Sonographic appearances of the normal ulnar nerve in the cubital tunnel

Ultra high-frequency ultrasound of fascicles in the ulnar and radial nerves

INTRODUCTION/AIMS

Ultra high-frequency ultrasound (UHFUS) has been demonstrated to allow easy visualization and quantification of median and digital nerve fascicles; however, there is a lack of normative data for other upper limb nerves. The purpose of this study was to use UHFUS to establish normative reference values and ranges for fascicle count and density within selected upper extremity nerves.

METHODS

Twenty-one healthy volunteers underwent sonographic examination of the ulnar, superficial branch of the radial, and radial nerves on one upper limb using UHFUS with a 48 MHz linear transducer. The number of fascicles in each peripheral nerve and fascicle density were assessed.

RESULTS

The mean fascicle number and fascicle density for each of the measured nerves was ulnar nerve at the wrist 11.7 and 2.0, ulnar nerve at the elbow 9.2 and 1.1, superficial branch of the radial nerve 7.3 and 2.5, and radial nerve at the spiral groove 4.2 and 0.8. A single significant association was observed between CSA and fascicle number in the ulnar nerve at the wrist (p = .023, r = 0.66). Neither fascicle number nor density could be predicted by age, sex, height, weight, or body mass index.

DISCUSSION

UHFUS may help to establish a baseline of normative data on upper limb nerves that are not frequently biopsied due to their mixed motor and sensory functions and has the potential for increased understanding of nerve fascicular anatomy to improve diagnostic accuracy of focal nerve lesions, particularly those with selective fascicular involvement.

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.

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.

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

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

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.

Dynamic analysis of the ulnar nerve and cubital tunnel morphology using ultrasonography: a cadaveric study

BACKGROUND

The causes of ulnar neuropathy at the elbow are unclear. The authors hypothesized that the humeral trochlea protrudes into the cubital tunnel during elbow flexion and causes a dynamic morphologic change of the ulnar nerve in the cubital tunnel.

METHODS

An ultrasonic probe was fixed to the ulnar shafts of 10 fresh cadavers with an external fixator, and dynamic morphology of the cubital tunnel and ulnar nerve was observed. The distance from the Osborne band to the trochlea (OTD), distance from ulnar nerve center to the trochlea (UTD), and the short- and long-axis diameters of the nerve at 30°, 60°, 90°, and 120° of elbow flexion were recorded. We compared the OTD, UTD, and the flattening of the ulnar nerve at the different angles of flexion using single-factor analysis of variance. Correlation between the ulnar nerve flattering, OTD, and UTD was examined using Spearman correlation coefficient. A P value less than .05 was used to denote statistical significance.

RESULTS

Flattening of the ulnar nerve progressed with increasing elbow flexion and was significantly different between 0° and 60°, 90°, and 120° (P = .03 at 60°, P < .01 at 90° and 120°). OTD decreased with elbow flexion, and there was a significant difference at all elbow flexion angles (all P < .01). UTD decreased significantly from 0° flexion to 90° flexion (P = .03). Flattening of the nerve was significantly correlated with the OTD (r = 0.66, P < .01).

CONCLUSIONS

A positive correlation was found between the protrusion of the humeral trochlea into the cubital tunnel during elbow flexion and ulnar nerve flattening using cadaveric elbow and ultrasonography.

Role of dynamic ultrasound in assessment of the snapping elbow and distal biceps tendon injury

Introduction

Ultrasound is useful in assessing patients with snapping syndromes around the elbow joint. The dynamic nature of the examination allows for direct visualisation of the underlying causative factor.Topic description: We discuss the role of dynamic ultrasound in assessing various snapping syndromes around the elbow, such as ulnar nerve instability, snapping triceps and less commonly, snapping brachialis. Ultrasound is also useful in evaluating the distal biceps tendon, particularly in differentiating partial from complete tendon injury.

Discussion

Ulnar nerve instability and snapping triceps can be assessed via a medial approach with the transducer placed transversely between the medial epicondyle and the olecranon. In ulnar nerve instability, the nerve can be seen crossing over the medial epicondyle on elbow flexion. In snapping triceps syndrome, both the ulnar nerve and the distal triceps can be seen dislocating over the medial epicondyle. Dynamic assessment of the distal biceps tendon using a lateral approach minimises anisotropy artefact often seen on the anterior approach. Passive pronation and supination of the forearm will reveal little or no movement in a completely torn tendon whereas moving tendon fibres will be appreciated in partial tears. In a snapping brachialis, the medial portion of brachialis will be seen abnormally translocating anterolateral to the medial border of the trochlea during elbow flexion and snapping back into its normal position on elbow extension.

Conclusion

Dynamic ultrasound of the elbow is valuable in diagnosing patients with snapping sensations around the joint and in evaluating the integrity of the distal biceps tendon.

Mass effect of the distal triceps brachii muscle on ulnar nerve movement during elbow flexion

INTRODUCTION/AIMS

Hypertrophic triceps brachii contributes to ulnar nerve movement, but the location of the mass effect of the triceps brachii muscle is not known This study aimed to investigate mass effect of distal medial head of the triceps brachii (DMTB) muscle on ulnar nerve movement.

METHODS

In 48 arms, the movement of the ulnar nerve at the medial epicondyle and muscle thickness (the medial and long head of the triceps brachii [MLTB], medial head of the triceps brachii [MTB], DMTB, and the biceps brachii [BB]) were measured using ultrasonography.

RESULTS

Ulnar nerve movement at the elbow was consistently correlated with the DMTB muscle thickness (horizontal ulnar nerve movement at the elbow [HM]/vertical ulnar nerve movement at the elbow [VM] with 90-degree elbow flexion: r=0.668/r=0.313, HM/VM with full elbow flexion: r=0.481/r=0.391). With multiple linear regression, the DMTB was the most important muscle with regard to the contribution of thickness to ulnar nerve movement. Individuals with partial and complete dislocation showed a thicker DMTB than those without dislocation.

DISCUSSION

Our data suggest that the mass effect of the triceps brachii muscle is exerted primarily by its distal portion. When ulnar nerve dislocation is observed, thickness and anatomical variation of DMTB in the retrocondylar area during elbow flexion should be assessed.

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.

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.

Ultrasonography evaluation of the normal ulnar nerve in adult: Comparison of the cross-sectional area at elbow extension and flexion

Background

Cross-sectional area (CSA) measurement of the ulnar nerve in the adult population by using ultrasonography (US) at elbow extension and flexion has previously been reported, but not much evidence showed a significant difference between elbow extension and flexion position.

Purpose

To compare the ulnar nerve CSA between elbow extension and flexion position.

Methods

A comparative cross-sectional study was conducted by involving 36 healthy adults with normally functioning ulnar nerve proven by Nerve Conduction Study (NCS) or Electroneurography. The ulnar nerve CSA was measured on each elbow by using US at the level of the medial epicondyle, 2 cm distal and 2 cm proximal from the medial epicondyle.

Results

The average ulnar nerve CSA at the medial epicondyle, 2 cm distal and proximal to the medial epicondyle at elbow extension respectively were 5.95 ± 0.74 mm2, 6.27 ± 0.92 mm2, and 5.92 ± 0.73 mm2. At elbow flexion, the average ulnar nerve CSA at the positions was 5.70 ± 0.83 mm2, 5.23 ± 0.87 mm2, dan 5.73 ± 0.71 mm2 respectively. The CSA of the ulnar nerve at elbow extension was significantly larger compared to the flexion position in the three areas observed in this study (p < 0.001).

Conclusion

The CSA of the ulnar nerve at elbow extension position was larger compared to the flexion position. Elbow position should be considered in measuring CSA of the ulnar nerve.

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.

The impact of pre-existing ulnar nerve instability on the surgical treatment of cubital tunnel syndrome: a systematic review

BACKGROUND

The decision to perform nerve transposition (NT) or in situ decompression (SD) during surgical treatment of cubital tunnel syndrome is often based on nerve subluxation through elbow motion. This review assesses what impact nerve instability has on study design and reported outcomes.

METHODS

A search was performed with Boolean operators: "ulnar nerve" OR "cubital tunnel" AND "decompression" OR "transposition" on PubMed, Clinical Key, and CINAHL to identify primary studies comparing NT and SD that report pre-existing nerve instability. Primary outcome was the effect of instability on study design. Secondary outcomes were nerve instability, patient-reported scores, and complications.

RESULTS

Five studies met criteria after screening 134 articles. In 3 studies, nerve instability dictated treatment. Prospective randomization was maintained in 1 study. Included cases totaled 464 SD and 304 NT. The complication rate was 8.6% overall, 4.3% for SD and 21.1% for NT. Bishop scores were 56.9% excellent and 37.3% good for stable nerves and 62.0% excellent and 29.3% good for unstable nerves.

CONCLUSIONS

Very few studies report ulnar nerve instability, and study design is biased by ulnar nerve subluxation. Outcomes showed similar symptomatic improvement for both decompressed and transposed groups with higher complication rates for the transposed group.

Current and future applications of ultrasound imaging in peripheral nerve disorders

Neuromuscular ultrasound (NMUS) is a rapidly evolving technique used in neuromuscular medicine to provide complimentary information to standard electrodiagnostic studies. NMUS provides a dynamic, real time assessment of anatomy which can alter both diagnostic and management pathways in peripheral nerve disorders. This review describes the current and future techniques used in NMUS and details the applications and developments in the diagnosis and monitoring of compressive, hereditary, immune-mediated and axonal peripheral nerve disorders, and motor neuron diseases. Technological advances have allowed the increased utilisation of ultrasound for management of peripheral nerve disorders; however, several practical considerations need to be taken into account to facilitate the widespread uptake of this technique.

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.

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.

Decision-Making Factors for Ulnar Nerve Transposition in Cubital Tunnel Surgery

Background  We designed a survey to ascertain the current perspectives of hand surgeons on the evaluation and management of ulnar nerve instability at the elbow. The secondary aim was to assess the concordance of hand surgeons on definitions of the terms "subluxated" and "dislocated" for classification of ulnar nerve instability. Methods  A questionnaire, including demographic practice variables, cubital tunnel practice patterns, preoperative imaging and electrodiagnostic evaluation, and a series of standardized intraoperative photographs of ulnar nerve instability at the elbow were developed and distributed to the current American Society for Surgery of the Hand (ASSH) membership. Results  A total of 690 (26.8%) members completed the survey; 84.2% of respondents indicated that they evaluate for ulnar nerve instability preoperatively with clinical examination, whereas only 6.1% indicated they routinely obtained dynamic ultrasound. Respondents indicated that the factors most strongly influencing their decision to proceed with anterior transposition of the ulnar nerve were subluxation on physical examination (89.6%), history consistent with ulnar nerve subluxation (85.8%), and muscle atrophy (43.2%). On review of clinical photographs, respondents demonstrated varying degrees of agreement on the terms "subluxated" or "dislocated" and recommendations for ulnar nerve transposition at intermediate degrees of ulnar nerve instability. Conclusion  ASSH members routinely evaluate for ulnar nerve instability with history and clinical examination without uniform use of preoperative ultrasound, and nearly half of the time the decision to transpose the ulnar nerve is made intraoperatively. Definitions for the degree of ulnar nerve instability at the elbow are not uniformly agreed upon, and further development of a classification system may be warranted to standardize treatment.

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.

Estimation of ultrasound reference values for the ulnar nerve fascicular number and cross-sectional area in young males: A cross-sectional study

The objective of this study is to estimate the reference values for the number of fascicles and cross-sectional area (CSA) of the ulnar nerve at a single predetermined site by ultrasound in healthy young adult males.The demographic and physical characteristics of 50 adult male volunteers were evaluated and recorded. The subjects were positioned supine with the elbow flexed at 90° and the palm of the hand placed on a hard surface. The ulnar nerve was scanned bilaterally 1 cm proximal to the medial epicondyle in projection of the cubital tunnel. The number of fascicles and mean CSA of the ulnar nerve were identified. In addition, the side-to-side differences of the estimated reference values and their correlations with the age, weight, height, and body mass index (BMI) were evaluated.The mean fascicular number was 5.66 ± 1.48, the mean ultrasound-estimated CSA of the ulnar nerve was 6.54 ± 1.67 mm and both sides were comparable in the mean CSA and fascicular number (6.43 ± 1.80 mm and 5.88 vs 6.64 ± 1.55 mm and 5.44, for right and left side, respectively). No significant correlations were observed between CSA and fascicles number and age, weight, height, or BMI of study subjects.The reference values for the number of fascicles number and the CSA of the ulnar nerve at a single predetermined site were identified. These values could be used for the sonographic diagnosis and follow-up of the ulnar nerve lesions.

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.

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

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

LEVEL OF EVIDENCE

IV.

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.

Peripheral nerve imaging

Disorders of peripheral nerve have been traditionally diagnosed and monitored using clinical and electrodiagnostic approaches. The last two decades have seen rapid development of both magnetic resonance imaging (MRI) and ultrasound imaging of peripheral nerve, such that these imaging modalities are increasingly invaluable to the diagnosis of patients with peripheral nerve disorders. Peripheral nerve imaging provides information which is supplementary to clinical and electrodiagnostic diagnosis. Both MRI and ultrasound have particular benefits in specific clinical circumstances and can be considered as complementary techniques. These technologic developments in peripheral nerve imaging will usher in an era of multimodality assessment of peripheral nerve disorders, with clinical evaluations supported by anatomic information from imaging, and functional information from electrodiagnostic studies. Such a multimodality approach will improve the accuracy and efficiency of patient care.

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.

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.

Optimal Elbow Angle for Sonographic Visualization of the Ulnar Collateral Ligament

OBJECTIVE

To formally examine the sonographic appearance of the elbow ulnar collateral ligament (UCL) at 30° versus 70° of elbow flexion in asymptomatic baseball pitchers.

DESIGN

A prospective, cross-sectional design.

SETTING

Sports medicine clinic in a tertiary academic medical center.

PARTICIPANTS

Thirty asymptomatic adolescent baseball pitchers 13-18 years of age (mean 15.8 years), with at least 3 years of continuous pitching experience and no significant history of elbow pain or injury.

METHODS

Static sonographic images of the bilateral UCLs were obtained at 30° and 70° of elbow flexion by a single experienced examiner. Images were anonymized and randomized into a slide set. Three clinicians with different levels of ultrasound experience reviewed the static 30° and 70° images for each elbow and chose their preferred image based on UCL conspicuity. The clinicians reviewed a re-randomized slide set 1 week later. A different study co-investigator measured UCL cross-sectional area (CSA) on all images using ultrasound machine electronic calipers.

MAIN OUTCOME MEASURES

Preference for the sonographic conspicuity of the UCL at 30° versus 70° of elbow flexion, and UCL CSA at 30° versus 70° of flexion.

RESULTS

Each clinician demonstrated a significant preference for UCL images obtained at 70° of flexion when compared to those obtained at 30° (80.3% overall preference for 70°, P < .001). There was no statistically significant effect of clinician experience or arm dominance on image preference. The sonographically determined CSA of the UCLs were on average 1.4 mm(2) greater at 70° than at 30° of flexion (P < .001) when combining dominant and nondominant arms.

CONCLUSIONS

Static sonographic evaluation of the UCL at 70° of elbow flexion should be integrated into UCL imaging protocols. Furthermore, when performing sonographically guided procedures targeting the UCL, clinicians should consider positioning the elbow at >30° of flexion to optimize UCL conspicuity and CSA.

Ultrasonography for nerve compression syndromes of the upper extremity

Nerve compression syndromes commonly involve the nerves in the upper extremity. High-resolution ultrasonography (US) can satisfactorily assess these nerves and may detect the morphological changes of the nerves. US can also reveal the causes of nerve compression when structural abnormalities or space-occupying lesions are present. The most common US finding of compression neuropathy is nerve swelling proximal to the compression site. This article reviews the normal anatomic location and US appearances of the median, ulnar, and radial nerves. Common nerve compression syndromes in the upper extremity and their US findings are also reviewed.

The Snapping Elbow Syndrome as a Reason for Chronic Elbow Neuralgia in a Tennis Player - MR, US and Sonoelastography Evaluation

Background

Ulnar neuropathy is the second most common peripheral nerve neuropathy after median neuropathy, with an incidence of 25 cases per 100 000 men and 19 cases per 100 000 women each year. Skipping (snapping) elbow syndrome is an uncommon cause of pain in the posterior-medial elbow area, sometimes complicated by injury of the ulnar nerve. One of the reason is the dislocation of the abnormal insertion of the medial triceps head over the medial epicondyle during flexion and extension movements. Others are: lack of the Osboune fascia leading to ulnar nerve instability and focal soft tissue tumors (fibromas, lipomas, etc). Recurrent subluxation of the nerve at the elbow results in a tractional and frictional neuritis with classical symptoms of peripheral neuralgia. As far as we know snapping triceps syndrome had never been evaluated in sonoelastography.

Case Report

A 28yo semi-professional left handed tennis player was complaining about pain in posterior-medial elbow area. Initial US examination suggest golfers elbow syndrome which occurs quite commonly and has a prevalence of 0.3–0.6% in males and 0–3–1.1% in women and may be associated (approx. 50% of cases) with ulnar neuropathy. However subsequently made MRI revealed unusual distal triceps anatomy, moderate ulnar nerve swelling and lack of medial epicondylitis symptoms. Followed (second) US examination and sonoelastography have detected slipping of the both ulnar nerve and the additional band of the medial triceps head.

Discussion

Snapping elbow syndrome is a poorly known medical condition, sometimes misdiagnosed as the medial epicondylitis. It describes a broad range of pathologies and anatomical abnormalities. One of the most often reasons is the slipping of the ulnar nerve as the result of the Osborne fascia/anconeus epitrochlearis muscle absence. Simultaneously presence of two or more “snapping reasons” is rare but should be always taken under consideration.

Conclusions

There are no sonoelastography studies describing golfers elbow syndrome, additional triceps band and ulnar neuritis. Our data suggest that the sonoelastography signs are similar to those seen in well described lateral epicondylitis syndrome, Achilles tendinitis and medial nerve neuralgia.

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.

The association between cubital tunnel morphology and ulnar neuropathy in patients with elbow osteoarthritis

BACKGROUND

Morphologic changes in the cubital tunnel during elbow motion in patients with elbow osteoarthritis have not been examined in vivo. We examined changes in cubital tunnel morphology during elbow motion and characteristics of medial osteophyte development to elucidate whether cubital tunnel area and medial osteophyte size are factors contributing to cubital tunnel syndrome in patients with elbow osteoarthritis.

METHODS

We performed computed tomography of 13 primary osteoarthritic elbows in patients with cubital tunnel syndrome (group A) and 25 primary osteoarthritic elbows in patients without cubital tunnel syndrome (group B) at full extension, 90° of flexion, and full flexion. Cubital tunnel area, humeral and ulnar osteophyte area, and proportion of osteophytes within the cubital tunnel were analyzed at each position.

RESULTS

Humeral osteophytes and osteophyte proportion within the cubital tunnel were larger at full flexion (24.7 mm(2) and 49.9% in group A; 18.7 mm(2) and 39% in group B) and 90° of elbow flexion (20.3 mm(2) and 45.3% in group A; 10.2 mm(2) and 30.2% in group B) than at full extension (9.0 mm(2) and 31.3% in group A; 2.3 mm(2) and 12.5% in group B). These parameters were significantly greater in group A than in group B at full extension and 90° of flexion.

CONCLUSIONS

The effect of medial osteophytes on the ulnar nerve, especially on the humeral side, rather than narrowing of the cubital tunnel, may be a causative factor for cubital tunnel syndrome with elbow osteoarthritis.

Dynamic analysis of the ulnar nerve in the cubital tunnel using ultrasonography

BACKGROUND

We investigated the dynamics of the ulnar nerve during elbow flexion and the relationships between these dynamics and the morphology of the ulnar nerve groove in healthy individuals.

MATERIALS AND METHODS

Twenty healthy volunteers (40 elbows) underwent ultrasonographic examination of the ulnar nerve at the elbow. We measured the breadth and depth of the ulnar nerve groove at 90° of elbow flexion and calculated the depth-to-breadth ratio. We recorded the distance from the trochlea of the humerus to the nerve and the short-axis diameter of the nerve at 30°, 60°, 90°, and 120° of elbow flexion. We calculated the medial shift and flattening of the ulnar nerve at each angle relative to 30° of flexion, compared the values among the different angles, and compared the depth-to-breadth ratio with the location, medial shift, and flattening ratio of the ulnar nerve.

RESULTS

The medial shift was significantly greater at 120° than at other angles (P < .001). Flattening increased with increasing elbow flexion and was significantly different at 60°, 90°, and 120° (all P < .001). The flattening ratios were significantly correlated with the depth-to-breadth ratio at 120° (r = -0.43, P = .005).

CONCLUSIONS

The ulnar nerve moves medially and is flattened with the elbow flexed between 90° and 120°. When the ulnar nerve groove is shallow, high degrees of elbow flexion result in flattening of the ulnar nerve in the groove.

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.

Sonographic measurements of the ulnar nerve at the elbow with different degrees of elbow flexion

OBJECTIVE

To determine whether there were differences in the cross-sectional area (CSA) and the flattening ratio of the normative ulnar nerve as it passes between the medial epicondyle and the olecranon at 30° of elbow flexion versus 90° of elbow flexion.

DESIGN

Bilateral upper extremities of normal healthy adult volunteers were evaluated with ultrasound. The CSA and the flattening ratio of the ulnar nerve at the elbow as it passes between the medial epicondyle and the olecranon were measured, with the elbow flexed at 30° and at 90°, by 2 operators with varying ultrasound scanning experience by using ellipse and direct tracing methods. The results from the 2 different angles of elbow flexion were compared for each individual operator. Finally, intraclass correlations for absolute agreement and consistency between the 2 raters were calculated.

SETTING

An outpatient clinic room at a regional rehabilitation center.

PARTICIPANTS

Twenty-five normal healthy adult volunteers.

MAIN OUTCOME MEASUREMENT

The mean CSA and the mean flattening ratio of the ulnar nerve at 30° of elbow flexion and at 90° of elbow flexion.

RESULTS

First, for the ellipse method, the mean CSA of the ulnar nerve at 90° (9.93 mm(2)) was slightly larger than at 30° (9.77 mm(2)) for rater 1. However, for rater 2, the mean CSA of the ulnar nerve at 90° (6.80 mm(2)) was slightly smaller than at 30° (7.08 mm(2)). This was found to be statistically insignificant when using a matched pairs t test and the Wilcoxon signed-rank test, with a significance level of .05. Similarly, the difference between the right side and the left side was not statistically significant. The intraclass correlations for absolute agreement between the 2 raters were not very high due to different measurement locations, but the intraclass correlations for consistency were high. Second, for the direct tracing method, the mean CSA at 90° (7.26 mm(2)) was slightly lower than at 30° (7.48 mm(2)). This was found to be statistically nonsignificant when using the matched pairs t test and the Wilcoxon signed-rank test with a significance level of .05. There was no significant difference in the average flattening ratio between the 2 angles for the left arm (0.54 at 30° vs 0.56 at 90°; P = .619 for the matched pairs t test and .274 for the Wilcoxon signed-rank test). However, for the right arm, the flattening ratio at 90° was significantly higher than that at 30° (0.58 at 90° vs 0.50 at 30°; P = .007 for both the matched pairs t test and the Wilcoxon signed-rank test).

CONCLUSIONS

The mean CSA of the ulnar nerve at the elbow at 30° was not significantly different than at 90°. However, the average flattening ratio at 90° was found to be significantly higher than at 30° for the right arm.

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.

Neuromuscular ultrasound in common entrapment neuropathies

Neuromuscular ultrasound involves the use of high-resolution ultrasound to image the peripheral nervous system of patients with suspected neuromuscular diseases. It complements electrodiagnostic studies well by providing anatomic information regarding nerves, muscles, vessels, tendons, ligaments, bones, and other structures that cannot be obtained with nerve conduction studies and electromyography. Neuromuscular ultrasound has been studied extensively over the past 10 years and has been used most often in the assessment of entrapment neuropathies. This review focuses on the use of neuromuscular ultrasound in 4 of the most common entrapment neuropathies: carpal tunnel syndrome, ulnar neuropathy at the elbow and wrist, and fibular neuropathy at the knee.

Ultrasonography of peripheral nerves

Over the last decade, neuromuscular ultrasonography has emerged as a useful tool for the diagnosis of peripheral nerve disorders. This article reviews sonographic findings of normal nerves, including key quantitative ultrasound measurements that are helpful in the evaluation of focal and possibly generalized peripheral neuropathies. It also discusses several recent articles outlining the evidence base for the use of this technology, as well as new findings in compressive, traumatic, and generalized neuropathies. Ultrasonography is well suited for use in electrodiagnostic laboratories, where physicians, experienced in both the clinical evaluation of patients and the application of hands-on technology, can integrate findings from the patient's history, physical examination, electrophysiological studies, and imaging for diagnosis and management.

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

INTRODUCTION

The aim of this study was to assess the presence of (sub)luxation of the ulnar nerve in patients with ulnar neuropathy at the elbow (UNE) compared with healthy controls (HC). We assessed its clinical patterns, electrodiagnostic, and sonographic characteristics.

METHODS

Using high-resolution sonography, we studied the incidence of (sub)luxation in a cohort of 342 patients and 70 HC.

RESULTS

Subluxation occurred in 14% and luxation in 6.7% of the UNE patients versus 5.7% and 5.7%, respectively, in HC (no significant differences). Pain at the elbow occurred more often in patients with (sub)luxation (P = 0.007). Electrodiagnostic and sonographic findings did not differ between patients with or without (sub)luxation.

CONCLUSIONS

The incidence of ulnar nerve (sub)luxation between patients with UNE and HC does not differ. UNE patients with (sub)luxation do not have specific clinical or electrodiagnostic findings, apart from experiencing pain at the elbow more often.