Objective
To explore the effects of different recording electrodes on motor nerve conduction latencies.

Method
Median motor conduction study was performed in 10 healthy subjects. Motor conduction latency was determined by placing different recording electrodes (surface disc, monopolar needle and concentric needle) at the motor point of the left abductor pollicis brevis muscle, and reference electrodes on the proximal interphalangeal joint of the thumb. Motor nerve conduction recording was performed by using a surface disc, monopolar needle, and concentric needle. For the intramuscular recordings, needles were inserted both superficially and deep. The stimulus electrodes were secured 8 cm proximal to the recording electrodes, and the same intensity was applied throughout the tests.

Results
Deep intramuscular monopolar and concentric needle electrodes recorded the shorter latencies, 3.0⁑0.4 ms and 3.0⁑0.3 ms, respectively. Superficial concentric needle electrode recorded the longest latency of 3.4⁑0.3 ms. Motor nerve conduction latencies using a surface disc and superficial monopolar electrode were 3.2⁑0.3 ms and 3.2⁑0.3 ms, respectively.

Conclusion
We conclude that the distal motor nerve conduction latency is variable depending on the type of recording electrodes.