Craniorachisis totalis: a rare neural malformation

Abstract

Nowadays, neural tube defects (NTDs - encephalomyelodysraphies) are a growing entity in developing countries. The spectrum for this group of malformations ranges from "benevolent" entities (occult spinal dysraphisms), to alterations incompatible with life for the carrier (anencephaly with exencephaly).^1-5 These defects usually have a multifactorial origin (environmental, genetic, among others).^1-3

The embryological process of formation of the neural tube begins on the 18th day of gestation; during this period the neural plate invaginates on its longitudinal axis, which originates the neural groove with its corresponding folds on both sides. Around week three of gestation, the folds begin their fusion to give rise to the neural tube, during days 21-23 approximately.^6,7 This fusion occurs irregularly, starting from the fourth somite and continues in both directions. As a result, the neural tube is totally or partially open at the ends during different stages and maintains communication with the amniotic cavity. The rostral end or anterior neuropore (cranial orifice) undergoes closure around day 24-25 of intrauterine life, with subsequent closure of the lumbar opening (posterior neuropore) around the end of week four (days 26-27, approximately); these processes are known as primary and secondary neurulation, respectively.^6-8

NTDs are divided into cephalic and lumbar defects, and can be open or closed; however, there is a neural tube malformation whose magnitude is total, that is, that presents with encephalic absence in conjunction with spina bifida, which generally presents in an open form, which is called craniorachischisis.^2,6 The incidence for this defect is currently unknown and is the rarest form of NTD, which is incompatible with life.²