Craniofacial Bone Anomalies In Microtia And Hemifacial Microsomia Patient:An Analysis Based On CT Scan And Digitalization

ObjectiveMicrotia is a spectrum of congenital deformities and lots of the patients are associated with other anomalies such as hemifacial microsomia(HFM).HFM is a serious congenital malformations of the face.The symptoms of HFM include numerous abnormalities,and among them,cranial and maxillofacial bone deformities is the most important clinical manifestations.However,the pathogenic characters of bone deformities related to HFM are still unclear,which may limits the research progress of the etiology and therapeutics of HFM tremendously.In order to analysis the pathogenic characters of craniofacial bone deformities related to HFM,we designed this research.The purpose of the present study was to reveal the pathogenic characters of craniofacial bone deformities related to HFM.We will probe into the following questions:1.To describe the incidence and distribution of HFM associated with microtia and to identify the specific associations between HFM and gender,affected side and ear deformity;2.To reveal which bones may be involved in HFM;3.To reveal the incidence and severity bone malformation;4.To reveal the correlation between these deformities;5.To describe the morphology of craniofacial bone deformities of patients with different HFM grades,and describe the characteristics of deformities in different bones;6.To describe the amount of bone defect and the degree of asymmetry of patients with different HFM grades.Method1.From November 2015 to August 2017 a total of 687 patients with microtia were admitted to this retrospective study.The following information was determined for each patient:gender,grade of microtia,affected side(right,left,or bilateral).The CT scan plus 3-dimensional reconstruction covering the head were performed using a helical technique.All the individuals were scored according to the OMENS classification.The patients were examined and assessed by a single experienced clinician.We also evaluate the relationship between HFM and microtia.2.Patients with HFM who visit our hospital were enrolled in this study.Patients underwent skull CT scan plus three dimensional reconstruction of the skull.The malformations of fifteen craniofacial bone structures,which may be involved in HFM,was all studied and diagnosed.The bones are studied separately and the incidence of deformity and classification of patients was recorded.3.Patients were evaluated by OMENS classification system,A Spearman analysis were performed to evaluate the relationship between craniofacial bone malformations and OMENS abnormalities.4.Medical image analysis software were used to reconstruct the digital head model of HFM patients,digital image processed mirror-imaged and registration fitting.The software contrasted and calculated differences of the bilateral faces.The appearance of craniofacial bone deformities can be observed by reading the registration figures;The severity of deformity was evaluated and graded according to the registration figures,the pathogenic characters of craniofacial bone deformities,of patients with different OMENS grades was studied respectively.5.Medical image analysis software were used to segment the digital head model.The skull was divided into chin area,temporal-zygomatic-orbital-maxillary area and the calvarium area.The amount of bone defect and asymmetric index were tested for every patient.Results1.A total of 687 cases with microtia were included,and facial paralysis was found in 364(53.0%)cases.We found a right-sided and male predominance of HFM.No significant difference of microtia grade and gender distributions was observed between HFM and microtia population.We found a significant difference of affected side between HFM and microtia population.2.All the fifteen bone structures was affected in HFM patients.The incidence of bone deformities in centeral area of the lateral skull was relativly higher;the incidence of bone deformities in marginal area of the skull was relativly lower.3.The occurrence of craniofacial bone deformities and OMENS abnormalities was correlated positivly in hemifacial microsomia patients.The relationship was stronger in the center area of the lateral skull.Temporal-mandibular joint deformities,were found to have relationship with every othe deformities.The relationship was looser in the marginal area of the lateral skull,which is only related to adjacent bony structures and central bone structures,and is not associated with distant bone structures.4.The deformity was more severe in the central area of the lateral skull,and more slight in the surrounding area;HFM patients with different OMENS grades shown different deformity characteristics.5.No difference was discovered between bone volume of alvarium in the two sides;The volume of bone defect in the temporal-zygomatic-orbital-maxillary area were significantly greater than the mandibular area;HFM patients with MO to M2A OMENS grades shown higher asymmetry degree in the temporal-zygomatic-orbital-maxillary than the mandibular area,HFM patients with M2B to M3 OMENS grades show approximate asymmetry degree.Conclusion1.About 53.0%of the microtia patients are with HFM syndrome,and the other 47.0%patients are with isolated microtia.2.Bone deformities in HFM involved numerous craniofacial bone structure,the incidence of the deformity,the correlation with other malformations,the severity of deformities is higher in the central area of the lateral skull,and is lower in the marginal area of the skull.3.The temporomandibular joint own higher deformity incidence and relevance,so we suggest to add the temporomandibular joint in the OMENS system as a separated index for HFM evaluation.4.The bone defect is more serious in the upper and middle face than in the lower face;HFM patients with MO to M2A OMENS grades shown higher asymmetry in the upper and middle face than in the lower face.