RESUMO
Arhinia is a rare congenital malformation characterized by lack of the formation of external and internal nasal structures. Restricted midfacial growth is secondary to the loss of the midfacial growth centers. Staged reconstruction of the nasal passage and external nose is required. Vertical distraction osteogenesis is a beneficial step in the overall reconstructive program. This provides for additional bone and soft tissue for both improved aesthetic facial proportions and later surgical interventions.
Assuntos
Ossos Faciais/cirurgia , Nariz/anormalidades , Osteogênese por Distração , Pré-Escolar , Ossos Faciais/anormalidades , Ossos Faciais/diagnóstico por imagem , Humanos , Imageamento Tridimensional , Aparelho Lacrimal/anormalidades , Masculino , Maxila/cirurgia , Seio Maxilar/anormalidades , Nariz/diagnóstico por imagem , Órbita/anormalidades , Osteotomia de Le Fort , Tomografia Computadorizada por Raios XRESUMO
Although the combination of radiation and tissue expansion has been associated with a significant rate of complications, the specific pathophysiology has yet to be clearly elucidated. The objective of this study was to develop a model to identify and examine specific histologic changes associated with tissue expansion and irradiation. Rectangular 50-cc silicone tissue expanders were placed subcutaneously over the midline dorsum of 18 adult New Zealand white rabbits. Preoperative radiographic dosimetry demonstrated that the radiation portal was away from vital intraabdominal structures. The expanders were inflated with 10 cc of saline every other day for a total of 80 cc. Expanders were left in place for 2 to 3 weeks to allow fibrovascular capsule formation. The rabbits were then divided into three groups (six rabbits per group), each receiving one of three nonfractionated doses of radiation (20, 25, or 35 Gy). Half of the expanded skin was irradiated using a single dose, and the other half served as a nonirradiated control. Capsules and skin were harvested 6 weeks after the delivery of radiation, allowing the beginning of chronic radiation changes to occur. Using hematoxylin and eosin staining, histomorphometric analysis was performed. The data were analyzed using Student's test. Although irradiation did not affect dermal thickness, it did cause a statistically significant increase in epidermal thickness. At 20, 25, and 35 Gy the increase in epidermal thickness was 43, 90, and 130 percent, respectively. Although significant epidermal changes could be identified, capsular and dermal alterations were not evident. Further studies evaluating the long-term effects of alterations in capsular formation caused by radiation may be required.