Contents
Uncommon and heterogeneous congenital disorder caused by entrapment of fetal parts by fibrous amniotic bands, causing distinctive structural abnormalities involving limbs, trunk, and craniofacial regions.
History:
Amniotic deformity, adhesion, and mutilation (ADAM) sequence, acronym used by Hermann and Opitz in the 1974 is a heterogeneous condition, with a broad spectrum of anomalies, where intrinsic causes, as defect of germ plasm, vascular disruption and disturbance of threshold boundaries of morphogens during early gastrulation, alternate with extrinsic causes as amniotic band rupture to explain the condition.
Pathophysiology
Intrinsic model (Streeter,1930):
Existence of an early embryo lesion with alterations of the germinal disc that would produce an inflammatory response of the adjacent amnions and that would then develop a fibrous band.
Extrinsic model (Torpin, 1968): More accepted
Disruption of the amnion initiates a cascade of secondary events that cause ABS- the amniotic fluid and the fetus exit the amniotic cavity and come to lie within the chorion, transient oligoamnios occurs and from the chorionic side of the amnion multiple mesodermic strands emanate that entangle the fetal parts. These strands can cause anomalies by malformation, deformation or disruption.
Clinical features
ABS can cause malformations that range from mild deformities to severe anomalies that are incompatible with life.
Limb defects:
- Focal constrictions (may occur with distal lymphoedema)
- Amputations
- Psuedosyndactyly
- Brachydactyly
Craniofacial anomalies:
- Acalvaria, acrania
- Asymmetric encephalocoele
- Asymmetric microphthalmia
- Severe nasal deformity
- Non-embryological facial clefting
