Orthopedically Induced Condylar Growth in a Patient With Hemifacial Microsomia

True hemifacial microsomia and hemimandibular hypoplasia with condylar-coronoid collapse: diagnostic and prognostic differences

INTRODUCTION

Long-term results after orthopedic or surgical treatment of hemifacial microsomia (HFM) have shown a tendency toward recurrence of the facial asymmetry. However, the literature contains a number of successful case reports that show surprising changes in the morphology of the condyles. In addition, patients with similar mandibular asymmetries, treated early with surgery, have excellent long-term follow-ups, especially those who have little or no soft-tissue involvement, but only severe mandibular ramal deformities. The phenotypes of these cases are unexpectedly similar, with a consistent collapse of the condyle against the coronoid and a deep sigmoid notch. The objectives of this article were to help distinguish true HFM from this peculiar type of hemimandibular asymmetry morphologically and to quantify their differences before treatement and in the long term.

METHODS

Panoramic radiographs taken at pretreatment and the long-term follow-up of 9 patients with hemimandibular hypoplasia, characterized by the collapse of the condyle against the coronoid, were compared with those of 8 patients with severe type I and type II HFM; these records were collected before and at least 10 years after distraction osteogenesis.

RESULTS

Ratios and angular measurements before and after treatment differed significantly between the 2 groups.

CONCLUSIONS

Perhaps these patients were misdiagnosed and actually had secondary injuries of the condyle, which have a normal functional matrix. Therefore, with growth and functional stimulation, they would tend to grow toward the original symmetry. To make a differential diagnosis between true HFM and this peculiar type of hemimandibular hypoplasia, the collaboration between not only orthodontists and surgeons, but also geneticists and dysmorphologists, is of great importance because of the different prognoses.

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

Long-term results after surgical treatment of the mandibular asymmetry in growing children with hemifacial microsomia (HFM), whether with osteotomies or distraction osteogenesis, have mostly shown a tendency towards the recurrence of the asymmetry. In contrast, in the literature we find sporadic case reports where the long-term post-surgical follow-up of patients diagnosed as HFM, are surprisingly stable. All these reports refer to patients who have substantially no soft tissue involvement, but only severe mandibular ramus and condyle deformities. The phenotypes of these cases are unexpectedly similar. The authors suggest, that it is possible that all of these cases might be isolated hemimandibular hypoplasias, misdiagnosed as HFM, which present a normal functional matrix and, therefore, tend to grow towards the original symmetry. Differential diagnosis between true HFM and this HFM-like isolated hemimandibular hypoplasia (pseudo-HFM) is of great importance given the very different prognosis and it is possible through the collaboration between not only surgeons and orthodontists, but also of geneticists and dysmorphologists.

Aneurysmal bone cyst located in the mandibular condyle

A rare case of aneurysmal bone cyst (ABC) located in the mandibular condyle in a 10-year-old boy is presented. The patient came to our attention for a sudden swelling in the right temporomandibular region, the mouth opening was not reduced.

A rapid growing mass, depicting soft tissue invasion, in the right condyle of the mandible was found. Clinically and radiographically it resembled to a malignant lesion. The surgical excision of the mandibular condyle allowed a complete removal of the lesion. The histological examination revealed a pseudocystic expanding osteolytic lesion containing blood-filled space separated by connective tissue and many osteoclastic giant cells, which was a conventional vascular ABC.

The ABC is an infrequent bone lesion which can only be found very rarely at the craniofacial skeleton. There have been described about 160 cases of ABC originated in the molar region or in upper maxilla and even more rare is the location of this cyst in the mandibular condyle. Only 6 cases were reported in the literature to date.

A complete surgical resection of this osteolytic lesion is the treatment of choice considering its high recurrence rate. The condyle was not replaced with any graft. Therefore a functional device was used after surgery to overcome the lack of the condyle and to stimulate the growth of the ramus.

Management of facial asymmetry

Asymmetries of the craniofacial region encompass a multitude of diverse and potentially complex abnormalities that may be the result of numerous causes. The expression and degree of asymmetry for a given condition, although a highly variable process, is the ultimate determinant of the nature of its treatment. This article highlights some of the key features and treatment strategies for various common facial asymmetries.