Diagnosis Of Ulnar Neuropathy At The Elbow Research Articles

Diagnostic efficiency of conventional ultrasound, shear wave elastography, and superb microvascular imaging in evaluating ulnar neuropathy at the elbow.

The current diagnosis of ulnar neuropathy at the elbow (UNE) relies mainly on the clinical presentation and nerve electrodiagnostic (EDX) testing, which can be uncomfortable and yield false negatives. The aim of this study was to investigate the diagnostic value of conventional ultrasound, shear wave elastography (SWE), and superb microvascular imaging (SMI) in diagnosing UNE. We enrolled 40 patients (48 elbows) with UNE and 48 healthy volunteers (48 elbows). The patients were categorized as having mild, moderate or severe UNE based on the findings of EDX testing. The cross-sectional area (CSA) was measured using conventional ultrasound. Ulnar nerve (UN) shear wave velocity (SWV) and SMI were performed in a longitudinal plane. Based on the EDX findings, UNE severity was graded as mild in 4, moderate in 10, and severe in 34. The patient group showed increased ulnar nerve CSA and stiffness at the site of maximal enlargement (CSA mean at the site of max enlargement [CSAmax] and SWV mean at the site of max enlargement [SWVmax]), ulnar nerve CSA ratio, and stiffness ratio (elbow-to-upper arm), compared with the control group (p < .001). Furthermore, the severe UNE group showed higher ulnar nerve CSAmax and SWVmax compared with the mild and moderate UNE groups (p < .001). The cutoff values for diagnosis of UNE were 9.5 mm2 for CSAmax, 3.06 m/s for SWVmax, 2.00 for CSA ratio, 1.36 for stiffness ratio, and grade 1 for SMI. Our findings suggest that SWE and SMI are valuable diagnostic tools for the diagnosis and assessment of severity of UNE.

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

Given the relatively high false negative rate of electrodiagnostic studies (EDX) in patients with clinically diagnosed ulnar neuropathy at the elbow (UNE), we sought to determine whether an alternative objective test could more effectively detect UNE. Additionally, we proposed to determine the relationship between the cross-sectional area (CSA) of the ulnar nerve on ultrasound(US), EDX, and clinical symptoms. This was a retrospective study of patients presenting with symptomatic UNE. The performance characteristics of EDX versus ultrasound were calculated using the clinical diagnosis of UNE as the reference standard. Standard EDX studies and US of the ulnar nerve were analyzed. Maximal CSA of the ulnar nerve and EDX severity were analyzed for patients with each combination of US-positive/negative and EDX-positive/negative findings. Analysis was performed on 89 patients and 115 nerves with signs and symptoms of cubital tunnel syndrome. In total, 56 (49%) nerves were diagnosed as mild UNE, 32 (28%) nerves were diagnosed as moderate UNE, 17 (15%) nerves were diagnosed as severe UNE, and 10 (8%) nerves were negative for UNE by EDX. Maximal-maximal CSA was highly correlated with disease severity as determined by nerve conduction studies/electromyography. Compared with EDX+/US+, patients with EDX-/US+ showed higher rates of ulnar sensory loss and elbow tenderness with similar rates of positive Tinel and intrinsic muscle atrophy. In this sample of patients with clinically diagnosed UNE, 91.3% of the patients demonstrated positive EDX studies, whereas 94.8% had a positive US. Ultrasound is an alternative to EDX that could be incorporated clinically in the diagnosis and management of UNE. Ultrasound was able to consistently detect clinically positive cubital tunnel syndrome demonstrating its utility as a confirmatory or supplemental test to the clinical assessment if one is required. Ultrasound additionally may be able to better identify patients with early stages of UNE with negative EDX findings. Diagnostic IV.

Mixed Nerve Conduction Study in the Diagnosis of Ulnar Neuropathy at the Elbow

Purpose: This study aims to investigate the ulnar-median mixed nerve latency difference (U-MLD) recorded from the medial aspect of the arm both in patients with ulnar neuropathy at the elbow (UNE) and in healthy individuals and thus to assist in the diagnosis of UNE. Materials and Methods: Twenty-nine patients meeting electrophysiological criteria defined by the American Association of Neuromuscular and Electrodiagnostic Medicine for diagnosis of UNE, and 50 healthy individuals were included in the study retrospectively. All participants' data were evaluated, such as median/ulnar motor and sensory response, U-MLD and the percentage of ulnar mixed nerve response amplitude difference between sides. Results: The U-MLD was significantly higher in patients with UNE than in the control group (1.78 ± 0.64 ms vs. 0.6 ± 0.22 ms, P = 0.000). The percentage of the ulnar mixed nerve response amplitude loss was significantly higher in the patient group compared to the control group (43.9% ± 30.3% vs. 21.4% ± 12.2%, P = 0.018). The U-MLD was significantly higher in the patients with amplitude loss ≥50%, and the ulnar mixed nerve response amplitude loss was ≥50% in all five patients with the ulnar sensory nerve action potential pathology. Conclusions: U-MLD is higher in patients with UNE; it can provide additional data in mild cases regarding the diagnosis of UNE, especially. Furthermore, the criterion that the ulnar mixed nerve response amplitude difference between the sides ≥50% suggests that it can be used to evaluate the severity of UNE.

Length of affected nerve segment in ulnar neuropathies at the elbow

ObjectiveTo establish length of the affected nerve segment (LANS) in ulnar neuropathy at the elbow (UNE). MethodsIn a group of our previously reported UNE patients we identified 2-cm segments with reduced motor nerve conduction velocity (MNCV) on electrodiagnostic (EDx) studies and increased nerve cross-sectional areas (CSA) on ultrasonographic (US) studies. LANS was obtained by summation of these abnormal 2-cm segments separately for each approach. We also studied effect of selected independent parameters on LANS. ResultsAltogether we studied 189 patients (194 arms). Mean (SD) LANS determined in 171 arms with reduced ulnar MNCV was 4.15 (1.89) cm, and was similar (p = 0. 21) to LANS obtained in 147 arms with increased CSA 4.46 (2.29) cm. Longer LANS were found in right arms, clinically severe UNE, axonal UNE and UNE due to entrapment. The most commonly affected 6 cm segment included 89% of abnormal 2-cm segments, with 50% of included 2-cm segments being normal. By contrast, the whole 10 cm segment included all abnormal 2-cm segments, with 66% of included segments being normal. ConclusionsIn UNE both EDx and US studies revealed average LANS of around 4 cm. LANS was longer in more severe UNE. SignificanceLANS needs to be taken into account in discussion of the mechanisms of UNE and approach to EDx diagnosis of UNE, particularly length of the segment used in nerve conduction studies across the elbow.

High-Resolution Ultrasound in the Diagnosis and Surgical Management of Ulnar Neuropathy at the Elbow.

High-resolution ultrasound (HRU) has recently demonstrated the potential to facilitate diagnosis and treatment of upper extremity compression neuropathy. The authors hypothesized that HRU can improve preoperative evaluation of ulnar neuropathy at the elbow (UNE) and that changes in ulnar nerve cross-sectional area (CSA) after cubital tunnel release may correlate with outcomes. Nineteen adult patients diagnosed with UNE who were scheduled for surgical decompression by a single hand surgeon were enrolled. Electrodiagnostic (EDX) testing, HRU of the ulnar nerve, Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) score, and McGowan grade were obtained pre- and postoperatively. Fourteen patients completed the study. Statistically significant improvements were found in CSA measurements and QuickDASH scores. High-resolution ultra-sound was found to confirm UNE in all 7 patients with positive results on EDX, and additionally detected UNE in 3 of 6 patients with negative results on EDX and in 1 patient with equivocal (nonlocalized) EDX testing. All 4 of these additional HRU-detected cases improved clinically and by CSA measurements after surgery. In this series, HRU was superior to EDX testing in the diagnosis of UNE and demonstrated objective improvement in ulnar nerve CSA after successful cubital tunnel release. This modality, which is better tolerated, less costly, and less time-consuming than EDX testing or magnetic resonance imaging, should therefore be considered in the diagnosis and surgical management of UNE, particularly in cases with negative or equivocal results on EDX testing, or when outcomes are suboptimal. [Orthopedics. 2021;44(5):285-288.].

Diagnostic Accuracy of Sensory Clinical Findings of the Hand Dorsum and of Neurography of the Dorsal Ulnar Cutaneous Nerve in Ulnar Neuropathy at the Elbow

ObjectiveThe main objective is to investigate the diagnostic accuracy and the relation of touch sensation and subjective sensory symptoms in the medial aspect of the hand dorsum, and neurography of the dorsal ulnar cutaneous nerve (DUCN) in ulnar neuropathy at the elbow (UNE). Secondary objective is to report the electrophysiological occurrence of anatomical variant of sensory innervation of the medial aspect of the hand dorsum from superficial radial nerve (SRN). DesignProspective, cohort study. SettingElectromyography laboratory. ParticipantsConsecutive participants (N=282), those with UNE (n=81) and those without UNE (n=201), were enrolled. InterventionsNot applicable. Main Outcome MeasuresAccuracy and agreement between sensory clinical findings of the medial hand dorsum and neurography of DUCN in UNE diagnosis. ResultsDUCN neurographic and sensory findings had high specificity and relatively low sensitivity. Normal or abnormal sensory nerve action potential (SNAP) of DUCN matched with normal or abnormal touch sensation of the medial aspect of hand dorsum. Abnormal DUCN SNAP was related to the clinical severity of UNE and to the axonal damage of the ulnar nerve. Anatomical variant of the innervation of hand dorsum from SRN was demonstrated in 31 of 564 hands (6.2%) belonging to 26 of 282 participants (9.2%). If the variant was present, DUCN SNAP of the same side was more frequently absent or of low amplitude. ConclusionsThe utility of DUCN neurography and sensory findings of the medial aspect of the dorsum of the hand is limited in the diagnosis of UNE. However, if DUCN SNAP is absent or low in amplitude, it is advisable to check the presence of the anatomical variant of the innervation of the medial aspect of the hand dorsum from SRN.

Doppler sonography for intraneural vascularization of ulnar neuropathy at the elbow – Before and after surgery

The finding of intraneural blood flow (IBF) signal by doppler sonography was interpreted in several ways at entrapment neuropathy. There is no report of IBF after surgery of ulnar neuropathy at the elbow (UNE). We investigated IBF in UNE before and after surgery. Case series study. Subject: nine arms (only men) diagnosed and confirmed as UNE by surgery. All arms were performed grey scale sonography (GS) using an ultrasound machine (AprioXV; Toshiba) with 12 MHz linear-array transducer and electrodiagnostic study (EDX) before and after surgery. We performed Doppler sonography (DS): 5 arms before surgery, 6 arms after surgery and 2 arms both. In EDX, diagnosis of UNE as follows: absolute motor CV from above elbow to below elbow of less than 50 m/s and (1) or (2) (1) differential slowing (10 m/s across elbow). (2) conduction block across elbow. In GS, diagnosis of UNE as follows: cut-off value was the largest cross-sectional area from 2 cm distal to 2 cm proximal to the medial epicondyle > 11 mm 2 . General findings before surgery: EDX diagnosed 8 arms as UNE but one. Seven arms were diagnosed as UNE by GS. General findings after surgery: All 9 arms were improved in clinical signs. EDX did not change. Eight were diagnosed as UNE by GS. DS findings before surgery: IBF signal was not detected in 3 arms and detected in 2 arms but absent pulse. DS findings of after surgery: six arms were detected IBF signal and pulsatility. These findings may suggest that releasing entrapment site might decrease endoneurial fluid pressure and increase IBF. About recovery from UNE after surgery, it may be useful to evaluate intraneural vascularity at the affected site with DS.

Neurologic examination and instrument‐based measurements in the evaluation of ulnar neuropathy at the elbow

The aim of the study was to compare the utility of instrument-based assessment of peripheral nerve function with the neurologic examination in ulnar neuropathy at the elbow (UNE). We prospectively recruited consecutive patients with suspected UNE, performed a neurologic examination, and performed instrument-based measurements (muscle cross-sectional area by ultrasonography, muscle strength by dynamometry, and sensation using monofilaments). We found good correlations between clinical estimates and corresponding instrument-based measurements, with similar ability to diagnose UNE and predict UNE pathophysiology. Although instrument-based methods provide quantitative evaluation of peripheral nerve function, we did not find them to be more sensitive or specific in the diagnosis of UNE than the standard neurologic examination. Likewise, instrument-based methods were not better able to differentiate between groups of UNE patients with different pathophysiologies. Muscle Nerve 57: 951-957, 2018.

Proposal for electrodiagnostic evaluation of patients with suspected ulnar neuropathy at the elbow.

To develop an evidence-based electrodiagnostic (EDx) approach to patients with suspected ulnar neuropathy at the elbow (UNE). We prospectively recruited patients with suspected UNE, took a history and performed clinical neurologic, EDx and ultrasonographic (US) examinations. Ulnar motor and mixed nerve 5 × 2 cm, 2 × 4 cm and 10 cm studies across the elbow were compared regarding sensitivity and precise localization of UNE. In 175 evaluated patients, the highest sensitivity/precise localization was demonstrated by the motor 5 × 2 cm study (93%/92%), followed by the 2 × 4 cm study (89%/83%) and the 10-cm study (82%/0%). The sensitivities of mixed ulnar nerve studies to diagnose/precisely localize UNE were 12-23%/27-36% lower than the corresponding motor studies. Based on our data, we suggest starting EDx evaluation of UNE with a motor 2 × 4 cm study (recording from either the abductor digiti minimi or the first dorsal interosseous muscles), with two additional stimulation sites being added if the initial result is negative. This results in a motor 4 × 2 cm study. In all suspected UNE patients, an antidromic sensory study to the 5th finger should also be performed. The proposed EDx protocol is robust, sensitive and time efficient. We hope that it will improve the diagnosis of UNE.

Precise localization of ulnar neuropathy at the elbow

ObjectiveTo report the utility of short-segment nerve conduction studies (SSNCSs) and ultrasonography (US) in the precise localization of ulnar neuropathy at the elbow (UNE) and differentiation between lesions in the retroepicondylar (RTC) groove and under the humeroulnar aponeurotic arcade (HUA; i.e., cubital tunnel). MethodsIn a group of prospectively recruited patients with suspected UNE, four blinded examiners took a history and performed neurologic, electrodiagnostic (EDx) and ultrasonographic (US) examinations. Precise UNE localization was determined by SSNCSs criteria (conduction slowing and conduction block), and by US criteria (changes in cross-sectional area – CSA). Localizations obtained by EDx and US studies were compared. ResultsWe included 83 patients (86 arms) with SSNCSs or US diagnosis of UNE. US confirmed the SSNCSs localization in 45%, provided localization alone in 24%, and was unable to confirm SSNCSs localization in 23% of arms. Lesions in RTC (76%) were mainly demyelinating (63%), and localized at the medial epicondyle (29%) or 2cm proximal to it (69%). By contrast, lesions at HUA (17%) were mainly axonal (73%), and localized 2cm (57%) or 3cm (43%) distal to the medial epicondyle. ConclusionSSNCSs and US are able to precisely localize UNE in the majority (93%) of arms with pathologic SSNCSs or US. UNE in RTC are predominantly demyelinating, and approx. 5-times more common than UNE at HUA that are more commonly axonal. SignificanceSSNCSs and US are of similar utility and complement each other in precise UNE localization.

Ulnar neuropathy at the elbow: Five new things.

Ulnar neuropathy at the elbow (UNE) is the second most frequent compression neuropathy. While other diagnostic imaging tools are emerging to assist in the diagnosis of UNE, electrodiagnosis remains the gold standard. However, the electrodiagnostic approach to UNE presents unique challenges limiting its diagnostic accuracy. We review advances in 5 areas relevant to the diagnosis of UNE: technologic advancements with modern EMG machines have allowed for reconsideration of the question of experimental error and lesion detection; how temperature effects can lead to misdiagnosis; the effect of body mass index on the electrodiagnosis of UNE; the validation of short segment studies; and the emerging role of high-resolution sonography as a diagnostic tool.

Relation between electrophysiological findings and diffusion weighted magnetic resonance imaging in ulnar neuropathy at the elbow

As only a limited number of studies have used diffusion-weighted imaging (DWI) and conventional magnetic resonance imaging (MRI) in patients with ulnar neuropathy at the elbow (UNE), the present study aimed to investigate the diagnostic value of the non-invasive DWI technique in patients with UNE. A total of 26 elbows in 19healthy controls (age range: 22-56 years) with no symptoms and 24elbows in 21 symptomatic patients (age range: 21-46years) with cubital tunnel syndrome underwent DWI. The electrophysiological and clinical criteria for the diagnosis of UNE were examined. No pathological signal from the ulnar nerve was detected in the healthy controls, whereas there was an increase in signals on DWI in all patients with UNE. On T2-weighted (T2W) imaging, there was increased signal intensity in 20elbows, while low signal intensity was observed in the remaining four. A positive correlation was found between disease duration and presence of hyperintensity (P=0.044, r=0.42) on T2W images. DWI can be used together with electrophysiological methods for the diagnosis of UNE. Furthermore, DWI might be preferred in some cases, as it is non-invasive compared with the electrophysiological method for UNE diagnosis.

Which ultrasonographic measure has the upper hand in ulnar neuropathy at the elbow?

ObjectiveTo compare the diagnostic accuracy of ultrasonographic ulnar nerve diameter, cross-sectional area (CSA) and swelling ratio measurement in ulnar neuropathy at the elbow (UNE). MethodsUltrasonographic diameter, CSA, and swelling ratio measurements were compared with a reference standard including clinical examination, electrophysiological studies, and follow-up in a prospective cohort of patients. All patients in whom a diagnosis of UNE was considered were eligible for the study. Reference values for ultrasonography were obtained in 73 healthy volunteers. ResultsOf 191 patients, 137 had UNE or probable UNE, while 54 had another condition and these were analysed as patient controls. Patients with UNE had a larger ulnar nerve diameter, CSA and swelling ratio than healthy controls and patient controls (p<0.01). The diagnostic accuracies of these different measurements were comparable with a specificity of 78–87%, a positive predictive value of 87–90%, a sensitivity of 42–61% and negative predictive value of 37–44%. ROC-analysis for these measurements showed an area under the curve of 0.75–0.77. ConclusionUltrasonographic measurements of ulnar nerve diameter, CSA and swelling ratio have comparable diagnostic value, which was lower than reported previously. SignificanceUltrasonographic ulnar nerve diameter, CSA and swelling ratio measurements are equally useful in diagnosing UNE.

Ulnar neuropathy at the elbow: a review and single case cadaveric study

Introduction Ulnar neuropathy at the elbow (UNE) causes sensory and motor dysfunction of the ulnar nerve and can lead to permanent loss of hand function. Hand therapists frequently encounter this pathology and are required to be cognisant of symptoms, diagnosis, therapeutic and surgical management. A detailed understanding of the anatomical structures will give the therapist greater expertise in managing this pathology. Methods A single case cadaveric study was undertaken to investigate known sites of ulnar nerve compression and observe the mechanisms by which compression occurs. A literature review reports on knowledge relating to the pathology, diagnosis, therapeutic and surgical management of UNE. Results Anatomic structures compressing the ulnar nerve are the Arcade of Struthers, the medial intermuscular septum, the cubital tunnel and the deep flexor aponeurosis. UNE is attributable to mechanical compression from fibrous and bony structures at these sites and to traction on the ulnar nerve from elbow flexion. Provocative tests are a useful tool in the diagnosis of UNE but should be used cautiously due to limitations in statistical accuracy. Conservative treatment approaches of splintage, ergonomic adaptations, education and neural mobilizations lack high-quality evidence but may have benefit primarily for early or mild to moderate disease. There is some evidence in support of conservative management in longer standing disease. Discussion Therapists play an important role in the diagnosis and management of UNE and should have a sound understanding of the relevant anatomy, pathology, diagnosis and treatment. Conservative treatment may be efficacious for UNE but lacks evidence from randomized, controlled trials. Further research is needed to verify current precepts and traditional approaches.

The diagnostic value of provocative clinical tests in ulnar neuropathy at the elbow is marginal

Background:Provocative clinical tests are often performed in the diagnosis of ulnar neuropathy at the elbow (UNE) although the evidence for the usefulness of these tests is limited. The aim of...

Die Wertigkeit elektroneurographischer Messparameter in der Diagnostik der chronischen Ulnarisneuropathie am Ellenbogen

Ulnar neuropathy at the elbow (UNE) is the second most common compressive neuropathy of the upper limb. Besides clinical evaluation, electrodiagnostic studies are usually applied to confirm the diagnosis. However, there are certain limitations to the diagnosis of UNE by electrodiagnostic studies. In a prospectively performed study we compared the diagnostic value of the electrodiagnostic parameters to the symptoms and the clinical parameters for different degrees of sensory and motor dysfunctions. Between 2001 and 2003, 38 patients (mean age 53.9 +/- 8.8 years, 19 men and 19 women) were treated at our institution for UNE. For 34 (89%) patients complete electrodiagnostic studies were performed and for 25 patients there was also an electrodiagnostic evaluation of the asymptomatic contralateral arm. According to the symptoms and clinical parameters (grip and pinch grip, two-point discrimination), the patients were assigned to three stages (mild, moderate, and severe). Electrophysiological measurements for each stage were compared with one another. The diagnostic value for each electrophysiological parameter was evaluated in comparison to the normal limits of the "Deutsche Gesellschaft für Neurologie (DGN)" and the "American Association of Electrodiagnostic Medicine (AAEM)". In the 34 symptomatic arms the mean values for motor nerve conduction were: conduction velocity (MNCV) = 41.2 +/- 11.6 m/s; velocity change above-to-below-elbow segment = 12.8 +/- 7.7 m/s; CMAP = 9224 +/- 5514 microV; dL = 3.24 +/- 0.82 mg. For the moderate stages of nerve compression (n = 11) the mean values are: MNCV = 42.5 +/- 12.7; velocity change MNCV = 13.2 +/- 6.8; CMAP = 11 890 +/- 4750; dL = 2.97 +/- 0.57; for severe nerve compression (n = 23): MNCV = 40.6 +/- 11.0; change MNCV = 12.7 +/- 8.3; CMAP = 7948 +/- 5358; dL = 3.37 +/- 0.8. The difference for each parameter between the symptomatic and asymptomatic contralateral arm was statistically significant (p < 0.05) as it was for the difference of the parameters of the group with severe nerve compression in comparison to the asymptomatic arm. In the comparison of the moderate stage group with the asymptomatic arm there was only a significant difference for MNCV and there was no significant difference between the moderate and the severe group. In our study the calculated sensitivities for the electrodiagnostic studies were 76% for all symptomatic arms, 64% for the moderate group, and 83% for the severe nerve compression group. In all patients the MNCV was the most sensitive parameter. Electrodiagnostic studies were only able to reveal 3/4 of all patients with an affection of the ulnar nerve and only 2/3 of the patients with a moderate stage of ulnar nerve compression. Although important for the further therapy, a differentiation between a moderate and severe degree of nerve compression was not possible.

Effect of body mass index on ulnar nerve conduction velocity, ulnar neuropathy at the elbow, and carpal tunnel syndrome

Both high and low body mass index (BMI) have been reported as risk factors for ulnar neuropathy at the elbow (UNE), and a high BMI as a risk factor for carpal tunnel syndrome (CTS). To determine whether the extremes of BMI are risk factors for UNE or CTS, and whether BMI affects calculation of median and ulnar motor nerve conduction velocity (NCV), we retrospectively analyzed the electrodiagnostic records of control patients, UNE patients, and CTS patients. The BMI was calculated for 50 patients with a sole diagnosis of UNE and compared to the BMI of 50 patients with CTS and 50 control subjects. The mean BMIs were 25.9 +/- 4.4, 30.1 +/- 5.5, and 28.3 +/- 5.6 for the UNE, CTS, and controls, respectively. By one-way analysis of variance, the difference in BMI between the UNE patients and the normal patients was significant (P < 0.01). In the control groups, increasing BMI directly correlated with increasing ulnar motor NCV across the elbow but not with forearm NCV. Across-elbow (AE) ulnar motor NCV may be falsely increased in patients with a high BMI, probably due to distance measurement factors. Not only do relatively slender individuals have comparatively slower AE ulnar NCVs, they are also at increased risk for developing UNE. Patients with a high BMI are at increased risk for CTS.

Diagnostic value of high-resolution sonography in ulnar neuropathy at the elbow

To determine the diagnostic value of high-resolution sonography in ulnar neuropathy at the elbow (UNE). Sonographic ulnar nerve diameter measurement was compared at three levels around the medial epicondyle with a criterion standard including clinical and electrophysiologic characteristics in a cohort of 123 patients presenting with clinical signs of UNE. UNE or probable UNE was diagnosed in 84 patients and a different condition in 39 patient controls. Reference values were obtained in 56 healthy volunteers. One hundred thirty-six affected arms were studied in 123 patients (UNE in 82, probable UNE in 9, and a different condition in 45 affected arms). Patients with UNE had a larger ulnar nerve diameter than patient controls (p < 0.0001). The sensitivity of sonography was 80%, specificity 91%, positive likelihood ratio 9, and negative likelihood ratio 0.2. The highest diagnostic yield was found in patients in whom electrodiagnostic studies showed signs of ulnar neuropathy but could not localize the lesion (17/20 cases, 86%) and in patients who had motor conduction velocity slowing across the elbow without conduction block (32/37 cases, 86%). High-resolution sonography is an accurate and easily applied test for the diagnosis of UNE. The authors recommend its use in addition to electrodiagnostic studies because it improves the reliability of the diagnosis of UNE.

Abstract 14: The utility of proximal motor latency in ulnar neuropathy at the elbow.

Objective: To study sensitivity and specificity of above-elbow motor latency recorded at abductor digiti minimi (ADM) and first dorsal interosseous (FDI) in screening for ulnar neuropathy at the elbow (UNE). Design: Retrospective review of electrophysiologic data. Setting: Electromyography laboratory of a university hospital. Participants: Subjects having undergone ulnar motor conduction studies that included above-elbow motor latency simultaneously recorded at the ADM and FDI. Our “true-positive” group consisted of 74 subjects with the diagnosis of UNE. Our “true-negative” group consisted of 42 subjects with the diagnosis of carpal tunnel syndrome (CTS) and without clinical UNE. Diagnoses were based on clinical presentation and electrodiagnostic data. Interventions: Not applicable. Main Outcome Measures: Ulnar motor latency data were reviewed. Distribution curves constructed of above-elbow ulnar motor latency (AE-UML) recorded at the ADM and FDI. Receiver operator characteristic curves constructed to graphically represent the relationship between sensitivity and specificity as a function of the cutoff value for normal latency. Results: The mean AE-UML for the UNE group was 11.0ms at the ADM, 11.6ms at the FDI, and 11.3ms at the average of the ADM and FDI (COMB-ADM+FDI). The mean AE-UML for the CTS group was 8.6ms at the ADM, 9.2ms at the FDI, and 8.9ms at the COMB-ADM+FDI. The AE-UML cutoff to give 95% sensitivity was 7.9ms at the ADM, 8.4ms at the FDI, and 8.3ms at the COMB-ADM+FDI. The specificities were 24% at the ADM, 26% at the FDI, and 29% at the COMB-ADM+FDI. Conclusions: The AE-UML can be used as a highly sensitive screen in the electrodiagnostic evaluation of patients with possible UNE; however, its low specificity means that many of the patients undergoing full ulnar nerve testing will have normal studies. Recordings at the ADM and the FDI, as well as their average, resulted in similar specificities.