasonable level of equipment and training. The evidence currently supports using neuromuscular ultrasound to diagnose carpal tunnel syndrome and ulnar neuropathies at the elbow and as a supplementary test when electrodiagnostic studies are suspected to be falsely negative or in axonal nonlocalizing lesions. Neuromuscular ultrasound can identify the causes of focal mononeuropathies, which can change treatment in specific cases. It is sensitive at identifying fasciculations and providing complementary evidence of autoimmune demyelinating polyneuropathies. It is particularly helpful in assessing nerves after trauma. Neuromuscular ultrasound is likely to prove even more useful in the electrodiagnostic laboratory as the technology continues to advance.

Ulnar nerve dislocation in ulnar nerve entrapment at the elbow. Influence on surgical outcome

Our aim was to assess the incidence of symptomatic ulnar nerve dislocation and its influence on surgical outcome after primary and revision surgeries in ulnar nerve entrapment at the elbow (ulnar neuropathy at the elbow (UNE) or cubital tunnel syndrome). The influence of pre- or intra-operative ulnar nerve dislocation on postoperative outcome was assessed in 548 surgically treated cases (548 nerves) from two hand surgery departments reporting to the Swedish National Quality Registry for Hand Surgery, using QuickDASH, a patient-reported outcome measure (PROM), before surgery and at 3 and 12 months postoperatively, and a doctor-reported outcome measure (DROM), grading as "cured-improved "or "unchanged-worsened," at a median follow-up of 3.0 months [IQR, 1.5-6.0]. 109 of the 548 cases (20%) showed documented pre- or intra-operative ulnar nerve dislocation; more often found at revision (35/75, 47%) than at primary surgery (74/473, 16%) (p < 0.0001). Cases with dislocation presented higher QuickDASH scores at 12 months (p = 0.026). A linear regression model, adjusted for age and gender, predicted higher QuickDASH scores at 12 months postoperatively for cases with dislocation (unstandardized B 11.3 [95% CI 0.4-22.2], p = 0.043). DROM grading as unchanged-worsened at a median 3 months predicted worse QuickDASH scores (p < 0.0001) than in cured-improved cases at 3 (unstandardized B, 18.4 [95% CI 9.4-27.3]) and 12 months (unstandardized B, 18.1 [9.1-27.0]). Primary surgeries had better DROM grading than revision surgeries (p = 0.033; cured-improved, 75% and 63%, respectively), but QuickDASH scores did not differ. Presence of a clinically relevant ulnar nerve dislocation resulted in worse outcome, perhaps due to more extensive surgery with transposition. Nerve dislocation needs attention when treating UNE patients.

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.

Review Article "Spotlight on Ultrasonography in the Diagnosis of Peripheral Nerve Disease: The Evidence to Date"

Neuromuscular ultrasound is rapidly becoming incorporated into clinical practice as a standard tool in the assessment of peripheral nerve diseases. Ultrasound complements clinical phenotyping and electrodiagnostic evaluation, providing critical structural anatomical information to enhance diagnosis and identify structural pathology. This review article examines the evidence supporting neuromuscular ultrasound in the diagnosis of compressive mononeuropathies, traumatic nerve injury, generalised peripheral neuropathy and motor neuron disease. Extending the sonographic evaluation of nerves beyond simple morphological measurements has the potential to improve diagnostics in peripheral neuropathy, as well as advancing the understanding of pathological mechanisms, which in turn will promote precise therapies and improve therapeutic outcomes.

Ulnar Nerve Dislocation and Subluxation from the Cubital Tunnel Are Common in College Athletes

Background: Hypermobility of the ulnar nerve from the cubital tunnel reportedly occurs in healthy people without symptoms of ulnar neuropathy. However, the occurrence rate in athletes is unknown. We examined the occurrence rate of ulnar nerve hypermobility using ultrasonography, symptoms, and physical findings in athletes and compared the results of four types of sports. Methods: Medical charts of college athletes competing in baseball, rugby, soccer, and long-distance running between March and November 2018 were retrospectively examined. Dynamic evaluation of the ulnar nerve was performed using ultrasonography and categorized as Types N, S, and D respectively, indicating normal position, subluxation, and dislocation. Subjective and objective findings were evaluated. Results: The present study included 246 male athletes (mean age, 19.7 years; 492 elbows) including 46% Type D, 29.8% Type S, and 24.2% Type N. Subjective findings showed pain and dysesthesia in 9% and 4.5% of participants, respectively, whereas objective findings showed Tinel sign in 6%, nerve tension test in 1.3%, Froment’s sign in 0.5%, and weakness of strength of opponens digiti minimi muscle in 8% of patients with Types D and S. Conclusions: There was a high-frequency hypermobility of the ulnar nerve from the cubital tunnel with or without subjective and objective findings in college athletes.

Ultrasonographic prevalence of ulnar nerve displacement at the elbow in young baseball players

BACKGROUND

Overhead-throwing athletes are at risk of elbow injury because of valgus stress, leading to unstable ulnar nerves and neuropathy. Studies regarding ulnar nerve damage/displacement have been performed primarily in adults.

OBJECTIVE

To determine the prevalence and related factors associated with ulnar nerve displacement at the elbow in young baseball players.

DESIGN

Cross-sectional study.

PARTICIPANTS

Youth baseball players ages 10-12 years were eligible to participate. Exclusion criteria were history of neuropathic pain, trauma, or prior surgery of the upper limb. Fifty-seven participants were eligible for inclusion in the study.

MAIN OUTCOME MEASUREMENTS

Demographic data and ultrasonography findings of ulnar nerve dynamics at the cubital tunnel were analyzed in a total of 114 elbows. Elbows were grouped into nondislocation and displacement (subluxation or dislocation) groups according to ultrasound findings. Logistic generalized estimating equations were used to identify factors associated with ulnar nerve displacement.

RESULTS

Thirty-six (31.6%) elbows demonstrated sonographic findings of ulnar nerve displacement, with 13 (11.4%) subluxations and 23 (20.2%) dislocations. Fourteen (24.6%) participants experienced nerve displacement in the dominant elbow only, whereas nerve displacement in both elbows occurred in 11 (19.3%) participants. Nerve displacement in the nondominant elbow only was not observed. Hand dominance and tenderness of the arcade of Struthers' were factors associated with ulnar nerve displacement (odds ratio, 2.81, and 9.73; 95% confidence interval, 1.34-5.91 and 2.45-38.68; p = .006 and .001, respectively).

CONCLUSION

One-third of the young baseball players evaluated had ultrasonographic findings compatible with ulnar nerve displacement at the elbow. Hand dominance and tenderness of Struthers arcade were the only factors associated with ulnar nerve displacement. Ultrasound may help identify patients with ulnar nerve displacement and contribute to the understanding of its pathophysiology in young baseball players.

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.

Ulnar Neuropathy at the Elbow: From Ultrasound Scanning to Treatment

Ulnar neuropathy at the elbow (UNE) is commonly encountered in clinical practice. It results from either static or dynamic compression of the ulnar nerve. While the retroepicondylar groove and its surrounding structures are quite superficial, the use of ultrasound (US) imaging is associated with the following advantages: (1) an excellent spatial resolution allows a detailed morphological assessment of the ulnar nerve and adjacent structures, (2) dynamic imaging represents the gold standard for assessing the ulnar nerve stability in the retroepicondylar groove during flexion/extension, and (3) US guidance bears the capability of increasing the accuracy and safety of injections. This review aims to illustrate the ulnar nerve's detailed anatomy at the elbow using cadaveric images to understand better both static and dynamic imaging of the ulnar nerve around the elbow. Pathologies covering ulnar nerve instability, idiopathic cubital tunnel syndrome, space-occupying lesions (e.g., ganglion, heterotopic ossification, aberrant veins, and anconeus epitrochlearis muscle) are presented. Additionally, the authors also exemplify the scientific evidence from the literature supporting the proposition that US guidance is beneficial in injection therapy of UNE. The non-surgical management description covers activity modifications, splinting, neuromobilization/gliding exercise, and physical agents. In the operative treatment description, an emphasis is put on two commonly used approaches-in situ decompression and anterior transpositions.

Is There an Association Between Ulnar Nerve Hypermobility and Neuropathy at the Elbow?

OBJECTIVE

To systematically review the association between ulnar nerve hypermobility (UNH) at the elbow and ulnar neuropathy (UNE).

DATA SOURCES

Cumulative Index to Nursing and Allied Health, MEDLINE, and Embase databases were searched for English language studies published up to July 4, 2020.

STUDY SELECTION

We included case-control, cohort, and randomized controlled studies that established the presence or absence of UNH and UNE. Twenty out of 654 studies identified met the inclusion criteria.

DATA EXTRACTION

Two reviewers independently extracted data for analysis. Risk of bias and applicability were assessed with the QUADAS-2 tool.

DATA SYNTHESIS

We compared rates of UNH between patients diagnosed with and without UNE and found no significant difference. The meta-analysis pooled rate of UNH was 0.37 (95% confidence interval, 0.20-0.57) for those without UNE and 0.33 (95% confidence interval, 0.23-0.45) for those with UNE.

CONCLUSIONS

The clinical finding of UNH is unhelpful when assessing for UNE, as the presence of UNH does not make the diagnosis of UNE more likely.

Ulnar nerve subluxation and dislocation: a review of the literature

The pathogenesis of ulnar nerve subluxation and dislocation is widely debated. Upon elbow flexion, the ulnar nerve slips out of the groove for the ulnar nerve, relocates medial or anterior to the medial epicondyle, and returns to its correct anatomical position upon extension. This chronic condition can cause neuritis or neuropathy; however, it has also been suggested that it protects against neuropathy by reducing tension along the nerve. This article reviews the extant literature with the aim of bringing knowledge of the topic into perspective and standardizing terminology.

Ultrasound Measurements and Assessments of the Ulnar Nerve at the Elbow and Cubital Tunnel: A Scoping Review

Ulnar neuropathy at the elbow (UNE) is the second most frequent peripheral nerve entrapment neuropathy in the upper extremity. The diagnosis is determined through a combination of history, physical examination, and electrodiagnostic testing. However, the use of high-resolution sonography is increasing, with sonographic measurements of ulnar nerve dimension established as a reliable diagnostic criterion for UNE. Sonographic imaging can describe anatomical features beyond ulnar nerve size, and therefore additional observations could potentially be used in UNE diagnosis and treatment follow-up. This review was a scoping of the literature on different sonographic measurements and assessments that have been reported to evaluate the ulnar nerve and cubital tunnel. This should provide a guide to scanning protocols for sonographers.

Upper extremity neuropathies

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

Retrospective study on the impact of ulnar nerve dislocation on the pathophysiology of ulnar neuropathy at the elbow

Introduction

High resolution ultrasonography (US) has been used for diagnosis and evaluation of entrapment peripheral neuropathy. Ulnar neuropathy at the elbow (UNE) is the second most common focal entrapment neuropathy. The ulnar nerve tends to move to the anteromedial side and sometimes subluxates or dislocates over the medial epicondyle as the elbow is flexed. Dislocation of the ulnar nerve during elbow flexion may contribute to friction injury. We aimed to investigate the effects which the dislocation of ulnar nerve at the elbow could have on the electrophysiologic pathology of UNE.

Materials

We retrospectively reviewed 71 arms of UNE. The demographic data, electrodiagnosis findings and US findings of ulnar nerve were analyzed. We classified the electrodiagnosis findings of UNE into three pathologic types; demyelinating, sensory axonal loss, and mixed sensorimotor axonal loss. The arms were grouped into non-dislocation, partial dislocation, and complete dislocation groups according to the findings of nerve dislocation in US examination. We compared the electrodiagnosis findings, ulnar nerve cross sectional areas in US and electrodiagnosis pathology types among the groups.

Results

A total of 18 (25.3%) arms showed partial dislocation, and 15 (21.1%) arms showed complete dislocation of ulnar nerve in US. In the comparison of electrodiagnosis findings, the partial and complete dislocation groups showed significantly slower conduction velocities and lower amplitudes than non-dislocation group in motor conduction study. In the sensory conduction study, the conduction velocity was significantly slower in partial dislocation group and the amplitude was significantly lower in complete dislocation group than non-dislocation group. In the comparison of US findings, patients in partial and complete dislocation groups showed significantly larger cross sectional areas of the ulnar nerve. The comparison of electrodiagnosis pathologic types among the groups revealed that there were significantly larger proportions of the axonal loss (sensory axonal loss or mixed sensorimotor axonal loss) in partial and complete dislocation groups than non-dislocation group.

Conclusion

The ulnar nerve dislocation could influence on the more severe damage of the ulnar nerve in patients with UNE. It might be important to evaluate the dislocation of the ulnar nerve using US in diagnosing ulnar neuropathy for predicting the prognosis and determining the treatment direction of UNE.

Ulnar nerve instability in the cubital tunnel of asymptomatic volunteers

PURPOSE

Ulnar nerve instability (UNI) in the cubital tunnel is defined as ulnar nerve subluxation or dislocation. It is a common disorder that may be noted in patients with neuropathy or in the asymptomatic. Our prospective, single-site study utilized high-resolution ultrasonography (US) to evaluate the ulnar nerve for cross-sectional area (CSA) and measures of shear-wave elastography (SWE). Mechanical algometry was obtained from the ulnar nerve in the cubital tunnel to assess pressure pain threshold (PPT).

METHODS

Forty-two asymptomatic subjects (n = 84 elbows) (25 males, 17 females) aged 22-40 were evaluated. Two chiropractic radiologists, both with 4 years of ultrasound experience performed the evaluation. Ulnar nerves in the cubital tunnel were sampled bilaterally in three different elbow positions utilizing US, SWE, and algometry. Descriptive statistics, two-way ANOVA, and rater reliability were utilized for data analysis with p ≤ 0.05.

RESULTS

Fifty-six percent of our subjects demonstrated UNI. There was a significant increase in CSA in subjects with UNI (subluxation: 0.066 mm² ± 0.024, p = 0.027; dislocation: 0.067 mm² ± 0.024, p = 0.003) compared to controls (0.057 mm² ± 0.017) in all three elbow positions. There were no significant group differences in SWE or algometry. Inter- and intra-observer agreements for CSA of the ulnar nerves within the cubital tunnel were assessed using intraclass correlation coefficient (ICC) and demonstrated moderate (ICC 0.54) and excellent (ICC 0.94) reliability.

CONCLUSIONS

Most of the asymptomatic volunteers demonstrated UNI. There was a significant increase in CSA associated with UNI implicating it as a risk factor for ulnar neuropathy in the cubital tunnel. There were no significant changes in ulnar nerve SWE and PPT. Intra-rater agreement was excellent for the CSA assessment of the ulnar nerve in the cubital tunnel. High-resolution US could be utilized to assess UNI and monitor for progression to ulnar neuropathy.

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.

Is triceps hypertrophy associated with ulnar nerve luxation?

INTRODUCTION

The mechanism of ulnar nerve luxation is unclear, but the triceps brachii muscle may be a contributing factor. Therefore, we explored whether hypertrophy of the triceps brachii muscle is more frequently accompanied by nerve luxation.

METHODS

In this investigation we used a cross-sectional design to study a group of amateur bodybuilders (n = 31) in a comparison with a group of age-matched healthy controls (n = 31). Triceps hypertrophy was determined clinically and sonographically. The position of the ulnar nerve in relation to the medial epicondyle was classified according to a graded (0-4) scale.

RESULTS

In full flexion of 62 hypertrophic arms, 22 (35.5%) revealed subluxation and 27 (43.5%) complete luxation. In the controls, 21 (33.9%) demonstrated subluxation and 10 (16.1%) complete luxation.

DISCUSSION

The higher frequency of ulnar nerve luxation in arms with hypertrophic triceps indicates that triceps muscle mass may be a factor contributing to ulnar nerve luxation. Muscle Nerve 58: 523-527, 2018.

Ulnar neuropathy with abnormal non-localizing electrophysiology: Clinical, electrophysiological and ultrasound findings

OBJECTIVE

To systematically study demographic, clinical, electrophysiological and nerve ultrasound characteristics of ulnar neuropathy with abnormal non-localizing electrophysiology (NL-UN) and further define the utility of ultrasound over and above the conventional electro-diagnostic approach.

METHOD

NL-UNs were prospectively identified from 113 consecutive referrals with suspected ulnar neuropathy. All received electro-diagnostic tests and ulnar nerve ultrasound. NL-UN severity was graded using clinical and electrophysiological scales.

RESULTS

In 64 of 113 referrals, an ulnar mono- neuropathy was confirmed by electrophysiology. Sixteen of these 64 (25%) had NL-UN, predominantly males (14 out of 16 patients) with severe or moderate clinical and electrophysiological ratings. Ultrasound showed focal ulnar neuropathy at the elbow in 13 out of 16, and diffuse ulnar nerve abnormality in three, and identified a likely or possible causative mechanism in 11.

CONCLUSION

A significant proportion (a quarter) of ulnar neuropathies with abnormal electrophysiology were NL-UN, of heterogeneous etiology; the majority were males with significant disability and axonal loss. Ultrasound had a significant role in localization and classification that facilitated management.

SIGNIFICANCE

To our knowledge, this is the first systematic prospective study that analyzes the demographic, clinical, electrophysiological and ultrasound characteristics of NL-UN in a routine clinical neurophysiology setting.

Common Entrapment Neuropathies

PURPOSE OF REVIEW

This article addresses relevant peripheral neuroanatomy, clinical presentations, and diagnostic findings in common entrapment neuropathies involving the median, ulnar, radial, and fibular (peroneal) nerves.

RECENT FINDINGS

Entrapment neuropathies are a common issue in general neurology practice. Early diagnosis and effective management of entrapment mononeuropathies are essential in preserving limb function and maintaining patient quality of life. Median neuropathy at the wrist (carpal tunnel syndrome), ulnar neuropathy at the elbow, radial neuropathy at the spiral groove, and fibular neuropathy at the fibular head are among the most frequently encountered entrapment mononeuropathies. Electrodiagnostic studies and peripheral nerve ultrasound are employed to help confirm the clinical diagnosis of nerve compression or entrapment and to provide precise localization for nerve injury. Peripheral nerve ultrasound demonstrates nerve enlargement at or near sites of compression.

SUMMARY

Entrapment neuropathies are commonly encountered in clinical practice. Accurate diagnosis and effective management require knowledge of peripheral neuroanatomy and recognition of key clinical symptoms and findings. Clinical diagnoses may be confirmed by diagnostic testing with electrodiagnostic studies and peripheral nerve ultrasound.

Ultrasonography in Peripheral Nervous System Diagnosis

PURPOSE OF REVIEW

High-resolution ultrasound has made it possible to view most nerves and muscles in real time and to identify pathologic change in size, echo texture, and vascularity. This article focuses on the principles underlying ultrasound imaging and the application of ultrasound imaging to clinical disorders commonly seen in an electrodiagnostic laboratory.

RECENT FINDINGS

Ultrasound is a sensitive and specific tool for evaluating myopathic and neurogenic muscle disease. It provides useful information about muscles difficult to study with other technologies, such as the tongue and diaphragm, and is also helpful in evaluating smaller muscles in the hands or feet where correlation with electrodiagnostic studies is possible. For nerves, the resolution of ultrasound is such that it can sensitively identify focal nerve enlargement, which is accurate in the diagnosis of entrapment neuropathies. Furthermore, it can recognize diffuse or multifocal nerve enlargement seen in hereditary and inflammatory neuropathies.

SUMMARY

Neuromuscular ultrasound is an informative noninvasive tool for evaluating nerve and muscle disease. As the technology continues to advance and becomes widely available, it may become a routine part of residency training, neuromuscular research, and clinical practice.

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.

Medial elbow pain

Medial elbow pain is uncommon when compared with lateral elbow pain.

Medial epicondylitis is an uncommon diagnosis and can be confused with other sources of pain.

Overhead throwers and workers lifting heavy objects are at increased risk of medial elbow pain.

Differential diagnosis includes ulnar nerve disorders, cervical radiculopathy, injured ulnar collateral ligament, altered distal triceps anatomy or joint disorders.

Children with medial elbow pain have to be assessed for ‘Little League elbow’ and fractures of the medial epicondyle following a traumatic event.

This paper is primarily focused on the differential diagnosis of medial elbow pain with basic recommendations on treatment strategies.

Cite this article: EFORT Open Rev 2017;2:362-371. DOI: 10.1302/2058-5241.2.160006

Ultrasonographic and Electrophysiological Evaluation of Ulnar Nerve Instability and Snapping of the Triceps Medial Head in Healthy Subjects

OBJECTIVE

To evaluate the relationship between ulnar nerve instability and snapping of the triceps medial head during elbow flexion.

DESIGNS

Twenty-six healthy individuals were recruited. The primary outcome measures were ultrasonographic and electrophysiological parameters of the ulnar nerve. Ulnar nerve instability was classified into three types based on the degree of ulnar nerve movement: no dislocation (Type N), subluxation (Type S), and dislocation (Type D).

RESULTS

In the elbow 90-degree position, the incidences of Type N, S, and D were 41 (78.8%), 8 (15.4%), and 3 (5.8%) elbows, respectively; in the full flexion position, the incidences of Types N, S, and D were 24 (46.2%), 19 (36.5%), and 9 (17.3%) elbows, respectively. Spearman's correlation coefficients between ulnar nerve instability and snapping of the triceps medial head in the elbow 90-degree and full flexion positions were 0.808 and 0.889 (P < 0.001), respectively. The ulnar sensory response in Type S was of prolonged latency and decreased amplitude compared with that in Type N or D in the elbow full flexion position.

CONCLUSIONS

Ulnar nerve instability increased with elbow flexion and correlated with snapping of the triceps medial head. Ultrasonography of the ulnar nerve is an important tool in ulnar nerve instability assessment.

Tips to avoid nerve injury in elbow arthroscopy

Elbow arthroscopy is a technical challenging surgical procedure because of close proximity of neurovascular structures and the limited articular working space. With the rising number of elbow arthroscopies being performed nowadays due to an increasing number of surgeons performing this procedure and a broader range of indications, a rise in complications is foreseen. With this editorial we hope to create awareness of possible complications of elbow arthroscopy, particularly nerve injuries, and provide a guideline to avoid complications during elbow arthroscopy.

Ultrasonography Detects Ulnar Nerve Dislocation Despite Normal Electrophysiology and Magnetic Resonance Imaging

BACKGROUND

Dislocation of the ulnar nerve (UN) occurs in a subset of patients with ulnar neuropathy. Electrodiagnostic and magnetic resonance imaging (MRI) studies are performed to support the clinical diagnosis. We report the case of a patient with ulnar neuropathy with normal electrodiagnostic and MRI studies but with ultrasonography (US) showing UN dislocation, which prompted successful treatment by UN submuscular transposition.

CASE DESCRIPTION

A healthy 15-year-old female softball player presented with right medial elbow pain and paresthesias of the fourth and fifth digits. She had 4+/5 strength in the right hand intrinsic muscles and a Tinel sign at the right elbow. A snap was palpated at the elbow upon flexion. MRI showed mild common flexor tendonitis, and electrodiagnostic studies showed normal motor responses and no conduction block at the elbow. High-resolution US showed dislocation of the UN over the medial epicondyle. UN dislocation was confirmed intraoperatively, and, after UN submuscular transposition, the patient reported complete resolution of her preoperative symptoms at 6-week follow-up and continued resolution at 1 year.

CONCLUSIONS

Normal findings on electrodiagnostic or MRI studies should not immediately dissuade surgeons from operating on a symptomatic patient with a clinical examination supporting ulnar neuropathy and with US evidence of UN dislocation, because such a patient may experience postoperative symptom relief. Furthermore, the dynamic capability of US imaging complements data obtained from electrodiagnostic and MRI studies, especially when these tests are normal, and it should be considered by clinicians when evaluating patients with medial elbow pain or signs of ulnar neuropathy.

The Ulnar Nerve at Elbow Extension and Flexion: Assessment of Position and Signal Intensity on MR Images

Purpose To assess the position and signal intensity of the ulnar nerve at elbow extension and flexion by using magnetic resonance imaging. Materials and Methods Institutional review board approval and written informed consent were obtained. Transverse T2-weighted images were obtained perpendicular to the upper arm in 100 healthy elbows of 50 volunteers (23 men, 27 women; age range, 21-57 years) and nine elbows with ulnar neuropathy (five men, four women; age range, 24-59 years) with extension and 130° of flexion. Ulnar nerve position was classified into three types: no dislocation, subluxation, or dislocation. One-way analysis of variance, paired t tests, Student t tests, and multiple regression analysis were used to analyze correlations between ulnar nerve movement angle during flexion and age, sex, presence of the anconeus epitrochlearis muscle, and ulnar neuropathy and to compare the contrast-to-noise ratio of nerve to muscle between extension and flexion. Results Nerve positions in healthy elbows were as follows: All had no dislocation at extension, and at flexion, 51 of 100 elbows (51.0%) had no dislocation, 30 of 100 elbows (30.0%) had subluxation, and 19 of 100 elbows (19.0%) had dislocation. Nerve movement angle was smaller in elbows with the anconeus epitrochlearis muscle than in those without the muscle (P = .045, .015). Presence of the muscle was the only significant factor associated with nerve movement angle (P = .047, .013). Only dominant elbows with nerve movement angle of less than 15° and nondominant elbows with nerve movement angle of less than 10° showed contrast-to-noise ratio increase at flexion (P = .021-.030). Conclusion Ulnar nerve movement during flexion was apparent in approximately half of healthy elbows and was similar between healthy elbows and elbows with ulnar neuropathy. Nerve signal intensity increased during flexion only in elbows without apparent nerve movement. (©) RSNA, 2016 Online supplemental material is available for this article.

Entrapment and traumatic neuropathies of the elbow and hand: An imaging approach

Ultrasound and magnetic resonance imaging currently offer a detailed analysis of the peripheral nerves. Compressive and traumatic nerve injuries are the two main indications for imaging investigation of nerves with several publications describing the indications, technique and diagnostic capabilities of imaging signs. Investigation of entrapment neuropathies has three main goals, which are to confirm neuronal distress, search for the cause of nerve compression and exclude a differential diagnosis on the entire nerve. For traumatic nerve injuries, imaging, predominantly ultrasound, occasionally provides essential information for management including the type of nerve lesion, its exact site and local extension.

What causes ulnar neuropathy at the elbow?

OBJECTIVE

To determine what causes ulnar neuropathy at the elbow (UNE) by analyzing patients' clinical, electrodiagnostic (EDx) and ultrasonographic (US) findings.

METHODS

In prospectively recruited patients with definite UNE, four blinded examiners took a history and performed neurologic, EDx and US examinations. A multivariate logistic regression model was used to investigate the association between UNE location and patient variables.

RESULTS

We included 117 patients; 73% with lesions in the retroepicondylar (RTC) groove and 27% under the humeroulnar aponeurotic arcade (HUA). In our multivariate model, hard manual labor (OR=152; 95% CI 12-1847; p<0.001), dominant arm involvement (OR=4.12; 95% CI 1.01-16.72; p=0.048), and age (OR=1.10; 95% CI 1.03-1.18; p=0.004) were predictive of ulnar neuropathy at HUA.

CONCLUSION

Our data suggest that UNE at HUA is related to years of hard labor affecting mainly dominant hands, and is caused by work-related changes in the HUA. By contrast, UNE in the RTC groove affects mainly the non-dominant arms of younger administrative workers and is caused by external compression of the ulnar nerve.

SIGNIFICANCE

We believe that our findings will help to improve the diagnosis and treatment of UNE patients, hopefully leading to improved clinical outcomes.

Nerve Ultrasound in Peripheral Neuropathies: A Review

Peripheral neuropathies are one of the most common reasons for seeking neurological care in everyday practice. Electrophysiological studies remain fundamental for the diagnosis and etiological classification of peripheral nerve impairment. The recent technological development though of high resolution ultrasound has allowed the clinician to obtain detailed structural images of peripheral nerves. Nerve ultrasound mainly focuses on the evaluation of the cross sectional area, cross sectional area variability along the anatomical course, echogenity, vascularity and mobility of the peripheral nerves. An increase of the cross sectional area, hypervascularity, disturbed fascicular echostructure and reduced nerve mobility are some of the most common findings of entrapments neuropathies, such as the carpal or cubital tunnel syndrome. Both the cross-sectional area increase and the hypervascularity detected with the Doppler technique seem to correlate significantly with the clinical and electrophysiological severity of the later mononeuropathies. Significantly greater cross sectional area values of the clinically affected cervical nerve root are often detected in cases of cervical radiculopathy. In such cases, the ultrasound findings seem also to correlate significantly with disease duration. On the other hand, multifocal cross sectional area enlargement of cervical roots and/or peripheral nerves is often documented in cases of immune-mediated neuropathies. None of the later pathological ultrasound findings seem to correlate significantly with the electrophysiological parameters or the functional disability. The aim of this review is to provide a timely update on the role of neuromuscular ultrasound in the diagnostic of the most common entrapment and immune-mediated peripheral neuropathies in clinical practice.