Visual input effect on EMG activity of masticatory and postural muscles in healthy and in myopic children

ABSTRACT. Aim The purpose of this study was to evaluate the activity of Anterior Temporal, Masseter, Sternocleidomastoid and Anterior Digastric muscles in response to changes in visual input in subjects with defective vision by means surface electromyography. Methods A total of 20 children, aged between 7 and 13 years, were evaluated. In the study group 10 children with myopic defects were enlisted, selected among patients afferent to the paediatric dentistry clinic. Ten subjects with normal vision, the control group, were chosen through the Pair Matching procedures, so that each myopic child had a matching age case control. Both study group and control group patients maintained mandible at rest with teeth apart and were submitted to a 15-sec electromyography (EMG) recording with closed eyes followed by a 15-sec EMG recording with open eyes. Results/Statistics The Root Mean Square (RMS) values were elaborated to obtain means and standard deviation. Statistical analysis was undertaken using the Student’s T-test for independent samples. Analysis of the results demonstrated a marked difference in tonic activity of temporal anterior muscles at open eyes between the myopic and the normal groups. Conclusion The findings suggest that in the evaluation of masticatory muscles tenderness, such as episodic tension type headaches, attention should be paid to vision defects.