The importance of a differential diagnosis between true hemifacial microsomia and pseudo-hemifacial microsomia in the post-surgical long-term prognosis

Growth characteristics and classification systems of hemifacial microsomia: a literature review

BACKGROUND

Hemifacial microsomia is characterized by the hypoplasia of the mandible and temporomandibular joint, involving a variety of abnormalities of the craniofacial area. Since it gradually worsens as patients grow, it is necessary to understand the characteristics of facial bone growth and facial deformity in hemifacial microsomia patients in order to determine appropriate treatment timing and treatment methods.

MAIN BODY

Appropriate classification of hemifacial microsomia would facilitate accurate diagnosis, selection of treatment methods, and prognosis prediction. Therefore, in this article, we review previously published hemifacial microsomia classification and provide an overview of the growth of the facial skeleton and the characteristics of hemifacial microsomia-related facial deformities. The OMENS system is the most comprehensive classification method based on the characteristics of hemifacial microsomia deformity, but it needs to be improved to include malar/midface abnormalities and nerve involvement. In hemifacial microsomia, growth is progressing on the affected side, but to a lesser degree than the unaffected side. Therefore, surgical intervention in growing patients should be performed selectively according to the severity of deformity.

CONCLUSION

Understanding growth patterns is important to develop appropriate treatment protocols for correcting asymmetry in adult patients and to minimize secondary anomalies in growing patients.

Dermal-Fat Graft for Facial Contouring in Patients With Craniofacial Microsomia

Craniofacial microsomia (CFM) is a variable craniofacial malformation, related to the development of the structures originated from the first and second brachial arches, affecting skeletal tissue, soft tissue, and neuromuscular components. In the situation of subcutaneous tissue and chewing muscles hypoplasia, free tissue transfer is a treatment option. Dermal-fat graft allows easy modeling during surgery, volumetric gain and improvement of asymmetry. The aim of this study was to evaluate the facial contour and the percentage of symmetry after the use of dermal-fat graft in patients with CFM, who had already submitted to osteotomies, attended at the Associate Center for Cleft Lip and Palate (CAIF) during 2001 to 2018. For analysis, the authors selected 17 patients who fulfilled the above prerequisites. The symmetry study was done by the analysis of preoperative and postoperative photographs in the Image J software. Two standard points were used: nasal base and upper lip limit. On the nasal base, the preoperative analysis showed a hypoplastic side with a median of 93.00% of the normal side size, rising to 97.78% in the postoperative period. On the upper lip limit, the preoperative analysis showed a median of 87.80% and, in the postoperative period, 98.15%. Analysis of the interaction between the operative moments and the modified Pruzansky classification showed that there were no significant differences between grades. Long-term evaluation demonstrated that the use of a dermal-fat graft for correction of facial symmetry was effective and close to 100%, regardless of the degree of hypoplasia of the patient.

Early Orthopaedic Treatment of Hemifacial Microsomia

The aim of this paper is to report treatment effects of functional therapy in a growing patient affected by hemifacial microsomia (HM). According to Kaban's classification, the patient was classified as grade IIa as she presented all mandibular and temporomandibular joint components and a normal shaped, hypoplastic mandible. The therapeutic approach included the use of an asymmetrical functional activator (AFA) to stimulate the growth of the affected side and consequently to improve symmetry of the mandible and maxillary deficiency. Further effects were the lengthening of the mandibular ramus, restoration of occlusion, and expansion of soft tissues.

[Congenital malformations of the temporo-mandibular joint and the mandibular ramus: Grafting vs distraction osteogenesis]

Congenital deformities of the mandibular ramus and of the temporo-mandibular joint are treated by surgery since the early 20th century. However, morphological and functional results are often disappointing, accounting for iterative operations. Today, a clear consensus concerning the type of intervention to be proposed, and at what age it should be carried out does not yet exist. For mild cases, "conventional" orthognathic or osteogenic distraction procedures seem to work well, especially if they are carried out at the end of growth. In severe cases, it is often necessary to proceed in several surgical steps, usually starting with a chondrocostal graft, especially when interceptive surgery, performed before the end of growth, is preferred in order to improve the patient's quality of life.

The isolated mandibular ramus - a hitherto rarely described anomaly of the mandible. Pathogenesis and treatment

INTRODUCTION

A very famous paper by Sam Pruzansky, published in 1969, was entitled "Not all dwarfed mandibles are alike". This is the topic of this paper: to describe the shape and discuss the possible pathogenesis of an extremely rare congenital dysplasia found in a unilaterally hypoplastic mandible, namely the isolated mandibular ramus.

MATERIAL AND METHODS

A unique malformation of the lower jaw was found in more than 75 patients with developmental abnormalities of the mandible diagnosed and treated by the two authors in two different university hospitals over the last 40 years. We performed the following teratological experiments with laboratory rodents in order to try to understand the pathogenesis of this special dysplasia (and others): at first the normal development of the lower jaw was studied in rat and mouse foetuses. Then a variety of teratogenic drugs were applied to pregnant females and then the foetuses of these pregnancies were studied following Caesarian section.

RESULTS

One rat foetus was identified which presented the identical dysplasia that had been noted in the patient described here. The dam pregnant with this foetus had been given 25 mg/kg bodyweight of 6-mercaptopurine on day 12 of pregnancy. The explanation found for the pathogenesis of this anomaly was deducted from the scientific literature regarding normal development of the mandibular condyle.

CONCLUSION

The nucleus of the so-called secondary cartilage that will produce the ascending ramus (plus condyle and coronoid) is a separate growth centre which fuses a short time later with the dental bone which becomes the mandible proper by this fusion.

Facial asymmetry and clinical manifestations in patients with novel insertion of the TCOF1 gene

This study explored the role of TCOF1 insertion mutations in Taiwanese patients with craniofacial anomalies. Twelve patients with single or multiple, asymmetrical congenital craniofacial anomalies were enrolled. Genomic DNA was prepared from leukocytes; the coding regions of TCOF1 were analyzed by polymerase chain reaction and direct sequencing. Clinical manifestations were correlated to the TCOF1 mutation. Six of 12 patients diagnosed with hemifacial microsomia exhibited a novel insertion mutation 4127 ins G (frameshift) in exon 24 in the TCOF1 gene. All six patients were diagnosed with anomalies on the left side. In addition, four of these six patients had hearing impairment; three had other major anomalies; and two had developmental delay. The insertion caused a frameshift, an early truncation, the loss of two putative nuclear localization signals (residues 1404-1420 and 1424-1440), and the loss of coiled coil domain (1406-1426) in treacle protein. These findings support the existence of two regulators of growth of the mandibular condyles.