急性有机磷农药及其混剂中毒患者单肌纤维肌电图的研究

目的探讨电刺激单肌纤维肌电图(SSFEMG)技术在急性有机磷农药(OPs)及其混剂中毒患者"中间期肌无力综合征"(IMS)诊断、分级及病情转归中的意义.方法对41例急性有机磷农药及其混剂中毒患者进行了SSFEMG和重频神经刺激肌电图(RNS)检测.结果(1)电刺激频率为5Hz和20 Hz时,SSFEMG检测所见单肌纤维动作电位平均连续差(MCD)增高与肌无力发生的一致性均较好(5 HzKappa系数=0.634,P=0.002;20 HzKappa系数=1.000,P=0.000),且以20 Hz者更好;RNS的检测结果与肌无力发生的一致性不如SSFEMG(5 HzKappa系数=0.153,P=0.400;20 HzKappa系数=0.188,P=0.319);(2)重型与轻型IMS患者MCD差异无显著性[5 Hz轻型(25.43±14.08)μs、重型(29.80±14.37)μs,P＞0.05;20 Hz轻型(34.30±11.19)μs、重型(39.40±18.98)μs,P＞0.05];(3)IMS患者肌力恢复后MCD明显下降,且趋于正常.结论 SSFEMG较同一频率的RNS敏感,可用于IMS的诊断与病情转归的评价,但在诊断分级中的意义还需进一步探讨.     

Electromyographical Study on Muscle Fatigue in Repetitive Forearm Tasks

The purpose of this study was to examine whether repetitive muscle tasks in low weight load might influence the fatigue of forearm muscles,and to identify ergonomic risk factors of forearm muscle fatigue in these tasks.Sixteen healthy male volunteers performed eight wrist extensions in different frequency,weight and angle loads while being instructed to keep a dominant upper limb posture as constant as possible.Surface electromyograph(sEMG) was recorded from right extensors digitorium(ED),flexor carpi radialis(FCR),flexor carpi ulnaris(FCU) and extensor carpi ulnaris(ECU) during the task performance.Our results showed that mean power frequency(MPF) and me-dian frequency(MF) values of ED,FCR and FCU were significantly lower(P<0.05) at high fre-quency load level than at low load level.However,MPF and MF values of ED were significantly lower(P<0.01) in higher load groups of frequency,angle and weight than in lower load groups.These results indicated that the fatigue of muscles varied in the same task,and the number-one risk factor of ECU,ED and FCR was angle load.     

瞬目反射对Bell氏麻痹预后判断的作用

目的：观察Ｂｅｌ氏麻痹患者瞬目反射（ＢＲ）的特点,探讨其判断预后的临床意义。方法：检测３６例Ｂｅｌ氏麻痹患者及３０名健康人ＢＲ,并对３２例患者进行随访。结果：ＢＲ反应电位潜伏期患者均较健康人延长,波幅较健康人低;在临床恢复过程中波幅,潜伏期有恢复趋势;病情预后差者潜伏期比预后好者延长更明显,波幅比预后好者下降更明显。结论：ＢＲ检测对估计Ｂｅｌ氏麻痹预后有判断价值。     

Influence of gum-chewing on the haemodynamics in female masseter muscle

Summary  Blood flow in active skeletal muscles provides energy substrate, oxygen and reduction of excessive heat and metabolic by-products. Although cyclic jaw motions such as those during mastication and speech articulation are the primitive oro-facial functions, possible effects of the cyclic muscle contractions on the intramuscular haemodynamics of the jaw muscles remains scarcely known. We investigated the masseteric haemodynamics during and after gum-chewing. Ten healthy female adults participated in the study. Electromyography, kinetics of masseter muscle oxygenation, electrocardiogram and blood pressure were recorded simultaneously. The subjects were asked to perform gum-chewing and cyclic jaw motion without gum bolus (empty-chewing task). The haemodynamics parameters were compared between the two experimental conditions. During gum-chewing task, deoxygenated haemoglobin and sympathetic nerve activity increased, while tissue blood oxygen saturation decreased. Blood pressure and parasympathetic nerve activity did not change. The overall behaviour of haemodynamic parameters during empty-chewing task was similar to that observed during gum-chewing task. However, the latency periods from the end of chewing until significant changes in the haemodynamic parameters were notably shorter ( P  < 0·05) in gum-chewing task as compared with those associated with empty-chewing task. The duration of the changes was shorter with empty-chewing than with gum-chewing. Fluctuations in masseter muscle haemodynamics associated with chewing jaw movement differed depending on the level of muscle contraction during movement. The differences became statistically significant immediately after the commencement of chewing and after the cessation movement. During the chewing movement, automatic nerve activities increased in response to the level of muscle contraction during movement.     

Influence of nocturnal bruxism on the stomatognathic system. Part I: a new device for measuring mandibular movements during sleep

The purpose of this study was to investigate the influence of bruxism on the stomatognathic system. A new device for measuring nocturnal mandibular movements was developed using a PIN photodiode sensor, integrated with polysomnography including electromyography (EMG), electroencephalography (EEG) and electro oculography (EOG). One bruxing event was defined depending upon EMG activities above 5% maximum voluntary contraction (MVC), and mandibular movement for each event was classified into three patterns (clenching, grinding and mix). Three subjects were selected for this study. Two of these reported a bruxing habit and one subject had some symptoms of temporomandibular dysfunction (TMD). Mandibular movement was analysed for these subjects. Frequency and duration of the bruxism events were 4.5-10.9 and 47.8-174.9 s h(-1) respectively. Clenching type bruxism was most frequently observed for all three subjects and EMG activities during clenching were stronger than grinding.     

Postural and dynamic masseter and anterior temporalis muscle EMG repeatability in serial assessments

Summary  Electromyographic (EMG) assessment has been used as a non-invasive tool to objectively assess muscle function, although with controversial research and clinical potential. The aim of this study was to assess within-, inter-subject and between-day repeatability of serial EMG recordings. The study sample included 10 asymptomatic subjects with no history of temporomandibular disorders or muscle parafunctions. Bilateral masseter and anterior temporalis muscle EMG parameters were assessed in two standardized serial recordings (day1 to day2) using a portable EMG equipment (ME 6000 recorder, Mega Electronics, Kuopio, Finland). The functional tasks included postural/resting activities as pre- and post-recording series of 30 s each and jaw opening/closing, intercuspal and maximal voluntary clenching activities of 5 s, repeated three times. The assessed EMG parameters included the mean amplitude, s.d. and error. In addition, the power spectrum EMG parameter assessment included the median power frequencies and the averaged EMG spectrum data values. The results of the intraclass correlation coefficient analysis indicated reliability for nearly all of the intercuspal and all clenching EMG amplitude and power spectrum parameters. This was complemented by the repeated measures anova and post hoc analyses that indicated non-significant differences between day 1 and 2 in task- and muscle-related analyses. Most variability was noted in postural and some in opening/closing tasks. In conclusion this study assessed the reliability, repeatability and limitations of postural and various dynamic masseter and temporalis EMG recordings for serial assessment.