Nerve ultrasound normal values - Readjustment of the ultrasound pattern sum score UPSS

Abstract

Objective: Reference values are crucial for nerve ultrasound. Here, we reevaluated normal nerve and fascicle cross-sectional area (CSA) values in humans and compared them to published values. Based on these data, ultrasound pattern sum score (UPSS) boundary values were revisited and readjusted.

Methods: Ultrasound of different peripheral nerves was performed in 100 healthy subjects at anatomically defined landmarks. Correlations with age, gender, height and weight were calculated.

Results: Overall, correspondence to other published reference values was high. Gender-dependency was found for the proximal median nerve. Dependency from height occurred in the tibial nerve (TN). Weight-dependency was not found. However, the most obvious differences were found in the TN between men >60 years and women <60 years. Thus, general boundary values were defined using the mean plus the twofold standard deviation for all subjects and nerve segments except for the TN, in which different cut-offs were proposed for elder men. Accordingly, the cut-offs for the UPSS were re-adjusted, none of the individuals revealed more than 2 points at maximum.

Conclusions: The influence of distinct epidemiological factors on nerve size is most prominent in the TN, for which thus several normal values are useful.

Significance: Adjusted reference values improve the accuracy of the UPSS.

Keywords: Fascicle size; Nerve ultrasound; Normal values; Reference values; Scoring systems; Ultrasound pattern sum score.