Pathophysiological changes in lumbar disc herniation

Abstract

Objective To investigate pathophysiological changes in the multifidus muscles of patients with lumbar disc herniation.Methods Thirty-six patients with unilateral symptoms caused by lumbar disc herniation were enrolled.They were divided into a symptomatic side group and a contralateral side group according to whether their symptomatic (algetic) or contralateral side would be studied.The percentage area of pimelosis and the mean gross signal intensity of each multifidus were measured with magnetic resonance imaging (MRI)_ The amplitude and duration of motor unit potentials of each multifidus were recorded using electromyography (EMG) when the patients were performing isometric contraction.Results The bilateral multifidus muscles of 36 patients displayed various degrees of pimelosis on magnetic resonance images.The percentage of pimelosis cross-sectional area in the symptomatic side group was significantly higher than in the contralateral side group.[(44.20 ± 15.14)％ versus(37.31 ± 13.85)％,P ＜ 0.05] The mean value of the gross signal intensity was also significantly higher.Both the amplitudes and duration of the motor unit potentials recroded from the multifidus had increased and widened,but significantly more in the symptomatic side group than in the contralateral side group.Conclusions Both the imaging and electrophysiological data showed more significant changes on the symptomatic side in patients with unilateral symptoms caused by lumbar disc herniation. Key words: Multifidus; Unilateral symptoms; Lumbar disc herniation; Magnetic resonance imaging; Electromyography