Childhood hydrocephalus secondary to posterior fossa tumor is both an intra- and extraaxial process

Abstract

<jats:sec> <jats:title>OBJECTIVE</jats:title> <jats:p>Ventricular dilation secondary to tumor obstruction of the posterior fossa CSF outflow in childhood is an intraaxial process. However, third ventriculostomy or complete tumor removal often fails to reduce the pressure in some children, and in others there is a delayed reduction in intracranial pressure; this is termed the adaptation period. The cause of this adaptation period has not been studied. Venous sinus compression is highly correlated with other forms of childhood hydrocephalus, and this study seeks to follow the changes that occur in sinus cross-sectional area after surgery.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>Twelve children with posterior fossa tumors underwent MRI examination that included standard T2-weighted and 3D contrast-enhanced images obtained preoperatively, in the immediate postoperative period, and after several months. The volumes of the lateral and third ventricles and the minimum cross-sectional area of the transverse and sigmoid sinuses were measured. Patients were categorized by 1) shunt status (those who required a shunt vs those who did not) and 2) by age (those younger than 3 years vs those older than 3 years at diagnosis).</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>There was a significant reduction in ventricular volume in both the immediate and secondary follow-up periods for all patients. There was preoperative venous sinus compression in all groups, which did not change significantly in the immediate postoperative period but did improve in the secondary follow-up period. The younger children had larger ventricles and smaller sinuses before surgery compared with the older children.</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>In children with obstructed hydrocephalus caused by tumor, there is secondary compression of venous outflow, indicating both an intra- and extraaxial process. The expansion of the sinuses following decompression of the posterior fossa is delayed and may correlate with the adaptation period. Younger children have greater sinus compression than older ones.</jats:p></jats:sec>

The incidence of significant venous sinus stenosis and cerebral hyperemia in childhood hydrocephalus: prognostic value with regards to differentiating active from compensated disease

“…The findings in external hydrocephalus are similar to a previous study, where 3/6 children had venous stenosis [12]. The findings in obstructed hydrocephalus also mirror previous findings [11,15] i.e. that a significant outflow stenosis rather than a presumed increase in CSF outflow resistance secondary to aqueduct occlusion predominates.…”

“…Using the current methodology 11/17 or 65% had a significant outflow stenosis and 2/17 or 12% a non-significant stenosis. Twelve of these 17 patients (who had venous sinus stenosis) were the subject of a prior publication [15] and these were excluded to limit literature duplication. The clinical findings and follow-up for these patients can be found in this publication [15].…”

“…Twelve of these 17 patients (who had venous sinus stenosis) were the subject of a prior publication [15] and these were excluded to limit literature duplication. The clinical findings and follow-up for these patients can be found in this publication [15]. There were 6 infants aged between 7 and 48 days with hydrocephalus (all of whom had high grade venous sinus stenosis) but they could not be included due to the lack of available controls in such a young cohort.…”

Risk factors for hydrocephalus following fourth ventricle tumor surgery: A retrospective analysis of 121 patients

“…Previous studies have shown that younger patients with posterior fossa are at higher risk for the development of persistent hydrocephalus. [3,4,15,21,22] Bognar et al [3] and Kumar et al [21] have demonstrated that age< 3 years at tumor surgery is a significant predictor of postoperative CSF diversion. This might be explained by the finding that the younger patient with…”

Hydrocephalus in a patient with an unruptured pial arteriovenous fistula: hydrodynamic considerations, endovascular treatment, and clinical course

“…The exact mechanism, like in the pial AVF, is unclear. 5,22 In this case, the arteriovenous shunt was considered the cause of hydrocephalus, and therapeutic embolization was planned. We speculate that excessive intracranial venous pressure can affect the paravascular pathway secondary to an inverted hydrodynamic flow.…”