F49. Creatine kinase level and its relationship with quantitative electromyographic characteristics in ALS

Abstract

Introduction Creatine Kinase (CK) level has been reported to be mildly to moderately elevated in some amyotrophic lateral sclerosis (ALS) patients. The mechanism of CK elevation is still not well understood, and to date, the main hypothesizes include up-regulated CK expression and increased muscle membrane permeability due to muscle denervation. Objective To explore the relationship between serum CK level and electromyographic characteristics in patients with ALS. Methods Two hundred thirty-eight consecutive ALS patients were enrolled. All patients underwent CK level test and electrophysiological study with a consistent approach. We calculated a compound muscle action potential (CMAP) sum score and spontaneous potentials were graded from 0 to 4 depending on their density and distribution. We tested for any independent correlation between CK levels and CMAP sum score, mean spontaneous potential (MSP) score, F wave persistence or conduction velocity. Results The median serum CK level was 151 U/L. Log CK was independently correlated with MSP score ( β = 0.07, 95% CI: 0.01–0.14, p = 0.032) and F persistence ( β = −0.0013, 95% CI: −0.00251 to −0.0002, p = 0.02) but not with CMAP sum score or F wave conduction velocity. When stratified by sex, the correlation between log CK and MSP score and F persistence was significant in male patients but not in female patients. Conclusion The results supported an effect of functional lower motor neuron loss and muscle denervation associated with CK levels of ALS patients. The severity of lower motor neuron loss and denervation may be implicated in pathophysiological mechanisms of CK elevation in ALS patients.