First-trimester diagnosis of exencephaly by transvaginal ultrasonography.

First-Trimester Echogenic Amniotic Fluid in the Acrania-Anencephaly Sequence

“…In addition, there was absence of cerebral tissue in 1 case, poorly developed brain in 2 cases, and disorganized brain tissue in the remaining 6 cases. Lateral widening of the cerebral hemispheres with a clear depiction of the interhemispheric fissure (the "Mickey Mouse" sign) 10,11 was identified in 3 cases. The diagnosis of acrania was confirmed further by three-dimensional sonography in 2 cases.…”

“…13 Several authors have described the firsttrimester features of acrania in isolated case reports, the spectrum of the disease ranging from almost a normal amount of brain tissue with poorly mineralized calvaria to disorganized brain tissue covered by a thin membrane. 10,12,14 However, in a large first-trimester sonographic screening study at 10 to 14 weeks' gestation, the diagnosis of anencephaly was missed initially in 26% of cases. 4 During audit, it became evident that the main reason for missing the diagnosis was the fact that well-preserved brains were present in several cases (exencephaly), and only the lack of cranial ossification could provide a clue for the diagnosis.…”

Exencephaly in autosomal dominant brachydactyly syndrome

“…Even though unprotected brain tissue exposed to amniotic fluid may atrophy early in pregnancy, some disorganized cerebral tissue may persist throughout the second trimester, which has led to the prenatal diagnosis of exencephaly in about 35 cases (Mannes et al, 1982;Cox et al, 1985;Vergani et al, 1987;Kwon et al, 1991;Bronshtein and Ornoy, 1991;Ekici and Gulmezoglu, 1991;Wilkins-Haug and Freedman, 1991;Yang et al, 1992;Casellas et al, 1993). The diagnosis early in pregnancy, even in the first trimester, is also possible with transvaginal ultrasonography (Kennedy et al, 1990;Nishi and Nakano, 1994). Differential diagnoses include encephalocoele as well as conditions with poor mineralization of the calvarial bones such as osteogenesis imperfecta and hypophosphatasia (Romero et al, 1988;Nyberg and Mack, 1991).…”

Acalvaria and hydrocephalus: a case report and discussion of the literature.

“…19 Support for this idea exists in human literature as well. [20][21][22] For this reason, a fetus that appears by ultrasonography to be without a neurocranium but with tissue consistent with neural tissue echogenicity cannot be automatically excluded as an anencephalic or exencephalic fetus based on the presence of neural tissue alone. However, resolution of cerebral hemispheres with intact ventricles is fairly strong evidence against a forebrain closure defect and should suggest acalvaria.…”