Revising nerve conduction reference limits.

Area of Science:

• Neurophysiology
• Clinical Electrophysiology

Background:

• Current reference limits (RL) for electrodiagnostic laboratories are often decades old.
• Advancements in instrumentation and techniques necessitate re-evaluation of existing RL.
• Demographic-based RL can enhance diagnostic accuracy.

Purpose of the Study:

• To validate and revise current laboratory reference limits (RL) for motor nerve conduction studies.
• To explore the utility of extrapolated reference value (ERef) and multi-variable extrapolated reference value (MeRef) methods for establishing updated RL.
• To investigate the influence of patient demographics on nerve conduction parameters.

Main Methods:

• Analysis of latency and velocity data from 740 adult patients undergoing motor nerve conduction studies.
• Derivation of RL using ERef and MeRef methodologies.
• Correlation analysis of nerve conduction parameters with patient age and height.

Main Results:

• ERef limits for median and ulnar nerve latency were similar to current RL, while tibial and fibular nerve latency limits were slightly shorter.
• Ulnar nerve conduction velocity showed no dependence on age or height, with ERef matching current RL.
• Median, tibial, and fibular nerve conduction velocities demonstrated age and/or height-dependent decreases.

Conclusions:

• ERef and MeRef methods are effective for validating and revising nerve conduction study RL.
• Updated RL, incorporating demographic factors via MeRef for velocity analysis, will enhance diagnostic specificity.
• The study supports the adoption of revised RL for improved electrodiagnostic practice.