Clinical and prognostic role of sarcopenia based on masticatory muscle index on MR images in patients with extranodal natural killer/T cell lymphoma, nasal type

Sarcopenia is known to be associated with an increased risk of adverse outcomes in a variety of malignancies, but its impact in extranodal natural killer/T cell lymphoma, nasal type (ENKTL-NT) is unknown. The aim of this study was to explore the prognostic relevance of sarcopenia defined by MRI-based masticatory muscle index in ENKTL-NT patients. A total of 112 patients with newly diagnosed ENKTL-NT who underwent cranial magnetic resonance imaging (MRI) were enrolled. The masticatory skeletal muscle index (M-SMI) was measured based on T2-weighted MR images and sarcopenia was defined by M-SMI<5.5 cm2/ m2. The median M-SMI was 5.47 (4.91-5.96) cm2/m2; 58 were identified with sarcopenia in this cohort. On multivariate analyses, sarcopenia was the only independently risk factor predicting overall survival (HR, 4.590; 95% CI, 1.657-12.715; p = 0.003), progression-free survival (HR, 3.048; 95% CI, 1.515-6.130; p = 0.002), and treatment response (HR, 0.112; 95% CI, 0.042-0.301; p < 0.001). In addition, we found that integrating sarcopenia into prognostic indices could improve the discriminative power of the corresponding original model. Stratification analysis showed that sarcopenia was able to further identify survival differences in patients that could not be distinguished by prognostic models. In summary, our study suggests that sarcopenia defined by MRI-based M-SMI represents a new and routinely applicable prognostic indicator of clinical outcome or predictor of treatment response in ENKTL-NT patients, and may aid in risk stratification and treatment decisions.

Masticatory muscle index for indicating skeletal muscle mass in patients with head and neck cancer

Background

A typical assessment for sarcopenia involves the use of abdominal computed tomography (CT) for calculating the skeletal muscle index (SMI) at the level of the third lumbar vertebra (L3). However, abdominal CT is not regularly performed on patients with head and neck cancer (HNC). We investigated whether masticatory SMI (M-SMI) measurements based on head and neck CT scans can be used to conduct sarcopenia assessments by evaluating whether M-SMI is correlated with L3-SMI.

Methods

Abdominal and head and neck CT images of patients with trauma (n = 50) and HNC (n = 52) were analyzed retrospectively. Both manual delineation and threshold selection methods were used to measure cross-sectional areas of masticatory muscles and those of muscles at the L3 level on CT images. Muscle cross-sectional areas were normalized to height squared to calculate SMI, and a multivariate linear regression model was established to evaluate the correlation between the M-SMI and L3-SMI. Receiver operating characteristic curve analysis was used to assess the ability of the M-SMI to identify sarcopenia, and Cox logistic regression was used to identify predictors of sarcopenia.

Results

Patients with HNC had significantly lower M-SMI and L3-SMI than did patients with trauma (p = 0.011 and 0.03, respectively). M-SMI and L3-SMI were strongly correlated (r = 0.901, p < 0.001); in the multivariate model that included sex, the correlation was stronger (r = 0.913, p < 0.001). The associations of sarcopenia with a lower M-SMI (p < 0.001), male sex (p = 0.028), and advanced age (p = 0.011) were significant, and multivariate logistic analysis demonstrated that an M-SMI of <5.5 was an independent predictor of sarcopenia (hazard ratio = 5.37, p < 0.001).

Conclusions

M-SMI assessment in routine head and neck CT scans is feasible and can be an alternative for detecting sarcopenia in patients with HNC.

Multicompartmental Epidermoid Cyst Causing Chronic Parotid Gland and Masticator Space Muscle Atrophy

Epidermoid cysts are rare benign intracranial tumors of congenital origin. They are slow-growing and are seen to insinuate between brain structures. These are commonly located in cerebello-pontine angle and parasellar regions. The symptoms produced are primarily due to mass effect. Hearing loss, facial nerve palsy, and trigeminal neuralgia are reported when cranial nerves are involved; motor palsy of trigeminal nerve is uncommon. Here, we present an interesting case of an extensive multicompartmental epidermoid cyst causing atrophy of trigeminal nerve with radiologic evidence of chronic motor trigeminal nerve palsy characterized by atrophy of masticator space muscles and parotid gland.

[Dysfunction of the manducatory apparatus]

Temporo-mandibular disorders -TMD- involve a whole set of anatomical, physiological and clinical disorders that exceed by far the sole temporo-mandibular joint. The main symptom of this condition, most frequent in female patients, is pain. Three syndromes are associated with TMD: a muscular syndrome, not only involving masticatory muscles but also muscles of the neck and pain in seemingly unrelated anatomical regions, which can be misleading; an inflammatory articular syndrome; a mechanical syndrome affecting mouth-opening path. The main treatment of this very common and benign disorder is based on physical therapy. However, physicians should be warned that some patients might exhibit similar symptoms in rare cases of malignant tumor.

Clinical findings and outcome of dogs with unilateral masticatory muscle atrophy

BACKGROUND

Little is known about the spectrum of underlying disorders in dogs with unilateral masticatory muscle (MM) atrophy.

OBJECTIVES

To evaluate the clinical presentation, magnetic resonance imaging (MRI) findings, and outcome of dogs with unilateral MM atrophy.

ANIMALS

Sixty-three client-owned dogs.

METHODS

The medical database was retrospectively reviewed for dogs that underwent MRI for evaluation of unilateral MM atrophy. Imaging studies were reviewed and follow-up information was obtained from telephone interviews.

RESULTS

Presumptive trigeminal nerve sheath tumor (pTNST) was diagnosed in 30 dogs (47.6%); survival time varied from 1 day to 21 months (median, 5 months). Other extra-axial mass lesions were observed in 13 dogs (20.6%); survival time varied from 6 days to 25 months (median, 2.5 months). In 18 dogs (28.6%), no abnormalities were observed on MRI; neurological signs only progressed in 1 dog. Diagnosis had a significant influence on the type of neurological abnormalities, with additional neurological deficits observed in most dogs with pTNST and in all dogs with other extra-axial mass lesions. Diagnosis had a significant effect on euthanasia at the time of diagnosis and likelihood of neurological deterioration. Dogs with mass lesions were more likely to be euthanized or experience neurological deterioration, whereas these outcomes occurred less often in dogs in which no causative lesion could be identified.

CONCLUSIONS AND CLINICAL IMPORTANCE

Trigeminal nerve sheath tumors should not be considered the only cause of unilateral MM atrophy. Our results illustrate the importance of performing a neurological examination and MRI when evaluating dogs with unilateral MM atrophy.

Effect of aquaporin 1 and 4 on masticatory muscles degeneration as a result of aging

OBJECTIVE

The changes in the mouth structures due to aging cause some structural and functional changes by affecting masticatory muscles over time. The aim of this study was to evaluate the aging-related histopathologic changes and immunohistochemically assessed aquaporin 1 and 4 expressions on masseter and temporal muscles.

MATERIAL AND METHODS

14 Balb/c white mice (50-80 g) were used in this study. Group I consisted of young animals (2-month-individuals) (n = 7) and Group II consisted of older animals (18-month-old) (n = 7). After routine histological follow-ups were made, tissues were stained immunohistochemically for aquaporin 1 and aquaporin 4 as well as with hematoxylin-eosin.

RESULTS

It was seen that while the masseter and temporalis muscle tissues showed a high immunoreactivity (+++) for aquaporin 1 and 4 in young mice, they showed a weak immunoreactivity (+) for aquaporin 1 and 4 in old mice (p = 0.001). In the H-score assessment, aquaporin 1 and 4 immunoreactivity was significantly higher in young mice than in old mice (p = 0.002).

CONCLUSIONS

Consequently, it was shown that degeneration of the masticatory muscles increased with aging and there was a decrease in intra- and intercellular exchange of substances because of changing aquaporin 1 and aquaporin 4 expressions (Tab. 2, Fig. 4, Ref. 20).

Size and Orientation of Masticatory Muscles in Patients with Mandibular Laterognathism

Size measurements of jaw muscles reflect their force capabilities and correlate with facial morphology. Using MRI, we examined the size and orientation of jaw muscles in patients with mandibular laterognathism in comparison with a control group. We hypothesized that the muscles of the deviated side would be smaller than those of the non-deviated side, and that the muscles of both sides would be smaller than in controls. In patients, a comparison of deviated and non-deviated sides showed, in orientation, differences for masseter and medial pterygoid muscles, but, in size, differences only for the masseter muscle. Nevertheless, muscle sizes in patients were much smaller than in controls. Lateral displacement of the mandible can explain the orientation differences, but not the smaller muscle size, in patients. It is possible that the laterodeviation initiates an adaptive process in the entire jaw system, resulting in extensive atrophy of the jaw muscles.

The prognosis of nasopharyngeal carcinoma involving masticatory muscles: a retrospective analysis for revising T subclassifications

This work is a retrospective study of magnetic resonance imaging (MRI) and T-stage subclassifications of nasopharyngeal carcinoma (NPC) involving the masticatory muscles (MMs). We examined how involvement of MMs influences the clinical T-stage classifications and the survival outcomes of NPC patients. MRI data as well as the medical records from 816 NPC patients were analyzed retrospectively. All cases were restaged according to the seventh edition of American Joint Committee on Cancer staging system criteria. The overall survival (OS), local relapse-free survival (LRFS), and distant metastasis-free survival (DMFS) were analyzed by the Kaplan-Meier method, and their survival outcomes between different degrees of MM involvement and different T classifications were compared by using the log-rank test. All statistical analyses were conducted on SPSS 18.0 software. P > 0.05 was considered significant. Of the 816 NPC patients analyzed, 283 (34.68%) had tumors that involved MMs. All of those 283 patients involved the medial pterygoid muscle, and 125 cases (15.32%) involved the lateral pterygoid muscle. Multivariate analysis identified MM involvement as an independent prognostic factor for patient's OS (P = 0.007) and LRFS (P = 0.024). MM involvement significantly correlated with a lower OS and LRFS (P < 0.01). In addition, compared with concurrent involvement of the medial and lateral pterygoid muscle, the medial pterygoid muscle involvement correlated with a higher OS and LRFS (P < 0.05). Among NPC patients, T-classifications 1 to 4 usually predicted the ultimate OS, LRFS, and DMFS (P > 0.1), unless the cancer involved the lateral pterygoid muscle. NPC involving the lateral pterygoid muscle presents a worse survival outcome than that involving the medial pterygoid muscle. Any cancer involving the lateral pterygoid muscle should be classified in a higher T-stage subclassification.

Physiologic neuromuscular dental paradigm for the diagnosis and treatment of temporomandibular disorders

Shifting from traditional anatomical/mechanistic models, the physiologic neuromuscular dentistry (PNMD) paradigm acknowledges the primacy of physiology in shaping and controlling anatomy in a functioning human body. Occlusal disharmony from mandibular discrepancy to cranium leads to temporomandibular disorders (TMD), which is a disease of musculoskeletal imbalance in the postural chain exceeding the individual's physiologic adaptive capacity. To diagnose optimal craniomandibular alignment, PNMD is guided by real-time objective physiologic data such as electromyography (EMG).

Necrotizing and eosinophilic masticatory myositis in farmed mink: a preliminary description

This report describes necrotizing and eosinophilic myositis affecting the masticatory muscles of a group of mink. Affected animals demonstrated sudden death with marked subcutaneous oedema over the dorsal head. The temporalis and masseter muscles were pale, swollen and friable. Histologic changes consisted of varying degrees of myodegeneration, myonecrosis and inflammation. Eosinophils were prominent in the inflammatory infiltrate. Similar to dogs, masticatory muscles in mink were found to contain unique type 2M fibres, suggesting a possible target for an immune response. Aerobic and anaerobic tissue cultures of the affected musculature revealed no significant pathogens. Histological and nutritional analyses were not typical of vitamin E/selenium deficiency. This case series supports the existence of a novel disease entity in mink with some features comparable with masticatory muscle myositis in dogs.

Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) for Clinical and Research Applications: recommendations of the International RDC/TMD Consortium Network* and Orofacial Pain Special Interest Group†

AIMS

The original Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I diagnostic algorithms have been demonstrated to be reliable. However, the Validation Project determined that the RDC/TMD Axis I validity was below the target sensitivity of ≥ 0.70 and specificity of ≥ 0.95. Consequently, these empirical results supported the development of revised RDC/TMD Axis I diagnostic algorithms that were subsequently demonstrated to be valid for the most common pain-related TMD and for one temporomandibular joint (TMJ) intra-articular disorder. The original RDC/TMD Axis II instruments were shown to be both reliable and valid. Working from these findings and revisions, two international consensus workshops were convened, from which recommendations were obtained for the finalization of new Axis I diagnostic algorithms and new Axis II instruments.

METHODS

Through a series of workshops and symposia, a panel of clinical and basic science pain experts modified the revised RDC/TMD Axis I algorithms by using comprehensive searches of published TMD diagnostic literature followed by review and consensus via a formal structured process. The panel's recommendations for further revision of the Axis I diagnostic algorithms were assessed for validity by using the Validation Project's data set, and for reliability by using newly collected data from the ongoing TMJ Impact Project-the follow-up study to the Validation Project. New Axis II instruments were identified through a comprehensive search of the literature providing valid instruments that, relative to the RDC/TMD, are shorter in length, are available in the public domain, and currently are being used in medical settings.

RESULTS

The newly recommended Diagnostic Criteria for TMD (DC/TMD) Axis I protocol includes both a valid screener for detecting any pain-related TMD as well as valid diagnostic criteria for differentiating the most common pain-related TMD (sensitivity ≥ 0.86, specificity ≥ 0.98) and for one intra-articular disorder (sensitivity of 0.80 and specificity of 0.97). Diagnostic criteria for other common intra-articular disorders lack adequate validity for clinical diagnoses but can be used for screening purposes. Inter-examiner reliability for the clinical assessment associated with the validated DC/TMD criteria for pain-related TMD is excellent (kappa ≥ 0.85). Finally, a comprehensive classification system that includes both the common and less common TMD is also presented. The Axis II protocol retains selected original RDC/TMD screening instruments augmented with new instruments to assess jaw function as well as behavioral and additional psychosocial factors. The Axis II protocol is divided into screening and comprehensive self report instrument sets. The screening instruments' 41 questions assess pain intensity, pain-related disability, psychological distress, jaw functional limitations, and parafunctional behaviors, and a pain drawing is used to assess locations of pain. The comprehensive instruments, composed of 81 questions, assess in further detail jaw functional limitations and psychological distress as well as additional constructs of anxiety and presence of comorbid pain conditions.

CONCLUSION

The recommended evidence-based new DC/TMD protocol is appropriate for use in both clinical and research settings. More comprehensive instruments augment short and simple screening instruments for Axis I and Axis II. These validated instruments allow for identification of patients with a range of simple to complex TMD presentations.

Predicting the severity and prognosis of trismus after intensity-modulated radiation therapy for oral cancer patients by magnetic resonance imaging

To develop magnetic resonance imaging (MRI) indicators to predict trismus outcome for post-operative oral cavity cancer patients who received adjuvant intensity-modulated radiation therapy (IMRT), 22 patients with oral cancer treated with IMRT were studied over a two-year period. Signal abnormality scores (SA scores) were computed from Likert-type ratings of the abnormalities of nine masticator structures and compared with the Mann-Whitney U-test and Kruskal-Wallis one-way ANOVA test between groups. Seventeen patients (77.3%) experienced different degrees of trismus during the two-year follow-up period. The SA score correlated with the trismus grade (r = 0.52, p<0.005). Patients having progressive trismus had higher mean doses of radiation to multiple structures, including the masticator and lateral pterygoid muscles, and the parotid gland (p<0.05). In addition, this group also had higher SA-masticator muscle dose product at 6 months and SA scores at 12 months (p<0.05). At the optimum cut-off points of 0.38 for the propensity score, the sensitivity was 100% and the specificity was 93% for predicting the prognosis of the trismus patients. The SA score, as determined using MRI, can reflect the radiation injury and correlate to trismus severity. Together with the radiation dose, it could serve as a useful biomarker to predict the outcome and guide the management of trismus following radiation therapy.

Temporomandibular joint involvement in a cohort of patients with Juvenile Idiopatic Arthritis and evaluation of the effect induced by functional orthodontic appliance: clinical and radiographic investigation

AIM

The aim of the study was to assess possible correlations between the clinical parameters of temporomandibular joint (TMJ) arthritis and pathologic MRI findings of the TMJ in patients affected by juvenile idiopathic arthritis (JIA), and the effect of a functional orthodontic therapy on the evolution of TMJ disorders.

MATERIALS AND METHODS

A prospective clinical and nuclear magnetic resonance (NMR) investigation was conducted on a sample of 53 patients (41 female, 12 male) with JIA, treated for 24 months with an Andresen appliance. The involvement of TMJ was defined by clinical and radiological signs. NMR assessments were performed in closed and maximum opening mouth position before (T0) and at the end of functional orthodontic therapy (T1).

RESULTS

Fifteen patients showed physical and radiologic TMJ abnormalities. Changes were not uniformly distributed among the different JIA subtypes. Patients with poliarticular JIA (≥5 peripheral joints affected) showed more destructive bony changes. No correlation existed between clinical symptoms and NMR alterations. Approximately one half of the patients experienced significant improvement of the TMJ and muscular pain using the Andresen appliance.

CONCLUSION

The prevalence of TMJ involvement in patients suffering of JIA, and the improvement of TMJ and muscular pain associated with the use of functional appliance found in the present study, suggest an alert for TMJ dysfunction in patients with JIA and demonstrate the utility of functional orthodontic therapy in preventing the morbidities associated with TMJ arthritis in JIA.

[Pure trigeminal motor neuropathy with an antecedent infection: a case report]

Pure trigeminal motor neuropathy is a rare clinical manifestation, and its etiology remains obscure. Here, we report the case of a 67-year-old woman who presented with jaw deviation to the right. Neurological examination revealed atrophy of the right temporal and masseter muscles and jaw deviation to the right. Absence of other cranial nerve abnormalities, such as loss of sensation in the trigeminal nerve territory, suggested involvement of only the motor component of the right mandibular nerve. Results of laboratory tests, including hematologic, serologic, and biochemical analysis, were unremarkable, except for the finding of lymphocytic pleocytosis in the cerebrospinal fluid on symptom onset. Brain MRI revealed no abnormality in the brainstem or trigeminal nerve. Electromyography indicated chronic denervation in the right temporal muscle. A few days before the occurrence of the neurological signs, the patient had experienced flu-like symptoms; this suggests that post-infection neuropathy may be a possible cause of the right motor trigeminal neuropathy observed in our case.

MRI findings of radiation-induced changes of masticatory muscles: a systematic review

BACKGROUND

Radiotherapy to the head and neck regions can result in serious consequences to the temporomandibular joint (TMJ) and chewing muscles. Magnetic resonance imaging (MRI) demonstrates soft-tissue alterations after radiotherapy, such as morphology and signal intensity.

OBJECTIVE

The purpose of this review is to critically and systematically analyse the available evidence regarding the masticatory muscles alterations, as demonstrated on MRI, after radiotherapy for head and neck cancer.

DATA SOURCES

Electronic search of MEDLINE, EMBASE, EBM reviews and Scopus.

INCLUSION CRITERIA

Reports of any study design investigating radiation-induced changes in masticatory muscles after radiotherapy in patients with head and neck cancer were included.

RESULTS AND SYNTHESIS METHODS

An electronic database search resulted in 162 papers. Sixteen papers were initially selected as potentially relevant studies; however, only four papers satisfied all inclusion criteria. The included papers focused on the MRI appearance of masticatory muscles following radiotherapy protocol. Two papers reported outcome based on retrospective clinical and imaging records, whereas the remaining two papers were case reports. Irradiated muscles frequently show diffuse increase in T2 signal and post-gadolinium enhancement post-irradiation. Also, muscle size changes were reported based on subjective comparison with the contralateral side. The quality of all included papers was considered poor with high risk of bias.

CONCLUSION

There is no evidence that MRI interpretations indicate specific radiation-induced changes in masticatory muscles. There is a clear need for a cohort study comparing patients with pre- and post-radiotherapy MRI.

Masticatory tensile developed in upper anterior teeth with chronic apical periodontitis. A finite-element analysis study

Commonly is accepted that a non-vital tooth has a higher risk of root fracture but there is a relatively little knowledge about the specific biomechanical behavior of non-vital frontal teeth with chronic apical periodontitis. The aim of our study was to evaluate the deformation and tensile generated in these teeth while vertically loading them because it is crucial to assess the moment when the absorbed occlusal forces exceed the elasticity of root dentine. Using the method of finite-element analysis, we highlighted the distribution patterns of the compressive and tension tensile, as well as their concentration areas. The vertical forces of 100 N generate deformations of no clinical risk in teeth with chronic apical periodontitis. The tensile developed in these teeth are higher than those in the vital teeth are but do not exceed the value of the elastic modulus of the radicular dentin. By increasing the force to 300 N occur elastic deformations, which cannot be neglected anymore. Even so, the 300 N forces do not generate deformations of the alveolar bone. The highest tensile at loading with 300 N was generated in vertical direction but in the cervical area of the tooth also developed tensile in lingual and mesiodistal direction that must be taken into consideration because they are near the risk limit of the elasticity modulus. The crack lines or fractures can appear both in case of excessive or even usual but accumulative occlusal forces that gradually alter the mechanical resistance of the tooth.

Finite element stress analysis of Ti-6Al-4V and partially stabilized zirconia dental implant during clenching

OBJECTIVE

The purpose of this paper is to compare the differences in stress between Ti-6Al-4V and PS-ZrO(2) dental implant during clenching and whether these changes are clinically significant to limit the use of zirconia in oral implantology.

MATERIALS AND METHODS

The model geometry was derived from position measurements taken from 28 diamond blade cut cross-sections of an average size human adult edentulous mandible and generated using a special sequencing method. Data on anatomical, structural, functional aspects and material properties were obtained from measurements and published data. Ti-6Al-4V and PS-ZrO(2) dental implants were modelled as cylindrical structure with a diameter of 3.26 mm and length of 12.00 mm was placed in the first molar region on the right hemimandible.

RESULTS

The analysis revealed an increase of 2-3% in the averaged tensile and compressive stress and an increase of 8% in the averaged Von Mises stress were recorded in the bone-implant interface when PS-ZrO(2) dental implant was used instead of Ti-6Al-4V dental implant. The results also revealed only relatively low levels of stresses were transferred from the implant to the surrounding cortical and cancellous bone, with the majority of the stresses transferred to the cortical bone.

CONCLUSION

Even though high magnitudes of tensile, compressive and Von Mises stresses were recorded on the Ti-6Al-4V and PS-ZrO(2) dental implants and in the surrounding osseous structures, the stresses may not be clinically critical since the mechanical properties of the implant material and the cortical and cancellous bone could withstand stress magnitudes far greater than those recorded in this analysis.

Clinical anatomy of the auriculotemporal nerve in the area of the infratemporal fossa

The auriculotemporal nerve is a sensory branch extending from the posterior section of the mandibular nerve trunk. Its nerve roots form a short trunk, which gives off a number of branches, innervating: the temporomandibular joint, the temporal region, structures of the external ear: auricle, and external acoustic meatus, and the parotid gland. It also conducts excretory fibres to the buccal and labial glands. Anatomical relationships between the auriculotemporal nerve and the muscles of mastication, temporomandibular joint, and surrounding vessels in the area of the infratemporal fossa create favourable conditions for entrapment syndromes. Entrapment of the auriculotemporal nerve plays a role in the pathogenesis of temporomandibular joint pain syndromes, headaches, as well as pain symptoms or paraesthesias within the external acoustic meatus and auricle. The current study was performed on 16 specimens containing the infratemporal fossa. Some variations in the nerve roots of the auriculotemporal nerve were found and described as one-, two-, three-, four-, and five-root variants. The topography of the auriculotemporal nerve and its close relationship to the structures of the temporomandibular joint were described. Individually, the variable topography of the nerve course may play a role in the symptomatology of headaches and localisation of pain in the face regions and masticatory system.

Occlusal contact in children with Temporomandibular Disorders. A pilot study

AIM

The aim of the present study was to perform a comparative analysis of occlusal contact points in children with and without signs and symptoms of Temporomandibular Disorders (TMD).

STUDY DESIGN

Cross-sectional study. One hundred fifty children between 6 and 14 years of age were evaluated using the Helkimo questionnaire and a clinical exam. The occlusal contact points in each child were recorded during maximal intercuspation with the aid of carbon strips. Digital photographs were taken of the upper and lower arches before and after recording the occlusal contacts. The number of contact points between sides were compared and recorded on individual charts (occlusograms).

STATISTICS

Student's t-test and Pearson's chi-square test were used for the statistical analysis, with the level of significance set at 0.05, which revealed no statistically significant differences between genders. The Student's t-test revealed a statistically significant difference in the mean number of occlusal contact points between the participants with and without TMD, with a higher number of contact points among those without TMD. There was no significant difference between sides. RESULTS The results of this study show a difference in the number of occlusal contact points in centric occlusion between children with and without TMD. CONCLUSION Regardless of the degree of severity, the number of occlusal contact points is lower among children with TMD.

Talin, vinculin and nestin expression in orofacial muscles of dystrophin deficient mdx mice

The activity of cytoskeletal proteins like talin, vinculin and nestin increases in muscle that regenerates. Little is known about their role or at least their expression in the process of regeneration in masticatory muscles of mdx mice, a model of Duchenne muscular dystrophy. To determine a potential role of cytoskeletal proteins in the regeneration process of mdx masticatory muscles, we examined the expression of talin 1, talin 2, vinculin and nestin in 100-day-old control and mdx mice using quantitative RT-PCR, Western blot analyses and histochemistry. The protein expression of talin 1, talin 2, nestin and vinculin in mdx muscles remained unchanged as compared with normal mice. However, in mdx masseter it was found a relative increase of nestin compared to controls. The protein expression of talin 1 and vinculin tended to be increased in mdx tongue and talin 2 to diminish in mdx masseter and temporal muscle. In mdx mice, we found significantly lower percentage of transcripts coding for nestin, talin 1, talin 2 and vinculin in masseter (p < 0.05) and temporal muscle (p < 0.001). In contrast, the mRNA expression of nestin was found to be increased in mdx tongue. Activated satellite cells, myoblasts and immature regenerated muscle fibres in mdx masseter and temporal revealed positive staining for nestin. The findings of the presented work suggest dystrophin-lack-associated changes in the expression of cytoskeletal proteins in mdx masticatory muscles could be compensatory for dystrophin absence. The expression of nestin may serve as an indicator for the regeneration in the orofacial muscles.

Possible difficult laryngoscopy caused by masticatory muscle tendon-aponeurosis hyperplasia: we anesthesiologists should be aware of this disease

Masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) is a new disease entity characterized by limited mouth opening due to contracture of the masticatory muscles resulting from hyperplasia of tendons and aponeuroses. The other clinical feature is that the face of the patient with this disease displays a square mandible configuration. Muscle relaxants provide no relief for the limited mouth-opening ability. Anesthesiologists need to suspect difficult airway when patients have limited mouth opening with square mandible configuration. MMTAH can therefore be a possible cause of difficult intubation.

Evaluation of facial asymmetry and masticatory muscle thickness in children with normal occlusion and functional posterior crossbite

AIM

The aim of this study was to evaluate facial asymmetry and the thickness of the masticatory muscles in young children with normal occlusion and functional posterior crossbite.

METHODS

The sample comprised 72 children of both genders (64.71±7.04 months) in the primary and early mixed stage of dentition, divided into four groups: primary-normal occlusion (PriN; N=19), primary-crossbite (PriC; N=19), mixed-normal occlusion (MixN; N=27), and mixed-crossbite (MixC; N=16). The thickness of the masseter and anterior portion of the temporalis muscle at rest and during maximal clenching were assessed by ultrasonography. Facial morphology and asymmetry were evaluated by standardized front-view photographs, in which the following measurements were recorded: anterior face height (AFH), bizygomatic facial width (BFW), angle of the eye (AE) and angle of the mouth (AM) (interpupillary and commissure planes in relation to mid-sagittal plane, respectively).

RESULTS

The results showed that muscle thickness did not differ significantly between the sides of the dental arches in all groups (paired t-test). Only the groups with normal occlusion presented significant positive correlation between AE and AM (Pearson's correlation test). In PriN, only body weight was significantly related to masseter thickness; in MixN, facial morphology contributed significantly to masseter thickness at rest and maximal clenching, while the covariates weight, height and age did not relate to muscle thickness (stepwise backward multiple regression).

CONCLUSION

In the studied sample, children with crossbite presented greater facial asymmetry than those with normal occlusion, and a greater masseter thickness was related to larger faces in the mixed dentition.

Structural changes in the ageing periosteum using collagen III immuno-staining and chromium labelling as indicators

The periosteum and Sharpey's fibre extensions occupy the musculoskeletal interface and may be strategic in age-related deterioration. Because of its exceptionally powerful insertions the porcine mandible is an ideal model and its periosteal system was compared in 4 separate regions of adult young (1 year) and older (3 year) animals. These were examined by undecalcified histology, collagen immunohistochemistry and mineral histochemistry using polarization, epifluorescence and laser confocal microscopy; mineral ultrastructure was facilitated by chromium labelling with EDX microanalysis. Birefringent Sharpey's fibres were coarse (>8 microm) or fine and classified as horizontal (more common with age), oblique (most common in youth) or vertical (least common); in addition they were designated "superficial", "transcortical" and "intertrabecular" (the latter being deep, coarse and vertical). Their specific affinity for collagen type III FITC-labelled antibody demonstrated 3-dimensional arrays of bone-permeating fibres. With age at each region the cortical thickness rose (e.g. 4.9 mm to 9.3 mm), the periosteum thinned (e.g. 180-/+7 microm to 129-/+8 microm; p<0.001), and the periosteum: bone ratio diminished (e.g. 3.65-/+0.36 to 1.40-/+0.14; p<0.001) while Sharpey's fibres became fewer, fragmented, superficial and shortened (e.g. 226-/+27 microm to 55-/+6 microm; p<0.001). Accompanying was the sporadic encroachment of calcified particles, 1 microm diameter, in irregular periosteal aggregates or interlinked around Sharpey bundles (resembling calcifying turkey leg tendon). EDX microanalysis confirmed prominent chromium spectral peaks in the older periosteum only, coincident with chromium-labelled mineral "ghosts". It was concluded that the periosteum and Sharpey's fibres, deep-penetrating and complex in youth, partially hardens and regresses with age with implications for its functional properties.

[Jaw muscle tumors]

Muscular tumors are rare. They hardly ever present in jaws. Rhabdomyoma have never been reported in this localization. Clinical and radiological features are non-specific. The diagnosis is based on histopathological features. It is difficult to make for leiomyosarcoma. Surgical excision is the recommended treatment, conservative for leiomyoma, radical for other malignant tumors. Rhabdomyosarcoma has a good prognosis unlike leiomyosarcoma.

Association between temporomandibular joint symptoms, signs, and clinical diagnosis using the RDC/TMD and radiographic findings in temporomandibular joint tomograms

AIM

To identify associations between clinical symptoms of temporomandibular joint disorders and radiographic findings.

METHODS

Two hundred four adult patients (156 women, 48 men, mean age 40 years) with temporomandibular joint (TMJ) pain/sounds or changes in mandibular motion were examined according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Bilateral sagittal corrected TMJ tomograms in closed and open positions were assessed for the presence of flattening, erosion, osteophytes, and sclerosis in the joint components and the range of mandibular motion. Logistic regression analyses were performed with the radiographic findings as the dependent variables and the following clinical variables as independent variables: opening pattern, maximal jaw opening, TMJ sounds, number of painful muscle/TMJ sites, duration of pain, presence of arthritic disease, depression and somatization scores, graded chronic pain, and age and gender.

RESULTS

Coarse crepitus on opening/closing (odds ratio [OR] > or = 3.12), on lateral excursions (odds ratio > or = 4.06), and on protrusion (OR > or = 5.30) was associated with increased risk of degenerative findings in tomograms. A clinical diagnosis of osteoarthritis increased the risk of radiographic findings (OR > or = 2.95) and so did increasing age (OR > or = 1.03 per year) and the female gender (OR > or = 2.36). Maximal assisted opening and maximal opening without pain (< 40 mm) was associated with a posterior condyle-to-articular tubercle position (OR > or = 2.60). No other significant associations were observed.

CONCLUSION

Age, gender, and coarse crepitus, but no pain-related variables, were associated with increased risk of degenerative findings in TMJ tomograms. Maximal opening < 40 mm was associated with a posterior condyle-to-articular tubercle relation on opening.

Retromolar Ridge in Edentulous Patients: Clinical Considerations

PURPOSE

A removable denture base should cover the mandibular retromolar regions to provide proper basal seal and denture function in edentulous patients. The bony residual ridge form, attached muscles, and covering mucosa provide support, stability, and retention of the planned prosthesis. There is insufficient information regarding bone anatomy, mucosal tissues, and muscles in the retromolar region after tooth loss. The purpose of this study was to examine the tissue morphology in the mandibular retromolar area of edentulous subjects and report on the clinical inferences in prosthetic and implant dentistry.

MATERIALS AND METHODS

Specimens included 75 edentulous and eight dentate dry mandibles examined by macroscopic observations and linear measurements for size determinants in the left and right retromolar regions. Buccolingual histological sections of the mandibular retromolar region from seven edentulous subjects were also examined. The specimens were from the Department of Anatomy and Anthropology, Sackler School of Medicine, Tel Aviv University.

RESULTS

The specimens evaluated in this study revealed that a bony retromolar ridge can be large, with adjacent muscles attached several millimeters below its edentulous bone crest, or small, with muscles attached to the buccal and lingual bone crests. In all examined jaws, bony mylohyoid ridges (MR) and buccal shelves with affixed muscle fibers were present regardless of the remaining mandibular bone form and size.

CONCLUSIONS

The mylohyoid muscles attached to MRs and the buccinator muscles affixed to buccal bony shelves are some of the barriers to the chronic but limited bone resorption, following tooth loss, time of edentulism, systemic factors, and denture wear.

Computed tomographic appearance of masticatory myositis in dogs: 7 cases (1999–2006)

OBJECTIVE

To document computed tomography (CT) features in dogs with masticatory myositis.

DESIGN

Retrospective case series.

ANIMALS

7 dogs with an immunologic diagnosis of masticatory myositis and an absence of clinical abnormalities of any skeletal muscles other than the masticatory muscles.

PROCEDURES

History; clinical, hematologic, biochemical, immunologic, cytologic, and histologic findings; and pre- and postcontrast CT imaging features of masticatory muscles and head and neck lymph nodes were extracted from medical records.

RESULTS

On CT images, changes in size (atrophy or swelling) were common for all masticatory muscles except the digastricus muscles, which were involved only in 1 dog. Pre-contrast attenuation changes, most often hypoattenuation with varied distribution patterns, were seen in masticatory muscles of 4 dogs. Contrast enhancement with a predominantly inhomogeneous distribution pattern was seen in the temporalis, masseter, and pterygoid muscles of all dogs. Head and neck lymph nodes were enlarged in all but 1 dog and had contrast enhancement with predominantly central or homogeneous distribution patterns. Muscle biopsy was performed in 6 dogs, with biopsy specimens obtained from areas that had the most obvious contrast enhancement on CT images. For all 6 dogs, biopsy specimens had histologic features indicative of masticatory myositis.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that CT may be a useful adjunct in the diagnosis of masticatory myositis in dogs, including selection of sites for diagnostic muscle biopsy.

Relationship Between the Masticatory Muscles and Mandibular Skeleton in Mandibular Prognathism With and Without Asymmetry

PURPOSE

The purpose of the present study was to evaluate the relationship between masticatory muscle volume and mandibular skeletal measurements in patients with and without facial asymmetry. This was done in order to determine whether asymmetric mandibular prognathism is related to masticatory muscle asymmetry.

PATIENTS AND METHODS

The study was conducted with 40 adult patients with mandibular prognathism composed of 2 groups, the asymmetry group (n = 20) and the nonasymmetry group (n = 20). Using 3-dimensional reformatted computed tomography (CT) images, the volume of masticatory muscle (masseter, temporal, medial, and lateral pterygoid muscles) and various skeletal measurements (hemimandibular volume, ramal height, body length, mandibular length, gonial angle) were evaluated and compared. The right-left difference was expressed by an asymmetry index {(right-left)/left, %}.

RESULTS

The results showed that in the asymmetry group, the longer mandibular side (contralateral side of chin deviation) exhibited longer ramal and body length, a wider gonial angle, and more hemimandibular volume with less medial pterygoid volume, whereas the nonasymmetry group did not show a statistical bilateral difference between the skeletal and muscular measurements. The correlation analysis showed that patients with facial asymmetry did not have similar patterns of muscle-bone relation as compared with the symmetrical subjects.

CONCLUSION

In patients with mandibular prognathism, the bilateral difference in muscle volume would reflect the difference in the spatial anatomy of a skeletal structure and could not predict mandibular skeletal asymmetry.

From dog to man: the broad spectrum of inflammatory myopathies

The purpose of this review is to describe the various forms of inflammatory myopathy that occur spontaneously in dogs, and discuss the similarities and differences between inflammatory myopathy in dogs and humans. Some interesting muscle-specific autoantigens have recently been discovered in canine autoimmune myositis, and they are associated with specific forms of inflammatory myopathy. These autoantigens may now be investigated in humans. Furthermore, the association of distinct inflammatory myopathies with certain breeds of dogs point to important genetic components of inflammatory myopathy that can now be studied using dogs as both parallel disorders and animal models. Other canine myositides, associated with infectious and histiocytic diseases, may also be relevant to similar human disorders.

Oromandibular dystonia involving the lateral pterygoid muscles: four cases with different complexity

The report describes oromandibular dystonia (OMD) in four women with involuntary activity of the lateral pterygoid muscles (LP), causing incapacitating protrusive and lateral jaw movements and displacements, and treatment with botulinum toxin type A (BTX). For initial survey and treatment control, OMD was analyzed with several, independent, and standardized methods. OMD severity and functional difficulties were evaluated subjectively and scored from videotapes. Jaw movements were assessed graphically with a magnetic tracking system, and electromyographical activity (EMG) of LP was recorded with needle electrodes using an intraoral approach, whereas activity of masseter muscles was recorded with surface electrodes. EMG-guided BTX injections (25-40 units Botox per muscle) into the muscles were performed with cannula electrodes. Compared with reference values for LP, OMD was associated with a markedly increased level of spontaneous activity, but almost normal level of maximum voluntary activity. The central pattern generator for mastication seemed to override the dystonic activity, as all patients were able to chew despite some distortion. BTX reduced both the spontaneous and the maximum activity for 3-9 months. Concomitantly, a marked reduction of the OMD severity, mandibular movements and functional disturbances were also present with the best effect in localized OMD with late onset.

[The use of the panoramic radiograph for diagnosis of temporomandibular joint disorders (TMD)--comparison to other imaging techniques]

The panoramic radiograph is the most commonly used radiographic technique for initial evaluation and diagnosis of temporomandibular joint disorders (TMD). The purpose of this article is to highlight the principles of interpretation and limitations of the panoramic radiograph as an imaging technique of the temporomandibular joint. The indications for selecting the most suitable imaging technique for various TMD diagnoses are presented in accordance with the most recent position paper of the American Academy of Oral and Maxillofacial Radiology.

Cardioembolism: a rare cause of jaw claudication

Jaw claudication (JC) results from ischemia of the masticatory muscles, typically caused by temporal arteritis and other arteriopathies affecting the external carotid artery (ECA).

We documented a case of JC resulting from cardioembolic occlusion of the ECA and searched both English and French literature on the Medline database (1966-October 2006) to identify previous reports. We combined the keywords “jaw claudication” with either “cardiogenic embolism”, “cardiac embolism”, “cardioembolism”, “etiology”, “cause”, or “carotid occlusion”.

Atypical masticatory muscle myositis in three cavalier King Charles spaniel littermates

This case report describes a novel manifestation of the immune-mediated disease, masticatory muscle myositis. Clinical signs, including difficulty in opening the mouth (trismus), were seen in three of four 12-week-old cavalier King Charles spaniel littermates. Diagnosis was established by 2M immunohistochemistry, supported by characteristic histopathological changes in affected temporal muscle. Treatment using corticosteroids at immune-modifying doses resulted in resolution of clinical signs in all the affected animals. Masticatory muscle myositis should be considered as a differential diagnosis in groups of young dogs with clinical signs of myositis localised to the head.

[Useful imaging in maxillofacial surgery. Part II: practical applications]

Various pathologic patterns are discussed with advice on appropriate radiographic imaging. The choice of the most suitable modality for each condition depends on the need to obtain the most accurate results. Panoramic radiography remains a basic and low cost method. Choice of CT or MR as the principal or only modality depends on anatomic patterns: CT being preferred for bone and cavities, MR for soft tissue and cavity content. Much progress has been made in MR machines and the variety of sequences enables high discrimination between normal and pathologic tissues.

The volume of muscles of mastication in patients receiving mandibular contouring surgery: a comparative study

PURPOSE

As the management of prominent mandibular angle and masseter muscle hypertrophy becomes increasingly popular, proper understanding of the volumetric component of the related structures becomes important but is currently lacking.

MATERIALS AND METHODS

Three-dimensional computed tomographic (CT) scans of 18 female and eight male adult patients with square-face appearance were used for volumetric measurement of the osseous hemi-mandible, masseter, medial and lateral pterygoid muscles. CT scans of 28 female and 17 male adult patients without square-face appearance were selected from the imaging laboratory archive to serve as controls.

RESULTS

Compared with the sex-matched controls, the square-faced patients had significantly higher volume of the osseous hemi-mandible as well as the masseter and medial pterygoid muscles. There was no significant difference in the volume of the lateral pterygoid muscle between the two groups. This study confirms a significantly greater volume in the osseous mandible and masseter muscle in patients complaining of square-face appearance. The implication of this information on treatment is discussed.

[Changes in the masticatory muscles, periodontal tissues and the pharyngeal ring in Wistar rats subjected to chronic psychophysical stress]

Experimental study, performed in 120 male Wistar rats, using histological and morphometric methods, has demonstrated changes of the oral tissues in response to chronic psychophysical stress (dosed swimming). Masticatory muscle showed the foci of non-infectious inflammation, dystrophic changes of muscle fibers and contractures. Periodontal ligament demonstrated the disturbances of microcirculation, with the pronounced congestion of the venous portion, local hemorrhages, changes in the orientation of collagen bundles and their deformation. In the tissues of the pharyngeal ring, the reduction in the number of lymphocytes was detected, as well as a progressing loosening of connective tissue, and a decrease in the number of non-degranulated mast cells as compared to similar parameters in the control group. The intensity of these manifestations was dependent on the level of physical load and individual adaptation capacity of an animal. The changes of the oral tissues detected in this study, may become an etiopathogenetic basis for the development of chronic inflammatory periodontal disease.

Ultrasonography and electromyography of masticatory muscles in a group of adolescents with signs and symptoms of TMD

The thickness and electrical activity of masseter and anterior temporalis muscles were compared in adolescents with and without signs and symptoms of TMD. Forty individuals were selected using the Cranio Mandibular Index and a questionnaire. There was no significant correlation between thickness and activity (p > 0.05). However, there were correlations between thickness and weight and height (p < 0.05). The effect of signs and symptoms on muscle thickness and activity was weak, considering the low CMI scores found.

MRI and clinical studies of facial and bulbar muscle involvement in MuSK antibody-associated myasthenia gravis

A proportion of patients with myasthenia gravis (MG) without acetylcholine receptor (AChR) antibodies have antibodies to muscle-specific kinase (MuSK). MG with MuSK antibodies (MuSK-MG) is often associated with persistent bulbar involvement, including marked facial weakness and tongue muscle wasting. The extent of muscle wasting in MuSK-MG, and whether it is also found in the few acetylcholine receptor (AChR-MG) patients who have persistent bulbar involvement, is not clear. We studied 12 MuSK-MG patients and recruited 14 AChR-MG patients matched broadly for age, sex ratio, duration of disease and degree of ocular, bulbar and facial weakness. We used coronal and sagittal T1-weighted (T1W) and T2-weighted (T2W) magnetic resonance imaging (MRI) to assess muscle wasting in facial and tongue muscles. Hyperintense signal on T1W MRI and comparison of axial T1W sequences with cUTE sequences were used to assess fibrous/fatty tissue in the tongue. We compared the results with those of four patients with myotonic dystrophy and 12 healthy individuals. We correlated the changes with clinical and treatment histories, and established a new ocular-bulbar-facial-respiratory (OBFR) score. At the time of study, none of the clinical measures, including the OBFR score, differed between the two MG groups. MRI demonstrated thinning of the buccinator, orbicularis oris (O.oris) and orbicularis oculi (O.oculi) muscles in MuSK-MG patients compared with healthy controls, whereas thinning of these muscles was not significant in AChR-MG. Tongue areas with T1W high signal were increased in MuSK-MG patients and the intensity of the signal on axial T1W sequences was greater in MuSK-MG than in controls. To look for possible correlations between imaging and clinical findings, we pooled results from all MG patients. The duration of treatment with prednisolone at >40 mg on alternate days (AD) correlated positively with the percentage of tongue area with high signal (P = 0.006) and negatively with MRI measurements of individual muscles and with the mean muscle dimensions (P = 0.001). The new OBFR score correlated positively with current Myasthenia Gravis Foundation of America grades and with the percentage of high signal (P = 0.004) and negatively with the mean muscle dimensions (P < 0.001). The results show that bulbar and facial muscle weakness and wasting are associated with significant muscle atrophy and fatty replacement in MuSK-MG, which was not found in the AChR-MG patients. MuSK antibodies per se may predispose to muscle thinning, but the difficulties in obtaining clinical remission under steroid therapy in some patients, resulting in long duration of treatment with higher doses (>40 mg AD), may be an additional factor.

FDG uptake in benign asymmetric hypertrophy of the masticator muscles

A case of asymmetric increased fluorodeoxyglucose (FDG) uptake in unilateral pterygomasseter muscles is shown. The authors report an example of intense F-18 FDG uptake in the benign pterygomasseteric muscle complex hypertrophy in a patient with a history of longstanding unilateral chewing.

Sensibilitätsstörung und pathologische Unterkieferfraktur als Erstsymptome bei metastasiertem Prostatakarzinom

BACKGROUND

Distant metastases of solid tumors account for about 1% of all malign neoplasms. In about 30% of all patients who present with an oral metastasis, the distant primary tumour has not been diagnosed yet.

CASE REPORT

We report the case of a 71-year-old man who clinically demonstrated unilateral mental neuropathy as well as pathologic fracture of the mandible. Prostate carcinoma was identified as a primary tumor. Clinically, there was significant hypesthesia of the skin area innervated by the left inferior alveolar nerve. X-ray examination revealed an osteolytic lesion of the ascending ramus of the mandible as well as a pathologic fracture of the mandible. Further imaging showed an extensive neoplasm of the mandible and adjacent soft tissues and significant supraclavicular lymph node enlargement. The diagnosis of metastatic carcinoma of the prostate was histopathologically confirmed.

CONCLUSION

Mental neuropathy without a dental focus indicates screening for an osseous metastasis. In cases of left-sided supraclavicular lymph node enlargement in men over 45 years, metastatic prostate carcinoma must be excluded.

[Pure trigeminal motor neuropathy presenting with temporo-mandibular joint dysfunction in a patient with HIV and HCV infections]

Pure trigeminal motor neuropathy (PTMN) is a rarely described condition. We report the case of a 41-year-old woman infected with the human immunodeficiency virus (HIV1) and hepatitis C virus who presented with weakness of left temporalis and masseter muscles and painful left temporomandibular joint dysfunction (TMD) a few months after cerebral toxoplasmosis revealing acquired immunodeficiency syndrome (AIDS). Magnetic resonance imaging revealed severe wasting and fat replacement of the left temporalis, pterygoid and masseter muscles and showed neither abnormalities in the left motor nucleus of the trigeminal nerve nor compression of the left trigeminal nerve. Electromyographic examination gave evidence of denervation in the left temporalis, masseter and pterygoid muscles and blink reflex studies were normal, confirming the diagnosis of PTMN which was probably secondary to HIV and HCV co-infection.

[Brain activities during maximum voluntary clenching with and without soft splint in patients with hemimasticatory spasms by functional magnetic resonance imaging]

OBJECTIVE

Functional magnetic resonance imaging (fMRI) was used to detect the cerebral cortical somatotopy during maximum voluntary clenching with and without soft splint in patients with hemimasticatory spasms (HMS) and the central mechanisms of HMS and the rule of the splint therapy.

METHODS

Four HMS patients were selected and the spasms sides were right in two cases and left in the other two cases. FMRI images were obtained on Elscint/GE 2.0 Tesla MR system. Block design was used and the movement pattern was the onset of spasms after maximum voluntary clenching with and without soft splint. The fMRI data were analyzed by SPM99 software.

RESULTS

With the onset of spasms after maximum voluntary clenching, the activation of motor cortex in 3 HMS patients was found lateral dominance on the left side, and the other one showed bilateral activation. All the 4 patients were found activation in cingulate area. With the onset of spasms after maximum clenching wearing soft splints, the activation of motor cortex showed no lateral dominance on the left side, and 3 patients were not found activation in cingulate area.

CONCLUSIONS

The changes of the activation in motor cortex and cingulate area during the onset of spasms after clenching with and without soft splint might be the central mechanisms of the rule of splint therapy, through which the soft splint might function in alleviating muscle pain.

[CT and MRI features of diseases involving masticator spaces]

OBJECTIVE

This is a study on the CT and MRI features of diseases involving the masticator spaces; the purpose is to improve the diagnostic accuracy.

METHODS

Fifty-seven cases involving the masticator spaces were collected, among which, 11 cases were originated from the masticator space, another 46 cases were secondary invasion from the adjacent structures, including 18 cases from the buccal mucosa, 10 from the nasopharynx, 5 from the gingiva, 3 from the parotid gland, 6 from the maxillary sinus, 1 from the intracranial location, 2 from the palate and 1 from the orbit. The CT and MRI features of the masticator space involvement were analysed.

RESULTS

Masticator space involvement is visualized on CT and MRI as effacement of the fat plane, swelling of the masticatory muscles, and erosion of the mandibular ramus. Disease from surrounding structures can invade the masticator space via the pterygopalatine fossa, the buccal space immediately anterior to the ramus, the foramen ovale, or by way of direct invasion.

CONCLUSION

Masticator space involvement is not uncommon in the maxillofacial diseases, which must be noticed in the imaging diagnosis.

A dynamic model of mouth closing movements in clariid catfishes: the role of enlarged jaw adductors

Some species of Clariidae (air breathing catfishes) have extremely large (hypertrophied) jaw closure muscles. Besides producing higher bite forces, the enlarged muscles may also cause higher accelerations of the lower jaw during rapid mouth closure. Thus, jaw adductor hypertrophy could potentially also enable faster mouth closure. In this study, a forward dynamic model of jaw closing is developed to evaluate the importance of jaw adductor hypertrophy on the speed of mouth closure. The model includes inertia, pressure, tissue resistance and hydrodynamic drag forces on the lower jaw, which is modelled as a rotating half-ellipse. Simulations are run for four clariid species showing a gradual increase in jaw adductor hypertrophy (Clarias gariepinus, Clariallabes longicauda, Gymnallabes typus and Channallabes apus). The model was validated using data from high-speed videos of prey captures in these species. In general, the kinematic profiles of the fastest mouth closure from each species are reasonably well predicted by the model. The model was also used to compare the four species during standardized mouth closures (same initial gape angle, travel distance and cranial size). These simulations suggest that the species with enlarged jaw adductors have an increased speed of jaw closure (in comparison with the non-hypertrophied C. gariepinus) for short lower jaw rotations and when feeding at high gape angles. Consequently, the jaw system in these species seems well equipped to capture relatively large, evasive prey. For prey captures during which the lower jaw rotates freely over a larger distance before impacting the prey, the higher kinematic efficiency of the C. gariepinus jaw system results in the fastest jaw closures. In all cases, the model predicts that an increase in the physiological cross-sectional area of the jaw muscles does indeed contribute to the speed of jaw closure in clariid fish.

The deep belly of the temporalis muscle: an anatomical, histological and MRI study

In order to achieve a better functional and clinical knowledge of a masticatory muscle called the sphenomandibularis that is suspected to be responsible for headaches by compressing the maxillary nerve, bilateral dissections of the infratemporal fossa were performed on ten human cadavers and completed by histological and radiological studies of the same areas. Both macroscopic and microscopic observations obviously showed that the so-called sphenomandibularis muscle corresponds to the deep portion of the temporalis muscle, since there is no epimysial septum between these two structures, which previously have been described as being completely independent from each other. In spite of the close topographic relationship between the deep belly of the temporalis and the lateral pterygoid muscle, as well as their similar innervation pattern, the sphenomandibularis in fact has to be considered functionally as an original but non-isolated positional fascicle of the temporalis muscle itself. Our observations, correlated with MR images, suggest indeed that the deep belly of the temporalis muscle is of functional importance in the masticatory movements, but is not involved by its neurovascular vicinity in the genesis of specific headaches. Its surgical release, however, should be discussed in the case of a temporal myoplasty.

Canine inflammatory myopathies: a clinicopathologic review of 200 cases

A retrospective study was performed on 200 randomly selected cases of inflammatory myopathy in dogs from diagnostic muscle biopsies received at the Comparative Neuromuscular Laboratory, University of California, San Diego. The most common clinical signs in dogs diagnosed with an inflammatory myopathy were generalized weakness, stilted gait, dysphagia, masticatory or generalized muscle atrophy, inability to open the jaw, megaesophagus, and dysphonia. Myalgia was rarely described. Age of onset ranged from 0.25 to 14 years. Genders were equally represented. Breed distribution approximated the 2002 American Kennel Club registration statistics (r = .85) with the notable exception of Boxers and Newfoundlands. From the results of muscle biopsies, clinical signs, and presence or absence of antibodies against type 2M fibers, dogs were classified as a generalized inflammatory myopathy (gIM)--including immune-mediated polymyositis; infectious and preneoplastic myositis; and, rarely, dermatomyositislike or overlap syndromes or unclassified myositis-or a focal inflammatory myopathy (flM)--including masticatory muscle and extraocular myositis. Average creatine kinase (CK) and aspartate aminotransferase (AST) concentrations in gIMs were significantly higher than those with fIMs (P < .05). Neoplasia developed in 12 of 200 dogs within 12 months of diagnosis of polymyositis, with lymphoma diagnosed in 6 of 32 Boxers. Inflammatory myopathy was associated with antibody titers against infectious diseases in 38 dogs. Neospora caninum and Hepatozoon americanum cysts were found in tissues of 2 dogs not serologically tested. Antibodies against an unidentified sarcolemmal antigen were found in 9 of 19 Newfoundlands with polymyositis. The spectrum of canine inflammatory myopathies can be broad, with infectious etiologies relatively common, and can include preneoplastic and uncharacterized syndromes.