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

OBJECTIVE

To compare the diagnostic accuracy of ultrasonographic ulnar nerve diameter, cross-sectional area (CSA) and swelling ratio measurement in ulnar neuropathy at the elbow (UNE).

METHODS

Ultrasonographic 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.

RESULTS

Of 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.

CONCLUSION

Ultrasonographic measurements of ulnar nerve diameter, CSA and swelling ratio have comparable diagnostic value, which was lower than reported previously.

SIGNIFICANCE: Ultrasonographic ulnar nerve diameter, CSA and swelling ratio measurements are equally useful in diagnosing UNE.