Fetal hydrocephalus often refers to an extension of fetal ventriculomegaly where the ventricular dilatation is more severe. It is usually defined when the fetal lateral ventricular diameter is greater than 15 mm 1.
The estimated incidence is 0.5-3% per 1000 live births. There may be a very slight increased female predilection 10.
It can be either obstructive or non-obstructive and each can arise from a number aetiologies. It a small proportion of cases it carries a familial X-linked inheritance (congenital X linked hydrocephalus).
The vast majority of of conditions are are associated with other intracranial and cranial anomalies 5. The list includes:
- central nervous system anomalies: (more common 6 and reported in more than 80% of cases)
- non central nervous system anomalies
- chromosomal anomalies: may be present in ~20% of cases 10
Will demonstrate enlarged ventricles with variable degrees of parenchymal thinning. The choroid may seen floating within the ventricle giving a dangling choroid sign. Often a separation of more than 3 mm between the choroid plexus and the margin of the ventricle in considered abnormal. In some cases, there may also be evidence of macrocephaly.
Treatment and prognosis
The overall prognosis with depend in the underlying cause and associated anomalies. Some cases can slowly progress during the fetal period. Antenatal shunting has been considered in a small proportion of selected cases 2.
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- 8. Humphreys P, Muzumdar DP, Sly LE et-al. Focal cerebral mantle disruption in fetal hydrocephalus. Pediatr. Neurol. 2007;36 (4): 236-43. doi:10.1016/j.pediatrneurol.2006.12.013 - Pubmed citation
- 9. Nyberg DA, Mack LA, Hirsch J et-al. Fetal hydrocephalus: sonographic detection and clinical significance of associated anomalies. Radiology. 1987;163 (1): 187-91. Radiology (abstract) - Pubmed citation
- 10 .Entezami M, Albig M, Knoll U et-al. Ultrasound Diagnosis of Fetal Anomalies. Thieme. (2003) ISBN:1588902129. Read it at Google Books - Find it at Amazon