PracticeUpdate Neurology February 2019

EDITOR’S PICKS 13

Diagnostic Sensitivity of Electrophysiology and Ultrasonography in Ulnar Neuropathies of Different Severity Clinical Neurophysiology Take-home message • The authors compared the diagnostic performance of electrophysiological (EP) testing and ultrasonography (US) in 135 patients with ulnar neuropathies of varying clinical severity, and they evaluated the benefit of using both methods in the diagnostic work-up. US had a higher sensitivity than EP in both clinically “very mild” and mild neuropathies. US was also superior to EP testing for localizing ability in axonal ulnar neuropathies and identifying nerve hypermobility. • The use of US can improve diagnostic yield when evaluating ulnar neuropathies, especially mild and axonal type of neuropathies. Omar Khan MD

COMMENT By Simon Podnar MD, DSc U lnar neuropathy at the elbow (UNE) actually consists of two neuropathies. 1 The majority of NE (approximately 85%) is caused by external compression of the ulnar nerve in the retrocondylar groove, and it mainly occurs in people using a com- puter mouse. It affects predominantly nondominant (ie, left) arms, and gener- ally causes less severe nerve damage. These patients probably only need neu- rological examination and advice on elbow positioning, with follow-up eval- uation in case of persistent symptoms. Due to its ease of use, ultrasonography might also be practical in these patients to confirm the diagnosis. The remaining 15% of patients have UNE due to entrapment 2–3 cm distal to the medial epicondyle under the humer- oulnar aponeurosis. These patients are usually hard manual laborers, and their dominant hands are predominantly affected. In these patients, surgical division of the aponeurosis is indi- cated, if possible, before the nerve lesion becomes severe. 2 In addition to clinical examination, neurophysiologic testing and ultrasonography are indi- cated in these patients. These studies are aimed not only to localize the lesion to the elbow, but also to differentiate between both UNE varieties and con- firm entrapment under the humeroulnar aponeurosis before surgical release. As shown by Pelosi and Mulroy, the yield of diagnostic studies is generally higher in more affected nerves. Ultra- sonography is probably more useful for precise UNE localization, and is particu- larly useful in most severe axonal and other neurophysiologically non-localiz- able UNE. Pelosi and Mulroy also claim that ultrasonography might be particu- larly useful in mild UNE, which was not our experience, and needs to be con- firmed in future studies. References 1. Omejec G, Podnar S. What causes ulnar neuropathy at the elbow? Clin Neurophysiol 2016;127(1):919-924. 2. Omejec G, Podnar S. Long-term outcomes in patients with ulnar neuropathy at the elbow treated according to the presumed aetiology. Clin Neurophysiol 2018;129(8):1763-1769. Dr. Podnar is Head of Department, Ljubljana University Medical Centre in Slovenia.

Abstract OBJECTIVE To assess the diagnostic performance of electrophysiology and nerve ultrasound in ulnar neuropathies of varying clinical severity in 135 consecutive patients. METHODS Clinical severity of ulnar neuropathy was graded on a 4 point scale from very mild (symp- toms only) to severe (marked atrophy of intrinsic hand muscles). Sensitivity and localization ability of electrophysiology and nerve ultrasound were assessed for each point of the scale. RESULTS Ultrasound had higher sensitivity than electrophysiology in clinically very mild (20% and 3% for ultrasound and electrophysiology, respectively) and mild (62% and 47% for ultra- sound and electrophysiology, respectively) neuropathies, had greater localizing ability in axonal ulnar neuropathies, and identified nerve hypermobility. Ultrasound nerve cross-sectional area had strong positive correlation with both clinical and electrophysiological severity scores,

but with significant overlap across the sever- ity groups. CONCLUSION The diagnostic work-up of ulnar neuropathies was improved by using both electrophysiology and ultrasound at all levels of clinical severity. Ultrasound increased the diagnostic yield in very mild and mild neuropa- thies, localized all the ulnar neuropathies with abnormal non-localizing electrophysiology and identified nerve hypermobility. SIGNIFICANCE This is the first detailed analysis of the diagnostic performance of electrophys- iology and ultrasound in ulnar neuropathies of varying severity. Diagnostic Sensitivity of Electrophysiology and Ultrasonography in Ulnar Neuropathies of Dif- ferent Severity. Clin Neurophysiol 2018 Dec 07;[EPub Ahead of Print], L Pelosi, E Mulroy. www.practiceupdate.com/c/78001

VOL. 4 • NO. 1 • 2019