Centronuclear Myopathy: Clinical Characteristic And MRI Image Analysis Of Oral And Maxillofacial Region

Centronuclear myopathy(CNM)is an inherited skeletal muscle myopathy characterised by centrally placed nuclei on muscle biopsy.It is the most representative one in a group of congenital myopathies(CN)with similar clinical findings that classically includes central core disease,multicore disease,nemaline myopathy,and congenital fiber type disproportion.The clinical presentations and genetic background have highly heterogeneity.Main symptoms are generalized muscle weakness and hypotonia,typically presenting at birth or in infancy.The illness relatively stable or slowly.Ptosis and extraocular muscle involvement are frequently seen in CNM.In addition,the facial muscles involvement can be prominent and have a characteristic "thin" face.Almost all of the patients have high-arched palate.There are three inheritance patterns : x-linked recessive inheritance,autosomal dominant and autosomal recessive inheritance.At present,the research of oral and facial clinical manifestations with CNM patients,have been reported at home and abroad,but mainly in the form of case reports,that is not full-scale;MRI images analysis about affected muscle mainly focuses on the study of the systemic skeletal muscles,also a rare MRI image analysis of facial muscles.Objective: To investigate the oral and maxillofacial features of CNM,and MRI image analysis to discuss the affected masseter,medial pterygoid,lateral pterygoidMethods:1 The study consisted of 8 participants,who were patients in the Third Hospital of Hebei Medical University from 2013 to 2015,which were diagnosed as CNM by genetic testing and histopathologic biopsy as study group.20 healthy persons with oral health examination in the Second Hospital of Hebei Medical University from 2013 to 2015 was selected as contral group.2 To gather relevant medical information,our study designed a unified questionnaire and collected data of all the patients,also we examined patients with ptosis situation.We detectded the form surface high and wide morphological to calculate the facial index calculation.And we took lateral cephalometric radiographs for them to measure MP –FH.To measure the maximal hight of palate and the width of palate,patients and volunteers were made impressions.We also checked their maximum bite force and maximal opening of mouth.And then we made oral health examinations for them to record DMFT and CI-S.At last,patients and volunteers were taken head-and-neck MIR to observe the affected situation of masseter muscle,medial pterygoid muscle and lateral pterygoid muscle.Results: 1 In study group,there was no significant gender differences of CNM.7 patients(88%)liked to eat soft foods;6 patients(75%)had inverse v-shaped mouth;4 patients(50%)were anterior open bites;3 patients(38%)were difficulty in swallowing;3 patients(38%)were mouth breathing.2.1 In study group,patients with ptosis 6 cases(75%),of which one case for severe ptosis,three cases for moderate ptosis and two cases for mild ptosis.2.2 Morphological facial index with the study and control group were 91.3 ±0.4%,80.7±3.9% respectively,and there were significant difference between the two groups(P <0.05).2.3 MP-FH with the study and control group were 37.56±0.82°,28.05±2.04°respectively,and there were significant difference between the two groups(P <0.05).2.4 Male and female biggest palatal arch height were 18.99±0.15 mm,18.01±0.59 mm respectively in study group,and 15.04±1.65 mm,14.61±1.21 mm respectively in control group.Male and female biggest palatal arch width were 34.52±0.76 mm,33.47±0.97 mm respectively in study group,and 38.63±1.26 mm,38.14±0.81 mm respectively in control group.There were significant difference between the two groups of male and female(P <0.05).2.5 Male and femal maximum bite force were 464.34±78.22 N 、320.66±13.83 N respectively in study group,and 562.07±34.86 N 、387.44±23.15 N respectively in control group,there were significant difference between the two groups of male and female(P <0.05).2.6 Maximal opening of mouth were 3.3±0.4cm,3.4±0.2cm respectively with the study and control group,there were significant difference between the two groups(P <0.05).3 DMFT were 4.88±2.85,1.35±1.39 and CI-S were 4.75±2.31,1.36±0.30 respectively with the study and control group,there were significant difference between the two groups(P <0.05).4 MRI showed that 7’patients msseter,4 patients’ medial pterygoid and 6 patients’ lateral pterygoid muscles were affected,The degree of muscle involvement concentrated in Grade 1 to 4.There were 1’patients msseter,4 patients’ medial pterygoid and 2 patients’ lateral pterygoid muscles were not affected.The affected muscles on T2-WI similar to those of subcutaneous fat with higher signal.The characteristics of the homogeneity with skeletal muscle was reduced and presented in or diffuse signal enhancement area.Affected muscle and the surrounding fat line is not clear,also left and right sides is similar,and found no inflammation and edema of the lesions.Patients with CNM,chewing muscles have different degree of atrophy and fat.Conclusions:1 CNM patients with oral and maxillofacial region characteristics including ptosis,inverse v-shaped mouth opening and anterior open bites is due to facial muscle fatty degeneration and dysplasia;2 CNM patients’ masticatory muscles(masseter,medial pterygoid,lateral pterygoid)by MRI image analysis in different degrees of fatty infiltration phenomenon conform to the pathological characteristic of systemic skeletal muscle;3 CNM patients’ changes of oral and maxillofacial region inclduing thin face,the steep angle of mandible,palatal cover high arch and low bite is associateg with fatty degeneration and atrophy of the muscles;Oral and maxillofacial tissue reduce coordination is the important reason for the poor oral hygiene with CNM patients and prompt us to make oral health education and early oral function training with CNM patients.