title: The Ulnar Nerve at Elbow Extension and Flexion: Assessment of Position and Signal Intensity on MR Images.
abstract: Purpose To assess the position and signal intensity of the ulnar nerve at elbow extension and flexion by using magnetic resonance imaging. Materials and Methods Institutional review board approval and written informed consent were obtained. Transverse T2-weighted images were obtained perpendicular to the upper arm in 100 healthy elbows of 50 volunteers (23 men, 27 women; age range, 21-57 years) and nine elbows with ulnar neuropathy (five men, four women; age range, 24-59 years) with extension and 130° of flexion. Ulnar nerve position was classified into three types: no dislocation, subluxation, or dislocation. One-way analysis of variance, paired t tests, Student t tests, and multiple regression analysis were used to analyze correlations between ulnar nerve movement angle during flexion and age, sex, presence of the anconeus epitrochlearis muscle, and ulnar neuropathy and to compare the contrast-to-noise ratio of nerve to muscle between extension and flexion. Results Nerve positions in healthy elbows were as follows: All had no dislocation at extension, and at flexion, 51 of 100 elbows (51.0%) had no dislocation, 30 of 100 elbows (30.0%) had subluxation, and 19 of 100 elbows (19.0%) had dislocation. Nerve movement angle was smaller in elbows with the anconeus epitrochlearis muscle than in those without the muscle (P = .045, .015). Presence of the muscle was the only significant factor associated with nerve movement angle (P = .047, .013). Only dominant elbows with nerve movement angle of less than 15° and nondominant elbows with nerve movement angle of less than 10° showed contrast-to-noise ratio increase at flexion (P = .021-.030). Conclusion Ulnar nerve movement during flexion was apparent in approximately half of healthy elbows and was similar between healthy elbows and elbows with ulnar neuropathy. Nerve signal intensity increased during flexion only in elbows without apparent nerve movement. (©) RSNA, 2016 Online supplemental material is available for this article.
authors.affiliation: From the Departments of Radiology (Y.K., Y.T.) and Orthopedic Surgery (Y.H.), Nagasaki Rosai Hospital, 2-12-5 Setogoshi, Sasebo 857-0134, Japan; Department of Radiology, Nagasaki University Hospital, Nagasaki, Japan (T.Y.); and Department of Radiological Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan (M.U.).
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kawahara
authors.affiliation: From the Departments of Radiology (Y.K., Y.T.) and Orthopedic Surgery (Y.H.), Nagasaki Rosai Hospital, 2-12-5 Setogoshi, Sasebo 857-0134, Japan; Department of Radiology, Nagasaki University Hospital, Nagasaki, Japan (T.Y.); and Department of Radiological Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan (M.U.).
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: From the Departments of Radiology (Y.K., Y.T.) and Orthopedic Surgery (Y.H.), Nagasaki Rosai Hospital, 2-12-5 Setogoshi, Sasebo 857-0134, Japan; Department of Radiology, Nagasaki University Hospital, Nagasaki, Japan (T.Y.); and Department of Radiological Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan (M.U.).
authors.forename: Yuzo
authors.initials: Y
authors.lastname: Honda
authors.affiliation: From the Departments of Radiology (Y.K., Y.T.) and Orthopedic Surgery (Y.H.), Nagasaki Rosai Hospital, 2-12-5 Setogoshi, Sasebo 857-0134, Japan; Department of Radiology, Nagasaki University Hospital, Nagasaki, Japan (T.Y.); and Department of Radiological Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan (M.U.).
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Tomita
authors.affiliation: From the Departments of Radiology (Y.K., Y.T.) and Orthopedic Surgery (Y.H.), Nagasaki Rosai Hospital, 2-12-5 Setogoshi, Sasebo 857-0134, Japan; Department of Radiology, Nagasaki University Hospital, Nagasaki, Japan (T.Y.); and Department of Radiological Sciences, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan (M.U.).
authors.forename: Masataka
authors.initials: M
authors.lastname: Uetani
mesh_terms: D000328:Adult; D004551:Elbow Joint / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology*; D014459:Ulnar Nerve / Q000502:physiology*; D055815:Young Adult