Hydrocephalus and Vestibular Schwannomas: Considerations about the Impact of Gamma Knife Radiosurgery

Abstract

Hydrocephalus may occur at various stages of the natural course of vestibular schwannoma and can also be diagnosed after the therapeutic procedure. The aim of the present study was to analyze the impact of Gamma Knife radiosurgery (GKR) on previously diagnosed hydrocephalus (group A patients) and to evaluate the incidence of de novo hydrocephalus after GKR (group B patients). We reviewed retrospectively our case material and the data from the literature. Among the first 1,000 vestibular schwannoma patients treated by GKR in our institution, 30 patients (3%) belonged to group A and 1% to group B. In both groups, hydrocephalus was more often associated with the following data: Elderly, large tumor, previous MS, NF2 disease and bilateral tumors. Cerebrospinal fluid (CSF) shunting system was needed in 25% of the group A and in all of the group B patients. In this latter group, CSF shunting was justified by poor clinical tolerance, and the mean interval between GKR and CSF shunting was 14.8 months (range: 4-31 months). These data suggest that GKR does not decompensate the majority of preexisting radiological hydrocephalus. De novo post-GKR hydrocephalus is of low incidence, comparable to the postoperative rate. Generally, it comes early after GKR and justifies CSF shunting. Thus, it may be postulated that in a small subgroup of patients, GKR may disturb the normal hydrodynamic pathway. Mechanisms of such event remain controversial.

Gamma Knife Radiosurgery for the Vestibular Schwannomas, Technical Considerations and Hydrocephalus as a Complication

“…It has been reported that both gamma knife radiosurgery and microsurgery can contribute to the development or aggravation of hydrocephalus (Fukuda et al, 2007;Roche et al, 2008). However, the mechanism that is associated with the development of hydrocephalus following gamma knife radiosurgery is not known.…”

“…Several authors have reported treatment strategies for hydrocephalus before microsurgery or gamma knife radiosurgery (Atlas, et al, 1996;Fukuda, et al, 2007;Roche, et al, 2008). With respect to microsurgery, several investigators preferred a wait-and-see-approach and therefore focused only on the surgery for the tumour.…”

Communicating Hydrocephalus after Gamma Knife Radiosurgery for Vestibular Schwannoma: An MR Imaging Study

“…1,2 Although it has been reported that gamma knife radiosurgery may contribute to the development of hydrocephalus, a causal relationship has not been established and remains controversial. [1][2][3][4][5][6][7] The time course of events in this case suggests a contributory role of gamma knife treatment in the development or exacerbation of hydrocephalus. Indeed, in the few reported cases in which a time line is documented, the time course of events is similar, with hydrocephalus developing 4 to 18 months after radiosurgery.…”

Hydrocephalies and Vestibular Schwannoma of Great Size: Therapeutic Strategies: About a Series of 32 Cases

“…Studies have shown a high correlation between the presence of hydrocephalus and the size of schwannoma, the concentration of CSF proteins and the duration of disease [6] [9] [10]. They reveal that a prolonged duration of the disease and a high level of protein in the CSF secondary to the presence of the tumor in elderly patients contribute to the formation of communicating hydrocephalus [11].…”

“…The presence of schwannoma outside the blood-brain barrier allows blood proteins to pass through the cleft and interendothelial junctions of the tumor to the surrounding CSF [12]. Communicating hydrocephalus is thought to be predominant in older SV carriers [10] [16]. We will simply say that the presence of the neuroma is a predisposing factor to hydrocephalus whatever the age.…”