Hypertelorism is an abnormally increased distance between two organs or bodily parts, usually referring to an increased distance between the orbits (eyes), or orbital hypertelorism. In this condition the distance between the inner eye corners as well as the distance between the pupils is greater than normal. Hypertelorism should not be confused with telecanthus, in which the distance between the inner eye corners is increased but the distances between the outer eye corners and the pupils remain unchanged.Hypertelorism is a symptom in a variety of syndromes, including Edwards syndrome (trisomy 18), 1q21.1 duplication syndrome, basal cell nevus syndrome, DiGeorge syndrome and Loeys–Dietz syndrome. Hypertelorism can also be seen in Apert syndrome, Autism spectrum disorder, craniofrontonasal dysplasia, Noonan syndrome, neurofibromatosis, LEOPARD syndrome, Crouzon syndrome, Wolf–Hirschhorn syndrome, Andersen–Tawil syndrome, Waardenburg syndrome and cri du chat syndrome, along with piebaldism, prominent inner third of the eyebrows, irises of different color, spondyloepiphyseal dysplasia, mucopolysaccharide metabolism disorders (Morquio syndrome and Hurlers syndrome), deafness and also in hypothyroidism. Some links have been found between hypertelorism and attention deficit hyperactivity disorder. Embryology
Because hypertelorism is an anatomic condition associated with a heterogeneous group of congenital disorders, it is believed that the underlying mechanism of hypertelorism is also heterogeneous.
Theories include too early ossification of the lower wings of the sphenoid, an increased space between the orbita, due to increasing width of the ethmoid sinuses, field defects during the development, a nasal capsule that fails to form, leading to a failure in normal medial orbital migration and also a disturbance in the formation of the cranial base, which can be seen in syndromes like Apert and Crouzon. Treatment
The craniofacial surgery to correct hypertelorism is usually done between five and eight years of age. This aesthetic-focused procedure addresses the psychosocial aspects in the childs early school years. Another reason for a correction age of five years or older is that the surgery should be delayed until the tooth buds have grown out low enough into the maxilla, thus preventing damage to them. Also, before age five the craniofacial bones are thin and fragile, which can make surgical correction difficult. In addition, it is possible that orbital surgery during infancy may inhibit midface growth.For the treatment of hypertelorism there are two main operative options: The box osteotomy and the facial bipartition (also referred to as median fasciotomy). Box osteotomy
This treatment of orbital hypertelorism was first performed by Paul Tessier. The surgery starts off by various osteotomies that separate the entire bony part of the orbit from the skull and surrounding facial bones. One of the osteotomies consists of removing the bone between the orbits. The orbits are then mobilized and brought towards each other.