Department of Pathology, University of Oklahoma Health Sciences Center

NeuroTest Question #11 Next question Previous question

Click thumbnail to see picture.

Answer: A (Amnion rupture sequence) Level of difficulty: 4 NeuroTest NeuroLearn NeuroHelp

Discussion: 

• Amnion rupture sequence: This is an umbrella term that covers three very similar but overlapping conditions namely amniotic band syndrome, amniotic adhesion sequence, and limb-body wall complex. They are probably disruptive sequences secondary to vascular disruption or tissue necrosis and adhesion. The spectrum of pathology includes encephalocele and defects of cranium, cleft palates and other facial abnormalities, autoamputation of digits and limbs, and body wall defects with anomalies of internal organs. The brain is usually normal but cases with developmental abnormalities have also been reported. Karyotypes of affected individuals are normal. In this particular case, it is probably an amniotic adhesion sequence which is characterized by part of the fetus, usually the head, adhering to the placenta.
• Anton syndrome is produced by bilateral infarction of the visual cortex. It is often resulted from bilateral obstruction of the posterior cerebral artery. Typically, the patient does not realize that they could not see.
• Caudal Regression Syndrome (sacral agenesis): The caudal regression syndrome is a variable defect of lumbar vertebrae, sacrum, and coccyx. This is a severe developmental field defect of the posterior axis caudal blastema. The severest form is sirenomelia (mermaid syndrome). It is frequently associated with abnormalities of the anorectal and urogenital systems and lower limbs. The entire urinary tract can be absent. The pathogenesis is probably related to the failure of growth of the caudal eminence. The strongest association of caudal regression is with maternal diabetes, it has also been related to deletion of chromosome 7q, autosomal dominant and, probably, autosomal recessive transmission. 
• Both Down syndrome and fetal alcohol syndrome are associated with characteristic facial characteristic but not adhesion of the fetus to the placenta.
• Fetal alcohol syndrome: Fetal alcohol syndrome is resulted from the teratogenic effects of alcohol on human fetuses secondary to in utero exposure. The classic cases have the clinical triad of growth retardation, characteristic facial dysmorphology and dysfunction of the central nervous system (CNS). The degree of involvement is highly variable. Dysfunctions of the CNS include mental retardation in 85% of patients, irritability and poor suck in the newborn period, hypotonia, hypertonia, seizures and hyperactivity. In Fetal alcohol syndrome (FAS), patients must have all three chraracteristics, namely, prenatal and postnatal growth retardation (<2 SD for length and weight), characteristic facial features, and CNS dysfunction. When the features of the syndrome are not fully expressed, the term fetal alcohol effects (FAE) can be used. Characteristic morphological abnormalities of FAS include the followings:

• Growth retardation: Patients remained more than 2 standard deviations below the norm. Some patients may have postnatal catch-up growth.

• Characteristic facial features: The facial features are mainly hypoplastic in nature. These features include short palpebral fissures, maxillary hypoplasia with relative prognathism, epicanthal folds, thinning of vermilion border and hypoplastic upper lip, low nasal bridge and anteverted nostrils, hypoplastic upper helix, and apparent hypertelorism due to short palpebral fissure (blepharophimosis).

• CNS malformations include microcephaly and malformations of the brain, particularly those of abnormal neuronal migration in nature.

Comment: KarMing-Fung@ouhsc.edu