Unilateral Hemifacial Microsomia Research Articles

Exploring Progression and Differences in Facial Asymmetry for Hemifacial Microsomia and Isolated Microtia: Insights from Extensive 3D Analysis.

Aiming to measure and compare asymmetry of facial hard and soft tissues in patients with HFM and isolated microtia, examining how it evolves. This cross-sectional study assessed facial asymmetry in male East Asian patients aged 5-12 diagnosed with unilateral hemifacial microsomia (Pruzansky-Kaban types I and IIA) or isolated microtia. Using 3D imaging of computed tomography scans, it measured root-mean-square (RMS) values for surface deviations across facial regions. Statistical analyses explored differences between conditions and the relationship of age with facial asymmetry. A total of 120 patients were categorized into four groups by condition (HFM or isolated microtia) and age (5-7 and 8-12 years). Patients with HFM exhibited the greatest asymmetry in the lower cheek, while those with isolated microtia showed primarily upper face asymmetry. Significant differences, except in the forehead and nasal soft tissue, were noted between the groups across age categories. Notable distinctions in hard tissue were found between age groups in the nasal and mid-cheek areas for patients with HFM (median RMS (mm) 0.9 vs. 1.1, P = 0.02; 1.5 vs. 1.7, P = 0.03) and in the nasal and upper lip areas for patients with isolated microtia (median RMS (mm) 0.8 vs. 0.9, P =0.002; 0.8 vs. 1.0, P = 0.002). Besides these areas for HFM, no significant age-asymmetry correlation was detected. Significant differences in facial asymmetry were observed between HFM and isolated microtia, with the asymmetry in specific area evolving over time. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Accuracy and safety of robotic navigation-assisted distraction osteogenesis for hemifacial microsomia.

This study aimed to verify the accuracy and safety of distraction osteogenesis for hemifacial microsomia assisted by a robotic navigation system based on artificial intelligence. The small sample early-phase single-arm clinical study, available at http://www.chictr.org.cn/index.aspx, included children aged three years and older diagnosed with unilateral hemifacial microsomia (Pruzansky-Kaban type II). A preoperative design was performed, and an intelligent robotic navigation system assisted in the intraoperative osteotomy. The primary outcome was the accuracy of distraction osteogenesis, including the positional and angular errors of the osteotomy plane and the distractor, by comparing the preoperative design plan with the actual images one week postoperatively. Perioperative indicators, pain scales, satisfaction scales, and complications at one week were also analyzed. Four cases (mean 6.5 years, 3 type IIa and 1 type IIb deformity) were included. According to the craniofacial images one week after surgery, the osteotomy plane positional error was 1.77 ± 0.12 mm, and the angular error was 8.94 ± 4.13°. The positional error of the distractor was 3.67 ± 0.23 mm, and the angular error was 8.13 ± 2.73°. Postoperative patient satisfaction was high, and no adverse events occurred. The robotic navigation-assisted distraction osteogenesis in hemifacial microsomia is safe, and the operational precision meets clinical requirements. Its clinical application potential is to be further explored and validated.

Computed tomography assessment of hypodontia and crown size in hemifacial microsomia

ObjectiveOur aims were to assess the prevalence of hypodontia in unilateral hemifacial microsomia (HFM), and to compare tooth (crown) size between affected and unaffected sides. DesignIn a retrospective cross-sectional study of South Australians, computed tomography (CT) scans were used to assess hypodontia and crown size (mesiodistal length, buccolingual width and crown height). The inclusion criteria were the absence of other congenital anomalies and the availability of CT scans. The exclusion criteria were the lack of extraction history or reproducible landmarks for morphometric assessment. The final sample comprised 41 participants in both dentitions, including 32 children and 9 adults (median age 13.9 years, range 0.4 – 47.6 years; 19 males and 22 females). Hypodontia was assessed in all participants, and the permanent crown size in 30 (73.2%) participants. Linear mixed-effects models were performed to determine if crown size was significantly different between the two sides, controlling for sex, HFM severity, and tooth and jaw type. ResultsHypodontia occurred in none of the participants in the primary dentition, but in 6/30 (20%) participants in the permanent dentition (3/30 each on the affected and unaffected sides). There was no significant difference in the mean crown dimensions between the two sides, but the crown size was larger in males (p < 0.05), except for mesiodistal length, and became progressively smaller with increased HFM severity (p < 0.05). ConclusionsHypodontia spared the primary dentition but featured prominently in the permanent dentition. The permanent crown dimensions were unaltered between the two sides.

Three-Dimensional Morphology and Configuration Analyses of the Craniovertebral Junction in Children with Hemifacial Microsomia.

Observational and morphological study with three-dimensional (3D) computed tomography (CT) analysis. To discover the morphology and configuration deformities of craniovertebral junction (CVJ) and upper cervical spine in children with unilateral hemifacial microsomia (HFM). To determine whether there are specific HFM patients who are at higher risk of certain cervical vertebral anomaly. The evaluation for cervical vertebrae anomaly in HFM children, especially in CVJ region, is underreported. Eighty-eight unilateral HFM children (64 males, 24 females) with four Pruzansky-Kaban types (I, Ila, Ilb, and III) underwent cranial and cervical CT scanning from skull to C5 in neutral position. The 3D morphology and configuration of the occipital condyle, atlas, and axis, etc. were evaluated on the presence of deformed detailed structures of CVJ region. No C1 deformation was found in type I group. Six (14.3%) type Ila cases, seven (33.3%) type IIb cases, and six (37.5%) type Ill cases had lateral masses asymmetry of C1 (P < 0.05). Five (55.6%) type I cases, 17 (40.5%) type Ila cases, 12 (57.1%) type Ilb cases, and 10 (62.5%) type Ill cases had C2 anomaly (P > 0.05). The incidence rate of C1-C2 instability for four groups were 33.3% (type I), 33.3% (type IIa), 33.3% (type IIb), and 31.3% (type Ill), respectively (P > 0.05). For HFM children, the incidence of C1 deformation increased from type I to type Ill. The probability of C2 anomaly and C1-C2 instability in children with different types of HFM is nearly the same. The craniovertebral junction of every HFM child must be monitored carefully for C1-C2 instability before any surgical procedure to avoid atlantoaxial dislocation and spinal cord injury.Level of Evidence: N/A.

Correlations Between Mandible Condylar Structures and External Ear Deformities in Hemifacial Microsomia With Three-Dimensional Analysis.

This study aimed to explore correlations between mandible and ear deformities and quantitative volumetric relations between condylar structures and external ear in hemifacial microsomia. The authors reconstructed three-dimensional craniofacial models from 212 patients with unilateral hemifacial microsomia (the unaffected side as the controls). Patients were evaluated by Pruzansky-Kaban and Marx classification, and divided into 3 age groups (0-6, 7-12, and >12 years of age). The mandible condylar structures, including condyle and the condylar skeletal unit, were selected (except the classification of the mandibular or ear deformities (M3)). Along with the external ear (except the classification of the mandibular or ear deformities (E4)), their volumes were measured and analyzed. Spearman correlation coefficient analysis was applied. There was a positive correlation between the mandible and ear deformities (r = 0.301, P < 0.001). Either between the condyle and external ear ( P = 0.071-0.493) or between the condylar unit and external ear ( P = 0.080 - 0.488), there were no volumetric relations on the affected side, whereas on the unaffected side were (r = 0.492-0.929 for condyle, r = 0.443-0.929 for the condylar unit, P < 0.05). In most cases, the condylar structures of the classification of the mandibular or ear deformities (M2b) were significantly smaller than the classification of the mandibular or ear deformities (M2a). Results suggested deformities of mandibular condylar structures and ear did not correlate, although deformities of mandible and ear did. The condylar deformity might develop independently from microtia and be more severe within relatively more abnormal temporomandibular joints.

Postoperative Changes in the Upper Airway Following Mandibular Distraction Osteogenesis in Pediatric Hemifacial Microsomia.

Patients with hemifacial microsomia (HFM) may undergo unilateral mandibular distraction osteogenesis (MDO) before skeletal maturity in an effort to improve facial symmetry. Mandibular distraction osteogenesis's effect on airway volumes have been studied in the past, though to our knowledge, none have accounted for the effect of head and neck posture on airway morphology. This study aimed to tackle this shortcoming, using imaging to analyze the upper airway of patients with HFM before and after surgical intervention with MDO. The authors retrospectively reviewed patients with a diagnosis of unilateral HFM whom underwent unilateral MDO with an oblique vector at age 4 to 14 years at a single institution from 2004 to 2019. Patients with pre- and post-MDO three-dimensional computed tomography scans of the upper airway within 12 months of distractor placement and removal, respectively, were included. Head and neck postures were determined by craniocervical, pitch, roll, and yaw angles. Pre- and post-operative pharyngeal airway volumes, pharyngeal surface area, minimum retropalatal cross-sectional areas (RP CSA) and retroglossal (RG) CSA and associated anteroposterior distances were measured using Mimics 22.0 (Materialise; Leuven, Belgium). Comparison was done using Kruskal-Wallis tests and linear mixed-effects models controlling for head and neck postures. Ten patients met inclusion criteria. Mean age at pre-distractor placement computed tomography scan was 99 ± 35 months, and mean duration between pre- and post-surgery scans was 220 ± 90 days. Head and neck posture were found to be significant predictors of all airway dimensions. After controlling for significant factors with fixed effects linear modeling, surface area was found to be significantly smaller in patients after MDO by 189.48 mm2 (F[10.8] = -3.47, P = 0.0053), compared to their preoperative measurements. Surgery was not a significant predictor of changes in airway volume (F[11.6] = 0.52, P = 0.61), minimum RP CSA (F[12.2] = -0.64, P = 0.53), minimum RG CSA (F[12.6] = -1.64, P = 0.13), RP anteroposterior distance (F[14.0] = 0.30, P = 0.77), or RG anteroposterior distance (F[20.0] = -0.04, P = 0.97). Oblique vector MDO in patients with HFM is associated only with statistically significant changes in the surface area of the upper airway, and is not associated with statistically significant changes in dimensions like volume, CSA, or anteroposterior dimension. This is an important finding, as it may guide discussions surrounding risk/benefit ratio for MDO in childhood.

Mandibular Distraction Osteogenesis First for Children With Severe Unilateral Hemifacial Microsomia: Treatment Strategy and Outcomes.

The treatment for severe hemifacial microsomia (HFM), especially type III case, is extremely difficult. Mandibular distraction osteogenesis (MDO) was rarely used as the primary choice in the treatment of severe type cases. The authors sought to observe the short-term therapeutic outcomes of patients with severe unilateral HFM who underwent MDO first.A retrospective study of children underwent MDO or later received costochondral graft (CCG) for severe unilateral HFM from 2009 to 2019 was conducted. Cephalometric measurements and clinical variables were analyzed to evaluate the effectiveness of MDO first strategy for severe cases and compare disparity between Pruzansky-Kaban classification type IIb and type III groups.Thirty-six patients (23 males and 13 females) underwent MDO first for severe HFM were included for analysis in the present study. The average age at MDO was 8.33 ± 2.03 years. At the last follow-up, MDO acquired significant improvement in mandibular height, maxillary cant, chin deviation, lip commissural line tilt, and clinical chin deviation (P < 0.05). Distraction results were stable during the short-term follow-up in terms of the mandibular height ratio and maxillary cant (P > 0.05).MDO is a proper primary method for suitable type IIb and type III HFM cases. MDO can immediately and significantly improve the facial skeleton deficiency, extend the associated soft tissue at the same time, and lay foundation for secondary surgery. MDO can achieve the downgrade of HFM deficiency severity. MDO followed by costochondral graft can get satisfactory esthetic and structural consequence for type III patients.

Outcome of surgical-orthodontic treatment in hemifacial microsomia with and without early mandibular distraction osteogenesis

The aim of this study was to compare the outcomes of surgical-orthodontic treatment between hemifacial microsomia (HFM) patients who had and had not undergone early mandibular distraction osteogenesis (DO). Twenty adult unilateral HFM patients were included, seven who had undergone early mandibular DO (DO group) and 13 who had not (NDO group). All patients were type IIB, except for one type IIA patient in the NDO group. Mean age at definitive surgery was 20.72±2.96 years. Linear, cross-sectional, and volumetric measurements were obtained from serial cone beam computed tomography scans. Data were obtained pre-surgery (T0), 1 week after surgery (T1), and at treatment completion (T2) to determine surgical movement, post-surgical stability, and net gain movement. Surgical and ultimate outcomes did not differ significantly between the groups. The overall surgical movement among all patients was as follows (mean values): maxillomandibular complex (MMC) symmetry was achieved by Le Fort I differential roll movement (3.78mm extrusion on the affected side, 4.28mm impaction on the non-affected side), a combination of medial movement and yaw rotation of MMC, and genioplasty. Upper and lower dental midlines and deviated menton were shifted by 5.73mm, 5.08mm, and 12.38mm, respectively. Anterior impaction and advancement with counterclockwise rotation of MMC were also performed. Menton was advanced by 6.14mm and lower facial height was increased by 3.55mm. Neither group exhibited a significant difference in stability. Relapse at the maxilla was <1mm and relapse at the mandible was <1.5mm. The results suggest that early DO had limited beneficial effects on the definitive correction outcome. HFM patients achieved acceptable symmetry and a stable surgical outcome, regardless of early DO, following surgical-orthodontic correction at skeletal maturity with three-dimensional surgical simulation.

Treatment modalities for Korean patients with unilateral hemifacial microsomia according to Pruzansky-Kaban types and growth stages.

ObjectiveTo investigate the treatment modalities (Tx-Mods) for patients with unilateral hemifacial microsomia (UHFM) according to Pruzansky–Kaban types and growth stages.MethodsThe samples consisted of 82 Korean UHFM patients. Tx-Mods were defined as follows Tx-Mod-1, growth observation due to mild facial asymmetry; Tx-Mod-2, unilateral functional appliance; Tx- Mod-3, fixed orthodontic treatment; Tx-Mod-4, growth observation due to a definite need for surgical intervention; Tx-Mod-5, unilateral mandibular or bimaxillary distraction osteogenesis (DO); Tx-Mod-6, maxillary fixation using LeFort I osteotomy and mandibular DO/sagittal split ramus osteotomy; Tx- Mod-7, orthognathic surgery; and Tx-Mod-8, costochondral grafting. The type and frequency of Tx-Mod, the number of patients who underwent surgical procedures, and the number of surgeries that each patient underwent, were investigated.ResultsThe degree of invasiveness and complexity of Tx-Mod increased, with an increase in treatment stage and Pruzansky–Kaban type (initial < final; [I, IIa] < [IIb, III], all p < 0.001). The percentage of patients who underwent surgical procedures increased up to 4.2 times, with an increase in the Pruzansky–Kaban type (I, 24.1%; IIa, 47.1%; IIb, 84.4%; III, 100%; p < 0.001). However, the mean number of surgical procedures that each patient underwent showed a tendency of increase according to the Pruzansky–Kaban types (I, n = 1.1; IIa, n = 1.5; IIb, n = 1.6; III, n = 2.3; p > 0.05).ConclusionsThese findings might be used as basic guidelines for successful treatment planning and prognosis prediction in UHFM patients.

Association of Mandibular Dysplasia With Maxillary Volumetric and Linear Measurements in Children With Hemifacial Microsomia.

In hemifacial microsomia (HFM), the correlations between mandibular dysplasia and maxillary deformities in HFM patients have not yet been assessed. The objective of the present study was to examine the association of maxillary volumetric and linear measurements with mandibular ramus height or corpus length on the affected side in children with unilateral HFM.In this retrospective research, a total of 70 children with unilateral HFM were enrolled at our department from 2010 to 2019. Demographic information was recorded, and computed tomographic scan were reconstructed and analyzed by segmentation, volumetric, and cephalometric measurements. Analyses involved independent sample t-test, univariable, and multivariable linear regression.In the overall population, mandibular ramus height (MRH) was positively associated with the maxillary bone volume (MBV) (r = 0.484, P < 0.001) and maxillary total volume (MTV) (r = 0.520, P < 0.001). Similarly, mandibular corpus length (MCL) was significantly associated with the MBV (r = 0.467, P < 0.001) and MTV (r = 0.520, P < 0.001). Multivariate regression analysis revealed that the MRH or MCL were significantly and independently associated with MBV or MTV (MRH/MBV β = 0.420, P < 0.001; MRH/MTV β = 0.391, P < 0.001; MCL/MBV β = 0.403, P < 0.001; MCL/MTV β = 0.307, P < 0.01).These results demonstrated that the MBV and MTV are independently associated with MRH or MCL on the affected side in children with unilateral HFM, suggesting a potential interaction between mandibular dysplasia and maxillary deformities.

Distribution and phenotypes of hemifacial microsomia and its association with other anomalies.

ObjectiveTo investigate the distribution and phenotypes of hemifacial microsomia (HFM) and its association with other anomalies.MethodsThis study included 249 Korean patients with HFM, whose charts, photographs, radiographs, and/or computed tomography scans acquired during 1998–2018 were available from Seoul National University Hospital and Dental Hospital. Prevalence according to sex, side involvement, degree of mandibular deformity, compensatory growth of the mandibular body, and Angle's classification, and its association with other anomalies were statistically analyzed.ResultsPrevalence was not different between male and female patients (55.0% vs. 45.0%, p > 0.05). Unilateral HFM (UHFM) was more prevalent than bilateral HFM (BHFM) (86.3% vs. 13.7%, p < 0.001). Although distribution of the Pruzansky–Kaban types differed significantly in patients with UHFM (I, 53.0%; IIa, 18.6%; IIb, 24.7%; III, 3.7%; p < 0.001), no difference was observed in occurrence between the right and left sides (52.6% vs. 47.4%, p > 0.05). Among patients with BHFM, prevalence of different Pruzansky–Kaban types on the right and left sides was greater than that of the same type on both sides (67.6% vs. 32.4%, p < 0.05). Despite hypoplasia of the condyle/ramus complex, compensatory growth of the mandibular body on the ipsilateral side occurred in 35 patients (14.1%). Class I and II molar relationships were more prevalent than Class III molar relationships (93.2% vs. 6.8%, p < 0.001). Forty-eight patients (19.3%) had other anomalies, with 50.0% and 14.4% in the BHFM and UHFM groups (p < 0.001).ConclusionsPatients with HFM require individualized diagnosis and treatment planning because of diverse phenotypes and associations with other anomalies.

Hemifacial microsomia treated with a hybrid technique combining distraction osteogenesis and a mandible-guided functional appliance: Pilot study

The purpose of this study was to evaluate the therapeutic effect of a hybrid treatment for hemifacial microsomia that combines distraction osteogenesis and a mandible-guided functional appliance to correct mandibular asymmetry. This was a retrospective analysis of 10 patients with unilateral hemifacial microsomia who underwent mandibular ramus distraction osteogenesis in our hospital from February 2013 to July 2015. The cases were classified into 2 comparison groups: 5 patients were in the MG-DO group (distraction osteogenesis combined with an mandible-guided functional appliance) and 5 in the control group (distraction osteogenesis only). Anteroposterior cephalometric analyses were conducted before and after treatment. Soft tissue symmetry and the occlusal relationship were observed from facial and intraoral photographs. Statistical analyses were performed to determine changes between before and after treatment as well as intergroup differences. The MG-DO group showed greater vertical elongation of the mandibular ramus and less overcorrection and mandibular deviation than the control group. Occlusal reconstruction was enabled by the mandible-guided functional appliance owing to a decrease in lateral shifting. The symmetry of both skeletal and soft tissues was significantly improved in the MG-DO group. The hybrid technique combining distraction osteogenesis and the mandible-guided functional appliance proved to be effective in correcting canting and deviation during mandibular elongation, which improved facial symmetry and occlusal balance in patients with hemifacial microsomia.

The accuracy of virtual-surgical-planning-assisted treatment of hemifacial microsomia in adult patients: distraction osteogenesis vs. orthognathic surgery

Hemifacial microsomia (HFM) is a common congenital craniofacial deformity with a high prevalence. Orthognathic surgery and distraction osteogenesis are two conventionally used treatments of HFM. The main objective of this retrospective study was to evaluate the accuracy of two treatments with the help of virtual surgical planning in adult HFM patients. Sixty-eight adult patients with unilateral HFM were enrolled in this study. Preoperative surgical planning and simulation were performed on three-dimensional computed tomography models. Orthognathic surgery or distraction osteogenesis was performed under the guidance of three-dimensional surgical templates. Postoperative evaluation of the intervention was performed by comparison of the affected ramus height, chin deviation and the occlusal cant in surgical planning and actual result. Outcome and feedback information (an average of 14 months) showed that virtual surgical planning was accurately transferred to actual surgery in both surgical approaches. There were no statistical differences between the accuracy of affected ramus height and the occlusal cant in two surgical approaches. The orthognathic group showed significantly higher accuracy in chin deviation. In conclusion, virtual surgical planning and three-dimensional surgical templates were proved to facilitate treatment planning and offer an accurate surgical result in the treatment of adult HFM patients.

Relationship Between Mandibular Ramus Height and Masticatory Muscle Function in Patients With Unilateral Hemifacial Microsomia.

To clarify the relationship between mandibular ramus height and function of masticatory muscles in patients with hemifacial microsomia. Retrospective study of imaging and physiological data. Images and physiological data were obtained from the records of Sapporo Medical University Hospital. A total of 29 patients with hemifacial microsomia who showed Pruzansky grades I, II deformity. Mandibular ramus height and masticatory muscle volume were evaluated with multi-detector row computed tomography. The electromyographic value was measured by the K7 Evaluation System. The hemifacial microsomia patients were classified into three groups based on the mandibular ramus height ratio of the affected and unaffected sides: group 0, >1.00; group 1, 1.00 to 0.85; group 2, <0.85. The Tukey-Kramer method and Games-Howell method were used to determine correlations between parameters. Decreased mandibular ramus height was significantly correlated with both reduced electromyographic values of the masseter muscle (P < .05) and the amount of mandibular lateral deviation at the time of maximum opening (P < .05) on the affected side. These differences were prominent in unilateral hemifacial microsomia patients classified as group 2. Decreased mandibular ramus height may cause dysfunction of the masseter muscles but not the temporal muscle on the affected side in patients with hemifacial microsomia.

Computer-Assisted Distraction Osteogenesis in the Treatment of Hemifacial Microsomia.

To investigate the application of computer-assisted surgical planning and virtual guide in distraction osteogenesis for patients with hemifacial microsomia. Eight patients diagnosed with unilateral hemifacial microsomia were enrolled in this study. Preoperative surgical planning and simulation were performed on three-dimensional model. Distraction was simulated on virtual model and the new morphology of the mandible was predicted. Mandibular ramus osteotomy and distractor implant was performed under the guidance of tooth-borne virtual guide. Postoperative evaluation of the intervention was performed by comparison of surgical planning and actual result. Preoperative planning, simulation, osteotomy and distractor implant under the guidance of virtual guide were performed successfully on all patients. Tooth-borne guide defined the osteotomy line and accurate position of distractor. Facial symmetry was greatly improved. The osteogenesis and neomandible contour was checked by postoperative computed tomography, and a good matching with the preoperative planning was achieved. Computer-assisted surgical planning and intraoperative virtual guide shows its great value in improving the accuracy of distraction osteogenesis and restoring facial symmetry. It is regarded as a valuable technique in this potentially complicated procedure.

Simultaneous maxillo-mandibular distraction in early adolescence as a single treatment modality for durable correction of type II unilateral hemifacial microsomia: Follow-up till completion of growth.

Timing of surgical intervention in hemifacial microsomia (HFM) is controversial. Although mandibular osteodistraction in childhood for HFM is popular, recent data for single-stage distraction in growing HFM patients demonstrated long-term relapse. Literature suggests that adolescents in the late mixed dentition age or permanent dentition age (11-16-year-old) had more stable outcomes post-distraction than younger children. We present favorable experience using single-treatment simultaneous maxillo-mandibular distraction in early adolescent Pruzansky-Kaban type II HFM patients. This was a retrospective longitudinal study of seven consecutive type IIa/b HFM growing patients (12-16-year-old) treated with simultaneous maxillo-mandibular distraction. Oral commissure cant was photographically measured preoperatively and at 6 months and annually ranging 3-7 years post-distraction. Ramus height and chin deviation were measured from radiographs done preoperatively and at distractor-removal, 1 year, 2 years, and 4 years post-distraction. Average age at osteodistraction and at latest follow-up was 13.7 and 18.6 years, respectively. Improvement was significant (p<0.05) and sustained for mean oral commissure cant (5.1°-0.41°), mean ramus height ratio (0.59-0.86), and average chin deviation (15.9mm-1.2mm). Two subjects had mandibular branch palsy and one had mild pin-tract infection - all resolved. All were satisfied with their facial appearance. We have demonstrated good lasting outcomes at completion of growth with single-stage simultaneous maxillo-mandibular distraction for type II HFM adolescents in the late mixed-dentition or older age, and advocate this as an alternative to osteodistraction or orthognathic surgery upon skeletal maturity.

Sagittal split ramus osteotomy combined with intraoral distraction osteogenesis for hemifacial microsomia

To investigate the effect of sagittal split ramus osteotomy(SSRO) combined with distraction osteogenesis(DO) for hemifacial microsomia (HFM). From January 2013 to September 2015,7 cases of unilateral HFM were included in the study. The 3-dimensional reconstruction images were used for the operation design. The location of the germs and inferior alveolar nerve was marked to avoid injury. The distractor was fixed after SSRO. The distractor was distracted 2-4 mm intraoperatively and began enlongation 3-5 days after operation,1-2 mm every day until the pre-designed length attained. The patients were followed up for 3-D CT and measurement of the height of bilateral ramus. The enlongation length was 7 mm to 20 mm(mean,14.6 mm).The facial symmetry and occlusion plane was improved a lot. No complication occurred. The mean follow-up period was 22 months (range 17-32 months) with almost symmetrical appearance and occlusion function. SSRO combined with DO has a good therapeutic effect and low complication for patients with HFM. The distraction rate is relatively high with a short treatment period. The ramus width, even thickness, are not decreased, or even can be increased after DO.

Cranial Base Deviation in Hemifacial Microsomia by Craniometric Analysis

Although facial asymmetry in hemifacial microsomia (HFM) is well documented in the literature, no studies have concentrated on the morphology of the cranial base. This study aimed to evaluate the endocranial morphology in patients with HFM. Consecutive patients with unilateral HFM treated at a craniofacial center from 2000 to 2012 were included. The patients were grouped according to severity on the basis of the Kaban-Pruzansky classification: mild (0-1), moderate (2a), and severe (2b-3). Skull base angulation and transverse craniometric measures were recorded and then compared with those of age-matched controls. A total of 30 patients (14 males, 16 females) averaging 7.5 years of age (range, 1.1-15.7 y) were included. Four patients were classified as mild; 12, as moderate; and 14, as severe. The mean cranial base angle was found to be between 179 and 181 degrees with no significant difference between the severity groups (P = 0.57). The mean cranial base angle did not differ significantly in the patients compared with the controls(179.6 vs 180.0; P = 0.51) No significant differences between the affected and unaffected sides in the patients were found in distances from the midline to hypoglossal canal, internal acoustic meatus, lateral carotid canal, medial carotid canal, foramen ovale, and rotundum. There were no significant differences in transverse measurements between the severity classes using the same landmarks (P = 0.46, P = 0.30, P = 0.40, P = 0.25, P = 0.57, and P = 0.76, respectively). The cranial base axis is not deviated in the patients with HFM compared with the age-matched controls, and there exists little difference in endocranial morphologic measurements with increasing severity of HFM. These data are interesting, given the role of the cranial base in facial growth and the varying hypotheses regarding the mechanism of disease in HFM.

Evaluation of Mandibular Hypoplasia in Patients with Hemifacial Microsomia: A Comparison between Panoramic Radiography and Three-Dimensional Computed Tomography

To compare the accuracy of three-dimensional computed tomography (3D-CT) and panoramic radiography in the evaluation of mandibular hypoplasia in patients with hemifacial microsomia (HFM). Retrospective study of imaging data. Setting : Images selected from the archives of the University of Tokyo Hospital. Twenty patients with unilateral HFM who had undergone both panoramic radiography and 3D-CT in the same period. Mandibular deformities were classified according to the Pruzansky classification; eight patients had Grade I deformity and 12 patients had Grade II deformity. Ramus heights were measured on both panoramic radiographs and 3D-CT. Magnification in panoramic radiographs and extent of mandibular asymmetry as estimated by the affected/unaffected side ratio based on two methods were examined. The Pearson product-moment correlation coefficient was used to estimate correlations between parameters. The magnification of ramus heights on panoramic radiographs showed large variations in Grade II patients. The affected/unaffected side ratio estimated by the two methods showed a strong correlation in Grade I patients (correlation coefficient 0.99; p < .0001). Conversely, a weak correlation was seen in Grade II patients (correlation coefficient 0.77; p = .0036), and affected/unaffected side ratios from panoramic radiographs were both over- and underestimated. The accuracy of evaluation using panoramic radiography was fairly reliable in Grade I patients. Conversely, accuracy was poor in Grade II patients, and evaluation using 3D-CT seems preferable. The combination of two methods with careful consideration is recommended for clinical applications.

Changes of mandibular ramal height, during growth in unilateral hemifacial microsomia patients and unaffected controls

The aim of this study was to design mandibular ramal height growth curves for patients with HFM and compare those with the curves for a Dutch reference population. Two hundred fifty-one pre-operative orthopantomograms (OPTs) from 84 patients with unilateral HFM were used in conjunction with a control set of 2260 OPTs from 329 healthy individuals from the Nijmegen Growth Study (NGS) to determine mandibular ramal distances. For grades I/IIa and IIb/III, and for both sides, growth curves were constructed for mandibular ramal height with a linear curve-fitting procedure. This procedure revealed a significant difference between HFM patients and the NGS control group (p < 0.001); both in the mild and severe group mandibular ramal height differed significantly between the affected and non-affected side (p < 0.001). Growth was similar between HFM patients and the NGS control group. HFM patients therefore start with a smaller mandible and end with a smaller mandible, but experience growth similar to the Dutch normal population. These growth curves may aid the timing and determination of the combined surgical orthodontic treatment plan for HFM patients.