Complete Information on Acalvaria With Treatment and Prevention

By: Juliet Cohen

Acalvaria is an uncommon inborn deformity in which the thin bones of the cranial hurdle, duramater and associated muscles are missing but the key anxious structure is normally untouched. The circumstance is often confused by prenatal ultrasonography with anencephaly or an encephalocele. Whereas the cerebral hemispheres are missing in anencephaly, the cranial contents in acalvaria are mostly comprehensive, though some neuropathological irregularity is frequently existing. The presumed pathogenesis of acalvaria is defective migration of the membranous neurocranium with natural arrangement of the immature ectoderm, resulting in absence of the calvaria but an undamaged bed of rind over the mind parenchyma.

Acalvaria may be associated with holoprosencephaly, hydrocephalus and micropolygyria. Cardiac anomalies, omphalocele, hypertelorism, cleft mouth and palate, renal tubular dysgenesis, hexadactyly, club foot and congenital medulloblastoma have been reported. Acalvaria is a postneurulation defect, that is, it results due to faulty migration of the mesenchyme with normal placement of the embryonic ectoderm. There is, thus, an absence of the calvarium but an intact layer of skin over the brain parenchyma. It results because of the primary non-closure of the neural tube or may be a part of a spectrum of anencephaly. Acalvaria has also been described with amniotic bands. The disorder is etiologically and pathogenetically heterogeneous and its prevention by ingestion of folic acid has not been described.

Acalvaria has normally been described as a deadly anomaly and reports are uncommon in the Indian literature. Amniotic band syndrome is an aetiological factor in acalvaria. The diagnosis of acalvaria can be made by the 12th week of gestation by high-resolution ultrasonography. The sono graphic differential diagnosis includes anencephaly, cephalocele, osteogenesis imperfecta and hypophosphatasia. During pregnancy the alpha fetoprotein levels are reported to be very high, while the unconjugated estriol is undetectable. No surgical procedures to correct the skull defect have been reported in the newborn period and infancy. Spontaneous bone growth has been seen in some newborns with scalp defects such as in cutis aplasia. Conservative management with a careful follow-up and bone grafting at school age have been recommended.

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