Ultrasound Evaluation of the Normal Ulnar Nerve in Guyon's Tunnel: Cross-Sectional Area and Anthropometric Measurements

Introduction: Ulnar nerve entrapment is an infrequent disorder, but is often seen in long distance cycling. Electrodiagnosis and imaging modalities, including ultrasound, are employed for diagnosis. The goal of this study was to obtain sonographic normative data of the ulnar nerve (UN) in Guyon’s tunnel, in order to establish the diagnosis of Guyon’s tunnel syndrome in future studies. Anthropometric measures were also obtained. Methods: 46 healthy volunteers (male=30) were recruited (age=24.7±3.1 years), and a total 83 wrists were examined. The examinations included anthropometric measurements (wrist width, depth, circumference, palm length and hand width) and ultrasound measurement of the cross sectional area (CSA) of the UN in Guyon’s tunnel. B-mode sonography and power Doppler were employed. Results: The UN CSA in Guyon’s tunnel for males was 6.0 ± 2.0 mm2, and 5.0 ± 1.0 mm2 for females. There was a significant difference between female and male in the measurements of wrist width, depth, circumference; palm length, width and UN CSA (p<.001). The UN CSA was correlated with wrist width, wrist depth, wrist circumference, palm length and hand width (p