发育性下颌不对称患者咀嚼肌及颈背部肌肌电功率谱的研究

EMG power-spectrum of facial and head-cervical muscles in patients with developmental mandibular asymmetry

目的研究发育性下颌不对称（DMA）患者咀嚼肌及颈肩背部肌肌电功率谱特征,探讨此类患者口頜面及颈部痛的可能机制.方法采集15例 DMA 患者及15例正常咬合者在最大开闭口运动及头屈曲、伸展运动时,咬肌、二腹肌、胸锁乳突肌与斜方肌的表面肌电信号.使用 LabVIEW 和 METLAB 软件,获取并比较两组受试者双侧对称肌群肌电均方根值（RMS）、平均功率频率（MPF）及百分重叠系数（POC）的差异.结果（1）颈部肌群和咀嚼肌有协同作用;（2）患者双侧肌肉的肌电功率谱值明显不对称;开闭口中,4对肌肉患侧 RMS 低于对侧而 MPF 高于对侧,差异均有统计学意义（均 P〈0.05）.患侧胸锁乳突肌在头颈运动时,RMS 高而 MPF 频率分布于偏低频段;（3）开闭口运动时,患者胸锁乳突肌的 MPF 与 RMS 值明显高于正常组,咬肌 RMS 值低于正常组（均 P〈0.05）.结论 DMA 影响双侧咀嚼肌、颈肩背部肌肌电的协调性,可能是导致口面及颈肩痛的原因之一.

Objective To investigate EMG power-spectrum of facial and head-cervical muscles in patients with develop- mental mandibular asymmetry. Methods Muscle activity was recorded with surface electrodes in the masseter, suprahyoid, ster-nocleidomastoid and upper trapezius areas during jaw opening-closing-clenching and head-neck flexion-extension in 12 pa- tients with developmental mandibular asymmetry and 15 normal control subjects. Root-mean square （RMS）, mean power frequen- cy（MPF） and POC% were calculated and analyzed using ANOVA and t-tests with P〈0.05 as significance level. Results The ster-nocleidomastoid and masseter muscles showed co-activation during jaw and head movements. Significant differences were ob- served between sides in the patients with developmental mandibular asymmetry in all muscle areas during two tasks, but never in the control subjects（P〈0.05）. RMS values of patients were lower on the side with hyperplasia in the masseter and suprahyoid areas and sternocleidomastoid area during jaw open-close movement. The RMS and MPF were higher in the patients than those in the controls in the sternocleidomastoid areas on both sides during jaw opening-closing movement. Conclusion The results indicate that the ability to perform symmetric jaw and neck muscle activities is disturbed in patients with developmental mandibular asymmetry. This is of clinical interest because asymmetric activity may be an etiologic factor in orofacial pain and cervical pain.