Hydrocephalus Associated to Myelomeningocele

Abstract

Myelomeningocele (MM) is a form of dysraphism resulting from defective closure of the posterior portion of the neural tube, during the fourth week of gestation. In the past, it is well known that associated hydrocephalus is present in 80–90% of children with myelomeningoceles (Machado and de Oliveira, Childs Nerv Syst 20:107–109, 2004). Although some more recent papers are showing that this percentage is not so high, we should still expect that the majority of children affected by a myelomeningocele will sooner or later need surgical treatment for associated hydrocephalus. The pathogenesis of the hydrocephalus associated with myelomeningocele has been the subject of an extensive number of studies. The contemporary reduction of the incidence of the Chiari II malfor-mation and of the associated hydrocephalus after closure of the spinal defect in utero is in line with previous studies suggesting a prominent role of the posterior cranial fossa abnormalities, where even the increased venous pressure might be at least mostly a consequence of the constriction of the posterior cranial fossa structures. Pure absorptive abnormalities however coexist, the main ones documented to be abnormal cisternal spaces and peculiar cerebrospinal fluid chemical features. For these reasons, the hydrocephalus associated to myelomeningocele should be considered as a distinct clinical entity.