Management of hydrocephalus in pediatric patients with posterior fossa tumors: the role of endoscopic third ventriculostomy

Object. The authors undertook a study to evaluate the effectiveness of endo scopic third ventriculostomy in the management of hydrocephalus before and after surgical intervention for posterior fossa tumors in children. Methods. Between October 1, 1993, and December 31, 1997, a total of 206 con secutive children with posterior fossa tumors underwent surgery at Hopital Necker-Enfants Malades in Paris. Excluded were 10 patients in whom shunts h ad been placed at the referring hospital. The medical records and neuroimag ing studies of the remaining 196 patients were reviewed and categorized int o three groups: Group A, 67 patients with hydrocephalus present on admissio n in whom endoscopic third ventriculostomy was performed prior to tumor rem oval; Group B, 82 patients with hydrocephalus who did not undergo prelimina ry third ventriculostomy but instead received conventional treatment; and G roup C, 47 patients in whom no ventricular dilation was present on admissio n. There were no significant differences between patients in Group A or B with respect to the following variables: age at presentation, evidence of metas tatic disease, extent of tumor resection, or follow-up duration. In patient s in Group A, however, more severe hydrocephalus was demonstrated (p < 0.01 ); the patients in Group C were in this respect different from those in the other two groups. Ultimately, there were only four patients (6%) in Group A compared with 22 patients (26.8%) in Group B (p 0.001) in whom progressive hydrocephalus req uired treatment following removal of the posterior fossa tumor. Sixteen pat ients (20%) in Group B underwent insertion of a ventriculoperitoneal shunt, which is similar to the incidence reported in the literature and significa ntly different from that demonstrated in Group A (p < 0.016). The other six patients (7.3%) were treated by endoscopic third ventriculostomy after tum or resection. In Group C, two patients (4.3%) with postoperative hydrocepha lus underwent endoscopic third ventriculostomy. In three patients who required placement of CSF shunts several episodes of shunt malfunction occurred that were ultimately managed by endoscopic third ventriculostomy and definitive removal of the shunt. There were no deaths; however, there were four cases of transient morbidity associated with thir d ventriculostomy. Conclusions. Third ventriculostomy is feasible even in the presence of post erior fossa tumors (including brainstem tumors). When performed prior to po sterior fossa surgery, it significantly reduces the incidence of postoperat ive hydrocephalus. The procedure provides a valid alternative to placement of a permanent shunt in cases in which hydrocephalus develops following pos terior fossa surgery, and it may negate the need for the shunt in cases in which the shunt malfunctions. Furthermore, in patients in whom CSF has caus ed spread of the tumor at presentation, third ventriculostomy allows chemot herapy to be undertaken prior to tumor excision by controlling hydrocephalu s. Although the authors acknowledge that the routine application of third vent riculostomy in selected patients results in a proportion of patients underg oing an "unnecessary" procedure, they believe that because patients' postop erative courses are less complicated and because the incidence of morbidity is low and the success rate is high in those patients with severe hydrocep halus that further investigation of this protocol is warranted.