Hydranencephaly with cholestasis and giant hepatitis

Looking at the missing brain: hydranencephaly case series and literature review

Hydranencephaly is a severe congenital condition where most of the cerebral hemispheres are replaced by a membranous sac. Despite the growing amount of case reports, most pathogenic, phenotypic, and prognostic aspects of hydranencephaly remain controversial. By matching the recent literature data with the findings of our own series (four cases: two fetuses at the twelfth gestational week, a 32-year-old man, and a 14-year-old female), we attempted to date back the insult leading to hydranencephaly to understand its pathogenesis and to explain the basis of its protean phenotype. The variable detection of cerebral remnants seems to mirror the developmental pathway of cerebral arteries. Moreover, fetal and postnatal neuroimaging data and histopathologic findings point toward an early bilateral internal carotid artery occlusion, mostly occurring between the eighth and twelfth gestational weeks, as the main pathogenic mechanism of hydranencephaly.

Prenatal stroke

The main focus of this chapter is the comprehensive description of the neuropathology, the imaging correlates and underlying mechanisms of prenatal stroke. We describe established prenatal stroke in subgroups similar to postnatal stroke: arterial (forebrain or hindbrain) infarction, venous thrombosis, primary lobar haemorrhage. This longitudinal classification should facilitate the study of risk factors and mechanisms. Forebrain lesions of arterial type present as porencephaly, (hemi)hydranencephaly, multicystic encephalopathy or schizencephaly. Venous prenatal forebrain stroke presents as simple porencephaly (in some of genetic nature) and sinus thrombosis. A list of rare porencephaly-like conditions is added for differentiation from arterial and venous porencephaly. Hindbrain infarctions (so far the only reported variants seem to be of arterial nature) present as brainstem disconnection, focal brainstem destruction, uni- or bilateral cerebellar destruction and focal spinal cord ischaemia. Prenatal intracranial haemorrhage and congenital brain infection should be considered in the differential diagnosis of prenatal stroke.