Vibratory testing with the 64 Hz Rydel-Seiffer tuning fork and its relation to the sural nerve action potential

Area of Science:

• Neurology
• Neurophysiology

Background:

• The semi-quantitative Rydel-Seiffer tuning fork is widely used, yet its efficacy in assessing peripheral nerve function is not well-established.
• Understanding the relationship between vibratory sense and nerve electrophysiology is essential for accurate diagnosis.

Purpose of the Study:

• To investigate the correlation between vibration sense, measured by the Rydel-Seiffer tuning fork, and compound sensory nerve action potential (SNAP) parameters.
• To evaluate the tuning fork's ability to differentiate normal from abnormal sural nerve responses.

Main Methods:

• Vibratory thresholds were measured using a 64 Hz Rydel-Seiffer tuning fork on 303 subjects.
• Sural nerve sensory neurography was performed to obtain SNAP parameters.
• Multiple linear regression and ROC curve analysis were used to assess the relationship and classification efficacy.

Main Results:

• SNAP amplitude was the primary predictor of vibration sense in all subjects and those with normal SNAPs.
• Conduction velocity was more significant in subjects with abnormal SNAPs.
• Vibration sense demonstrated a fair classification ability (AUC=0.730) for reduced SNAP amplitudes, with an optimal cutoff of 4.2.

Conclusions:

• Age significantly influences vibration perception, impacting test results, particularly in older individuals.
• Despite its utility, the tuning fork test has limitations, showing 40% false negatives at the optimal threshold.
• Neurophysiological testing remains indispensable for comprehensive polyneuropathy evaluation.