Electromyography in patients affected by Juvenile Idiopathic Arthritis (JIA): The role of neuromuscular system un the protection of the temporomandibular articulation

Aim: The aim of this study is to evaluate the motorial model and to understand the role of the neuromuscular system in the protection of the temporomandibular articulation in patients affected by Juvenile Idiopathic Arthritis (JIA) with also articulation disorders. Methods: 20 patients with Juvenile Idiopathic Arthritis (JIA) were enrolled, these patients suffer from pathology on the temporomandibular articulation. It has been made an evaluation of the motorial function of the masseter muscle and temporal muscle. This evaluation is done through standardized Electromyography (EMG) and by using a software DAQ to analyze the results. The registrations were performed placing the patient in a sitting position, through the use of bipolar electrodes pregelled in Ag/Ag Cl. The test included a measurement in a maximum clenching and a measurement in occlusion on cotton rolls (cot) to determine the coefficient Percentage Overplaning Coefficient (POC). The obtained (POC) coefficient allowed the evaluation of the articular symmetry during muscle activation. Furthermore, the two measurements allowed to get other indices, which are; The asymmetry Index, Index of activation, index of twist, Index of impact, Results: From the study we notice that 18/20 of patients affected by Juvenile Idiopathic Arthritis (JIA) present hyperactivity of the temporal muscle and consequently Hypoactivity of the masseter muscle, which is a symptom of not correct neuromuscular balance. It is been registered a negative sign about the index of activation in 18 cases. This value of negative sign means that a greater differential recruitment of temporal muscles is involved during the motorial activity of maximum clenching; the difference is about 10% . Conclusion: In the 90 % of patients with Juvenile Idiopathic Arthritis (JIA) who suffer from articular disorder, it has been registered an adaptive response of protection to the temporomandibular articulation with an hyperactivity of the temporal muscles and/or the hypoactivity of the masseter muscle. From this study emerges, the importance of the evaluation of the motorial activity and the role of the neuromuscular system in the protection of the temporomandibular articulation, through the electromyographic test in maximum clenching.