Surface electromyography for evaluating patients with oromandibular dystonia

OBJECTIVE

To investigate myoelectric signals of dystonic activities in oromandibular dystonia (OMD) subjects using surface electromyography (EMG).

METHODS

Twelve OMD subjects were included in this study. Resting myoelectric activities of the superficial masseter, anterior temporalis, and anterior belly of the digastric muscle on both sides were monitored, and dystonic muscle contractions were recorded using surface EMG. Myoelectric signal amplitude, the type of muscle contraction, and contraction rate for phasic activities were evaluated.

RESULTS

Surface EMG revealed that eight subjects had dystonic muscle activities in the phasic contraction pattern, three subjects had a tonic contraction pattern, and one subject had a mixed pattern. Synchronous contraction of dystonic muscles was frequently observed. Many of the monitored muscles showed high resting amplitudes.

CONCLUSION

Surface EMG detects abnormal muscle activities related to oromandibular dystonia. Surface EMG can serve as an objective method for diagnosing oromandibular dystonia.

The impact of measurement technique and sampling on estimates of skeletal muscle fibre architecture

Skeletal muscle fibre architecture provides important insights into performance of vertebrate locomotor and feeding behaviours. Chemical digestion and in situ sectioning of muscle bellies along their lengths to expose fibres, fibre orientation and intramuscular tendon, are two classical methods for estimating architectural variables such as fibre length (Lf ) and physiological cross-sectional area (PCSA). It has recently been proposed that Lf estimates are systematically shorter and hence less accurate using in situ sectioning. Here we addressed this hypothesis by comparing Lf estimates between the two methods for the superficial masseter and temporalis muscles in a sample of strepsirrhine and platyrrhine primates. Means or single-specimen Lf estimates using chemical digestion were greater in 17/32 comparisons (53.13%), indicating the probability of achieving longer fibres using chemical digestion is no greater than chance in these taxonomic samples. We further explored the impact of sampling on scaling of Lf and PCSA in platyrrhines applying a bootstrapping approach. We found that sampling-both numbers of individuals within species and representation of species across the clade significantly influence scaling results of Lf and PCSA in platyrrhines. We show that intraspecific and clade sampling strategies can account for differences between previously published platyrrhine scaling studies. We suggest that differences in these two methodological approaches to assessing muscle architecture are relatively less consequential when estimating Lf and PCSA for comparative studies, whereas achieving more reliable estimates within species through larger samples and representation of the full clade space are important considerations in comparative studies of fibre architecture and scaling.

Bruxism and Botulinum Injection: Challenges and Insights

Botulinum toxin (BTA) is a bacterial-derived extract that can inhibit muscle contraction, acting directly on the absorption of acetylcholine. Thanks to this property, botulinum has been used in aesthetic and general medicine for several years. Nowadays, the use of botulinum toxin is being deepened to address the problem of bruxism. In this scoping review, the results of the studies in the literature of the last 10 years were analyzed. Indeed, 12 reports (found on PubMed, Web of Science, and Scopus, entering the keywords "BRUXISM" and "BOTULINUM TOXIN") were deemed eligible for inclusion in this review. In the studies reviewed, BTA was injected into different muscle groups: masseters, masseter and temporalis or masseter, temporalis, and medial pterygoid. Botulinum toxin injection is a viable therapeutic solution, especially in patients with poor compliance or without improvement in conventional treatment.

Sagittal suture strain in capuchin monkeys (Sapajus and Cebus) during feeding

OBJECTIVES

Morphological variation in cranial sutures is used to infer aspects of primate feeding behavior, including diet, but strain regimes across sutures are not well documented. Our aim is to test hypotheses about sagittal suture morphology, strain regime, feeding behavior, and muscle activity relationships in robust Sapajus and gracile Cebus capuchin primates.

MATERIALS AND METHODS

Morphometrics of sinuosity in three regions of the sagittal suture were compared among museum specimens of Sapajus and Cebus, as well as in robust and gracile lab specimens. In vivo strains and bilateral electromyographic (EMG) activity were recorded from these regions in the temporalis muscles of capuchin primates while they fed on mechanically-varying foods.

RESULTS

Sapajus and the anterior suture region exhibited greater sinuosity than Cebus and posterior regions. In vivo data reveal minor differences in strain regime between robust and gracile phenotypes but show higher strain magnitudes in the middle suture region and higher tensile strains anteriorly. After gage location, feeding behavior has the most consistent and strongest impact on strain regime in the sagittal suture. Strain in the anterior suture has a high tension to compression ratio compared to the posterior region, especially during forceful biting in the robust Sapajus-like individual.

DISCUSSION

Sagittal suture complexity in robust capuchins likely reflects feeding behaviors associated with mechanically challenging foods. Sutural strain regimes in other anthropoid primates may also be affected by activity in feeding muscles.

Can the subject reliably reproduce maximum voluntary contraction of temporalis and masseter muscles in surface EMG?

OBJECTIVE

To evaluate the repeatability of the surface EMG variables of myoelectric signals from the masseter and temporalis muscles according to three methods to induce maximum voluntary contraction (MVC) in healthy adults.

METHODS

Thirty healthy young subjects performed the following three MVC tasks three times each in three sessions on the same day without replacing surface electrodes: clenching the teeth (MVCIC) and biting down on two cotton rolls bilaterally with the posterior teeth (MVCBP) or first molars (MVCB6).

RESULTS

The intra-class correlation coefficient (ICC) of the amplitudes during the three MVC tasks ranged from 65 to 79%. The ICCs of the spectral variables ranged from 78 to 86%. The ICCs of the asymmetry index of the masseter ranged from 77 to 86%, and those of the activity index ranged from 68 to 90%.

CONCLUSION

The surface EMG measurements according to the three MVC methods exhibited good to excellent reproducibility.

Short-term Effects of a First-Line Treatment Including Counseling and Self-Management Strategies on Chronic TMD Muscle Pain and Awake Bruxism in Women

AIMS

To evaluate the short-term effects of a standardized first-line noninvasive approach (FL-A) including counseling and self-management strategies on pain, masticatory muscle tenderness, and awake bruxism in women with chronic temporomandibular disorder myalgia (mTMD) and to test whether patients' trait anxiety predicted their response to treatment.

METHODS

FL-A was administered to 14 women with chronic mTMD (mean age ± SD = 33.8 ± 11.1 years; 8 with Graded Chronic Pain Scale [GCPS] grade I and 6 with grade II). Its effects on facial pain, masticatory muscle tenderness, and spontaneous awake bruxism episodes were evaluated using questionnaires, surface electromyography, and quantitative sensory testing. General linear models were used to test FL-A efficacy after 1 (T1) and 2 (T2) months.

RESULTS

FL-A reduced pain (from baseline [T0] to T2, P = .010), the frequency of awake bruxism episodes (T0 to T1, P = .024), and their intensity by about 30% (T0 to T1, P < .001). Pressure pain thresholds at the masticatory muscle locations increased significantly from T0 to T2 (P < .001). Patients' trait anxiety decreased significantly from T0 to T2 (P = .030). Trait anxiety measured at baseline was not correlated with relative changes in pain (T0 to T2, P = .248).

CONCLUSION

In the short term, FL-A reduces facial pain, masticatory muscle tenderness, and awake bruxism in women with chronic mTMD with low disability. A conservative management strategy should be prioritized for the initial management of these patients.

Accuracy of sleep bruxism scoring based on electromyography traces of different jaw muscles in individuals with obstructive sleep apnea

STUDY OBJECTIVES

Sleep bruxism is characterized by rhythmic masticatory muscle activity (RMMA). This study aimed to determine the number and type of jaw muscles needed for a valid RMMA scoring in individuals with obstructive sleep apnea (OSA).

METHODS

10 individuals with OSA (4 males; age = 50.1 ± 8.1 years) were included in this study. RMMA was scored using one or more of the following jaw muscles' electromyography (EMG) traces of polysomnography recordings: bilateral masseter and temporalis (4MT; the reference standard), unilateral masseter (1M), bilateral masseter (2M), unilateral temporalis (1T), bilateral temporalis (2T), unilateral chin EMG (1C), and bilateral chin EMG (2C).

RESULTS

1M, 2M, 1T, and 2T showed excellent agreement with 4MT (intraclass correlation coefficient [ICC] = 0.751, 0.976, 0.815, and 0.950, respectively), while 1C and 2C presented fair agreement (ICC= 0.662 and 0.657). Besides, 2M and 2T displayed good sensitivity (87.8% and 72.0%) and positive predictive value (PPV; 83.1% and 76.0%). In contrast, 1M and 1T had good sensitivity (88.4% and 87.8%) but fair PPV (60.1% and 53.2%). 1C and 2C showed poor sensitivity (41.1% and 40.3%) and fair PPV (62.9% and 60.6%).

CONCLUSIONS

Polysomnography with bilateral masseter or temporalis muscle EMG traces is regarded valid in RMMA scoring in individuals with OSA. In contrast, unilateral masseter or temporalis muscle EMG showed only fair accuracy, and chin EMG had poor accuracy. Consequently, these montages cannot be recommended for RMMA scoring in the presence of OSA.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: The Effects of Oral Appliance Therapy on Masseter Muscle Activity in Obstructive Sleep Apnea; Identifier: NCT02011425.

The influence of jaw-muscle fibre-type phenotypes on estimating maximum muscle and bite forces in primates

Numerous anthropological studies have been aimed at estimating jaw-adductor muscle forces, which, in turn, are used to estimate bite force. While primate jaw adductors show considerable intra- and intermuscular heterogeneity in fibre types, studies generally model jaw-muscle forces by treating the jaw adductors as either homogeneously slow or homogeneously fast muscles. Here, we provide a novel extension of such studies by integrating fibre architecture, fibre types and fibre-specific tensions to estimate maximum muscle forces in the masseter and temporalis of five anthropoid primates: Sapajus apella (N = 3), Cercocebus atys (N = 4), Macaca fascicularis (N = 3), Gorilla gorilla (N = 1) and Pan troglodytes (N = 2). We calculated maximum muscle forces by proportionally adjusting muscle physiological cross-sectional areas by their fibre types and associated specific tensions. Our results show that the jaw adductors of our sample ubiquitously express MHC α-cardiac, which has low specific tension, and hybrid fibres. We find that treating the jaw adductors as either homogeneously slow or fast muscles potentially overestimates average maximum muscle forces by as much as approximately 44%. Including fibre types and their specific tensions is thus likely to improve jaw-muscle and bite force estimates in primates.

Evaluating bony predictors of bite force across the order Carnivora

In carnivorans, bite force is a critical and ecologically informative variable that has been correlated with multiple morphological, behavioral, and environmental attributes. Whereas in vivo measures of biting performance are difficult to obtain in many taxa-and impossible in extinct species-numerous osteological proxies exist for estimating masticatory muscle size and force. These proxies include both volumetric approximations of muscle dimensions and direct measurements of muscular attachment sites. In this study, we compare three cranial osteological techniques for estimating muscle size (including 2D-photographic and 3D-surface data approaches) against dissection-derived muscle weights and physiological cross-sectional area (PCSA) within the jaw adductor musculature of 40 carnivoran taxa spanning eight families, four orders of magnitude in body size, and the full dietary spectrum of the order. Our results indicate that 3D-approaches provide more accurate estimates of muscle size than do surfaces measured from 2D-lateral photographs. However, estimates of a muscle's maximum cross-sectional area are more closely correlated with muscle mass and PCSA than any estimates derived from muscle attachment areas. These findings highlight the importance of accounting for muscle thickness in osteological estimations of the masticatory musculature; as muscles become volumetrically larger, their larger cross-sectional area does not appear to be associated with a proportional increase in the attachment site area. Though volumetric approaches approximate muscle dimensions well across the order as a whole, caution should be exercised when applying any single method as a predictor across diverse phylogenies.

Pain in the temple? Headache, muscle pain or both: A retrospective analysis

AIM

Headache attributed to temporomandibular disorders and myalgia are two diagnoses included in the diagnostic criteria for temporomandibular disorders (DC/TMD). However, it is not clear if these two diagnoses are different clinical entities given their similar presentation and way in which they are diagnosed, when the myalgia is within the temporalis muscle. The purpose of this retrospective study was to assess the overlap between headache attributed to temporomandibular disorders and myalgia of the temporalis muscle.

METHODS

The charts of 671 patients seeking treatment at the Section of Orofacial Pain and Jaw Function, Aarhus University, Denmark, between January 2015 and February 2020 were screened for a diagnosis of headache attributed to temporomandibular disorders, myalgia of the temporalis muscle, or both.

RESULTS

A total of 89 patients fulfilled the DC/TMD criteria for either headache attributed to TMD, myalgia of the temporalis or both. Of these, two had a diagnosis of headache attributed to TMD, 16 of myalgia of the temporalis, and 71 were diagnosed with both. In 97.3% of the times that headache attributed to temporomandibular disorders was diagnosed, the patient was also diagnosed with myalgia of the temporalis. The Jaccard index was 0.8, indicating a substantial overlap between the two diagnoses. Finally, the overlap of pain location between the two diagnoses was substantial, with a Jaccard index of 0.9.

CONCLUSIONS

In the present study, headache attributed to temporomandibular disorders was almost exclusively diagnosed together with myalgia of the temporalis. Therefore, we propose that headache attributed to temporomandibular disorders and myalgia of the temporalis muscle have more clinical similarities than differences and as such could be considered one single clinical entity. Further studies will be needed to address the clinical consequences of this proposal.

Pressure Algometry Evaluation of Two Occlusal Splint Designs in Bruxism Management-Randomized, Controlled Clinical Trial

The aim of this pilot study was to evaluate the short-term effectiveness of two different occlusal devices and their impact on the pressure pain threshold (PPT) values among patients who reported to the Dental Prosthetics Outpatient Clinic of Pomeranian Medical University (Szczecin, Poland) and who were diagnosed with probable bruxism. Two groups were formed (A and B) to which patients were assigned randomly. Each group used a different occlusal splint for bruxism management. The occlusal appliance by Okeson, or the bimaxillary splint, was used overnight by each patient for 30 days of the study. The PPT was measured twice, at the first visit and after 30 days of using each occlusal device, with Wagner Paintest FPX 25 algometer. Bruxism was diagnosed based on data from the patient's medical history and from the physical examination. Nocturnal Bruxism Criteria according to the International Classification of Sleep Disorders (Third Edition) was used for the patient's evaluation. Results: similar pain factor (PF) reduction was observed in both the examined groups, regardless of the device used; canine guidance and no guidance were similarly effective in terms of increasing pain resilience.

Increased somatosensory amplification is associated with decreased pressure pain thresholds at both trigeminal and extra-trigeminal locations in healthy individuals

BACKGROUND

The diagnosis of temporomandibular disorders (TMD) is based on patient history and physical examination, and may require medical imaging. Masticatory muscle palpation is essential to make a diagnosis of TMD. However, the response of masticatory muscles to mechanical pressure stimuli depends on many physical and psychological factors.

OBJECTIVE

This study aimed at determining the impact of somatosensory amplification (SSA)-an estimate of somatic awareness and bodily hypervigilance-on pressure pain thresholds (PPTs) measured at both trigeminal and extra-trigeminal locations in healthy individuals.

METHODS

PPTs were measured at the right anterior temporalis and superficial masseter, and the thenar eminence of the right hand in one hundred healhty individuals (69F, 31M), divided in three groups based on their SSA scores: low (N = 32), intermediate (N = 34) and high (N = 34). General linear models were used to test between-group differences in PPTs including sex as a covariate. The level of significance was set at P < .05.

RESULTS

Individuals with high SSA had lower PPTs at the anterior temporalis than individuals with low (P = .006) and intermediate (P = .001) SSA. No significant between-group differences were found in PPTs measured at the masseter (P = .372). PPTs measured at the thenar eminence were significantly lower in the high than the low SSA group (P = .009). Females had lower PPTs at the masseter than males (P = .021) but not at other muscle locations (all P > .05).

CONCLUSION

Increased somatosensory amplification is associated with decreased pressure pain thresholds at both trigeminal and extra-trigeminal locations in healthy individuals. SSA could be a potential confounder while diagnosing TMD and evaluating treatment outcomes.

Remedial Massage Therapy Interventions Including and Excluding Sternocleidomastoid, Scalene, Temporalis, and Masseter Muscles for Chronic Tension Type Headaches: a Case Series

BACKGROUND

Tension-type headache (TTH) is the most prevalent primary headache type world-wide. Chronic TTH (CTTH) of >15 headache-affected days per month for > 3 months can cause considerable pain and disability.

PURPOSE

This case series aimed to investigate whether massage therapy interventions were more effective when muscles of the anterior neck, jaw, and cranium were included.

DESIGN

Four female clients suffering CTTH received six pre-determined massage therapy interventions, 45 minutes each, over three weeks. Case A and B (exclusion cases) received interventions addressing shoulder, posterior neck, and occiput muscles; Case C and D (inclusions cases) received interventions addressing the same areas as well as the sternocleidomastoid, scalene, temporalis, and masseter muscles.

INTERVENTION

Treatment included myofascial trigger point release, neuromuscular therapy, and consideration of central sensitization mechanisms present in CTTH.

OUTCOME MEASURES

Headache frequency (primary), intensity, and duration (secondary) were recorded via headache diaries for baseline measures (one week), interventions (three weeks), and a runout period (two weeks). Secondary measures also included a headache disability inventory (HDI) at baseline, intervention conclusion, and final measures. After final measures, clients received stretching education and four weeks later, a follow-up phone conversation to note subjective headache reports.

RESULTS

All cases had headache frequency and HDI score reductions, while intensity and duration measures fluctuated. At final measures, exclusion Case A and both inclusion cases (C and D) had headache frequency reductions to below CTTH diagnostic criteria, clinically meaningful (> 16%) HDI score reductions, and subjectively reported continued improvements after study completion. Inclusion cases overall had greater decreases in headache frequency and HDI measures.

CONCLUSION

Comparative results suggest there may be additional benefit in reducing headache frequency and disability with inclusion of anterior neck, jaw, and cranial muscles in treatment strategies of CTTH. However, limited sample size makes it difficult to rule out outliers or individual variables. Further investigation is recommended.

Inferior Repositioning of Coronoid Process for the Treatment of Temporomandibular Joint Subluxation/Dislocation

Subluxation/dislocation of the temporomandibular joint (TMJ) is characterized by transient locking of the jaw following wide mouth opening. The etiology of the condition is multifactorial relating to hard-tissue or soft-tissue components of the joint. Myriad treatment procedures have been described in the literature, each with its own advantages and disadvantages. We present a new intraoral technique of coronoid repositioning for the treatment of TMJ subluxation/dislocation.

Association of Dysplastic Coronoid Process with Long-Face Morphology

Vertical malocclusion is a developmental condition, resulting from complex interactions among multiple etiological factors during the growth period. As a tricky dentofacial deformity clinically, long-face (LF) morphology is characterized by excessive vertical facial growth with severe disarrangement of jaws and teeth. Since the improvement of LF patients on facial profile and occlusion is often difficult and lacks long-term stability, it becomes important to unravel the etiology of LF pattern formation for early prevention and treatment. In the current studies, we identified a transgenic mouse model that exhibited a dysplastic coronoid process and LF morphology. Although the mutant mice exhibited jaw structures and occlusion comparable to controls at birth, they all acquired typical LF morphology with anterior open bite during postnatal growth, resembling clinical features of the selected skeletal class III patients. Since the coronoid process provides an insertion site for the temporalis attachment, we examined the initial development and differentiation of the temporalis and found identical results in both control and mutant mice before E17.5 when the temporal muscle makes attachment to the coronoid process. However, thereafter, we observed altered orientation and reduced size of the cross-sectional area of the temporalis in mutant mice, which persisted to the weaning stage. Biomechanical analysis and simulation modeling further support the idea that altered morphology of the coronoid process may impair the efficiency of the vertical temporalis contraction and appears to correlate with LF formation. Consistently, we present evidence that a dysplastic mandibular coronoid process was also seen in some human patients with skeletal III LF morphology. Taken together, the results presented in this study establish an association of the craniofacial bony structures with vertical patterning, which will have implications in earlier prediction for clinical precaution and intervention.

Changes in the muscles of mastication before and after primary stereotactic radiosurgery in patients with idiopathic trigeminal neuralgia

OBJECTIVE

The motor root of the trigeminal nerve runs close to the sensory root and receives considerable radiation during Gamma Knife radiosurgery (GKRS) for trigeminal neuralgia (TN). The object of this study was to evaluate via MRI the changes in the muscles of mastication before and after upfront GKRS in patients with idiopathic TN.

METHODS

In this single-institution retrospective cohort study, all patients with idiopathic unilateral TN treated with primary GKRS at the University of Virginia in the period from 2007 to 2017 were included provided that they had pre- and post-GKRS MRI data. The thicknesses of the temporalis, pterygoid, and masseter muscles were measured on both pre- and post-GKRS MRI in a blinded fashion. Changes in the muscles like fatty infiltration, MRI signal, or atrophy were noted.

RESULTS

Among the 68 patients eligible for inclusion in the study, 136 temporalis muscles, 136 medial pterygoid muscles, 136 lateral pterygoid muscles, and 136 masseter muscles were assessed. A subset of patients was found to have muscle atrophy even prior to GKRS. Pre-GKRS atrophy of the masseter, medial pterygoid, lateral pterygoid, and temporalis muscles was seen in 18 (26%), 16 (24%), 9 (13%), and 16 (24%) patients, respectively. Logistic regression analysis showed that distribution of pain in the V3 territory (p = 0.01, OR 5.43, 95% CI 1.46-20.12) and significant pain on chewing (p = 0.02, OR 5.32, 95% CI 1.25-22.48) were predictive of pre-GKRS atrophy. Reversal of atrophy of these muscles occurred after GKRS in a majority of the patients. The incidence of new-onset permanent post-GKRS muscle atrophy was 1.5%. The median follow-up was 39 months (range 6-108 months).

CONCLUSIONS

A subset of patients with TN with significant pain on chewing have pre-GKRS disuse atrophy of the muscles of mastication. A reversal of the atrophy occurs in a majority of the patients following GKRS. New-onset motor neuropathy post-GKRS was rare.

Regional Reconstruction of Orbital Exenteration Defects

Aggressive disease such as invasive fungal infections or malignancies may necessitate orbital exenteration. The defects of orbital exenteration are often complex involving adjacent structures. Rehabilitation of the orbital exenteration defect poses unique challenges to the reconstructive surgeon. Various options have been described ranging from secondary intention to microvascular free tissue reconstruction. Here the authors review local/regional options for reconstruction of orbital exenteration defects.

Behavioral Correlates of Cranial Muscle Functional Morphology

This issue of the Anatomical Record is the first of a two-volume set that focuses on new investigations into behavioral correlates of muscle functional morphology. Much of the research on functional morphology and adaptation to specific functional niches focuses on the shapes of hard-tissues-bones and teeth. Investigations into soft-tissue anatomy tend to be predominantly descriptive with only brief allusion to ontogenetic or evolutionary origins of structures. When muscles are included in analyses of functional systems, their function tends to be oversimplified-usually considered a simple force vector connecting two osteological points, with the force treated as a constant derived from some simple calculation of muscle size. The goal of these special issues is to present a series of studies that take a more elaborate look at how muscles can be viewed from a functional perspective in studies searching for morphological correlates of behavior. This first volume focuses on the behavioral correlates of cranial muscles-starting with a paper about the mimetic musculature of primates and ending with a series of papers on the masticatory muscles of many lineages of vertebrates. The next issue of the Anatomical Record (March 2018) includes our papers on the behavioral correlates of postcranial muscles. Taken together, we hope you agree that this series presents valuable insights into these form/function relationships using both traditional approaches+ and cutting-edge techniques. Anat Rec, 301:197-201, 2018. © 2018 Wiley Periodicals, Inc.

Botulinum Toxin A for Spastic Trismus Due to Brain Stem Encephalitis in a Pediatric Intensive Care Setting: A Unique Case Report

Injection of botulinum toxin A to masseter and temporalis muscles improved mouth opening and facilitated suction and oral care in a child with spastic trismus. This is the first such report in a 3.5-year-old child on mechanical ventilator in pediatric intensive care unit setting.

A new adjunctive tool to aid in the diagnosis of myogenous temporomandibular disorder pain originating from the masseter and temporalis muscles: Twin-block technique

Myogenous temporomandibular disorder (TMD) is the most common type of nonodontogenic pain. The diagnosis is often elusive since diagnosing such conditions often requires a more comprehensive patient assessment. At present, there is no simple one-step diagnostic test to help render a definitive diagnosis of myogenous TMD pain. The twin-block injection can serve as a diagnostic aid to facilitate diagnosis of such myogenous TMD. The twin-block injection blocks the innervation to both the temporalis and masseter muscles, the two most common sources of referred pain to the teeth. This article reviews the twin-block technique along with a case report illustrating its potential role in the diagnosis and management of myogenous TMD pain of masseteric and temporalis origin.

Objective Outcomes of Minimally Invasive Temporalis Tendon Transfer for Prolonged Complete Facial Paralysis

OBJECTIVES

We describe an approach to reanimation of complete, prolonged facial paralysis using minimally invasive temporalis tendon transfer (MIT3) by the melolabial or transoral approach. Objective outcome measures are evaluated based on symmetry, and grading of preoperative/post-operative results and the scar at the melolabial fold.

STUDY DESIGN

Retrospective cohort study.

METHODS

Twenty-five patients undergoing the MIT3 technique were studied. Photographic analysis was used to determine the percentage of difference between the 2 sides (symmetry). Using the Delphi method to achieve consensus, a panel of experts graded pre/post-operative photos using the Terzis' Facial Grading System and a 1 to 10 Likert-type scale and the melolabial scar using the Beausang Scar Scale.

RESULTS

Percentage of difference (symmetry) with smiling improved from 18.6% ± 1.5% (mean ± standard error of the mean [SEM]) preoperatively to 5.0 ± 0.9% (mean ± SEM) post-operatively. Expert grading by the Terzis system showed improvement post-operatively (mean 3.7/5; median 3.6/5) versus preoperatively (mean 1.5/5; median 1.2/5). Perceived improvement was also largely favourable (mean 8.1/10; median 8.0/10). Melolabial scar grading was favourable in terms of colour (mean 1.53/4), surface character (mean 1.05/2), contour (mean 1.60/4), and distortion (mean 1.74/4).

CONCLUSIONS

The MIT3 technique offers immediate, predictable, and symmetrical return of smile function. Objective symmetry analysis and favourable expert grading of both pre-/post-operative photographs and the scar at the melolabial fold demonstrate applicability for facial reanimation in patients where other procedures have failed, or when a direct return to function is desired. Both the melolabial approach and transoral approach were found to be acceptable and effective, although applicability varies.

Influence of time and different tooth widths on masticatory efficiency and muscular activity in bilateral free-end saddles

PURPOSE

To evaluate the influence of time on masticatory efficiency and muscular activity during mastication of different types of test foods in participants fitted with a lower bilateral free-end saddle removable partial denture (RPD) with wide or narrow teeth.

METHODS

Thirty-six participants consented to undergo evaluation of their masticatory efficiency and recording of their muscular activity, while they wore an RPD with a unified bilateral design, during mastication of different types of test foods. The width of the artificial teeth was changed as follows. Initially (A), the length was adjusted so that the distal end of the mandibular second molars occluded with the distal end of the maxillary second molar (buccolingual width of 7-8 mm). Next (B), the width was decreased to half the maxillary second molars (buccolingual width of only 5 mm). A statistical analysis was performed using SAS software. One-way analysis of variance (ANOVA) was performed followed by Duncan's multiple range tests.

RESULTS

At the 2-month follow-up visit, wider teeth demonstrated greater masticatory efficiency than narrower teeth. However, after 4 months, no significant differences were observed between the two tooth widths. No significant differences in muscular activity were observed.

CONCLUSION

A reduction of the occlusal table width in free-end saddle RPDs resulted in decreased masticatory efficiency 2 months after denture fabrication, but there was no significant difference in muscular activity between narrow and wide teeth. However, after 4 months, the masticatory efficiency of the participants with narrower teeth improved without any changes in muscular activity.

Importance of ultrasonography and magnetic resonance imaging in diagnosis of cysticercosis of temporalis muscle mimicking temporal space infection

Cysticercosis cellulosae, caused by the larval stage of Taenia solium is a common parasitic infection in Indian subcontinent. Although cysticercosis is common in other parts of the human body, its involvement with temporalis muscle is an extremely rare entity and demands documentation. This paper reports a case of cysticercosis cellulosae in a 35-year-old male patient within the temporalis muscle mimicking temporal space infection; due to the presence of concomitant dental infection, which was diagnosed with the help of high resolution ultrasonography and magnetic resonance imaging and managed conservatively using oral antiparasitic medication. Here, in this case report, we are emphasizing the importance of imaging modalities in diagnosing space infection and cysticercosis.

Combined subgaleal/myocutaneous technique for temporalis muscle dissection

Background The frontal branch of the facial nerve (FBFN) is the most susceptible neural structure to injury during frontotemporal craniotomies. The balance between adequate temporalis muscle mobilization and frontal branch protection with minimal anatomical alteration is the philosophy behind our approach to temporalis muscle dissection. Objective To describe a combined subgaleal/myocutaneous technique for dissection and mobilization of the temporalis muscle in anterolateral cranial approaches. Methods Interdisciplinary literature review of the anatomical course of the FBFN was performed. Retrospective analysis of anterolateral craniotomies performed at our institution in which the combined subgaleal/myocutaneous (CSGMC) technique was performed. Results A total of 71 cases of anterolateral craniotomies (excluding full variant orbitozygomatic) were performed with the successful application of a CSGMC technique (36 pterional, 31 orbitopterional, and 4 fronto-orbital). Partial frontalis weakness was transient in one case. Conclusion The CSGMC technique provides sufficient protection for the FBFN and allows for adequate mobilization for a variety of skull base exposures while minimally violating myofascial anatomy. This is the first reported technique that allows both adequate temporalis muscle mobilization with performance of the one-piece orbitofrontal and orbitopterional approaches, without disruption of the superficial/deep temporalis fascia and fat-pad complex.

Longitudinal changes in muscle activity of masseter and anterior temporalis before and after Lefort I osteotomies, An EMG study

AIMS

The aim of this study was to compare the levels of electromyography (EMG) activity of masseter and anterior temporalis present presurgically with changes in the intensity of muscle activity that took place post surgically for a period of 6 months follow up.

SETTINGS AND DESIGN

Ten patients with vertical maxillary excess were selected from the department of Oral and Maxillofacial surgery at Saveetha Dental College and Hospitals, Chennai.

MATERIALS AND METHODS

Electromyography was used as a kinesiology tool to study muscle function of Masseter and Anterior Temporalis of all ten subjects pre surgically and post surgically with a 6 month follow up.

STATISTICAL ANALYSIS USED

The statistical package SPSSPC+ (Statistical Package for Social Science, Version 4.0.1) was used for statistical analysis. Mean and standard deviation were estimated from the sample. The tests that were used for the statistical analysis were one way ANOVA and student's T test.

RESULTS

The final inference elucidates that the muscular activity of masseter and temporalis are improved during chewing and clenching in the postoperative 6 months period when compared to preoperative values. The duration was constant at 7 milliseconds for both the positions.

CONCLUSIONS

From this study, it can be concluded that there is a strong correlation between vertical maxillary excess and associated weak musculature. Electromyography has been used as an important tool to demonstrate improved muscle activity after surgical correction of vertical maxillary excess and improvement in functional deficits associated with this dentofacial deformity. From this study it can be concluded that surgical correction of vertical maxillary excess improves occlusion, leading to increased eccentric tooth contacts, increased mean amplitude and increased mean power frequency of the muscles all of which translate into improved muscle activity.