An electromyographic study of masseter muscle activity amongst overdenture and complete denture patients

Recently, several systems of topical antibiotic administration have been investigated. Most systems use sustained release devices to obtain high levels of antibiotics in the deepened periodontal pockets. Metronidazole and tetracycline can be administered without causing systemic side-effects. All systems summarized in this article are to be used after scaling and root planing of the diseased sites to increase the effect of the mechanical treatment.     

The effect of pain from orthodontic arch wire adjustment on masseter muscle electromyographic activity

Pain has been shown to have an effect on muscle activity even when it does not originate in the muscle itself or in the related joint. The effect of pain from arch wire adjustment on jaw muscle activity is unclear. This study systematically evaluated the effects of orthodontic arch wire adjustment pain on masseter electromyographic (EMG) activity and on the swallowing threshold. The EMG recordings were made on 22 subjects (ages 11 to 15) under three conditions: chewing five peanuts (10 seconds), watching TV chewing gum (15 minutes), and watching TV with no gum (15 minutes). An arch wire adjustment or placebo adjustment was then made. Subjects returned after 48 hours, and the EMG measurements were made under the same conditions. After 3 weeks, subjects received arch wire or placebo treatment in a crossover design with identical recording procedures. The EMG levels while chewing peanuts decreased in 18 of 22 subjects after treatment, compared with 9 of 22 subjects after the placebo. While watching TV with gum, the EMG levels of 20 of 22 subjects decreased after treatment, compared with 9 of 22 subjects after the placebo. The number of chewing strokes before swallowing increased significantly after treatment compared with after placebo. The results suggest that orthodontic pain on teeth tend to reduce muscle activity during function.     

Consequences of trapezius relaxation on the distribution of shoulder muscle forces: an electromyographic study

Recent experiments have suggested a pathway of genes that regulate left-right asymmetry in vertebrate embryogenesis. The most downstream member of this cascade is nodal (XNR-1 in frogs), which is expressed in the left-side lateral mesoderm. Previous work in the chick [Levin, 1998] suggests that an inductive interaction by Shh (Sonic hedgehog) present at the midline was needed for the left-sided expression of nodal, which by default would not be expressed. Interestingly, it has been reported [Lohr et al., 1997] that in Xenopus, right-side mesoderm that is explanted at st. 15 and allowed to develop in culture, goes on to express nodal, suggesting that lateral mesoderm expresses this gene by default and that a repression of nodal by the midline is needed to achieve asymmetry. Such a contradiction raises interesting questions about the degree of conservation of the mechanisms upstream of nodal asymmetry and, in general, about the differences in the LR pathway among species. Thus we examined this issue directly. We show that in the chick, as in the frog, explanted mesoderm from both sides does, indeed, go on to express nodal, including both the medial and lateral expression domains. Ectopic nodal expression in the medial domain on the right side is not sufficient to induce an ectopic lateral domain. We also show that explanted lateral tissue regenerates node/notochord structures exhibiting Shh expression. Furthermore, we show that Xenopus explants done at st. 15 also regenerate notochord by the stage at which XNR-1 would be expressed. Thus explants are not isolated from the influence of the midline. In contrast to the midline repressor model previously suggested [Lohr et al., 1997] to explain the presence of nodal expression in explants, we propose that the expression is due to induction by signals secreted by regenerating node and notochord tissue (Shh in the chick). Thus our results are consistent with Shh being necessary for nodal induction in both species, and we provide an explanation for both sets of data in terms of a single conserved mechanism upstream of nodal expression.     

Bilateral experimental muscle pain changes electromyographic activity of human jaw-closing muscles during mastication

The effects of bilateral experimental muscle pain on human masticatory patterns were studied. Jaw movements and electromyographic (EMG) recordings of the jaw-closing muscles were divided into multiple single masticatory cycles and analyzed on a cycle-by-cycle basis. In ten men simultaneous bilateral injections of hypertonic saline (5%) into the masseter muscles caused strong pain (mean+/-SE: 7.5+/-0.4 on a 0-10 scale), significantly reduced EMG activity of jaw-closing muscles in the agonist phase, and significantly increased EMG activity in the antagonist phase. Nine of the subjects reported a sensation of less intense mastication during pain. Injections of isotonic saline (0.9%) did not cause pain or significant changes in masticatory patterns. The influence of higher brain centers on conscious human mastication can not be discarded but the observed phase-dependent modulation could be controlled by local neural circuits and/or a central pattern generator in the brain stem which are capable of integrating bilateral nociceptive afferent activity.     

The influence of gender on the masseter electromyographic jaw-jerk reflex in young human subjects

The purpose of this study was to investigate the effect of gender on the masseteric jaw-jerk reflex, evoked in a sample of nine male and nine female young subjects. Electromyographic jaw-jerk recordings elicited by chin-taps in the relaxed masseter muscle of the preferred chewing side, were obtained using a computerized recording and analysis system. In both groups, a jaw-jerk reflex was recorded in 95.56% out of the total number of chin-taps. The mean latency was significantly shorter in the females (5.75 ms) than in the males (6.14 ms, P = 0.0045), while the amplitude of the reflex was significantly higher in the females (P = 0.0005). No significant differences were found in the mean duration between males (6.86 ms) and females (6.73 ms). It was concluded that sex variation should be taken into consideration in the interpretation of the jaw-jerk reflex.     

The origin of the temporalis muscle flap

This paper explores the origin of the temporalis muscle flap which has been attributed to Golovine, a Moscow ophthalmic surgeon, who described a forehead skin transposition flap. Small temporalis muscle transpositions were used in surgery for TMJ ankylosis, but the use of the majority of the muscle for reconstruction of facial defects was first described by Sir Harold Gillies during the 1914-18 war.     

Effect of maximum ventilation on abdominal muscle relaxation rate

BACKGROUND: When the demand placed on the respiratory system is increased, the abdominal muscles become vigorously active to achieve expiration and facilitate subsequent inspiration. Abdominal muscle function could limit ventilatory capacity and a method to detect abdominal muscle fatigue would be of value. The maximum relaxation rate (MRR) of skeletal muscle has been used as an early index of the onset of the fatiguing process and precedes failure of force generation. The aim of this study was to measure MRR of abdominal muscles and to investigate whether it slows after maximum isocapnic ventilation (MIV). METHODS: Five normal subjects were studied. Each performed short sharp expiratory efforts against a 3 mm orifice before and immediately after a two minute MIV. Gastric pressure (PGA) was recorded and MRR (% pressure fall/10 ms) for each PGA trace was determined. RESULTS: Before MIV the mean (SD) maximum PGA MRR for the five subjects was 7.1 (0.8)% peak pressure fall/10 ms. Following MIV mean PGA MRR was decreased by 30% (range 25-35%), returning to control values within 5-10 minutes. CONCLUSIONS: The MRR of the abdominal muscles, measured from PGA, is numerically similar to that described for the diaphragm and other skeletal muscles. After two minutes of maximal isocapnic ventilation abdominal muscle MRR slows, indicating that these muscles are sufficiently heavily loaded to initiate the fatiguing process.     

Influence of the Esmarch splint on chewing and tongue muscle activity during sleep

To clarify the functional mechanism of the Esmarch device in the treatment of sleep apnea, its effect on muscle activity during sleep was studied electromyographically with and without the appliance at the inferior head of the lateral pterygoid muscle, the genioglossal muscle, and the masseter muscle in 15 patients with sleep apnea syndrome. During the obstructive apnea the muscles showed significantly lower amplitudes than before the apnea. No significant decrease in the amplitude was observed during the central apnea, but, after the obstructive and central apnea, significantly higher amplitudes were seen than beforehand. The amplitudes rose after the placement of the appliance, and the amplitudes of the genioglossal and lateral pterygoid muscles during obstructive apnea increased significantly after the insertion of the appliance. The results suggest that the device can activate the masticatory and tongue muscle activity and indicate that the muscles activated with the appliance can prevent obstruction in the oropharynx. The Esmarch device not only helps avoid obstruction by mandibular protraction, but also affects function by activating the muscles.     

Placebo-controlled evaluation of abbreviated progressive muscle relaxation and of relaxation combined with cognitive therapy in the treatment of tension headache.

Sixty-six tension headache patients were randomly assigned to one of four conditions for 8 weeks: (a) progressive muscle relaxation (PMR) alone; (b) PMR plus cognitive therapy (PMR?+?Cog); (c) pseudomedication, a credible attention-placebo control; or (d) continued headache monitoring. A comparison of overall headache activity (headache index), derived from a daily headache diary, for 4 weeks before treatment to 4 weeks after treatment revealed that active treatment (PMR and PMR?+?Cog) was superior to either control condition. Moreover, level of headache medication consumption decreased significantly for the active treatment groups. Although headache-index comparisons of the two active treatments showed no advantage for adding cognitive therapy to PMR, a measure of clinically significant change showed a trend for PMR?+?Cog to be superior to PMR alone. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of the mycotoxins penitrem, paxilline and lolitrem B on the electromyographic activity of skeletal and gastrointestinal smooth muscle of sheep

Myasthenia gravis (MG) is mediated by autoantibodies against the acetylcholine receptor at the muscle endplate. Some MG patients have in addition antibodies (Ab) to the skeletal muscle proteins ryanodine receptor (RyR) and titin. We have examined GM and KM allotypes, RyR and titin Ab in 44 MG patients (37 thymoma patients and 7 non-thymoma, late-onset patients) and 292 non-MG controls to see if GM/KM allotypes associate with differences in autoantibody production. All patients had titin Ab, and 15 thymoma patients had also RyR Ab. The phenotype GM 1, 2, 3 23 5, 21 was significantly increased in the patients with titin Ab compared with the non-MG controls (chi2 = 4.93, p < 0.05). Thymoma patients with RyR Ab had a higher frequency of the GM 3 23 5 phenotype compared with RyR Ab negative patients and controls (chi2 = 7.1, p < 0.05). KM allotypes did not differ between RyR Ab positive or titin Ab positive patients and controls. GM phenotypes may thus be associated with an autoimmune response against the muscle proteins titin and RyR in MG patients.     

Changes in torque and electromyographic activity of the quadriceps femoris muscles following isometric training

BACKGROUND AND PURPOSE: The purpose of this study was to examine the effect of isometric training of the quadriceps femoris muscles, at different joint angles, on torque production and electromyographic (EMG) activity. SUBJECTS: One hundred seven women were randomly assigned to one of four groups. Three groups trained with isometric contractions three times per week at a knee flexion angle of 30, 60, or 90 degrees. The fourth group, which served as a control, did not exercise. METHODS: Isometric torque was measured using a dynamometer, and EMG activity was measured using a multichannel EMG system. Measurements were obtained during maximal isometric contraction of the quadriceps femoris muscles at 15-degree increments from 15 to 105 degrees of knee flexion. Measurements were taken before and after 8 weeks of training. RESULTS: Following isometric exercise, increased torque and EMG activity occurred not only at the angle at which subjects exercised, but also at angles in the range of motion at which exercise did occur. Further analyses indicated that exercising in the lengthened position for the quadriceps femoris muscles (90 degrees of knee flexion) produced increased torque across all angles measured and appeared to be the more effective position for transferring strength and EMG activity to adjacent angles following isometric training as compared with the shorter positions of the muscle (30 degrees and 60 degrees of knee flexion). CONCLUSION AND DISCUSSION: These findings suggest that an efficient method for increasing isometric knee extension torque and EMG activity throughout the entire range of motion is to exercise with the quadriceps femoris muscles in the lengthened position.     

Acoustic myography, electromyography and bite force in the masseter muscle

Acoustic myography (AMG) offers some advantages over electromyography (EMG) in certain circumstances, but the use of AMG on the jaw-closing muscles has not been fully tested. The purpose of this study was to examine the relationship between AMG, EMG and force in the masseter muscles of nine healthy male subjects. The AMG was recorded using a piezoelectric crystal microphone and the EMG was recorded simultaneously with surface electrodes. Force was recorded between the anterior teeth with a strain-gauge transducer. Analysis showed that Pearson's correlation coefficient was 0.913 for force/AMG and 0.973 for force/EMG in all subjects, indicating a linear relationship between force, AMG and EMG at the four different force levels tested (25-75% of maximum). It is apparent that AMG may be used as an accurate monitor of masseter muscle force production, although some care is required in the technique.     

Use of electromyographic biofeedback and cue-controlled relaxation in the treatment of test anxiety.

Studied the effect of using electromyographic (EMG) biofeedback to increase the efficacy of cue-controlled relaxation training in the treatment of test anxiety. 40 college undergraduates scoring in the upper third on the Test Anxiety Scale were randomly assigned to 1 of 4 treatment conditions—EMG-assisted cue-controlled relaxation, cue controlled relaxation alone, attention-placebo relaxation, and no-treatment control. Pre–post self-report measures of test anxiety, state anxiety, and trait anxiety (State-Trait Anxiety Inventory) were obtained. In addition, a performance measure (Otis-Lennon Mental Abilities Test) was administered. Ss from the 3 relaxation groups received 6 45-min individual sessions over 2 wks. All treatments were conducted using audiotape recordings. Results indicate that cue-controlled relaxation is effective in increasing test performance for test anxious Ss, that EMG biofeedback does not contribute to the effectiveness of this procedure, and that self-report measures of anxiety are susceptible to a placebo effect. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Craniomandibular disorders, edentulousness and the clinically estimated size of the masseter muscle

We report on an aphakic 30 year-old patient who underwent penetrating keratoplasty on his only functioning eye. On the first day after the operation he developed a total choroidal detachment due to suprachoroidal bleeding. The patient had no sense of orientation. Vision decreased to faulty light perception. One week postoperatively a posterior sclerotomy was performed in order to drain the suprachoroidal blood. Via a paracentesis the globe was pressurized with hyaluronic acid. The following day the suprachoroidal blood had almost disappeared. The retina had become reattached. During a follow-up period of 2 years the visual acuity remained 20/30.     

Musical relaxation therapy on the cerebral arteriosclerosis

The transcranial Doppler and psychological measurement methods were used to evaluate the effect of musical relaxation therapy on the cerebral arteriosclerosis. The results showed that the musical relaxation therapy could improve the cerebral blood flow (physiological), offset the Type A behavior and eliminate the emotional disturbance (psychological), and that its effect was better than that of the control patients. The mechanism of the effect may be related to the 1/f sound wave (physical), abdominal respiration with long expiration and involuntary inspiration (physiological) and the hinting effects of the inducing phrases (psychological).     

Transcranial magnetic-stimulation mapping of the cortical topography of the human masseter muscle

BACKGROUND: Population-based screening for prostate cancer is currently being evaluated in randomized clinical trials in the United States and in Europe. Side effects arising from the process of screening and from the earlier treatment of screen-detected prostate cancer may be important factors in the evaluation. To examine health-related quality of life (or health status) among men screened for prostate cancer, we conducted a longitudinal study of 626 attenders to the Rotterdam (The Netherlands) prostate cancer screening program and of 500 nonparticipants. METHODS: Attenders of the screening program and nonparticipants completed self-assessment questionnaires (SF-36 [i.e., Medical Outcomes Study 36-Item Short-Form Health Survey] and EQ-5D [i.e., EuroQol measure for health-related quality of life] health surveys) to measure generic health status, as well as an additional questionnaire for anxiety and items relating to prostate cancer screening. RESULTS: Physical discomfort during digital rectal examination and during transrectal ultrasound was reported by 181 (37%) of 491 men and by 139 (29%) of 487 men, respectively; discomfort during prostate biopsy was reported by 64 (55%) of 116 men. Mean scores for health status and anxiety indicated that the participants did not experience relevant changes in physical, psychological, and social functioning during the screening procedure. However, high levels of anxiety were observed throughout the screening process among men with a high predisposition to anxiety. Similar scores for anxiety predisposition were observed among attenders and nonparticipants. CONCLUSIONS: At the group level, we did not find evidence that prostate cancer screening induced important short-term health-status effects, despite the short-lasting side effects related to the biopsy procedure. However, subgroups may experience high levels of anxiety. The implication is that unfavorable health-status effects of prostate cancer screening occur mainly in the treatment phase.     

Less invasive reconstruction of the temporalis muscle for pterional craniotomy: modified procedures

BACKGROUND: I developed a modified pterional craniotomy technique which is less invasive for both the facial nerve and the temporalis muscle. METHODS: The keys to this procedure are subfascial dissection and reflection of the temporalis fascia without interfascial dissection, and posterior displacement of the temporalis muscle without muscular incision. The limited exposure from the bulky temporalis muscle can be avoided with this procedure. A small cuff of the fascia-periostium complex is left on a free bone flap along the superior temporal line to facilitate the subsequent muscle closure. RESULT: Since the facial nerve and temporalis muscle are not injured with this procedure, the functional and cosmetic results are satisfactory. CONCLUSION: To reduce functional and cosmetic complications, and the cost of pterional craniotomy, I believe that my procedure is recommended.