Unlocking Insights from Nerve Excitability Testing: Revealing Factors Shaping Nerve Health in Arm and Leg Data

Abstract

Introduction: The nerve excitability test (NET) assesses peripheral nerve properties, informing about nerve membrane integrity, ion channels, and axon function. Interpreting NET results is challenging due to the multitude of indices and their correlations. Exploratory factor analysis (EFA) offers a means to enhance interpretation by uncovering latent factors that link the measured indices. Objective: We analyzed correlations among 30+ NET indices in upper and lower limb nerves of healthy adults, then used EFA to identify latent constructs. We also explored EFA’s diagnostic potential for amyotrophic lateral sclerosis (ALS). Methods: Healthy adults underwent NET on median and common fibular nerves. Correlations were assessed within and between nerves. EFA-identified factors were compared across groups and for relations to age and sex. Results: 201 healthy participants and 15 people diagnosed with ALS were included. Correlations existed within, but not between nerves. EFA identified 4-5 factors per nerve. Factors reflected nerve excitability aspects affected by age and sex. One median nerve factor differed significantly between controls and people living with ALS. Conclusions: Nerve excitability indices within a nerve are interdependent, but not between nerves. EFA effectively summarized indices and identified a potential ALS diagnostic factor.