Cyclopia: a case study and review

ABSTRACT

A neonatal, human female cyclopic specimen, with brain exhibiting lobar holoprosencephaly was examined by detailed anatomical dissection. In addition to the pachygyric appearance of the cerebrum, the diencephalon failed to attain its normal position in relation to the cerebral hemispheres. The ethmoid bone was the focal point of skull malformations. Possible mechanisms for the generation of the malformations are discussed. Cyclopia is a monostrity that combines lack of separation of the eyes with lack of cleavage of the prosencephalon. The resulting undivided telencephion with a single ventricular cavity was called a holosphere[1] in contrast to the normal hemispheres with symmetrical lateral ventricles. The term holoprosencephaly, which is widely used now-a days to indicate impaired midline cleavage of the embryonic forebrain, is commonly associated with various gradations of facial dysmorphism including cyclopia, ethmocephaly and cebocephaly. According to its severity, holoprosencephaly has been graded into alobar, semilobar or lobar[2]. In cyclopia, a blind-ended proboscis usually occurs above the eye. In some instance, the proboscis may be absent[3]. In cyclopia, the anterior cranial base has been described as being shortened, roofing a medially placed orbital cavity. The ethmoid and the middle portion of the sphenoid are said to be absent. Also described as missing are the nasal bone, turbinates, vomer, lacrimal bones and premaxilla[4]. The present study examines in detail the gross anatomical abnormalities in a case of cyclopia. Special attention was made to the brain and eyes