Craniofacial Microsomia

Modern Mandibular Distraction Applications in Hemifacial Microsomia

Phenotypic severity dictates the timing and type of surgical intervention required. Mandibular distraction in children without respiratory and feeding difficulties remains controversial with regard to long-term mandibular growth outcomes and reducing surgical burden. Early mandibular distraction does not obviate secondary orthognathic surgery at skeletal maturity; it provides improved functional, aesthetic, and psychosocial outcomes, at least in the short term. Costochondral rib grafting for Pruzansky type IIB and III mandibles can produce reliable results, especially when combined with subsequent mandibular distraction. Secondary 2-jaw orthognathic surgery plus genioplasty at skeletal maturity benefits from improved bone volume from prior mandibular distraction.

Counterclockwise Craniofacial Distraction Osteogenesis

Anatomic studies have identified that patients with Treacher Collins syndrome and some cases of bilateral craniofacial microsomia are characterized by multilevel airway obstruction as a result of hypoplasia and clockwise rotation of the maxillomandibular complex. Patients often remain tracheostomy-dependent despite multiple airway surgeries. Counterclockwise craniofacial distraction osteogenesis aims to correct the facial skeletal deformity and expand the upper airway volume by rotating the subcranial complex en bloc around the nasofrontal junction. Early results have demonstrated significant increases in the nasopharyngeal and oropharyngeal airway volumes with successful decannulation in a majority of patients who have undergone this operation.

Examining the variability of bone and soft tissue morphology in Hemifacial Microsomia: A case series of 8 patients

AIM OF THE STUDY

Patients with Hemifacial Microsomia (HFM) exhibit highly variable skeletal and soft tissue asymmetries. The purpose of this study was to evaluate soft tissue discrepancies in patients with HFM and correlate them to the skeletal discrepancy. Eight patients were selected and studied retrospectively using 3-dimensional (3D) superimposition and color mapping of the soft and hard tissues. The skeletal and soft tissue facial structures were segmented and mirrored, resulting in a perfectly symmetric skull and face. Original and mirrored 3D models were superimposed. Differences between the affected and normal side were assessed in seven areas: frontal, endocanthion, exocanthion, malar, maxillary frontal, mandibular frontal and gonion area. The correlations between the skeletal and soft tissue asymmetry were evaluated by Pearson correlations. Hard tissue asymmetry ranged from 1.4 mm (Endocanthion) to 5.5 mm (Gonion), while soft tissue asymmetry ranged from 1.5 mm (Endocanthion) to 5.6 mm (Malar). Correlation between skeletal and soft tissue deficiency were highly variable, with the highest correlation at gonion and the lowest at exocanthion. Bone and soft tissue hypoplasia were highly correlated at the gonion and the malar area, while the remaining evaluated areas demonstrated poor correlation between skeletal and soft tissue asymmetries. Future studies will determine if target treatment can reliably improve bone and soft tissue hypoplasia in this area.

Hemifacial Microsomia Review: Recent Advancements in Understanding the Disease

Hemifacial microsomia (HFM) is the second most common congenital disability of the face, with a prevalence of 1 in 3000 to 5600 live births. Although etiology is still not fully understood, including both genetics and environmental factors, the latest reports indicate the prominence of premature loss of the neural crest cells. What is more, a deficit of muscles of mastication, except the masseter, correlates in the pathomechanism of mandibular underdevelopment. Due to the significant phenotypic diversification, the typical picture of HFM cannot be determined. It may present as an esthetic concern-minor asymmetry with deformed auricle, and on the contrary, as microtia/anotia with conductive type hearing loss, hypoplastic mandible, and microphthalmia, impairing patient's daily activities. Referring to psychosocial problems, it has been proved that in population with HFM, there is a modestly elevated risk for behavior problems, social competence, and less acceptance. Over the years, more comprehensive methods of assessing the extent and severity of the HFM as the OMENS (+) classification have emerged. The authors like to summarize and present for plastic surgery resident and plastic surgeons the critical features of HFM, including the epidemiology, clinical presentation, pathogenesis, and innovative management reported in the current literature.

Three-Dimensional Planning of the Mandibular Margin in Hemifacial Microsomia Using a Printed Patient-Specific Implant

Hemifacial microsomia (HFM) is also known as malformation of the first and second branchial arches (BAs), oculoauriculovertebral dysplasia syndrome, and Goldenhar syndrome. Possibilities resulting from CAD/CAM may be a valuable tool to existing procedures to treat these abnormalities. The aim of this study was to report a case where the planning and implementation of an intraorally inserted 2-part patient-specific mandible implant was used for the treatment of HFM esthetic remained problem after orthognathic surgery. A 20-year-old female patient who continued to suffer from the esthetic defect of the unilateral hypoplastic mandible after completion of the orthognathic surgery attended for consultation. Using CT scan and the software Geomagic Freeform (3D Systems, USA), a 2-piece titanium implant was designed and printed to restore the osseous frame of the basal border of the mandible. The base was made of solid polished titanium to minimize soft tissue abrasion. Due to its split design, the implant could be placed anatomically exactly at the mandibular margin via an intraoral access and to avoid damage of the mental nerve. There were no postoperative complications such as infections, soft tissue reactions to the implant, sensitivity disorders, or dehiscence. The occlusion was regular. A measurement of the postoperative x-rays showed a clear increase in bony symmetry. No postoperative pain or trismus was seen. Functionally, the therapy ended with the completion of wound healing and the jaw was fully resilient again. A combined treatment using PSI and additional autogenous fat grafting may represent a valid treatment option for the treatment of facial asymmetry in patients with HFM.

CXCL12-CXCR4 Interplay Facilitates Palatal Osteogenesis in Mice

Cranial neural crest cells (CNCCs), identified by expression of transcription factor Sox9, migrate to the first branchial arch and undergo proliferation and differentiation to form the cartilage and bone structures of the orofacial region, including the palatal bone. Sox9 promotes osteogenic differentiation and stimulates CXCL12-CXCR4 chemokine-receptor signaling, which elevates alkaline phosphatase (ALP)-activity in osteoblasts to initiate bone mineralization. Disintegration of the midline epithelial seam (MES) is crucial for palatal fusion. Since we earlier demonstrated chemokine-receptor mediated signaling by the MES, we hypothesized that chemokine CXCL12 is expressed by the disintegrating MES to promote the formation of an osteogenic center by CXCR4-positive osteoblasts. Disturbed migration of CNCCs by excess oxidative and inflammatory stress is associated with increased risk of cleft lip and palate (CLP). The cytoprotective heme oxygenase (HO) enzymes are powerful guardians harnessing injurious oxidative and inflammatory stressors and enhances osteogenic ALP-activity. By contrast, abrogation of HO-1 or HO-2 expression promotes pregnancy pathologies. We postulate that Sox9, CXCR4, and HO-1 are expressed in the ALP-activity positive osteogenic regions within the CNCCs-derived palatal mesenchyme. To investigate these hypotheses, we studied expression of Sox9, CXCL12, CXCR4, and HO-1 in relation to palatal osteogenesis between E15 and E16 using (immuno)histochemical staining of coronal palatal sections in wild-type (wt) mice. In addition, the effects of abrogated HO-2 expression in HO-2 KO mice and inhibited HO-1 and HO-2 activity by administrating HO-enzyme activity inhibitor SnMP at E11 in wt mice were investigated at E15 or E16 following palatal fusion. Overexpression of Sox9, CXCL12, CXCR4, and HO-1 was detected in the ALP-activity positive osteogenic regions within the palatal mesenchyme. Overexpression of Sox9 and CXCL12 by the disintegrating MES was detected. Neither palatal fusion nor MES disintegration seemed affected by either HO-2 abrogation or inhibition of HO-activity. Sox9 progenitors seem important to maintain the CXCR4-positive osteoblast pool to drive osteogenesis. Sox9 expression may facilitate MES disintegration and palatal fusion by promoting epithelial-to-mesenchymal transformation (EMT). CXCL12 expression by the MES and the palatal mesenchyme may promote osteogenic differentiation to create osteogenic centers. This study provides novel evidence that CXCL12-CXCR4 interplay facilitates palatal osteogenesis and palatal fusion in mice.

Evaluation of vertical ramus osteotomy for the surgical correction of unilateral mandibular posterior vertical insufficiency: Long-term follow-up results

PURPOSE

Unilateral posterior vertical insufficiency (PVI) is a growth defect of the mandibular condyle that results in a facial asymmetry. Various surgical procedures can be used to elongate the hypoplastic ramus. The aim of this study was to evaluate long-term aesthetic and architectural outcomes of vertical ramus osteotomy (VRO) in patients with unilateral PVI.

MATERIALS AND METHODS

Patients operated on with unilateral VRO were included in this retrospective study. Aesthetic and architectural parameters were evaluated on frontal photographs as well as on frontal and lateral cephalograms preoperatively, postoperatively, at 1-year and at the end of the follow-up.

RESULTS

A total of 48 patients were analyzed. The aesthetic assessment revealed significant correction of the chin deviation (CD) and of the lip commissural line tilt after VRO (p1 = 0.0038 and p2 = 0.0067, respectively) with stable results. The architectural analysis revealed significant improvement in the maxillary and mandibular occlusal planes, as well as the chin deviation (p < 0.0001). A tendency to relapse was noted for the mandibular canting and the CD during the follow-up. VRO allowed for a mean mandibular lengthening of 8.39 mm (ranging from 2.5 to 14 mm).

CONCLUSION

VRO allows for immediate restoration of the symmetry of the lower third of the face in patients with unilateral PVI. A revisional procedure may be needed due to a tendency for the chin deviation to relapse.

Polymethyl Methacrylate (PMMA) in the Treatment of a Case of Hemifacial Microsomia

Hemifacial microsomia (HMF) is a morphological alteration characterized by facial deformities. These alterations are a consequence of a congenital anomalous development of the first and second branchial arches. It may present a genetic or environmental origin or a mixture of both and is considered mostly multifactorial. The clinical presentation varies; however, some characteristics are predominant such as unilateral mandible hypoplasia, agenesis or malformation of the auricular pavilion, and agenesis or malformation of the eye globe. The aim of this paper was to report a clinical case of a patient with late diagnosis of HMF which presented multiple deformities and received treatment with polymethyl methacrylate (PMMA) implant in different concentrations. Aiming for facial harmony, the PMMA implant occurred in the following regions: canine fossa, nasolabial sulcus, mandible, Bichat Ball, chin outline, lip contour, nose base, columella, nose tip, and dorsum. The treatment resulted in significant improvement in the facial symmetry.

Level of Evidence: 5