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

•Cross sectional reference values for peripheral nerves and brachial plexus are reported.•The introduction of the intranerve-, internerve cross sectional area variability allows the quantification of pathological ultrasound changes in peripheral nerves.•The intraplexus cross sectional area variability may be helpful in studying pathologies of the brachial plexus.

ObjectiveUltrasound measurements of the cross sectional area (CSA) variability have been recently introduced to quantify pathological changes in peripheral nerves (PN).MethodsReference values from 75 healthy subjects and their correlation to age, height, weight and sex are reported.ResultsThe 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).ConclusionsThe CSA reference values reported seem to correlate at certain sites with age, weight and sex but not with height.SignificanceThe new CSA variability measures may be helpful in investigating pathologies of the PN.