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.
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● The lowest SRAR value in healthy adults was 0.20
● The SRAR had no relationship with by age, sex, weight, height, or BMI.
● The SRAR had no relationship with forearm length, wrist, leg, or ankle circumference.
● The SRAR supports early axonal polyneuropathy diagnosis.
● The SRAR is a robust diagnostic index for polyneuropathy.
Plain Language Summary
One way doctors assess nerve health is through special electrical tests. A common test examines the sural nerve, located in the leg, but its results can vary widely, making it challenging to identify early problems. To improve this, doctors often use the sural-to-radial sensory nerve action potential amplitude ratio (SRAR). This ratio compares the electrical signal from the sural nerve in the leg to the radial nerve in the arm, which is usually less affected by common nerve disorders. Our study examined 108 healthy adults, aged 20-70, to determine what the normal SRAR value and assess whether factors such as age, sex, height, weight, body shape, or limb measurements influence it or not. We found that the lowest normal SRAR value was 0.20. Importantly, our research showed that this ratio remained consistent regardless of age, sex, weight, height, or even the size of their forearms, wrists, legs, or ankles. Since SRAR is a stable and reliable measure, unaffected by a person's individual characteristics, it can be a more dependable tool for diagnosing early nerve damage, especially axonal polyneuropathy. This means doctors can use the SRAR more confidently to identify nerve problems sooner, potentially leading to earlier treatment and better outcomes for patients at risk of or experiencing polyneuropathy. Our findings help simplify the interpretation of this important diagnostic test, making it more practical for widespread use.
Type of Study:
Original |
Subject:
Clinical Neuroscience Received: 2024/05/24 | Accepted: 2025/01/22 | Published: 2025/05/1