Sural/Radial Amplitude Ratio in Healthy Adults: Influence of Anatomical and Demographic Variables

Introduction: The sural-to-radial sensory nerve action potential amplitude ratio (SRAR) can be used to diagnose peripheral axonal neuropathy. However, different studies have revealed varying lowest values for this index. This study aimed to identify the minimum normal value of SRAR in healthy individuals and evaluate the impact of age, sex, height, weight, body mass index (BMI), forearm length, wrist circumference, ankle circumference, and leg length on the lowest normal value of SRAR to distinguish between healthy individuals and those with axonal polyneuropathy. Methods: This study involved 108 individuals referred for four-limb electrodiagnostic tests with normal results. The participants were between 20 and 70 years old, and the study was conducted between July 2022 and December 2023. Electrodiagnostic tests were performed to determine the range of sensation in the sural and radial sensory nerves. Data were analyzed using SPSS software, version 26, and a P<0.05 was considered statistically significant. Results: The study revealed that the lowest SRAR value was 0.2 (mean 0.435±0.175). According to the Pearson correlation test, the SRAR has no significant correlation with age, BMI, forearm length, wrist circumference, ankle circumference, and leg length. Conclusion: The study found that the SRAR was not affected by various physical characteristics, such as age, sex, height, weight, forearm length, wrist circumference, ankle circumference, or leg circumference. An SRAR value of 0.2 was identified as the minimum normal value of SRAR in our healthy subjects.