Surgical correction of the midface in craniofacial microsomia. Part 1: A systematic review

A decade of clinical research on clinical characteristics, medical treatments, and surgical treatments for individuals with craniofacial microsomia: What have we learned?

AIM

This article provides a review of a decade of clinical research studies on clinical features, medical interventions, and surgical interventions for individuals with craniofacial microsomia (CFM). We also provide recommendations for future clinical research.

METHOD

A systematic search of literature was conducted in Embase and PubMed/MEDLINE Ovid. All publications from 2010 to 2020 that included at least 10 individuals with CFM were considered relevant for this study.

RESULTS

A total of 91 articles were included. In the past decade, many new studies on CFM have been published providing more insight on the diagnosis and management of patients with CFM. This review encompasses findings on the clinical difficulties patients with CFM encounter, including the craniofacial and extracraniofacial characteristics of patients with CFM and its related clinical consequences on breathing, feeding, speech, and hearing.

CONCLUSIONS

A considerable number of large multicenter studies have been published in recent years, providing new insights in the clinical consequences of CFM. The phenotypic variety between patients with CFM makes patient-specific treatment tailored to individual needs essential. The research and development of clinical care standards might be challenging because of the heterogeneity of CFM. Future research on clinical and patient-reported outcomes can help identify optimal treatment strategies. Cooperation between craniofacial centers, using uniform registration and outcome measurement tools, could enhance research and future care for these patients.

LEVEL OF EVIDENCE

Level IV.

Dynamic Reconstruction of Facial Paralysis in Craniofacial Macrosomia

BACKGROUND

Craniofacial microsomia is associated with maxillomandibular hypoplasia, microtia, soft-tissue deficiency, and variable severity of cranial nerve dysfunction, most often of the facial nerve. This study evaluated the incidence of patients with craniofacial microsomia and facial paralysis and their outcomes after free functioning muscle transfer for dynamic smile reconstruction.

METHODS

A single-center, retrospective, cross-sectional study was performed from 1985 to 2018 to identify pediatric patients with craniofacial microsomia and severe facial nerve dysfunction who underwent dynamic smile reconstruction with free functioning muscle transfer. Preoperative and postoperative facial symmetry and oral commissure excursion during maximal smile were measured using photogrammetric facial analysis software.

RESULTS

This study included 186 patients with craniofacial microsomia; 41 patients (21 male patients, 20 female patients) had documented facial nerve dysfunction (22 percent), affecting all branches (51 percent) or the mandibular branch only (24 percent). Patients with severe facial paralysis (n = 8) underwent midfacial (i.e., smile) reconstruction with a free functioning muscle transfer neurotized either with a cross-face nerve graft (n = 7) or with the ipsilateral motor nerve to masseter (n =1). All patients achieved volitional muscle contraction with improvement in symmetry and oral commissure excursion (median, 8 mm; interquartile range, 3 to 10 mm). The timing of orthognathic surgery and facial paralysis reconstruction was an important consideration in optimizing patient outcomes.

CONCLUSIONS

The authors' institution's incidence of facial nerve dysfunction in children with craniofacial microsomia is 22 percent. Free functioning muscle transfer is a reliable option for smile reconstruction in children with craniofacial microsomia. To optimize outcomes, a novel treatment algorithm is proposed for craniofacial microsomia patients likely to require both orthognathic surgery and facial paralysis reconstruction.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Displacement and stress distribution of the craniomaxillofacial complex under different surgical conditions: a three-dimensional finite element analysis of fracture mechanics

Objective

To provide a simplified treatment strategy for patients with maxillary transverse deficiency. We investigated and compared the fracture mechanics and stress distribution of a midline palatal suture under dynamic loads during surgically-assisted rapid palatal expansion.

Methods

Based on the cone-beam computed tomography (CBCT) data of a 21-year-old female volunteer, a three-dimensional model of the cranio-maxillofacial complex (including the palatal suture) was constructed. A finite element analysis model was constructed based on meshwork. After the yield strength of the palatal suture was set, an increasing expansion force (0–500 N) was applied within 140 ms to calculate the time–load curve, which mimicked nonsurgical bone expansion (model A). The same method was used to evaluate the fracture process, time and stress distribution of the palatal suture in maxillary lateral osteotomy-assisted (model B) and LeFort osteomy I (LFIO)-assisted expansion of the maxillary arch (model C).

Results

Compared with model A, the palatal suture of model B and model C showed a faster stress accumulation rate and shorter fracture time, and the fracture time of model B and model C was almost identical. Compared with model A, we discovered that model B and model C showed greater lateral extension of the maxilla, and the difference was reflected mainly in the lower part of the maxilla, and there was no difference between model B and model C in lateral extension of the maxilla.

Conclusions

Compared with arch expansion using nonsurgical assistance (model A), arch expansion using maxillary lateral wall-osteotomy (model B) or LFIO had a faster rate of stress accumulation, shorter time of fracture of the palatal suture and increased lateral displacement of the maxilla. Compared with arch expansion using LFIO (model C), arch expansion using lateral osteotomy (model B) had a similar duration of palatal suture rupture and lateral maxillary extension. In view of the trauma and serious complications associated with LFIO, maxillary lateral wall-osteotomy could be considered a substitute for LFIO.

Three-Dimensional Analysis of the Condylar Hypoplasia and Facial Asymmetry in Craniofacial Microsomia Using Cone-Beam Computed Tomography

PURPOSE

To assess the condylar hypoplasia and its correlation with craniofacial deformities in adults with unilateral craniofacial microsomia (CFM).

METHODS

Pretreatment cone-beam computed tomography scans of consecutive adults (mean age: 20.4 ± 3.0 years; range: 17.3 to 31.4 years) with Pruzansky-Kaban type I and IIA CFM were reconstructed in 3D. Both condyles were segmented. Asymmetry ratios (affected side/contralateral side) of condylar volume were calculated to indicate the extent of condylar hypoplasia. 3D cephalometry was performed to quantify the maxillomandibular morphology and facial asymmetry. The correlations in between were assessed by using Pearson's or Spearman's correlation coefficients.

RESULTS

Thirty-six subjects were enrolled, consisting of 22 subjects with Pruzansky-Kaban type I and 14 subjects with type IIA. The condyles in type IIA group were significantly more hypoplastic in height (asymmetry ratio: 40.69 vs 59.95%, P = .006) and volume (18.16 vs 47.84%, P < .001) compared to type I group. Type IIA group had a significantly smaller SNB value than type I group (72.94° vs 77.41°, P = .012), and a significantly greater facial asymmetry (P < .05). The hypoplastic extent of condylar volume and Pruzansky-Kaban types were significantly correlated with SNB (r = 0.457 and ρ = -0.411, respectively), upper incisor deviation (r = -0.446 and ρ = 0.362), chin deviation (r = -0.477 and ρ = 0.527), upper occlusal plane cant (r = -0.672 and ρ = 0.631), and mandibular plane cant (r = -0.557 and ρ = 0.357, P < .05).

CONCLUSION

For unilateral CFM adults, greater condylar hypoplasia in volume along with more severe mandibular retrusion and facial asymmetry objectively indicated a higher scale of Pruzansky-Kaban classification (type IIA). These quantitative distinctions are expected to enhance the diagnostic reliability of CFM.

Pseudo Hemifacial Microsomia With Condylar-Coronoid Collapse: New Therapeutic Approach in Growing Patients

The purpose of this study is to describe the management of 2 dimorphic patients affected by Hemimandibular Hypoplasia with Condylar-Coronoid Collapse (HH-CCC), also called Pseudo Hemifacial Microsomia, where the orthopedic treatment gave an excellent long-term follow-up. The patients were a 7-year-old female and a 6-year-old male with a HH-CCC on the left side, an asymmetrical face with chin deviation, class II dental malocclusion and canting of the occlusal plane. An X-ray evaluation and clinical observation confirmed the unilateral mandibular deficiency and the collapse of the condyle on the coronoid process on the affected side. The treatment plan consisted of the use of an asymmetrical functional appliance with a vertical screw. The appliance was gradually activated on the vertical plane on one side by a screw incorporated on an acrylic plate. It was used for 22 hours/day, including sleep time but not during meals. This treatment improved the patient' s facial appearance. HH-CCC showed a positive response to functional therapy.

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

Objective

To investigate the treatment modalities (Tx-Mods) for patients with unilateral hemifacial microsomia (UHFM) according to Pruzansky–Kaban types and growth stages.

Methods

The 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.

Results

The 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).

Conclusions

These findings might be used as basic guidelines for successful treatment planning and prognosis prediction in UHFM patients.

Three-dimensional characterization of mandibular asymmetry in craniofacial microsomia

Objectives

This study aimed to investigate the three-dimensional (3D) mandibular asymmetry in craniofacial microsomia (CFM) and its association with the Pruzansky–Kaban classification system.

Materials and methods

Cone-beam computed tomography images of 48 adult CFM cases were collected. The asymmetry of the mandibular body and ramus was analyzed with 3D landmarks. The mirrored mandibular model was registered on the original model, yielding a color-coded distance map and an average distance (i.e., asymmetry score) to quantify the overall mandibular asymmetry.

Results

The lengths of the mandibular body and ramus were significantly shorter on the affected than the contralateral side (p < 0.001). The ANB (p = 0.009), body and ramal lengths (both p < 0.001), and body and ramal length asymmetry (both p < 0.05) were significantly different between mild (types I/IIA) and severe (types IIB/III) cases. The mandibular asymmetry score correlated with mandibular body length asymmetry (r = 0.296, p = 0.046). CFM mandibles showed high variability in shape asymmetry.

Conclusions

CFM patients showed distinct body and ramal length asymmetries. In severe cases, mandibles were smaller, more retruded, and more asymmetric in length. The mandibular shape asymmetry was highly variable regardless of the Pruzansky–Kaban types, being a determinant in the extent of overall mandibular asymmetry.

Clinical relevance

The 3D morphologic analysis provides better insights into real mandibular asymmetry. Although the Pruzansky–Kaban classification was applied, high individual variability of the mandibular morphology still existed within the types. Therefore, individualized analyses and treatment plans for CFM patients are highly recommended.

Computer guided temporomandibular joint reconstruction of Kaban III hemifacial microsomia with anotia: A case report

INTRODUCTION, Hemifacial microsomia is the second most common craniofacial congenital anomaly. It corresponds to a group of malformations ranging from minimal facial asymmetry to sever form affecting mandible, soft tissues, orbit, ear, and cranial nerves. PRESENTATION OF CASE, We present a case of 6 years old patient with Kaban class III hemifacial microsomia with anotia. Temporomandibular joint was reconstructed by costochondral graft using computer guided surgery (simulation and rapid prototyping). A computer guided soft tissue guide, mandibular, and maxillomandibular/zygomatic models were constructed using rapid prototyping technology. The customized computer guided soft tissue guide was used to localize the proper position of skin incision, the mandibular model was used for preoperative reconstruction plate bending, and the maxillomandibular/zygomatic model was used to estimate the rib graft length and position. Postoperative assessment showed proper positioning of the graft, with no complications or facial nerve affection. DISCUSSION, In this report, we introduce a new computer guided technique to estimate and identify the proper position of the temporomandibular joint graft based on patient CT. This technique eliminated the need of extended incisions with excessive dissection and provided a more accessible field for rib graft fixation, facilitating the surgical procedures. CONCLUSION, The use of computer guided surgery (simulation and rapid prototyping) for temporomandibular joint reconstruction in Kaban III hemifacial microsomia with anotia facilitates the surgical procedure, minimizes procedure time, increases precision, and reduces possible complications.