Posterior interosseous nerve conduction. A new method of evaluation

Area of Science:

• Neuroscience
• Clinical Electrophysiology
• Orthopedics

Background:

• The posterior interosseous nerve (PIN) is crucial for forearm and hand motor function.
• Accurate assessment of PIN conduction is vital for diagnosing radial tunnel syndrome.
• Existing methods for evaluating PIN conduction present limitations in precision and variability.

Purpose of the Study:

• To introduce and validate a novel electrophysiological technique for assessing posterior interosseous nerve conduction.
• To compare the efficacy of two stimulation techniques (axillary vs. elbow) in measuring radial nerve motor latencies.
• To establish a reliable method for quantifying nerve conduction across the radial tunnel.

Main Methods:

• Studied 40 healthy controls using a new electrophysiological method.
• Compared motor latencies of brachioradialis and extensor carpi ulnaris muscles after radial nerve stimulation at the axilla and above the elbow.
• Utilized coaxial needle electrodes for axillary stimulation and surface electrodes for elbow stimulation.

Main Results:

• The latency difference between brachioradialis and extensor carpi ulnaris averaged 1.3 ms, reflecting PIN conduction through the radial tunnel.
• Both techniques yielded comparable mean latency differences, but elbow stimulation demonstrated reduced inter- and intraindividual variability.
• Right/left comparisons after elbow stimulation provided the most diagnostically valuable data, with a narrow normal range of 0.4 ms.

Conclusions:

• The developed method effectively measures posterior interosseous nerve conduction within the radial tunnel.
• Elbow stimulation offers superior precision and reduced variability compared to axillary stimulation for this assessment.
• Comparative latency analysis, particularly with elbow stimulation, serves as a sensitive diagnostic approach for radial tunnel pathologies.