Sural/radial nerve amplitude ratio: reference values in healthy subjects

Area of Science:

• Neuroscience
• Clinical Electrophysiology

Background:

• The sural/radial nerve amplitude ratio (SRAR) is a proposed sensitive indicator for early axonal polyneuropathy.
• Previous research has not fully addressed the impact of sex differences or varied calculation methodologies on SRAR.
• Establishing reliable reference values for SRAR is crucial for its application in clinical practice.

Purpose of the Study:

• To determine reference values and variability of the SRAR in healthy adults.
• To assess the influence of sex, age, weight, and calculation methods on SRAR.
• To recommend optimal methods for SRAR measurement and interpretation.

Main Methods:

• Nerve conduction studies measuring sural and superficial radial sensory nerve action potentials in 106 healthy adults.
• Correlation analysis with epidemiological variables (age, weight, sex).
• Calculation of SRAR using multiple methods and assessment of its robustness.

Main Results:

• The SRAR was found to be a robust measure, independent of age, weight, sex, or calculation method.
• Bilateral measurements of nerve amplitudes are recommended for improved reliability.
• A cut-off value (5th percentile) of 0.2 was established in healthy subjects, which is lower than previously reported.

Conclusions:

• The SRAR is a stable and reliable electrophysiological marker for early axonal polyneuropathy detection.
• Standardized bilateral measurements and a lower cut-off value should be considered for clinical use.
• Further research is warranted to fully elucidate the clinical utility of SRAR in diagnosing early-stage axonal polyneuropathies.