Nerve ultrasound reliability of upper limbs: Effects of examiner training

Introduction: Duration of training to reliably measure nerve cross-sectional area with ultrasound is unknown. Methods: A retrospective review was performed of ultrasound data, acquired and recorded by 2 examiners—an expert and either a trainee with 2 months (novice) or a trainee with 12 months (experienced) of experience. Data on median, ulnar, and radial nerves were reviewed for 42 patients. Results: Interrater reliability was good and varied most with nerve site but little with experience. Coefficient of variation (CoV) range was 9.33%–22.5%. Intraclass correlation coefficient (ICC) was good to excellent (0.65–95) except ulnar nerve-wrist/forearm and radial nerve-humerus (ICC = 0.39–0.59). Interrater differences did not vary with nerve size or body mass index. Expert–novice and expert–experienced interrater differences and CoV were similar. The ulnar nerve-wrist expert–novice interrater difference decreased with time (r_s = −0.68, P = 0.001). Discussion: A trainee with at least 2 months of experience can reliably measure upper limb nerves. Reliability varies by nerve and location and slightly improves with time. Muscle Nerve 57: 189–192, 2018.