Submitted by: Elliot Bodofsky, MD
Edited by: T. Darrell Thomas, MD
Pelosi L, Mulroy E. Diagnostic sensitivity of electrophysiology and ultrasonography in ulnar neuropathies of different severity. Clinical Neurophysiology, 2019
, 130: 297-302.
Ulnar neuropathy at the elbow is the second most common mononeuropathy. Electrophysiological sensitivity is lower than for carpal tunnel syndrome in a significant portion of cases. Frequently, studies are abnormal but not localizable. Recently nerve ultrasound has been used to evaluate ulnar compression. This study evaluated the accuracy of electrophysiological and ultrasound testing in 135 consecutive patients who were referred with neuropathic symptoms in the ulnar distribution of varying severity. Severity was graded with an established scale of symptoms and physical findings. Electrophysiologic studies were conducted using AANEM guidelines which included inching techniques when results were otherwise not conclusive. EMG of additional ulnar muscles was performed when NCS were non-localizing. Ultrasound testing involved scanning from the wrist to mid-humerus with measurements of cross-sectional nerve area.
Sensitivity was slightly higher for ultrasound (58%) than electrophysiology (47%). The difference was almost exclusively in the clinically very mild group (20% for ultrasound, 3% for electrophysiology) and the clinically mild group (62% vs. 47%). Both techniques had extremely high sensitivity for the clinically moderate and severe groups. A combination of the two techniques resulted is a higher sensitivity. Twenty-five patients with non-localizable EDX abnormalities showed abnormalities on ultrasound testing. There was very strong correlation between clinical and electrophysiological severity scores (R=0.87), between maximum ultrasound cross-sectional area and clinical severity (R=0.78), and between ultrasound and electrophysiological severity (R=0.82).
This is a study that compared electrophysiological and ultrasound testing for ulnar neuropathy symptoms of different severities. Ultrasound may detect more clinically very mild or mild cases providing evidence when EMG/NCS is abnormal but non-localizing. Clinical, electrophysiological and ultrasound severity are all highly correlated. Accuracy for clinically mild cases is improved when both techniques are used.