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

Marcel Prasetyo; Reiner Reza Rahardja; Ahmad Yanuar; Joedo Prihartono; Stefanus Imanuel Setiawan

doi:10.1016/j.ejro.2021.100331

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

Eur J Radiol Open. 2021 Feb 23:8:100331. doi: 10.1016/j.ejro.2021.100331. eCollection 2021.

Authors

Marcel Prasetyo¹, Reiner Reza Rahardja¹, Ahmad Yanuar², Joedo Prihartono³, Stefanus Imanuel Setiawan¹

Affiliations

¹ Department of Radiology, Faculty of Medicine, Universitas Indonesia, Dr. Cipto Mangunkusumo National Central General Hospital, Jakarta, Indonesia.
² Department of Neurology, Faculty of Medicine, Universitas Indonesia, Dr. Cipto Mangunkusumo National Central General Hospital, Jakarta, Indonesia.
³ Department of Community Medicine, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia.

Abstract

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.

Keywords: CSA, cross-sectional area; Cross-sectional area; FCU, Flexor carpi ulnaris; ME, Medial epicondyle; Medial epicondyle; NCS, Nerve Conduction Study; NL-UN, Non-localizing ulnar neuropathy; O, Olecranon; TR, Triceps brachii muscle; US, Ultrasonography; Ulnar nerve; Ultrasonography.