cyclopia

cyclopia

description

cyclopia is the most severe malformation in the spectrum of holoprosencephaly and consists of a single midline orbit that can be anophthalmic, monophthalmic or synophthalmic, with fusion of the eyes. in less severe forms there may be two separate eyes in a single median orbit, or two separate orbits set very close together in the midface. a proboscis is usually present and located above the orbit. nasal structures are absent. the anterior part of the brain and the mesodermal midline structures are always abnormal in infants with cyclopia or synophthalmia. cyclopia is very rare, and appears to occur preferentially in females. cyclopia and synophthalmia are part of a spectrum of ocular and facial malformations resulting from an abnormality in the development of the forebrain and frontonasal process, leading to holoprosencephaly. the eyes, orbits, and most of the midfacial structures may be absent; the eyes and orbits may be normally formed but closely set and with a single nostril; or the facial malformation may fit into the spectrum in between these extremes. the correlation between face and brain in holoprosencephaly suggests an intimate relationship between the developing prosencephalon and the neural crest cells which give rise to the frontonasal process. variation in severity may occur because of differences in magnitude, timing or susceptibility. chromosomal abnormalities have been found in 36% of all cases, trisomy 13 being the most common.

diagnosis

the finding of microcephaly is a frequent sign occurring in 64% of all cases. the spectrum of anomalies accompanying holoprosencephaly are best appreciated ultrasonographically if several planes are visualised. the sagittal plane evaluates the fetal profile, including forehead, nose, upper and lower lip and mandible. this view is the most useful in identification of a proboscis or absence of nasal structures. a coronal view through facial structures involving both orbits, maxilla and the anterior portion of the mandible in one vertical plane will reveal single, fused or closely spaced orbits, abnormalities of sphenoid and ethmoid bones and the integrity of the nose and lips. a transverse or axial plane slightly caudal to the one commonly applied for determination of the biparietal diameter will evaluate the orbit(s) and upper lip. orbital biometry can be performed in this plane. recently, a new technique of three dimensional ultrasound visualization using surface and volume rendering has been developed. the application of this technology may enhance imaging of the fetal face and resolve some of the difficulties inherent in distinguishing between the malformations of the cyclopia cebocephaly-ethmocephaly-median cleft face spectrum.

differential diagnosis

cyclopia with proboscis should be carefully distinguished from ethmocephaly, where a proboscis is situated between closely spaced eyes. nasal structures are absent. it may be possible to distinguish cyclopia from synophthalmia, although the two malformations, which are closely related, and part of a spectrum of anomalies, are considered together in this section. cyclopia may be associated with astomia-agnathia. this is generally a sporadic event, although chromosomally abnormal siblings have been reported. cyclopia is invariably associated with holoprosencephaly, which may be isolated or syndromal. a search should be made for additional anomalies.

sonographic features

a single midline orbit that can be anophthalmic, monophthalmic or synophthalmic, with fusion of the eyes.

in less severe forms there may be two separate eyes in a single median orbit, or two separate orbits set very close together in the midface.

a proboscis is usually present and located above the orbit.

nasal structures are absent.

the anterior part of the brain and the mesodermal midline structures are always abnormal in infants with cyclopia or synophthalmia.

associated syndromes

  • acalvaria holoprosencephaly-facial dysmorphism
  • agnathia holoprosencephaly-tetramelia
  • aicardi
  • alcohol
  • aqueductal stenosis
  • brachial amelia cleft lip/palate
  • charge association
  • chromosomal
  • craniosynostosis holoprosencephaly
  • diabetes insipidus coloboma-alobar holoprosencephaly
  • ectopia cordis embryonal neoplasms
  • familial, isolated
  • goldenhar
  • grote
  • hartsfield
  • holoprosencephaly-fetal hypokinesia
  • holoprosencephaly-ntd-nerve palsy-deafness
  • hydantoin
  • lambotte
  • lip synechia imperforate anus
  • majewski variant chondrodysplasia
  • martin
  • maternal diabetes
  • meckel-gruber
  • meckel-like (fried)
  • median cleft face other anomalies
  • pallister-hallpseudotrisomy 13
  • steinfeld
  • thomas
  • velo-cardio-facial

references

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