Iniencephaly

Iniencephaly is a rare form of neural tube defect in which a malformation of the cervico-occipital junction is associated with a malformation of the central nervous system.

Epidemiology

Incidence is estimated at between 1/1,000 and 1/100,000 live births, depending on the geographical area, and more female infants are affected (male:female sex ratio: 1:3 to 1:9).

Clinical description

The cardinal features are occipital bone defect, partial or total absence of cervicothoracic vertebrae, fetal retroflexion of the head and characteristic absence of the neck. It is associated with malformations of the central nervous (spina bifida and/or anencephaly), gastrointestinal (omphalocele) and cardiovascular systems.

Etiology

As with other neural tube defects, it is thought to be of multifactorial origin.

Antenatal diagnosis

Antenatal diagnosis is possible by ultrasonographic monitoring.

Prognosis

Prognosis is poor and iniencephaly is almost always lethal.