ORIGINAL ARTICLE Ulnar nerve measurements in healthy individuals to obtain reference values Elif Yalcin • Burcu Onder • Mufit Akyuz Received: 24 July 2012 / Accepted: 23 August 2012 / Published online: 5 September 2012 Ó Springer-Verlag 2012 Abstract The aim of this study was to obtain the ultr- asonographical reference values of ulnar nerve cross-sec- tional areas at the common areas of nerve entrapment as well as any differences related to age, sex, weight, height, dominant arm. Cross-sectional areas of the ulnar nerves of 72 healthy volunteers were measured bilaterally at the level of the epicondyle, 2 cm proximal to and 2 cm distal to the epicondyle, just at the entrance of cubital tunnel, at arterial split, at Guyon’s canal. Age, sex, body weight, height, body mass index, and dominant extremity were recorded. The mean ulnar nerve cross-sectional area was 5.8 ± 1.1 mm 2 at 2 cm proximal to medial epicondyle, 6.2 ± 1.1 mm 2 at the medial epicondyle, 5.6 ± 0.9 mm 2 at the entrance of the cubital tunnel, 5.6 ± 1.0 mm 2 at 2 cm distal to medial epicondyle (inside the flexor carpi ulnaris), 5.0 ± 0.6 mm 2 at arterial split, and 4.9 ± 0.6 mm 2 at Guyon’s canal. There was statistically no difference between the dominant and nondominant sides (p [ 0.05). Females had statistically smaller nerves than males (p \ 0.05). There was a significant correlation with height at all levels; also, weight was significantly corre- lated with cross-sectional areas except at two levels: tip of medial epicondyle and 2 cm distal. This study provides normative data of ulnar nerve ultrasonography and as well as any differences related to age, sex, height, weight, and dominant arm. Keywords Ulnar nerve Á Reference Á Ultrasound Introduction In recent years, there has been an increasing interest in peripheral nerve ultrasonography. Both in the diagnosis of the entrapment neuropathies and in evaluation of the ana- tomical etiological factors causing the entrapment, ultra- sonography has an important role [1]. Ultrasound is not a substitute tool for nerve conduction studies and electro- myography, but it is accepted as a powerful complementary tool to clinical findings and electrodiagnostic studies [2, 3]. Previous studies have reported that peripheral nerve ultra- sonography has a high sensitivity in the diagnosis of the ulnar neuropathy [4–6]. It is stated that ultrasonographical studies in addition to electrodiagnostic studies increase the diagnostic sensitivity from 78 to 98 % [6]. Also Yoon, et al. [7] stated that ultrasound could be a useful tool for assessing the patients with ulnar neuropathy symptoms and normal electrodiagnostic findings. Even so, there is no consensus on the reference values for the diagnosis of the ulnar neuropathy at elbow. Some investigators stated that a cross-sectional area of greater than 7.5–8.3 mm 2 has been proposed to be consistent with ulnar neuropathy at the elbow [4, 7]. Some of them gen- erally accepted the more stringent cut-off of 10 mm 2 [8]. The aim of the current study was to investigate the ulnar nerve ultrasonographically in healthy individuals and to measure the cross-sectional areas for normative ulnar nerve measures in order to help the evaluation of abnormal nerve conditions. Materials and methods We recruited 72 volunteers (144 elbows) from patients and employees in our rehabilitation center. A brief history was E. Yalcin (&) Á B. Onder Á M. Akyuz Ankara Physical Medicine and Rehabilitation Education and Research Hospital, Ankara, Turkey e-mail: elifyalcin78@gmail.com 123 Rheumatol Int (2013) 33:1143–1147 DOI 10.1007/s00296-012-2527-9