Intraparenchymal ventricular diverticula in chronic obstructive hydrocephalus: prevalence, imaging features and evolution

Expanding Ventricular Diverticulum Overlying the Cerebral Hemisphere through an Open-Lip Schizencephalic Cleft: A Report of Two Pediatric Cases

INTRODUCTION

Open-lip-type schizencephaly is characterized by trans-cerebral clefts filled with cerebrospinal fluid (CSF) between the subarachnoid space at the hemisphere surface and the lateral ventricles. Disorders related to CSF retention, including hydrocephalus and arachnoid cysts, have reportedly been associated with open-lip schizencephaly and have induced intracranial hypertension in some cases. However, detailed neuroimaging and surgical treatment findings have rarely been described.

CASE PRESENTATION

We report 2 cases of open-lip schizencephaly with an expanding CSF-filled cavity overlying the ipsilateral cerebral hemisphere that manifested as signs of intracranial hypertension. Detailed three-dimensional heavily T2-weighted imaging revealed thin borders between the CSF-filled cavity and the subarachnoid space, but no separating structures between the cavity and the lateral ventricle, suggesting that the cavity was directly connected to the lateral ventricle through the schizencephalic cleft but not to the subarachnoid space. Neuroendoscopic observation in case 1 confirmed this finding. Endoscopic fenestration of the cavity to the prepontine cistern was ineffective in case 1. Shunting between the lateral ventricle (case 1) or CSF-filled cavity (case 2) and the peritoneal cavity slightly decreased the size of the CSF-filled cavity.

DISCUSSION

We speculate that the thin borders along the margin of the CSF-filled cavity are membranes that previously covered the schizencephalic cleft and are now pushed peripherally. In addition, we believe that the cavity is a ventricular diverticulum protruding through the cleft and that shunting operation is effective against such expanding cavity. Detailed magnetic resonance imaging can be useful for evaluating patients with schizencephaly associated with CSF retention disorders.

Ventricular pseudodiverticula from intraparenchymal cerebrospinal fluid dissection secondary to high-grade obstructive hydrocephalus in children: magnetic resonance imaging findings

We report on a series of three children who presented with a focal cerebrospinal fluid collection within the periventricular white matter of the temporal and occipital lobes in the setting of high-grade obstructive hydrocephalus. Magnetic resonance imaging showed a focal defect within the ventricular wall associated with leakage of cerebrospinal fluid into the adjacent white matter. The white matter tracts appeared primarily displaced. This entity should be referred to as ventricular pseudodiverticulum, not lined by ependymal cells, in contrast to a true ventricular diverticulum in which the cerebrospinal fluid is contained by a focal outpouching of the intact ventricular wall lined by a dilated and prolapsed layer of ependymal cells. Correct interpretation and classification of the findings may be helpful in predicting prognosis and outcome.

Transependymal Cerebrospinal Fluid Flow: Opportunity for Drug Delivery?

Drug delivery to the central nervous system (CNS) is complicated by the blood-brain barrier. As a result, many agents that are found to be potentially effective at their site of action cannot be sufficiently or effectively delivered to the CNS and therefore have been discarded and not developed further for clinical use, leaving many CNS diseases untreated. One way to overcome this obstacle is intracerebroventricular (ICV) delivery of the therapeutics directly to cerebrospinal fluid (CSF). Recent experimental and clinical findings reveal that CSF flows from the ventricles throughout the parenchyma towards the subarachnoid space also named minor CSF pathway, while earlier, it was suggested that only in pathological conditions such as hydrocephalus this form of CSF flow occurs. This transependymal flow of CSF provides a route to distribute ICV-infused drugs throughout the brain. More insight on transependymal CSF flow will direct more rational to ICV drug delivery and broaden its clinical indications in managing CNS diseases.