Intrauterine high-resolution magnetic resonance imaging in fetal hydrocephalus and prenatal estimation of postnatal outcomes with "perspective classification"

Abstract

Object: It is possible to diagnose hydrocephalus prenatally based on the morphological appearance of the fetus on neurodiagnostic images; however, the prognosis of this disease shows wide variation. The authors previously proposed a classification system for the prediction of postnatal outcome based on progression of hydrocephalus and affected brain development, known as the "Perspective Classification of Congenital Hydrocephalus (PCCH)." In this study the authors have used their classification system to analyze long-term follow-up results obtained in each clinicoembryological stage of fetal hydrocephalus.

Methods: Sixty-one fetuses with hydrocephalus were examined to predict postnatal outcome by using this newly developed classification. The authors' recently developed method of using heavily T2-weighted imaging with a superconducting magnet clearly delineated the cerebrospinal fluid (CSF) space and the malformed brain and spinal cord. Imaging was achieved in less than 1 second per slice and required no sedation of the fetus. The technique appears to be simple and good at delineating intrauterine anatomy. Hydrocephalus was diagnosed in two fetuses at PCCH embryological Stage I (8-21 gestational weeks), in 28 fetuses at Stage II (22-31 weeks), and in 31 fetuses at Stage III (32-40 weeks). Among these 61 fetuses, clinicopathological typing showed that 19 had primary hydrocephalus (nine in Stage II and 10 in Stage III), 34 had dysgenetic hydrocephalus (two in Stage I, 16 in Stage II, and 16 in Stage III), and eight had secondary hydrocephalus (three in Stage II and five in Stage III). When the hydrocephalic state developed during PCCH Stage I or II, the prognosis was very poor, and only one of 18 fetuses with dysgenetic hydrocephalus and none of three fetuses with secondary hydrocephalus had an acceptable postnatal outcome. Even within the same category or subtype of fetal hydrocephalus, such as primary hydrocephalus in its simple form, or hydrocephalus with spina bifida aperta (myeloschisis), the postnatal outcomes differed depending on the time of onset of hydrocephalus. When the diagnosis of hydrocephalus was made during PCCH Stage II, the fetuses had a poorer postnatal outcome compared with those at Stage III (p < 0.05).

Conclusions: It is emphasized that postnatal prognosis is not simply a function of the form of the diagnosis but is also dependent on the progression of hydrocephalus and the degree to which that process affects neuronal development. Early decompressive procedures, conventionally performed after but, hopefully, performed before birth, are indicated to obtain the optimal postnatal prognosis of fetuses with hydrocephalus diagnosed at PCCH Stage II.