Dentofacial characteristics of growing patients with Duchenne muscular dystrophy: a morphological study

Factors influencing the decision to introduce alternative nutrition in patients with Duchenne muscular dystrophy

INTRODUCTION/AIMS

Nutritional management of adults with Duchenne muscular dystrophy (DMD) is an important clinical issue. However, it is not clear which dysphagia-related factors should prompt introduction of alternative nutrition (AN). We aimed to determine which patients with DMD were introduced to AN.

METHODS

This retrospective study included 56 patients with DMD (median age, 23.5 years). They were divided into patients able to continue oral feeding (OF) and those introduced to AN. Body weight, frequency of ventilator use, daily meals, history of steroid treatment, results of videofluoroscopic examination of swallowing (VF), and awareness of dysphagia were evaluated.

RESULTS

Of 56 patients, 19 were in the AN group. After AN introduction, 93% of the patients continued oral intake. The proportion of patients who consumed chopped and liquid diets was higher, and body weight was lower, in the AN than in the OF group. There were no significant differences in age, upper limb function of feeding, frequency of ventilator use, or history of steroid therapy between the two groups. The frequencies of aspiration and residue in the pyriform sinus in VF were higher in the AN group than in the OF group. Decision-tree analysis showed that food form and subjective difficulty swallowing solid foods were the most important factors affecting the decision-making for AN.

DISCUSSION

Patients with DMD who had difficulty eating solid foods were started on AN because they were unable to maintain their weight. These findings provide information for future longitudinal studies to assess the value of AN.

Open Bite Malocclusion and Orofacial Dysfunction in Patients with Myotonic Dystrophy Type 1 and Duchenne Muscular Dystrophy

Open bite (OB) is a common malocclusion in individuals with orofacial dysfunction and syndromes, especially in neuromuscular diseases.

OBJECTIVES

The objectives were to explore the prevalence of OB in myotonic dystrophy type 1 (DM1) and Duchenne muscular dystrophy (DMD) and to create and compare orofacial dysfunction profiles.

METHODS

In this database study, 143 individuals with DM1 and 99 with DMD were included. The Mun-H-Center questionnaire and observation chart were used together with the Nordic Orofacial Test -Screening (NOT-S) to create orofacial dysfunction profiles. OB was categorised as: lateral (LOB); anterior (AOB); severe anterior (AOBS); or both types of anterior OB (AOBTot). Descriptive and multivariate statistics were used to compare the OB prevalence and to study associations with orofacial variables, respectively.

RESULTS

There was a statistically significant difference in OB prevalence between the DM1 (37%) and DMD (49%) groups (p = 0.048). LOB was seen in < 1% of DM1 and 18% of DMD. LOB was associated with macroglossia and closed mouth posture, AOB with hypotonic lips, and open mouth posture and AOBS with hypotonic jaw muscles. The orofacial dysfunction profiles showed similar patterns, although the mean NOT-S total scores for DM1 and DMD were 4.2±2.8 (median 4.0, min-max 1-8) and 2.3±2.0 (median 2.0, min-max 0-8), respectively.

LIMITATIONS

The two groups were not age- or gender-matched.

CONCLUSION

OB malocclusion is common in patients with DM1 and DMD and is associated with different types of orofacial dysfunction. This study highlights the need for multi-disciplinary assessments to support tailored treatment strategies that improve or sustain orofacial functions.

Impact of Diet Consistency on the Mandibular Morphology: A Systematic Review of Studies on Rat Models

Apart from genetics, environmental factors, such as food consistency, may affect craniofacial morphology and development. The present systematic review aims to systematically investigate and appraise the available evidence regarding the effect of diet consistency on the anatomical structures of the basal bone of the rat mandible. The search was performed without restrictions in five databases (PubMed, Scopus, Web of Science, ProQuest Dissertations and Theses Global, including grey literature) and hand searching through January 2022. A total of 14,904 references were initially identified, and 16 articles were finally included in the systematic review. Rats that consumed hard diets were found to exhibit an increase inbigonial width, corpus height, condylar depth, condylar base inclination, condylar process inclination, mandibular plane inclination, height and length of angular process, mandibular body height, depth of antegonial notch, growth rate in the gonial angle, angular process convexity and height of condylar process. It was also noted that mandibular depth, mandibular height, ramus angle and angle between the angular process and mandibular plane were decreased in rats that were fed with a hard diet. On the other hand, there were conflicting results about the growth of mandibular length and width, corpus length, mandibular body length, ramus height, condylar length and width, gonial angle and height of coronoid process. From the abovementioned results, it can be concluded that food consistency may affect the morphology of anatomical structures and the overall growth and development of rat mandibles in various ways.

Occlusal traits and longitudinal dental changes in children and adolescents with congenital or childhood onset myotonic dystrophy

BACKGROUND/OBJECTIVES

This research aimed to study the malocclusions of children and adolescents with myotonic dystrophy type 1 (DM1), in respect to healthy individuals, and trace the occlusal changes that occurred in these individuals during growth.

MATERIALS/METHODS

Thirty-six dental casts, from children and adolescents with DM1 living in western and southern Sweden, were compared with a control group of 50 healthy individuals. To identify potential changes in occlusal traits, 26 casts were assessed and followed-up over a median time of 9 years. Independent samples t-tests were used to compare the two groups and their changes over time. Paired samples t-tests tested changes over time within each group (P < 0.05).

RESULTS

DM1 patients had a higher prevalence of anterior open bite, posterior crossbite, and Class III malocclusions. When compared to controls, patients presented smaller upper and lower intermolar as well as intercanine widths. In both groups, the individuals revealed longitudinal changes with a decrease in both upper and lower arch lengths and an increase on the palatal vault height. During the follow-up period, the prevalence of malocclusions remained almost the same, only significantly differing regarding the changes that occurred between groups referred to the upper intermolar width, which decreased among DM1 patients.

CONCLUSIONS/IMPLICATIONS

In comparison to healthy controls, children and adolescents with DM1 have shown already at an early age a higher prevalence of both anterior open bite and posterior crossbite. These occlusal traits did not change with time apart from the upper narrow intermolar width, which further decreased with time.

Alleviation of masticatory disturbance with an occlusal splint in a Duchenne muscular dystrophy patient

Aim

To present an occlusal splint effective for alleviating masticatory disturbance in Duchenne muscular dystrophy (DMD).

Case report

A 13‐year‐old male DMD patient with masticatory disturbance presented with an open bite, with occlusal contact only between the first and second molars bilaterally and reduced masticatory performance. We applied an occlusal splint that achieved occlusal contact for all teeth and monitored its effects on masticatory function over 6 years. The occlusal splint increased occlusal contact points from 11 to 60. Although occlusal force remained at 13.9‒16 kg, masticatory performance increased, and the number of mastication strokes increased from 124 to 169. Masseter muscle activity decreased from 76.8% to 33.4% maximum voluntary contraction (MVC) and digastric muscle activity increased from 8.7% to 18.0% MVC. Time from start of peanut mastication to swallowing decreased, and the vertical mastication cycle diameter and its width on the habitual side increased.

Conclusions

Masticatory disturbance in a DMD patient was alleviated using an occlusal splint. The number of mastication strokes and the digastric to masseter muscle activity ratio were increased. Furthermore, the mastication cycle was enlarged, which increased masticatory movement. As masseter muscle activity during mastication decreased, the occlusal splint likely reduced muscle fatigue during masticatory movement.

Influence of botulinum toxin A on craniofacial morphology after injection into the right masseter muscle of dystrophin deficient (mdx-) mice

BACKGROUND

Severe craniofacial and dental abnormalities, typical for patients with progressive Duchenne muscular dystrophy (DMD), are an exellcent demonstration of Melvin L. Moss "functional matrix theory", highlighting the influence of muscle tissue on craniofacial growth and morphology. However, the currently best approved animal model for investigation of this interplay is the mdx-mouse, which offers only a limited time window for research, due to the ability of muscle regeneration, in contrast to the human course of the disease. The aim of this study was to evaluate craniofacial morphology after BTX-A induced muscle paralysis in C57Bl- and mdx-mice, to prove the suitability of BTX-A intervention to inhibit muscle regeneration in mdx-mice and thus, mimicking the human course of the DMD disease.

METHODS

Paralysis of the right masseter muscle was induced in 100 days old C57Bl- and mdx-mice by a single specific intramuscular BTX-A injection. Mice skulls were obtained at 21 days and 42 days after BTX-A injection and 3D radiological evaluation was performed in order to measure various craniofacial dimensions in the sagittal, transversal and vertical plane. Statstical analysis were performed using SigmaStat®Version 3.5. In case of normal distribution, unpaired t-test and otherwise the Mann-Whitney-U test was applied. A statistical significance was given in case of p ≤ 0.05.

RESULTS

In contrast to C57Bl-mice, in mdx-mice, three weeks after BTX-A treatment a significant decrease of skull dimensions was noted in most of the measurements followed by a significant increase at the second investigation period.

CONCLUSIONS

BTX-A can induce changes in craniofacial morphology and presumably partially inhibit muscle regeneration in mdx-mice, but cannot completely intensify craniofacial effects elicited by dystrophy. Further research is necessary in order to fully understand muscle-bone interplay after BTX-A injection into dystrophic muscles.

Masticatory muscle function affects the pathological conditions of dentofacial deformities

The causes of dentofacial deformities include various known syndromes, genetics, environmental and neuromuscular factors, trauma, and tumors. Above all, the functional effects of muscles are important, and deformation of the mandible is often associated with a mechanical imbalance of the masticatory muscles. With the vertical position of the face, weakness of the sling of the masseter muscle and medial pterygoid muscle causes dilatation of the mandibular angle. In patients with a deep bite, excessive function of the masticatory muscles is reported. Myosin heavy chain　(MyHC) properties also affect jawbone morphology. In short-face patients, the proportion of type II fibers, which are fast muscles, is high. The proportions of muscle fiber types are genetically determined but can be altered by postnatal environmental factors. Orthognathic surgery may results in the transition of MyHC to type II (fast) fibers, but excessive stretching enhances the release of inflammatory mediators and causes a shift toward a greater proportion of slow muscle fibers. This feature can be related to postoperative relapse. Bones and muscles are in close crosstalk, and it may be possible to use biochemical approaches as well as biomechanical considerations for the treatment of jaw deformities.

Review of Etiology of Posterior Open Bite: Is There a Possible Genetic Cause?

Posterior open bite (POB) is one of the most severe malocclusions that can impair patients' masticatory functions, yet it is also a condition that is poorly understood and not well studied. Most reported cases are either sporadic or idiosyncratic with a diverse yet poorly understood etiology. Although primary failure of eruption (PFE), lateral tongue thrust, and certain medical syndromes or pathology of the temporomandibular joints have all been shown to cause POB, the complex interplay of environmental and genetic factors makes its etiopathogenesis a difficult subject to understand and investigate. Here, we provide a comprehensive review of the etiology of posterior open bite. Additionally, a genetic cause for POB is proposed through a report of an apparently non-syndromic familial case series with high POB penetrance across two generations. Further investigations of the gene(s) and mechanism(s) involved can not only provide a unique opportunity to better understand POB and the intricate muscular-occlusal relationship, but also offer powerful insight into the most effective approaches to clinical management of these (and potentially other) malocclusions.

Management of the dentoalveolar effects of tongue hypertrophy in patients with Duchenne muscular dystrophy: A pilot study

Subjects affected by Duchenne muscular dystrophy (DMD) develop severe malocclusions with the progression of the disease, due to changes in orofacial musculature and function, including tongue hypertrophy. We aimed to evaluate the benefits of maintaining mandibular interarch width with the help of a simple fixed orthodontic appliance. Three adolescent DMD boys were selected consecutively to receive a passive rigid mandibular lingual arch, and followed for 4-5 years. An untreated age-matched control group was chosen and followed for a similar period. Study casts were obtained at baseline and after follow-up. Outcomes measured were overjet, overbite, maxillary and mandibular intermolar widths, mandibular arch depth, molar relationships, and the presence of lateral crossbites and anterior or lateral openbites. Changes in measurements obtained between the two time points were compared in each age-matched pair. There was a clinically important increase in the mandibular intermolar width in the non-treated children ranging from 2.5 mm to 9 mm, but not in those treated. Malocclusions generally deteriorated in untreated children while they remained stable in treated children. The use of a rigid mandibular lingual arch in boys with DMD can help slow down the rapid deterioration of the developing malocclusions that accompanies the progression of the disease.

Growing patients with Duchenne muscular dystrophy: longitudinal changes in their dentofacial morphology and orofacial functional capacities

Aim

The aim of this study was to describe the longitudinal changes in facial morphology, dental arch alterations and oral functional capacities that occur in growing patients with Duchenne muscular dystrophy (DMD) in order to identify the effects of the progression of the disease.

Subjects and Methods

Twelve DMD patients (6.5-17.5 years of age) and 12 matched controls were screened on two different occasions (T1 and T2), 2 years apart. Dental casts, lateral cephalometric radiographs, maximal posterior bite force and labial force were measured to determine changes in their functional capacities and dentofacial morphology. Furthermore, the thickness and echogenicity of the masseter muscle were measured during clenching.

Statistical evaluation

Unpaired t-tests were performed to evaluate the differences between the DMD patients and their healthy matched controls; paired t-tests were used to assess the changes that occurred within each group between T1 and T2.

Results

Between T1 and T2 the following changes were observed: widening of the lower dental arch for the DMD patients of 2.6mm (±0.9mm) compared to a slight reduction of -0.1mm (±0.8mm) for the control group (P = 0.001). We found a statistically significant reduction of the sagittal skeletal intermaxillary relationship (ANB-angle) of 2.0° (±2.0°) in the DMD group (P = 0.012). In T1 and T2, the maximal posterior bite force and the labial force were lower for the DMD patients compared to the control group (P = 0.001), who showed an increase during this period.

Conclusion

The results indicate that DMD influences the facial morphology, dental arch dimensions and oral functional capacities. The longitudinal perspective of this study revealed that the worsening of most of the measured parameters is associated with the progression of the disease. Besides the expected deterioration of the functional measurements, we found in all patients, a marked transverse increase of the posterior part of the dental arches, more in the lower than in the upper, resulting in posterior crossbites, as well as a tendency towards a skeletal Class III relationship.

Genetic variants in ACTN3 and MYO1H are associated with sagittal and vertical craniofacial skeletal patterns

OBJECTIVE

This study aimed to evaluate the association of genetic variants inACTN3 and MYO1H with craniofacial skeletal patterns in Brazilians.

DESIGN

This cross-sectional study enrolled orthodontic and orthognathic patients selected from 4 regions of Brazil. Lateral cephalograms were used and digital cephalometric tracings and analyzes were performed for craniofacial phenotype determination. Participants were classified according to the skeletal malocclusion in Class I, II or III; and according to the facial type in Mesofacial, Dolichofacial or Brachyfacial. Genomic DNA was extracted from saliva samples containing exfoliated buccal epithelial cells and analyzed for genetic variants inACTN3 (rs678397 and rs1815739) and MYO1H (rs10850110) by real-time PCR. Chi-square or Fisher's exact tests were used for statistical analysis (α = 5%).

RESULTS

A total of 646 patients were included in the present study. There was statistically significant association of the genotypes and/or alleles distributions with the skeletal malocclusion (sagittal skeletal pattern) and facial type (vertical pattern) for the variants assessed inACTN3 (P < 0.05). For the genetic variant evaluated in MYO1H, there was statistically significant difference between the genotypes frequencies for skeletal Class I and Class II (P < 0.05). The reported associations were different depending on the region evaluated.

CONCLUSION

ACTN3 and MYO1H are associated with sagittal and vertical craniofacial skeletal patterns in Brazilian populations.

Craniofacial Manifestations in Severe Nemaline Myopathy

Nemaline myopathy (NM) is a rare congenital muscular disease characterized by the presence of rod (nemaline) bodies visualized on muscle biopsy. The disease is genetically and clinically heterogeneous, and the age of onset can vary from neonate to adult. Patients typically present initially with diffuse muscle weakness and hypotonia. The disease also afflicts facial musculature and can cause anomalous facial growth and development. The authors report a patient of early onset NM with significant craniofacial abnormalities. The untreated facial growth is discussed and illustrated in this article. The authors reviewed the current knowledge in the literature regarding the molecular and genetic pathogenesis of NM. The roles of both surgical and supportive management are discussed in this particular patient.

[Retaining corrected skeletal open bites. How can we increase the stability of our results?]

INTRODUCTION

Retaining corrected skeletal anterior open bites is challenging. If it is possible to identify the aetiological factors causing an open bite, an appropriate choice of treatment and retention may reduce relapse. Extruding anterior teeth to close anterior open bites is known to be unstable, so treatment is typically aimed at controlling the vertical position of maxillary molars, in addition to removing causative factors, such as breaking habits and improving tongue posture. Relapse rates are high, with relapse estimated at about 20-30%, with slightly more stability for a surgical approach.

MATERIALS AND METHODS

Various approaches with retainers are described that aim to restrict the eruption of posterior teeth, and improve the position of the tongue.

RESULTS

These retainers often require excellent patient compliance and there is a lack of high quality evidence to support their use. Further research is required to confirm the effectiveness of these approaches.

Influence of Botulinumtoxin A on the Expression of Adult MyHC Isoforms in the Masticatory Muscles in Dystrophin-Deficient Mice (Mdx-Mice)

The most widespread animal model to investigate Duchenne muscular dystrophy is the mdx-mouse. In contrast to humans, phases of muscle degeneration are replaced by regeneration processes; hence there is only a restricted time slot for research. The aim of the study was to investigate if an intramuscular injection of BTX-A is able to break down muscle regeneration and has direct implications on the gene expression of myosin heavy chains in the corresponding treated and untreated muscles. Therefore, paralysis of the right masseter muscle was induced in adult healthy and dystrophic mice by a specific intramuscular injection of BTX-A. After 21 days the mRNA expression and protein content of MyHC isoforms of the right and left masseter, temporal, and the tongue muscle were determined using quantitative RT-PCR and Western blot technique. MyHC-IIa and MyHC-I-mRNA expression significantly increased in the paralyzed masseter muscle of control-mice, whereas MyHC-IIb and MyHC-IIx/d-mRNA were decreased. In dystrophic muscles no effect of BTX-A could be detected at the level of MyHC. This study suggests that BTX-A injection is a suitable method to simulate DMD-pathogenesis in healthy mice but further investigations are necessary to fully analyse the BTX-A effect and to generate sustained muscular atrophy in mdx-mice.

Stomatognathic function in Duchenne muscular dystrophy: a case-control study

AIM

This study aimed to analyse electromyographic activity, masticatory efficiency, muscle thickness, and bite force of individuals with Duchenne muscular dystrophy (DMD).

METHOD

Forty males aged 4-15 years, 20 with DMD and 20 healthy age-, height-, and weight-matched controls, underwent electromyography and ultrasonography of temporalis, masseter, and sternocleidomastoid muscles during postural control of the jaw, mastication, and maximal molar bite force.

RESULTS

The normalized electromyography signals showed higher activity in masseter and temporal muscles at rest, during protrusion, left and right laterality, and fatigue condition in the group with DMD than in the comparison group (p≤0.05). For masticatory efficiency of cycles, in analysis of non-habitual chewing of flavourless gum, and habitual chewing of peanuts and raisins, the group with DMD presented lower averages (p≤0.05). For the muscle thickness, the results showed that there was a lower muscle thickness in the group with DMD for all muscles during the rest and maximal voluntary contraction, except for masseter and sternocleidomastoid in the maximal voluntary contraction. In the maximal molar bite force, the group with DMD presented higher values for both sides than the comparison group (p≤0.05).

INTERPRETATION

Patients with DMD show muscle changes related to the stomatognathic system, in their activity, bite force, and muscle thickness.

Retracted: 'The effects of Duchenne muscular dystrophy on the performance of the stomatognathic system: case-control study', by Ferreira B., Da Silva G.P., Gonçalves C.R., et al

The above article, published online on 13 February 2015 in Wiley Online Library Early View (wileyonlinelibrary.com), has been retracted by agreement between the authors, the journal editors, Bernard Dan and Peter Rosenbaum, the MacKeith Press and John Wiley & Sons Ltd. The retraction has been made due to concerns relating to the validity of the EMG methodology and its interpretation, which affect the results of the paper. Reference Ferreira B, Da Silva GP, Gonçalves CR, Arnoni VW, Siéssere S, Semprini M, Verri ED, Chaves TC, Regalo SH. The effects of Duchenne muscular dystrophy on the performance of the stomatognathic system: case-control study. Developmental Medicine & Child Neurology 2015. doi:10.1111/dmcn.12707.

Dystrophic changes in masticatory muscles related chewing problems and malocclusions in Duchenne muscular dystrophy

Dysphagia in Duchenne muscular dystrophy (DMD) worsens with age, with increasingly effortful mastication. The aims of this study were to describe mastication problems in consecutive stages in a group of patients with DMD and to determine related pathophysiological aspects of masticatory muscle structure, tongue thickness, bite force and dental characteristics. Data from 72 patients with DMD (4.3 to 28.0 years), divided into four clinical stages, were collected in a cross sectional study. Problems with mastication and the need for food adaptations, in combination with increased echogenicity of the masseter muscle, were already found in the early stages of the disease. A high percentage of open bites and cross bites were found, especially in the later stages. Tongue hypertrophy also increased over time. Increased dysfunction, reflected by increasingly abnormal echogenicity, of the masseter muscle and reduced occlusal contacts (anterior and posterior open bites) were mainly responsible for the hampered chewing. In all, this study shows the increasing involvement of various elements of the masticatory system in progressive Duchenne muscular dystrophy. To prevent choking and also nutritional deficiency, early detection of chewing problems by asking about feeding and mastication problems, as well as asking about food adaptations made, is essential and can lead to timely intervention.

Dysphagia in Duchenne muscular dystrophy: practical recommendations to guide management

Purpose: Duchenne muscular dystrophy (DMD) is a rapidly progressive neuromuscular disorder causing weakness of the skeletal, respiratory, cardiac and oropharyngeal muscles with up to one third of young men reporting difficulty swallowing (dysphagia). Recent studies on dysphagia in DMD clarify the pathophysiology of swallowing disorders and offer new tools for its assessment but little guidance is available for its management. This paper aims to provide a step-by-step algorithm to facilitate clinical decisions regarding dysphagia management in this patient population.

Methods: This algorithm is based on 30 years of clinical experience with DMD in a specialised Centre for Neuromuscular Disorders (Inkendaal Rehabilitation Hospital, Belgium) and is supported by literature where available.

Results: Dysphagia can worsen the condition of ageing patients with DMD. Apart from the difficulties of chewing and oral fragmentation of the food bolus, dysphagia is rather a consequence of an impairment in the pharyngeal phase of swallowing. By contrast with central neurologic disorders, dysphagia in DMD accompanies solid rather than liquid intake. Symptoms of dysphagia may not be clinically evident; however laryngeal food penetration, accumulation of food residue in the pharynx and/or true laryngeal food aspiration may occur. The prevalence of these issues in DMD is likely underestimated.

Conclusions: There is little guidance available for clinicians to manage dysphagia and improve feeding for young men with DMD. This report aims to provide a clinical algorithm to facilitate the diagnosis of dysphagia, to identify the symptoms and to propose practical recommendations to treat dysphagia in the adult DMD population.

Implications for Rehabilitation

Little guidance is available for the management of dysphagia in Duchenne dystrophy.

Food can penetrate the vestibule, accumulate as residue or cause aspiration.

We propose recommendations and an algorithm to guide management of dysphagia.

Penetration/residue accumulation: prohibit solid food and promote intake of fluids.

Aspiration: if cough augmentation techniques are ineffective, consider tracheostomy.

Reduced mandibular range of motion in Duchenne Muscular Dystrophy: predictive factors

Patients with Duchenne muscular dystrophy (DMD) experience negative effects upon feeding and oral health. We aimed to determine whether the mandibular range of motion in DMD is impaired and to explore predictive factors for the active maximum mouth opening (aMMO). 23 patients with DMD (mean age 16.7 ± 7.7 years) and 23 controls were assessed using a questionnaire about mandibular function and impairments. All participants underwent a clinical examination of the masticatory system, including measurement of mandibular range of motion and variables related to mandibular movements. In all patients, quantitative ultrasound of the digastric muscle and the geniohyoid muscle and the motor function measure (MFM) scale were performed. The patients were divided into early and late ambulatory stage (AS), early non-ambulatory stage (ENAS) and late non-ambulatory stage (LNAS). All mandibular movements were reduced in the patient group (P < 0.001) compared to the controls. Reduction in the aMMO (<40 mm) was found in 26% of the total patient group. LNAS patients had significantly smaller mandibular movements compared to AS and ENAS (P < 0.05). Multiple linear regression analysis for aMMO revealed a positive correlation with the body height and disease progression, with MFM total score as the strongest independent risk factor (R(2) = 0.71). Mandibular movements in DMD are significantly reduced and become more hampered with loss of motor function, including the sitting position, arm function, and neck and head control. We suggest that measurement of the aMMO becomes a part of routine care of patients with DMD.

The relation between idiopathic scoliosis and the frontal and lateral facial form

OBJECTIVE

The purpose of this study was to evaluate the relation between idiopathic scoliosis and facial deformity in the horizontal, vertical, and anteroposterior planes.

METHODS

A total of 123 female patients aged 14 years or older, who visited the Spine Clinic at the Department of Orthopedics, Korea University Guro Hospital for treatment of idiopathic scoliosis, were enrolled. Whole-spine anteroposterior and lateral radiographs were taken with the patient in a naturally erect position, and frontal and lateral cephalograms were taken in an erect position with the Frankfort horizontal line parallel to the floor. Scoliosis was classified according to the Cobb angle and Lenke classification of six curve types. Cephalometric tracing in all cases was carried out with V-Ceph 5.5 by the same orthodontist. The Kruskal-Wallis test was performed to determine whether any relation existed between each group of the idiopathic scoliosis classification and the cephalometric measurements of frontal and lateral cephalograms.

RESULTS

The measurements did not reveal any significant association between the Cobb angle and cephalometric measurements and between the curve type based on the Lenke classification and cephalometric measurements.

CONCLUSIONS

Based on the results of this study, no apparent relation was observed between the severity of scoliosis and facial form variations in idiopathic scoliosis patients.

Effectiveness of cationic liposome-mediated local delivery of myostatin-targeting small interfering RNA in vivo

This study evaluated the effectiveness of local administration of cationic liposome-delivered myostatin-targeting siRNA. Myostatin (Mst)-siRNA and scrambled (scr)-siRNA-lipoplexes were injected into the masseter muscles of wild type and dystrophin-deficient mdx mice, which model Duchenne muscular dystrophy. One week after injection, the masseter muscles were dissected for histometric analyses. To evaluate changes in masseter muscle activity, masseter electromyographic (EMG) measurements were performed. One week after local administration of Mst-siRNA-lipoplexes, masseter muscles and myofibrils were significantly larger compared to control masseter muscles treated with scr-siRNA-lipoplexes. Real-time polymerase chain reaction (PCR) analyses revealed significant upregulation of the myogenic regulatory factors MyoD and myogenin and significant downregulation of the adipogenic transcription factors peroxisome proliferator-activated receptor-γ (PPARγ) and CCAAT/enhancer binding protein-α (CEBPα) in masseter muscles treated with Mst-siRNA-lipoplexes. The duty times of masseter muscle activity exceeding 5% showed a slight tendency to increase in both wild type and mdx mice. Therefore, cationic liposome-mediated local administration of Mst-siRNA could increase muscular size and improve muscle activity. Since cationic liposomes delivered siRNA to muscles effectively and are safe and cost-effective, they may represent a therapeutic tool for use in treating muscular diseases.

Epigenetic influence of KAT6B and HDAC4 in the development of skeletal malocclusion

INTRODUCTION

Genetic influences on the development of malocclusion include heritable effects on both masticatory muscles and jaw skeletal morphology. Beyond genetic variations, however, the characteristics of muscle and bone are also influenced by epigenetic mechanisms that produce differences in gene expression. We studied 2 enzymes known to change gene expressions through histone modifications, chromatin-modifying histone acetyltransferase KAT6B and deacetylase HDAC4, to determine their associations with musculoskeletal variations in jaw deformation malocclusions.

METHODS

Samples of masseter muscle were obtained from subjects undergoing orthognathic surgery from 6 malocclusion classes based on skeletal sagittal and vertical dysplasia. The muscles were characterized for fiber type properties by immunohistochemistry, and their total RNA was isolated for gene expression studies by microarray analysis and quantitative real-time polymerase chain reaction.

RESULTS

Gene expressions for fast isoforms of myosins and contractile regulatory proteins and for KAT6B and HDAC4 were severalfold greater in masseter muscles from a patient with a deepbite compared with one with an open bite, and genes related to exercise and activity did not differ substantially. In the total population, expressions of HDAC4 (P = 0.03) and KAT6B (P = 0.004) were significantly greater in subjects with sagittal Class III than in Class II malocclusion, whereas HDAC4 tended to correlate negatively with slow myosin type I and positively with fast myosin gene, especially type IIX.

CONCLUSIONS

These data support other published reports of epigenetic regulation in the determination of skeletal muscle fiber phenotypes and bone growth. Further investigations are needed to elucidate how this regulatory model might apply to musculoskeletal development and malocclusion.

WITHDRAWN: Age-dependent muscle dystrophy related changes of craniofacial morphology in mdx mice

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Consensus statement on standard of care for congenital myopathies

Recent progress in scientific research has facilitated accurate genetic and neuropathological diagnosis of congenital myopathies. However, given their relatively low incidence, congenital myopathies remain unfamiliar to the majority of care providers, and the levels of patient care are extremely variable. This consensus statement aims to provide care guidelines for congenital myopathies. The International Standard of Care Committee for Congenital Myopathies worked through frequent e-mail correspondences, periodic conference calls, 2 rounds of online surveys, and a 3-day workshop to achieve a consensus for diagnostic and clinical care recommendations. The committee includes 59 members from 10 medical disciplines. They are organized into 5 working groups: genetics/diagnosis, neurology, pulmonology, gastroenterology/nutrition/speech/oral care, and orthopedics/rehabilitation. In each care area the authors summarize the committee's recommendations for symptom assessments and therapeutic interventions. It is the committee's goal that through these recommendations, patients with congenital myopathies will receive optimal care and improve their disease outcome.

Consensus statement on standard of care for congenital muscular dystrophies

Congenital muscular dystrophies are a group of rare neuromuscular disorders with a wide spectrum of clinical phenotypes. Recent advances in understanding the molecular pathogenesis of congenital muscular dystrophy have enabled better diagnosis. However, medical care for patients with congenital muscular dystrophy remains very diverse. Advances in many areas of medical technology have not been adopted in clinical practice. The International Standard of Care Committee for Congenital Muscular Dystrophy was established to identify current care issues, review literature for evidence-based practice, and achieve consensus on care recommendations in 7 areas: diagnosis, neurology, pulmonology, orthopedics/rehabilitation, gastroenterology/ nutrition/speech/oral care, cardiology, and palliative care. To achieve consensus on the care recommendations, 2 separate online surveys were conducted to poll opinions from experts in the field and from congenital muscular dystrophy families. The final consensus was achieved in a 3-day workshop conducted in Brussels, Belgium, in November 2009. This consensus statement describes the care recommendations from this committee.