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Counseling and physical therapy as treatment for myofascial pain of the masticatory system.

AIMS: To prospectively evaluate the effectiveness of a treatment regimen comprising counseling and physical therapy in patients with myofascial pain of the masticatory system, and to explore whether the duration of the physical therapy offered (4 vs 6 weeks) would influence the treatment result. METHODS: Twenty-six patients were randomly distributed over 2 groups. All patients received reassuring information, advice regarding relaxation of the jaws, avoiding parafunctions, and limited use of the jaws. In addition, a physical therapy program (heat application, massage, ultrasound and muscle stretching) was initiated 2 weeks after the start of the study (group I, receiving 4 weeks of physical therapy) or immediately from the start of the study (group II, receiving 6 weeks of physical therapy). The following parameters were taken at baseline, 2, 4, and 6 weeks: visual analog scale (VAS) scores of present pain; lowest and highest pain over the past period; percentage of pain relief; jaw function assessment by the Mandibular Function Impairment Questionnaire (MFIQ); and pressure pain thresholds (PPTs) of the masseter, temporalis, and thumb muscles. Statistical analysis used a linear mixed model and corrected for multiple testing (Tukey test). RESULTS: Pain and MFIQ scores decreased while PPTs increased in both groups. Only after 4 and 6 weeks, significant differences were present for the PPT of the masseter in group I (P < .02) and the temporalis in both groups (P < .01). Also, the VAS scores of present (P < .02), minimal (P < .01), and maximal (P < .0001) pain and the MFIQ score (P < .001) improved. After 6 weeks, a mean of 60% pain decrease was reported (P < .0001). There were no significant differences between the groups receiving 4 weeks vs 6 weeks of physical therapy. CONCLUSION: A conservative approach involving counseling and physical therapy resulted in significant improvement in parameters of pain and jaw function in patients with myofascial pain. A controlled study will be necessary to elucidate the specific effectiveness of physical therapy over counseling or no treatment.

Adolescent↗

Formation of leptofibrils is associated with remodelling of muscle cells and myofibrillogenesis in the border zone of myocardial infarction.

Leptofibrils, or leptomeres, remain the least studied cytoskeletal structures in muscle cells, and their function and mechanism of assembly are still poorly understood. Our ultrastructural study of the surviving cardiac myocytes located in the perinecrotic border zone of the infarcted left ventricle in rats revealed intense formation of leptofibrils and leptofibrillar clusters during 4-15 days following experimental myocardial infarction. In the perinecrotic myocytes, leptofibrils developed predominantly in the subsarcolemmal areas, near disassembled intercalated discs and at the sites of intense myofibrillogenesis in the peripheral zones of the sarcoplasm. We found that the development of these structures occurred before or at the time of assembly of myofibrils. In our material, leptofibrils consisted of longitudinally oriented filamentous bundles inserted in electron dense Z-band-like material and periodically crossed by 3-8 bands of this material with the period of cross-striation of 120-210 nm. The presence of leptofibrils in growing cytoplasmic processes and ruffles developing in the border zone in the areas of lost intercellular contacts indicates their formation de novo during post-infarction period. We observed four major morphological types of localization of these structures: (1) direct contact of one end of leptofibrils with Z bands of nascent, mature or disassembling myofibrils; (2) direct contact with the sarcolemma: (a) multifocal attachment of leptofibrils to the sarcolemma through the lateral surfaces of their minute Z band-like structures; (b) attachment of one or both ends of leptofibrils to the sarcolemma without contacts or in contact with myofibrils; (3) attachment of leptofibrils to subsarcolemmal accumulations of electron dense Z-band material in newly formed fasciae adherentes of the remodeled intercalated disks; (4) clustering and contacts of leptofibrils with one another predominantly at the level of their Z bands. Interestingly, most leptofibrils of all four types were topographically associated with the system of T-tubules, the sarcoplasmic reticulum and subsarcolemmal vesicles. Serial sections through the areas containing leptofibrils indicate their spindle-like or nearly cylindrical shape. Thus, we found that leptofibrils assemble in terminally differentiated cardiac myocytes following destabilization of their differentiated state and partial dedifferentiation induced by myocardial infarction. The results of this study demonstrate that formation of leptofibrils, earlier described mainly in the developing and malignant muscle, is temporally associated with adaptive structural remodelling and the activation of myofibrillogenesis in functionally overloaded cardiac myocytes of adult animals. Our findings suggest that re-expression of some structural characteristics of the embryonic muscle appear to represent one of the mechanisms that underlie adaptive plasticity of the myocardium following injury and under conditions of hyperfunction.

Animals↗

Influence of periodontal receptors on the jaw-jerk reflex amplitude in man.

To study the role of periodontal mechanoreceptors in the modulation of the human jaw-jerk reflex, 60 reflexes were elicited in each of six healthy individuals under three different conditions: (a) with unilateral tooth support on the ipsilateral side; (b) with support on the contralateral side; and (c) with support and local anesthesia of the periodontal tissues on the ipsilateral side. During all conditions, background muscle activity and mandibular displacement were kept as constant as possible. Using on-surface EMG and the amplitude of the first peak of the biphasic jaw-jerk potential as the outcome variable, a condition-dependent reflex amplitude was found for the visually controlled right anterior temporalis muscle. Specifically, the 'ipsilateral support plus anesthesia' condition yielded higher amplitudes than the 'ipsilateral support' condition. Highest amplitudes were found for the 'contralateral support' condition. It was concluded that periodontal mechanoreceptors on the ipsilateral side have an inhibitory effect on the jaw-jerk reflex amplitude in the anterior temporalis muscle.

Adult↗

Sarco(endo)plasmic reticulum Ca2+ pump and metabolic enzyme expression in rabbit fast-type and slow-type denervated skeletal muscles. A time course study.

Recent reports by d'Albis et al. have shown that denervation of 8-day-old rabbit fast-twitch muscle (gastrocnemius) leads to the transformation of the muscle towards a slow phenotype but the changes towards slow-type myosin isoforms and contractile properties of the muscle were temporally uncoordinated. We analyzed the time course of the effects of denervation of the gastrocnemius on the expression of the sarcoplasmic reticulum calcium pump isoforms (SERCA) and on the metabolic state of the muscle. Northern-blot analysis showed a rapid loss of the fast Ca2+ pump isoform (SERCA 1) mRNA from the denervated gastrocnemius which became of the oxidative type. The changes observed were complete as early as 35 days post-natal, i.e at the time when changes in contractile properties were previously observed. Denervation of the slow-twitch soleus led to a 50% decrease in the level of the slow Ca2+ pump isoform (SERCA 2) mRNA and was without effect on the metabolic state of the muscle. These findings extend previous results suggesting that in rabbit, continuous innervation is required for differentiation of fast-twitch muscles but is not an absolute requirement for differentiation of the slow-twitch muscle.

Animals↗

Excitatory actions of experimental muscle pain on early and late components of human jaw stretch reflexes.

It has recently been shown that a slow stretch evokes a short-latency (probably monosynaptic) and a long-latency (polysynaptic) reflex response in human jaw-closing muscles. The effect of nociceptive muscle input on the fusimotor system has not been investigated in detail. In order to investigate the effect of sustained muscle pain on the jaw stretch reflex, two main experiments were performed. Stretch reflex responses were evoked in the masseter and temporalis muscles by slow stretches (1-mm displacement, 40-ms ramp time) before, during and 15 min after a period of experimentally induced muscle pain. In experiment I, a dose of 1.0 M hypertonic or 154 mM isotonic (control) saline was infused in random order into the left masseter for up to 15 min (n=12). The level of excitation of the left masseter at 15% maximal voluntary contraction was controlled by visual feedback of the surface EMG (sEMG). In experiment II, a dose of 1.0 M saline was infused into the left masseter but with feedback from the sEMG of the right masseter (n=12). In a control experiment, both sEMG and intramuscular EMG (imEMG) were recorded from the left and right masseters; the feedback was from imEMG of the left masseter (n=12). The early (onset: 9--10 ms) and late (duration from 25 to 40 ms) reflex components were recorded and analysed in all experiments. Infusion of 1.0 M saline caused moderate pain (mean score on a Visual Analogue Pain Scale: 4.9--5.0 cm). The peak-to-peak amplitude of the early reflex component in the painful masseter normalized to the pre-stimulus EMG activity was significantly higher during the pain than the pre- and post-infusion conditions in all experiments. The normalized area of the late reflex component in the painful masseter was significantly larger than in the pre-infusion condition in all experiments. Isotonic saline had no significant effect on the jaw stretch reflexes. These results indicate that experimental jaw-muscle pain in humans facilitates the early as well as the late component of the jaw stretch reflex response as revealed by both sEMG and imEMG. This effect appears to be independent of the level of excitation of the muscle and not related to volume effects of the injected saline. A change in the sensitivity of the fusimotor system during muscle pain is suggested as an explanation.

Adult↗

The reproducibility of muscle and joint tenderness detection methods and maximum mandibular movement measurement for the temporomandibular system.

The purpose of this study was (1) to evaluate the reproducibility of two masticatory muscle and joint tenderness detection methods; (2) to evaluate the reproducibility of maximum mandibular movement measurements; and (3) to investigate factors influencing examiner agreement. The tenderness assessment procedures involved application of a standard pressure for 2 seconds over four anatomically defined masticatory muscle sites, one control forehead site, and two temporomandibular joint sites on each side of the face. One technique utilized a pressure algometer (PAP), while the other technique required that a trained examiner apply pressure with the index fingertip (FPP). Seventy-two subjects (36 patients and 36 controls) were evaluated in a single-blind study design. Control subjects were matched for age, gender, and race with temporomandibular disorder subjects. Each subject was examined twice with each of the described methods in a randomized, fully balanced sequence by calibrated examiners. Tenderness levels were determined by the subject via self-report of pain upon pressure using a standard set of verbal descriptors. Maximum pain-free, active, and passive opening, and maximum active right and left lateral movements were measured using a millimeter ruler. Intraclass correlation coefficients (ICC) for the tenderness assessment methods ranged from 0.220 to 0.739 for the FPP method and from 0.391 to 0.880 for the PAP method. ICCs for mandibular movement measurement were much less variable, ranging from 0.59 to 0.68 for lateral movement and from 0.78 to 0.93 for opening movement. These results indicate good to excellent agreement between calibrated examiners for mandibular movement measurement and for tenderness assessment methods at two masseter (i.e., superficial and deep) and the anterior temporalis sites. Only fair agreement was found for the middle temporalis and lateral TMJ capsule sites using these methods.

Adult↗

Lateral orbitotomy without removal of the lateral orbital rim.

Lateral orbitotomy is used for the removal of orbital tumors and for orbital decompression. Most surgeons make saw cuts through the lateral orbital rim and remove and rewire the bone. This procedure is time-consuming and requires repair of the lateral canthal structures. We describe a technique using an air-driven "acorn-tipped" bur that removes the posterolateral lip of the frontal process of the zygomatic bone and effectively straightens the external surface of the lateral orbital wall. This permits removal of the bone without serious injury to the periorbita. The technique creates a trapezoidal orbitotomy measuring approximately 20 mm anteroposterior, 25 mm at the anterior vertical base, and 6 mm at the posterior base. The orbital soft tissues can thus be safely exposed without removal of the lateral rim. We operated on one patient with cavernous hemangioma (27 X 21 X 19 mm) and three patients with bilateral Graves' ophthalmopathy. We discuss anatomic considerations for the prevention of complications, including injury to the frontotemporal branches of the facial nerve, injury to the superior head of the lateral pterygoid muscle, and inadvertent penetration of the dura.

Dissection↗

Exteroceptive silent periods of temporalis muscle activity: correlation with neuropsychological findings.

The latency and duration of the early (ES 1) and late (ES 2) exteroceptive silent period of temporalis muscle activity were determined in 51 neurological patients. We investigated whether these electrophysiological parameters correlated with neuropsychological variables of the patients using standardized scores for personality index, state of well-being and physical symptoms. There were no correlations between personality traits and the electrophysiological parameters, while we found significant correlations between the duration of ES 2 and momentary psychological and physical well-being variables. Moreover, the score of the momentary well-being item 'general feeling of well-being' was demonstrated to moderate significantly the ES 2 duration (P = 0.018). Therefore, neuropsychological factors prove to be of great relevance to the exteroceptive silent periods of temporalis muscle activity.

Adolescent↗

Juxtapositioning of the temporalis muscle for intractable subdural empyema in infants.

We present a case of refractory infantile subdural empyema secondary to pneumococcal meningitis. Initial treatment was with antibiotics and multiple burr hole drainage of the subdural space. As there was no significant improvement with this standard procedure, craniectomy, and juxtapositioning of the temporalis muscle was conducted and the patient recovered promptly.

Brain↗

Dynamic reconstruction of eye closure by muscle transposition or functional muscle transplantation in facial palsy.

For patients with facial palsy, lagophthalmus is often a more serious problem than the inability to smile. Dynamic reconstruction of eye closure by muscle transposition or by free functional muscle transplantation offers a good solution for regaining near-normal eye protection without the need for implants. This is the first quantitative study of three-dimensional preoperative and postoperative lid movements in patients treated for facial paralysis. Between February of 1998 and April of 2002, 44 patients were treated for facial palsy, including reconstruction of eye closure. Temporalis muscle transposition to the eye was used in 34 cases, and a regionally differentiated part of a free gracilis muscle transplant after double cross-face nerve grafting was used in 10 cases. Patients' facial movements were documented by a three-dimensional video analysis system preoperatively and 6, 12, 18, and 24 months postoperatively. For this comparative study, only the data of patients with preoperative and 12-month postoperative measurements were included. In the 27 patients with a final result after temporalis muscle transposition for eye closure, the distance between the upper and lower eyelid points during eye closing (as for sleep) was reduced from 10.33 +/- 2.43 mm (mean +/- SD) preoperatively to 5.84 +/- 4.34 mm postoperatively on the paralyzed side, compared with 0.0 +/- 0.0 mm preoperatively and postoperatively on the contralateral healthy side. In the resting position, preoperative values for the paralyzed side changed from 15.11 +/- 1.92 mm preoperatively to 13.46 +/- 1.94 mm postoperatively, compared with 12.17 +/- 2.02 mm preoperatively and 12.05 +/- 1.95 mm postoperatively on the healthy side. In the nine patients with a final result after surgery using a part of the free gracilis muscle transplant reinnervated by a zygomatic branch of the contralateral healthy side through a cross-face nerve graft, eyelid closure changed from 10.21 +/- 2.72 mm to 1.68 +/- 1.35 mm, compared with 13.70 +/- 1.56 mm to 6.63 +/- 1.51 mm preoperatively. The average closure for the healthy side was from 11.20 +/- 3.11 mm to 0.0 +/- 0.0 mm preoperatively and from 12.70 +/- 1.95 mm to 0.0 +/- 0.0 mm postoperatively. In three cases, the resting tonus of the part of the gracilis muscle transplant around the eye had increased to an extent that muscle weakening became necessary. Temporalis muscle transposition and free functional muscle transplantation for reanimation of the eye and mouth at the same time are reliable methods for reconstructing eye closure, with clinically adequate results. Detailed analysis of the resulting facial movements led to an important improvement of the authors' operative techniques within the last few years. Thus, the number of secondary operative corrections could be significantly reduced. These qualitative and quantitative studies of the reconstructed lid movements by three-dimensional video analysis support the authors' clinical concept of temporalis muscle transposition being the first-choice method in adult patients with facial palsy. In children, free muscle transplantation is preferred for eye closure, so as not to interfere with the growth of the face by transposition of a masticatory muscle. In addition, a higher degree of central plasticity in children might be expected.

Adolescent↗

Comparison of algometry and palpation in the recognition of temporomandibular disorder pain complaints.

AIMS: To determine the construct validity of algometry and to compare it with that of palpation, and to compare tenderness of masticatory muscle sites and the temporomandibular joint (TMJ) on palpation and on algometry. METHODS: Two hundred fifty subjects, 148 with temporomandibular disorder (TMD) pain complaints, underwent a standardized blinded physical examination that included pain-intensity measures on palpation and pressure pain threshold measures on algometry of masseter muscle sites, temporalis muscle sites, and the TMJ. RESULTS: Logistic regression analysis indicated that the recognition of TMD pain complaints based on pressure algometry was comparable to that of palpation (R2 = 0.22 and R2 = 0.21, respectively). The masseter muscles were most tender to palpation and algometry, followed by the TMJs and the temporalis muscles. CONCLUSION: Construct validity of algometry in the recognition of TMD pain complaints is comparable to that of palpation, and differences in tenderness on palpation and on algometry are found between masticatory muscle sites and the TMJ.

Adult↗

Value of EMG analysis of mandibular elevators in open-close-clench cycle to diagnosing TMJ disturbance syndrome.

The EMGs of the temporal and masseter muscle, in sixty patients with temporomandibular joint disturbance syndrome (TMJDS) and thirty normal controls, were recorded during rhythmical open-close-clench cycle movement and before and after occlusal splint therapy. The duration of the muscle contraction before initial tooth contact (DMC), the latent period (LP) and the silent period (SP) of the myoelectrical activity were used as indices for exploring their diagnostic value. In contrast with the controls, DMC, LP and SP lengthened in the patients. The DMC was prolonged in those patients where there were TMJ sounds, the inter-cuspated position did not coincide with the muscular contact position and there was deviated mandibular movement. An increase of the SP was related to tooth contact on the balancing side. After treatment, the DMC and SP in the patients returned to the level of the controls. It was found that the internal correction rate of Fisher's linear discriminate function established for the DMC and SP of the temporal and masseter muscles was 80.9% and 85.1% respectively. The results show that the DMC and SP of the temporal and masseter muscles have some value in diagnosing muscular dysfunction and discriminating therapeutic effectiveness.

Adult↗

[Uptake and transport of exogenous peroxidase in the masticatory muscles of cats. Localization of ganglionic neurons].

Retrograde axonal transport of Horseradish peroxydase (HRP) has been used to trace the cells of origin of proprioceptive fibers in jaw-closing and jaw-opening muscles. After injection of HRP in young cats' masticatory muscles (masseteric, temporal, pterygoid, mylohyoid and digastric) labelled neurons were found in the ipsilateral semi-lunar ganglion and trigeminal mesencephalic nucleus. It is concluded that sensory endings are present in jaw-opening as in jaw-closing muscles; possibly the afferent fibers from muscle endings of the opener muscles have their somata in the mesencephalic nucleus, afferent fibers from tendinous receptors in the semi-lunar ganglion.

Animals↗

Orexin B immunoreactive fibers and terminals innervate the sensory and motor neurons of jaw-elevator muscles in the rat.

The relationship between orexinergic terminals and the sensory and motor neurons of jaw-elevator muscles was examined by means of anti-orexin B (OXB) immunohistochemistry combined with horseradish peroxidase (HRP) retrograde tracing in the rat. HRP was initially injected into the jaw-elevator muscles; 48 h later the animals were sacrificed and fixed for HRP reaction and anti-OXB immunohistochemistry. OXB-like terminals were observed to distribute in the trigeminal mesencephalic nucleus (Vme) and the trigeminal motor nucleus (Vmo) where they closely contact the Vme neuronal somata and the Vmo neuronal somata and dendrites retrogradely labeled with HRP. The results of this study provide anatomical evidence of a direct OXB orexinergic innervation of the sensory and motor neurons controlling jaw-elevator muscles involved in mastication. Its functional significance related to the feeding behavior and bruxism is discussed.

Animals↗

Induction of facial muscle neurotization by temporalis muscle transposition: literature review and animal model evaluation using horseradish peroxidase uptake.

OBJECTIVE: To study the concept of facial muscle reinnervation from the trigeminal pathway following facial nerve paralysis. DESIGN AND METHODS: We studied this phenomenon in an animal model using the neuronal marker, horseradish peroxidase (HRP). The temporalis transposition procedure was performed at varying intervals post facial nerve transection. To evaluate the trigeminal-facial reinnervation process and its timing, the zygomaticus major muscle was injected with HRP at varied periods after temporalis transposition, and histologic sections of the brainstem nuclei were examined for the final location of the HRP. RESULTS: The presence of HRP in the trigeminal nucleus provided evidence of trigeminal-facial neurotization in those animals that underwent temporalis transposition up to 2 months following facial denervation and in which the HRP injection was performed 4 months after temporalis transposition. CONCLUSIONS: The findings of our pilot study are strongly supportive of the trigeminal-facial neurotization hypothesis in those animals that underwent temporalis transposition up to 2 months post facial denervation and in which 4 months were allowed thereafter for adequate neurite ingrowth and neurotization to occur. This suggests that the neurotrophic signals are greatest up to 2 months post denervation and denotes the optimal time for performance of reconstructive procedures. Future studies with a larger number of animals in each group will be necessary to ensure more potent statistical significance and to augment our experimental evidence that trigeminal-facial crossover does occur and can be used as an adjunctive concept to maximize early rehabilitation of the paralyzed face.

Animals↗

Does the ovarian cycle influence the pressure-pain threshold of the masticatory muscles in symptom-free women?

AIMS: To test the hypothesis that the ovarian cycle influences the pressure-pain threshold of the masticatory muscles. METHODS: Eighteen healthy women with a regular menstrual cycle (28 +/- 2 days), ranging in age from 18 to 35 years, participated in the study. For each subject, pressure-pain thresholds (PPTs) of the masseter and temporalis muscles were assessed at 4 muscular sites by means of an electronic algometer. Measurements were taken at 4 separate sessions across the menstrual cycle corresponding to the following phases: menstrual, follicular, periovulatory, and luteal. Menstrual cycle phases were determined by a pelvic ultrasonographic screening. The study was carried out in a single-blind design, and the initial session was randomly determined for each individual. Data collected were analyzed by repeated-measures analysis of variance. RESULTS: The findings suggest that the PPTs of several masticatory muscles (2 of 4) are influenced by the ovarian cycle, but to a minor extent (P < 0.05), and the influence is of limited clinical relevance. CONCLUSION: In healthy subjects, there is a link between mechanical sensitivity of the masticatory muscles and fluctuation of the ovarian hormones. The relationship between PPTs of the masticatory muscles and the ovarian cycle should be also investigated in patients with temporomandibular disorders and/or orofacial pain conditions.

Adolescent↗