Characteristics of surface electromyography of sternocleidomastoid in infants with congenital muscular torticollis

Objective To investigate the characteristics of surface electromyography (sEMG) of bilateral sternocleidomastoid in infants with congenital muscular torticollis (CMT). Methods Sixty CMT infant patients (CMT group) and 15 healthy infants (control group) were enrolled in this study. The CMT patients were divided into left and right CMT subgroups according to the affected side. The sEMG signals of bilateral sternocleidomastoid during cervical neutral, left and right rotation and lateral flexion posture in the supine position were collected, and the root mean square (RMS) was analyzed. Results The RMS value of the affected and unaffected sternocleidomastoid was(8.7±4.4)and (16.3±6.4), respectively in CMT group during cervical neutral in the supine position, and the RMS value of the affected side was significantly lower than that of the unaffected side(t=11.118, P 0.05)in control group during cervical neutral in the supine position. During cervical rotation and lateral flexion, there were no significant differences in the RMS values of bilateral sternocleidomastoid, and the RMS values of bilateral sternocleidomastoid were significantly increased, but there was no significant difference in the increased RMS value of bilateral sternocleidomastoid in control group(P>0.05). Conclusion The sEMG characteristics in infants with CMT show that the amount of motor units of the affected sternocleidomastoid which is activated, raised and involved in motions are less, and the muscle excitability is poor. The sEMG characteristics of left and right CMT are consistent. Key words: Electromyography; Infant; Torticollis