Needle electromyography features and values of paraspinal muscle parameters in assessment of respiratory function of patients with amyotrophic lateral sclerosis

Abstract

Objective: To analyze the features of needle electromyography (EMG) in patients with amyotrophic lateral sclerosis (ALS), and explore the correlation between EMG parameters of the tenth thoracic paraspinal muscle and disease duration, rate of disease progression, forced vital capacity (FVC) and revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R). Methods: Standard EMG was recorded from unilateral sternocleidomastoid muscle and/or tongue muscles, upper and lower limbs muscles and the tenth thoracic paraspinal muscle in 112 patients with definite ALS between March 2012 and June 2013 in the Department of Neurology at Chinese PLA General Hospital. Parameters studies included spontaneous potentials, duration and amplitude of motor unit potentials (MUP), pattern of recruitment. Results: EMG revealed diffuse neurogenic changes in each case. Fibrillation potential or positive sharp waves were found in some muscles in all of patients, and both of them were found in most of the cases. Fasciculation potentials (FPs) were found in 8 patients and accompanied with fibrillation potential and positive sharp waves in 5 of them. Complex repetitive discharges (CRDs) were found in only 1 patient. Duration and amplitude of MUP was prolonged and increased in ALS patients, and the rate of high amplitude and decreased recruitment pattern were 35.71% and 72.32%, respectively. Logistic regression analysis revealed an association of the FVC loss with the drop of ALSFRS-R and peak amplitude of the tenth thoracic paraspinal muscle. Conclusions: The abnormal spontaneous activity with high frequency are fibrillation potentials and/or positive sharp waves. However, FPs is observed in a small number of patients and CRDs is rarely seen in ALS. The ALSFRS-R and peak amplitude of thetenth thoracic paraspinal muscle may be of certain clinical value in estimating the severity of disease especially the respiratory dysfunction in ALS patients.