[Hemifacial microsomia. Embryological and clinical approach]

Hemifacial microsomia is an otomandibular dysplasia which includes congenital malformations affecting the jaw and ear apparatus. The knowledge of normal embryonic development is a prerequisite for optimal clinical management of those malformations. The development of craniofacial structures is a multi-step process, which involves many developmental events ranging from the migration of neural crest cells from the neural folds of the young neurula embryo to molecular signaling interactions that coordinate outgrowth and patterning of the facial primordia. Our current knowledge of craniofacial development is limited, but the use of animal developmental models will contribute significantly to our understanding of human otomandibular dysplasias. In this review we discuss both the classical and current aspects of otomandibular development. A clinical approach to hemifacial microsomia is proposed. Current pathogenetic hypotheses of hemifacial microsomia and also mandibulofacial dysostosis are reviewed.