Orbital Hypertelorism

► [Increased interorbital distance]

Like hypotelorism, ocular hypertelorism is a clinical diagnosis. Based on clinical measurements, it is possible to distinguish between primary telecanthus (in which the inner canthi are exceptionally far apart but the outer canthi are normally spaced) and true ocular hypertelorism (in which both inner and outer canthi are far apart and the interpupillary distance is increased) (Cohen 1980).

A mild increase in the interorbital distance occurs as a variant in otherwise normal individuals. A low nasal bridge and epicanthal folds may erroneously suggest the diagnosis of ocular hypertelorism if proper measurements are not obtained. Secondary forms of hypertelorism are seen with midface-ex-panding lesions, such as nasal glioma, fibromas, and chronic nasal polyps. Mild to severe ocular hyper-telorism is seen in a number of well-known or ill-defined syndromes, chromosomal aberrations, bone dysplasias, and malformation associations (Fig. 1.41). Therefore, hypertelorism is a totally nonspecific diagnostic sign.

An increased interorbital distance occurs as one important manifestation of certain craniofacial dys-raphic disorders, with or without frontal or basal en-cephalocele. When the craniofacial cleft is located off the midline (if, for example, it is through the frontal

Fig. 1.41. Hypertelorism in an adult male. Note increased interorbital distance in this individual with an unusual combination of anomalies, including brachycephalosyndactyly with ptosis, cataract, colobomas, and linear areas of skin depigmentation. [The case has already been published by Mingarelli et al. (1999), but this picture has not been published previously]

Fig. 1.41. Hypertelorism in an adult male. Note increased interorbital distance in this individual with an unusual combination of anomalies, including brachycephalosyndactyly with ptosis, cataract, colobomas, and linear areas of skin depigmentation. [The case has already been published by Mingarelli et al. (1999), but this picture has not been published previously]

process of the maxilla or between the maxilla and the nasal bone on one side) unilateral hypertelorism is observed (the involved orbit is set apart and may be variably rotated, whereas the unaffected orbit is normally positioned) (Tessier 1976). One remarkable example of median clefting syndrome is frontonasal dysplasia (median facial cleft syndrome, OMIM 136760), a condition consisting in hypertelorism, broad nasal root, lack of nasal tip, widow's peak, and anterior cranium bifidum occultum frontalis (Fig. 1.42a, b). Associated defects may include midline clefting of nose and upper lip, occasionally with involvement of the palate, and defects of the alae nasi (DeMyer 1967; Sedano et al. 1970). It is now considered to be an example of developmental field defect, caused primarily by failure of the nasal capsule to develop properly and subsequent filling of the empty space by the primitive brain vesicle, with resultant cranium bifidum occultum (Sedano and Gorlin 1988). The X-linked dominant cranio-fronto-nasal syndrome (OMIM 304110) consists in frontonasal malformation, craniosynostosis (especially involving

Fig. 1.42 a,b. Frontonasal malformation in a 10-month-old senting a flattened frontonasal encephalocele. Observe severe baby girl. There is a wide midline defect in the frontal bones hypertelorism. Congenital hydrocephalus was also present (anterior cranium bifidum) and bulging of the forehead, repre-

Fig. 1.42 a,b. Frontonasal malformation in a 10-month-old senting a flattened frontonasal encephalocele. Observe severe baby girl. There is a wide midline defect in the frontal bones hypertelorism. Congenital hydrocephalus was also present (anterior cranium bifidum) and bulging of the forehead, repre-

the coronal sutures), and various skeletal and soft tissue abnormalities, including prominent scapulae, small or absent clavicles, vertebral anomalies, and pectus excavatum (Cohen 1979). Uniquely for an X-linked dominant disorder, females are affected more frequently and severely than males, who usually have only hypertelorism and exotropia (Grutzner and Gorlin 1988). Most affected males represent new mutations. Craniofacial features include brachycephaly, unilateral or bilateral coronal synostosis (50%), frontal bossing, hypertelorism (95%), facial asymmetry, broad nasal root, and bifid nasal tip (55%). The orbits are asymmetrical in 50 % of cases. Additional features reported have included high-arched palate, malocclusion, pterygium colli, strabismus, and down-slanting palpebral fissures (Michels et al. 1989; Morris et al. 1987; Orr et al. 1997). Limb manifestations consist of splitting of nails (40%), broad great toes, partial syndactyly of fingers and toes, hy-perextensible joints, short 5th fingers, clinodactyly, and asymmetrical shortening of lower limbs (15%) (Saavedra et al. 1996). The differential diagnoses include frontonasal dysplasia, acro-fronto-facio-nasal dysostosis, Greig cephalopolysyndactyly syndrome (OMIM 175700), and other craniosynostosis syndromes. Teebi hypertelorism syndrome (brachy-cephalofrontonasal dysplasia, OMIM 145420), an au tosomal dominant condition with features of cran-iofrontal dysplasia (prominent forehead, widow's peak, marked hypertelorism, broad nasal bridge) also bears similarities with the cranio-fronto-nasal syndrome, but does not involve bifid nasal tip, craniosynostosis, or nail abnormalities (Teebi 1987). The disorder is also similar in some ways to Aarskog syndrome, but hypertelorism is more severe and short stature and joint laxity do not occur. Acro-fronto-fa-cio-nasal dysostosis (OMIM 201180) consists in bilateral cleft lip-palate, brachycephaly, hypertelorism, broad notched nasal tip, macrostomia, widow's peak, S-shaped palpebral fissures, mental retardation, and a constellation of limb anomalies, including occasional postaxial polysyndactyly of hands, brachy-metacarpalia, brachytelephalangia, camptodactyly, carpal fusion, fibular hypoplasia, short legs, iliac hy-poplasia, and talipes equinovarus (Richieri-Costa et al. 1985). Parental consanguinity suggests an autosomal recessive inheritance. Juberg-Hayward syndrome (OMIM 216100) is characterized by cleft lip/palate, microcephaly, hypertelorism, and thumb hypo-/apla-sia or proximal/distal thumb displacement (Juberg and Hayward 1969). Facial defects can range from the forme fruste of cleft lip to unilateral cleft lip/palate and cleft palate without cleft lip (Silengo and Tornet-ta 2000). Additional features are luxation of the radi-

al head, motion restriction at the elbow, minor vertebral and rib anomalies, horseshoe kidneys, mental retardation, anterior anal displacement, and ptosis (Verloes et al. 1992).

Was this article helpful?

0 0
Hearing Aids Inside Out

Hearing Aids Inside Out

Have you recently experienced hearing loss? Most probably you need hearing aids, but don't know much about them. To learn everything you need to know about hearing aids, read the eBook, Hearing Aids Inside Out. The book comprises 113 pages of excellent content utterly free of technical jargon, written in simple language, and in a flowing style that can easily be read and understood by all.

Get My Free Ebook


Post a comment