Cross sectional area reference values for sonography of peripheral nerves and brachial plexus

Objective: Ultrasound measurements of the cross sectional area (CSA) variability have been recently introduced to quantify pathological changes in peripheral nerves (PN). Methods: Reference values from 75 healthy subjects and their correlation to age, height, weight and sex are reported. Results: The mean values in PN were: (1) intranerve CSA-variability: median 1.05 (SD +/- 0.13), ulnar 1.53 (SD +/- 0.51), fibular 1.33 (SD +/- 0.37), tibial 1.39 (SD +/- 0.39), (2) internerve CSA-variability 1.76 (SD +/- 0.37), (3) intraplexus CSA-variability 1.52 (SD +/- 0.37), (4) side-to-side difference ratio of the CSA-variability: median 1.21 (SD +/- 0.04), ulnar 1.2 (SD +/- 0.25), fibular 1.19 (SD +/- 0.23), tibial 1.28 (SD +/- 0.24) and brachial plexus 1.19 (SD +/- 0.23). CSA did not correlate with height in PN, but correlated with weight in the ulnar nerve [Guyon's canal, r = 0.411, p = 0.0237, elbow r = 0.409, p = 0.0248]. Significant changes between sex were found only in the ulnar (Guyon's canal, p = 0.0265), fibular (popliteal fossa, p = 0.0336) and sural nerve (p = 0.048). CSA decreased with age in the median (axilla, p = 0.0236), and radial nerve (spiral groove, p = 0.0037) and increased in the tibial nerve (ankle, p < 0.0001). Conclusions: The CSA reference values reported seem to correlate at certain sites with age, weight and sex but not with height. Significance: The new CSA variability measures may be helpful in investigating pathologies of the PN. (C) 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.