Hypertelorism

Hypertelorism refers to an abnormal increase in distance between any two organs although some authors use the term synonymously with orbital hypertelorism meaning an abnormal increase in distance between the two eyes. The article mainly focuses on the latter. The abnormality is similar to telecanthus which means an increased distance distance between the medial canthi of the eyelids.

Pathology

Over development of the lesser wings of the sphenoid bone may be an undelying factor.

Associations

While it can as an isolated anomaly, there are numerous syndromic as well as non syndromic associations with orbital hypertelorism which include

• aneuploidic syndromic
  • trisomy 21
  • trisomy 13
  • monosomy X - Turner syndrome
• non aneuploidic syndromic
  • Aarskog syndrome
  • Apert syndrome ¹
  • Crouzon syndrome ¹
  • DiGeorge syndrome
  • Ehlers-Danlos syndrome
  • frontonasal dysplasia
  • Greig syndrome
  • Gorlin syndrome
  • LEOPARD syndrome
  • Loeys-Dietz syndrome (LDS) ²
  • mucopolysaccharidoses
    • Morquio syndrome
  • Neu-Laxova syndrome (NLS)
  • Noonan syndrome ⁵
  • Saethre-Chotzen syndrome ⁶
  • Sotos syndrome
  • Weaver syndrome
  • Wolf-Hirschhorn syndrome
• non syndromic
  • agenesis of the corpus callosum ^ref
  • autosomal recessive osteopetrosis ⁷
  • congenital dacrocystocoeles ⁴
  • hypospadia(s) ³
  • naso ethmoidal encephalocoele / frontal encephalocoele

There are many more associations other than those mentioned on this list. Please add and / or reference as appropriate :)

Radiographic assessment

Antenatal ultrasound

It is can be assesssed by measuring the distance between the lateral orbital walls or the medial orbital walls. The interocular distance / diameter (IOD) and the biocular diameter (BOD) are both typically increased with hypertelorism.

Due to its associations with other conditions, a detailed sonographic surveillence for other fetal anomalies are recommended if hypertelorism is seen on ultrasound.

Some indices used include

• orbital angle index : a value greater than 42 is suggestive of orbital hypertelorism
• interorbital - orbital index : a value greater than 8 is suggestive of orbital hypertelorism

See also

• hypotelorism