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Comparative electromyographic study of bite plates and stabilization splints.

The object was to study any influence on the integrated electromyographic activity in the masseter and temporal muscles of two types of occlusal appliances. Seventeen healthy subjects wore a bite plate with a frontal plateau and a full coverage stabilization splint at night, each for 1 wk. The EMG activity was recorded without appliances in situ, in the rest position, and during gentle and maximum biting before and after the use of the different appliances. After use of the bite plate, the EMG activity was not significantly different at any tested level. After use of the splint, the activity in the rest position was significantly lower in the anterior and posterior parts of the temporal muscles. The EMG activity was significantly lower in the rest position in both parts of the temporal muscle after use of the splint than after use of the bite plate. In a control group of eight subjects in whom no appliances were used, the EMG activity did not change significantly between the initial and 1- or 5-wk recordings. Thus, the occlusal design of the appliances seems to be of importance for the influence on the EMG activity in the masticatory muscles, at least in healthy subjects.

Adult↗

Neovascularization (angiogenesis) after revascularization in moyamoya disease. Which technique is most useful for moyamoya disease?

The effects of direct and indirect revascularization for moyamoya disease were analyzed for each donor artery to determine which surgical procedure is most useful for the induction of neovascularization. In the past 12 years, 85 patients with moyamoya disease were surgically treated by combined surgery consisting of indirect revascularization via encephalo-duro-arterio-myo-synangiosis (EDAMS) and direct revascularization via the superficial temporal artery and the middle cerebral artery (STA-MCA) bypass. Among those patients, the post-operative changes in digital subtraction angiography were examined in 56 sides, including 34 sides in paediatric cases and 22 sides in adult cases. The neovascularization after indirect revascularization using the 1) superficial temporal artery (skin), 2) middle meningeal artery (dura mater), 3) deep temporal artery (temporal muscle) was analyzed. As results, in paediatric cases, the deep temporal artery and middle meningeal artery induced good neovascularization. However, the induction of neovascularization from the superficial temporal artery was not always good in most pediatric and adult cases. On the other hand, the direct bypass was useful in 90% of adult cases. In indirect revascularization surgery for moyamoya disease, the temporal muscle (the deep temporal artery) and the dura mater (the middle meningeal artery) are useful donors to the ischemic brain. The simple encephalo-arterio-synangiosis is not always effective. The direct bypass is a useful technique for adult moyamoya disease.

Adult↗

Short-term effect of the stabilization appliance on masticatory muscle activity in myogenous craniomandibular disorder patients.

The short-term effect (4 to 6 weeks) of a stabilization appliance on masticatory muscle activity was investigated in 26 myogenous craniomandibular disorder patients. The patients were instructed to clench at 10% and 50% of their maximum clenching effort in the intercuspal position and on the appliance. Recordings were made before and immediately after appliance delivery, and 2 and 4 weeks after delivery. The average EMG activity of the masseter muscles remained the same during the period of appliance use, whereas the anterior temporal muscles showed an immediate and long-lasting reduction in activity. The appliance also resulted in an improvement in the balance of left and right masseter muscle activity. There was a minor improvement in temporal muscle symmetry at the 50% clenching level and after 4 weeks of appliance use.

Adolescent↗

Preliminary study of electromyographic characteristics for distinguishing centric relation and protrusion in edentulous patients.

The mean voltages of the masseter and anterior temporal muscles of 30 Chinese edentulous patients were recorded in centric relation and protrusive positions (from 1 mm to 4 mm anterior to centric relation) under two given occlusal force conditions. It was found that the mean ratio of individual voltages of the anterior temporal muscles to the masseter muscles was equal to or greater than 1.2 in centric relation, but the ratio was less than 1.2 in protrusive positions in most of the subjects. The results demonstrated that the ratio of voltages of the anterior temporal muscles to masseter muscles may be a reliable parameter for distinguishing centric relation from protrusion in Chinese edentulous patients.

Aged↗

[Electromyographic study of mastication as a function of the denture in humans].

A study of mastication was conducted using global electromyography of the masseter and anterior temporal muscles. Thirty subjects were studied and distributed between two groups. A control group of 5 patients had a complete natural dentition. A group of 25 patients presented important bimaxillary tooth-loss and wore dentures. They performed masticatory cycles with and without their dentures. The masticatory efficiency of the edentulous patients was very low when compared to the control group. The use of the dentures moderately improved function. The durations of activity of the temporal muscles were slightly lengthened (but not significantly) in the edentulous patients and the denture wearers compared to control patients. The cyclic pattern of the mastication tracings persisted. On the contrary, the durations of activity of the masseters muscles were strikingly lengthened until total disappearance of the resting phases. The cyclic pattern of the mastication tracings in controls disappeared in edentulous patients and denture wearers. In the latter, the tracings were less irregular than in the edentulous patients. In conclusion, the electrical activity of temporal muscles were slightly affected by the absence and replacement of teeth, whereas the electrical activity of the masseter muscles was markedly altered.

Adult↗

Quantitative surface EMG of pericranial muscles in headache. A population study.

Quantitative EMG from the right frontal and both temporal muscles was studied in 547 adults randomly selected from the general population. The study was part of a multifaceted, epidemiological study of different headache disorders. Surface EMG was recorded by an observer blinded to the persons' history of headache, previous illness and mental state. The present study provides data on amplitude and mean and median frequency levels in migraine and tension-type headache. Chronic headache sufferers had higher amplitude values at rest in their temporal muscles than migraineurs, subjects with episodic tension-type headache and subjects without any experience of headache, probably due to insufficient relaxation. Frequency values during maximal voluntary contraction were decreased in chronic headache subjects and decreased with increasing frequency of headache in the previous year, indicating that chronic fatigue and/or changed fiber type composition exist in frequent headache sufferers. During experimental cold and pain stimulation no significant differences between headache subjects and the rest of the population were detected. Only subjects without any experience of headache had increased amplitude values during pain stimulation. No significant relation of amplitude values to frequency of tension-type headache or migraine in the previous year was detected. In 66 subjects with actual headache amplitude values were increased in the frontal muscle during rest indicating increased tension. Moreover, amplitude values were decreased in both the temporal and the frontal muscles during maximal voluntary contraction indicating submaximal contraction during pain. The present study supports the importance of peripheral factors such as increased fatigability, morphological, and/or metabolic changes in the pathogenesis of tension-type headache. However, the diagnostic value of EMG in migraine and tension-type headache is limited.

Adult↗

Rate modulation of jaw-elevator motor units as revealed from the low-frequency power spectrum of the surface electromyogram in myogenous CMD patients.

The firing pattern of the motor units (MUs) in jaw-elevator muscles was studied within a wide range of isometric contraction levels by means of changes in the frequency and broadness of the primary peak in the low-frequency (5-40 Hz) power spectral density function of the surface EMG. EMG was recorded from both masseter and anterior temporal muscles in 11 myogenous CMD patients as well as in 11 gender- and age-matched controls who clenched in intercuspal occlusion under the control of visual feedback at various levels (0.5-67% MVC for the various muscles studied). The EMG was digitized for 12 periods of 1.6 s per condition; the power spectrum was averaged and smoothed for the various clenching levels. Linear regression analysis showed that the positive slope in the peak frequency (PF)/% MVC relationship, a measure of rate modulation of the MUs, did not differ significantly between patients and controls. At a low clenching level, PF was smaller (p < 0.01) for the anterior temporal muscles of the patients, suggesting lower firing rates for a wide range of clenching levels of the patients because of a similar rate modulation for patients and controls. Furthermore, the variance in the slope values was larger (p < 0.05) for the masseteric muscles of the patients, which may be explained by more heterogeneity of the masseteric rate modulation in the patient group. The broadness of the primary peak was smallest at a low clenching level (p < 0.001) for the anterior temporal muscles of the patients, suggesting a more uniform firing rate or more synchronization between MUs.

Action Potentials↗

Normal contrast enhancement of extraocular muscles: fat-suppressed MR findings.

PURPOSE: To evaluate contrast enhancement of normal extraocular muscles in the orbit. METHODS: Noncontrast and contrast-enhanced T1-weighted images of the orbit were acquired using a fat-suppression MR technique in eight patients with no orbital disease. Contrast enhancement of 64 extraocular muscles was evaluated and compared with that of 16 temporal muscles. RESULTS: Compared with temporal muscles, all extraocular muscles markedly enhanced after administration of contrast material. CONCLUSIONS: Because normal extraocular muscles enhanced markedly with contrast material, more attention should be paid to these muscles when using contrast-enhanced, fat-suppressed T1-weighted MR imaging to evaluate pathologic conditions.

Adipose Tissue↗

Analysis of masticatory muscle condition using the 4-dimensional muscle model for a patient with square mandible.

The present study was conducted to ascertain characteristics of mandibular movements in patients with SQM, observe the kinetics of masticatory muscles using a four-dimensional (4D) muscle model, and kinetically investigate the etiology of Square Mandible (SQM). As results, 1, In the maximum opening position, location of the condyle was beyond the articular tubercle for volunteer, but within the mandibular fossa for SQM patient. 2, While the temporal muscle of volunteer was markedly expanded, that of SQM patient was not. 3, In both volunteer and SQM during left lateral excursion, the right mandibular condyle moved to a position slightly before the lowest point of the articular tubercle. The 4D muscle model showed that the cause of limited mouth opening in SQM patient was insufficient expansion of the temporal muscle, and not dysfunction of the opening muscles. Insufficient expansion of the temporal muscle stresses the masseter muscle and leads to hypertrophy of the masseter muscle and hyperplasia of the mandibular angle, resulting in the unique facial configuration.

Adult↗

Biomechanical model of the human mandible in unilateral clench: distribution of temporomandibular joint reaction forces between working and balancing sides.

In a previous article we reported on our development of a biomechanical analog of the human mandible and a simple support model was introduced. The model has been further developed to calculate the relative degree of load on the working and balancing sides of the temporomandibular joint during unilateral clench. The relative load on each joint is a function of the biting force, the geometric setting (subject's anatomy, points of application of the biting force on the dental arch and of the resultant of the forces of the masticatory muscles), and the value of the electromyographic asymmetry (relative contribution of working-versus balancing-side muscles) and activity indexes (relative contribution of masseter versus anterior temporal muscle of both sides). The proposed biomechanical model showed that the reaction forces that act on the temporomandibular joint during unilateral clench do not always load the balancing-side joint more than the working-side joint. Modifications of the asymmetry index changed the relative load between the two joints, and a higher temporal muscle activity increased the joint load on both the working and the balancing sides.

Biomechanical Phenomena↗

[Influences of changing vertical dimension, occlusal contacts of bite plane and body position on masticatory muscle activities].

The Bite plane therapy has been accepted to be useful for treatment of the patients with the stomatognathic dysfunction. The purpose of this study is to make clear the influences of changing the vertical dimension and occlusal contacts of the bite plane on masticatory muscle activities in order to improve the bite plane therapy. The full arch bite plane with an interincisal distance of 5 mm was fabricated for each one of 30 subjects without stomatognathic dysfunction. The EMG activities were recorded from the anterior part of the temporal muscles, the masseter muscles and the anterior belly of the digastric muscles bilaterally while the subject exerted tapping and maximal voluntary clenching in a postural position. Four kinds of experiments were performed as follows. In Exp. 1, integrated EMG activities of each muscle were compared with and without the bite plane. In Exp. 2, the influences of changing the vertical dimension of the bite plane (2.5 mm, 5 mm and 7.5 mm) were tested in 17 subjects. In Exp. 3, the influences of changing the location of occlusal contacts of the bite plane were studied in 12 subjects. In Exp. 4, the influence of changing the body positions on EMG activities and mandibular positions was compared in 30 subjects between the sitting and supine positions. Furthermore, the influence of the same factor was compared with and without the bite plane which was adjusted in each position. The results were summarized as follows: 1. Wearing the bite plane mainly reduced activities of the temporal muscles. 2. The bite plane with an interincisal distance of 5 mm was most effective in reducing activities of the temporal muscles. 3. Wearing the bite plane with anterior occlusal contacts reduced activities of the elevator muscles significantly. 4. Significant differences in activities of the temporal and digastric muscles were recognized between the two body positions when the bite plane was not applied. However, no significant difference was recognized when the bite plane was inserted. Furthermore, those differences were correlated with the difference in the antero-posterior mandibular displacement between the two body positions while the subject tapped the teeth. These results suggest the possibility to control masticatory muscle activities by applying the bite plane with the proper vertical dimension and occlusal contacts. In addition, it is necessary to take a suitable body position for the patient who has a difference in the mandibular displacement between the sitting and supine positions when applying the bite plane.

Dental Occlusion↗

[Electromyographic study on lateral jaw movements].

This study aims to analyse how jaw-closing muscle activities are modulated during lateral jaw movement. Jaw movements were recorded by Sirognathograph (Siemens Co.) and electromyograms were simultaneously recorded from bilateral masseter, anterior temporal and posterior temporal muscles in 20 young adults without any stomatognathic dysfunction. Each subject sat upright in the chair with the head unsupported. The lateral jaw movements from the intercuspal position were guided three times for each lateral excurtion (right and left). The data were recorded on magnetic tape and later analysed by use of a computer. Following variables were analysed; the number of contacted teeth, the position of contacted teeth, the muscle activities during lateral jaw movement. The results can be summarised as follows; 1) The working-side posterior temporal muscle showed obvious activity in more than 90% subjects during lateral jaw movement. However, this muscle activity was not influence by the number or position of the contacted teeth. 2) The right side masseter muscle tended to show the obvious activity during both right and left lateral jaw movement. The results of this study suggest the difference in the activities between masseter and temporal muscle during lateral jaw movement.

Dental Occlusion↗

Tenderness on palpation and occlusal abnormalities in temporomandibular dysfunction.

Tenderness on palpation indicates objective painful symptoms. This study investigated the tenderness of the temporomandibular joint, muscles and their relation to occlusion in patients with temporomandibular dysfunction. Two hundred ten patients were examined; 96% had tenderness and 80% of cases of tenderness were diagnosed as occlusally related. The average number of tender areas was 5.4 per patient, despite the contribution of occlusion. Tenderness was observed most frequently in the lateral pterygoid muscle, followed by the insertion of temporal muscle. There was no correlation of temporomandibular joint tenderness to muscle tenderness, while tenderness of certain muscles to each other was correlated. Differences were related to the state of occlusion in the number of tender areas, to the ratio to tenderness of elevator muscles to horizontally acting muscles, and to the frequency of unilateral tenderness. The association of muscle tenderness and occlusion was suggested.

Adolescent↗

Giant petrous carotid aneurysm treated by submandibular carotid-saphenous vein bypass. Case report.

Petrous and cavernous sinus carotid artery (CA) aneurysms that are not amenable to clip ligation or endovascular therapy may be successfully treated by a saphenous vein bypass, thereby preserving the patency of the CA. The authors report the unique case of a 47-year-old man with a giant fusiform aneurysm of the petrous CA, who presented with a rapid onset of a lateral rectus palsy and diplopia. The lesion was treated by trapping the aneurysm and performing a saphenous vein bypass from the cervical to the intracranial CA. The saphenous vein graft was routed beneath the condyle of the mandible to reduce the overall length of the graft, thereby increasing the likelihood of long-term patency and offering protection to the graft by the mandible, temporal muscle zygomatic process, and masseter and temporal muscles. The presentation and technical aspects of the bypass graft in this unique case are discussed.

Anastomosis, Surgical↗

Patterns of electromyographic activity in subjects with different skeletal facial types.

Integrated electromyographic activity of masseter and anterior temporal muscles was recorded using bipolar surface electrodes in 33 young adults. Subjects were skeletally classified according to ANB angle reading corrected both for maxillary position and rotation of the jaw. Postural activity for both muscles was higher in Class III subjects than in Class I and Class II, whereas in Class I and II subjects activity was similar. During swallowing, masseter muscle activity in Class III subjects was higher than Classes I and II, whereas anterior temporal muscle activity was not different between Classes III and I. During maximal voluntary clenching, activity was not different among classes. High correlations between electromyographic activity and corrected ANB angle as well as with overjet were observed. Skeletal classification used in the present study may have clinical relevance regarding treatment and prognosis, as well as in the assessment of the relationship between muscular activity and craniofacial characteristics.

Adolescent↗

[Giant cell tumor of the temporal bone--case report (author's transl)].

The majority of giant cell tumors occurs in the long bones, especially around the knee, and only 1.4-1.8% of cases are found in the skull. In this communication, a case of giant cell tumor of the temporal bone is reported because of a rarity of the lesion in the skull. The 37-year-old housewife was admitted to our clinic complaining of swelling in right temporal region which had gradually developed over a two-month period. On examination, there was a swelling about 5cm in diameter beneath right temporal muscle; its surface was smooth and its consistency was hard. Tenderness was found in its center. Routine x-ray of the skull showed osteolytic lesion in right temporal bone with relatively clear margins. Computed tomography demonstrated heterogeneously high-density mass in right temporal bone and right middle fossa. The tumor located mainly within the temporal bone at the middle fossa, and intracranial epidural space at the convexity. After bolus injection of contrast material, the tumor of temporal bone and the peripheral portion of the intracranial tumor were enhanced markedly. Right external carotid angiograms disclosed tumor stain in capillary and venous phases. Abnormal RI uptake was disclosed by bone scintigrams with 99mTC-methylene diphosphonic acid. Her preoperative diagnosis was calvarial tumor with intracranial extension. A right fronto-temporal osteoplastic craniotomy was performed. The tumor located within the temporal bone and in epidural space which invaded temporal muscle and underlying dura. The tumor was elastic soft and vascular with central necrosis. The tumor was extirpated totally including surrounding temporal muscle and dura. Microscopic examination of the operative specimen revealed giant cell tumor of the skull. Therefore, she was treated with 60CO irradiation (3,000 rads) to the temporal region. In the 13 months since the completion of treatment, there has been no sign of recurrence nor metastasis. Giant cell tumor of the skull were reviewed with special references to diagnosis and treatment. Computed tomographic findings of this tumor were also discussed briefly.

Adult↗

[Amitriptyline in therapy of chronic tension headache].

In a double-blind, placebo-controlled trial, the effect of 75 mg of a slow-release formulation of amitriptyline on the clinical severity of chronic tension-type headache and on headache-associated neurophysiological parameters (EMG activity, exteroceptive suppression of temporal muscle activity, contingent negative variation (CNV) and experimental pain sensitivity) was investigated. All of the patients treated had a history of headaches of many years standing, and numerous failed attempts at treatment. In the amitriptyline group, a significant reduction in daily headache duration was already found in the third week of treatment, while in the placebo group no significant changes in headache duration were to be seen. In week 6 the amitriptyline group had a significantly shorter daily duration of headache than the placebo group. Treatment did not result in any significant effects on EMG recording of pericranial muscle activity either during relaxation or contraction, on exteroceptive suppression of the temporal muscle and on CNV. The sensitivity to suprathreshold experimental pain, however, was significantly reduced. The data show a statistically relevant reduction of daily headache duration in chronic tension-type headache. However, they also show that amitriptyline can only partly alleviate chronic headaches but cannot cure them.

Adolescent↗

Muscular tenderness evaluated by surface EMG frequency analysis of isometric contractions.

Myoelectric power spectrum analysis was used to compare muscular activity in the masseter and anterior temporal muscles between patients with tender masseter muscles and healthy controls. Surface EMG was recorded for 28 patients and nine controls while they were biting on a bite force transducer during a period of 10-15 s up to maximal effort (100% MVC). The mean frequency (MF) was calculated as a single estimate of the myoelectric power spectrum. Regression analyses of MF's for the masseter muscles versus the force level 0-60% MVC showed significantly less steep slopes of regression for the patients compared interindividually with the controls. As regards the anterior temporal muscles there was no significant difference between groups. One explanation for the difference in MF's for the masseter muscles between patients and controls is that the patients suffered an inhibition or difficulty in recruiting motor units. Different firing rate properties for motor units at high force levels (60-100% MVC) could be one reason for a significantly smaller decrease in MF for the patients' elevator muscles than for the controls.

Adult↗