The authors conducted a study to evaluate the effectiveness of endoscopically guided third ventriculostomy in the pre- and postoperative management of hydrocephalus in pediatric patients who harbored posterior fossa tumors.
Between October 1, 1993, and December 31, 1997, a total of 206 consecutive children with posterior fossa tumors underwent surgery at Hôpital Necker-Enfants Malades in Paris. Ten patients in whom shunts were implanted at the referring hospital were excluded. The medical records and neuroimaging studies obtained in the remaining 196 patients were reviewed. These patients were categorized into three groups: 67 patients with hydrocephalus on admission in whom endoscopically guided third ventriculostomy was performed prior to tumor removal (Group A); 82 patients with hydrocephalus in whom preliminary third ventriculostomy was not performed and who were managed in a “conventional way” (Group B); and 47 patients without ventricular dilation on admission (Group C).
There was no significant difference between Group A and Group B patients with respect to age at presentation, evidence of metastatic disease, degree of tumor resection, or follow up. In the patients in Group A, however, more severe hydrocephalus was present (p < 0.01). Patients in Group C were, in this respect, different from the other two groups.
Ultimately, only four patients (6%) in Group A as compared with 22 patients (27 %) in Group B (p = 0.001) had progressive hydrocephalus requiring treatment following removal of the posterior fossa tumor. Sixteen patients (20%) in Group B underwent insertion of a ventriculoperitoneal shunt, which is similar to the incidence of this procedure reported in the literature and significantly different from that in Group A (p < 0.016). The other six patients in Group B (6%) were treated by endoscopically guided third ventriculostomy after tumor removal. In Group C, two patients (4%) with postoperative hydrocephalus underwent endoscopically guided third ventriculostomy.
In three of the patients who required placement of cerebrospinal fluid shunts several episodes of shunt malfunction occurred; these were ultimately managed by performing endoscopic third ventriculostomy and definitive removal of the shunt.
There were no cases of death and four cases of transient morbidity associated with the ventriculostomy.
Third ventriculostomy is feasible even in the presence of posterior fossa tumors (including brainstem tumors). When performed prior to posterior fossa surgery, it significantly reduces the incidence of postoperative hydrocephalus. Furthermore, it provides a valid alternative to the placement of permanent shunts in cases in which hydrocephalus develops following posterior fossa surgery, and it may negate the need for the shunt in cases in which the shunt malfunctions.
Although the authors acknowledge that the routine application of third ventriculostomy in selected patients may result in a proportion of patients undergoing an “unnecessary” procedure, they believe that because of patients' less complicated postoperative course, the low morbidity rate, and the high success rate of third ventriculostomy, further investigation of this protocol is warranted.