Correlations Between Median Nerve Sonography and Conduction Study Results and Functional Scales in Amyotrophic Lateral Sclerosis

Abstract

We aimed to compare the sonographic measurement of median nerve cross-section area (CSA) in patients with Amyotrophic Lateral Sclerosis (ALS) and healthy individuals. The effect of duration of the disease on correlations between paraclinical findings and ALS functional rating scale (ALSFRS) were secondarily aimed to be evaluated. The cross-sectional study was approved by the Ethical Committee of Iran University of Medical Sciences and conducted between January 2017 and December 2018. We evaluated the median nerve surface area by means of sonography in 35 ALS patients and 35 healthy controls. Compound muscle action potential (CMAP) amplitudes during nerve conduction study and ALSFRS were recorded by the same trained specialist. Data were analyzed using SPSS software version 18. We did not find a significant difference between CSA in ALS patients and the normal population (P>0.05). Comparing to normal individuals, the mean CMAP decreased significantly in ALS patients (6.6±3.07 mV versus 10.25±2.2 mV, P<0.001). ALSFRS correlated with both CSA of the median nerve at the wrist (P:<0.001, r:0.78) and the CMAP (P:<0.001, r:0.74) that were confirmed by regression models designed to consider the effect of disease duration on these correlations. CSA was not different between ALS patients and the normal population, but CMAP decreased in ALS patients. ALSFRS correlated with both CSA and CMAP of the median nerve.