BODY POSITION EFFECTS ON STERNOCLEIDOMASTOID AND MASSETER EMG PATTERNACTIVITY IN PATIENTS UNDERGOING OCCLUSAL SPLINT THERAPY

This study was conducted in order to determine the effects of body pos ition on electromyographic (EMG) activity of sternocleidomastoid and m asseter muscles, in 15 patients with myogenic cranio-cervical-mandibul ar dysfunction undergoing occlusal splint therapy, EMG activity was re corded by placing surface electrodes on the sternocleidomastoid and ma sseter muscles (contralateral to the habitual sleeping side of each pa tient), EMG activity at rest and during swallowing of saliva and maxim al voluntary clenching was recorded in the following body positions: s tanding, supine and lateral decubitus, In the sternocleidomastoid musc le significant higher EMG activities at rest and during swallowing wer e recorded in the lateral decubitus position, whereas during maximal v oluntary clenching EMG activity did not change, In the masseter muscle significant higher EMG activity during maximal voluntary clenching in a standing position was observed, whereas EMG activity at rest and du ring swallowing did not change, The opposite pattern of EMG activity s upports the idea that there may exist a differential modulation of the motor neuron pools of the sternocleidomastoid and masseter muscles, o f peripheral and/or central origin, This suggests that the presence of parafunctional habits and body position could be closely correlated w ith the clinical symptomatology in these muscles in patients with myog enic craniomandibular dysfunction.