The role of external ventricular drainage for the management of posterior cranial fossa tumours: a systematic review.

Posterior cranial fossa tumours frequently develop hydrocephalus as first presentation in up to 80% of paediatric patients and 21.4% of adults, although it resolves after tumour removal in 70-90% and 96%, respectively. New onset hydrocephalus is reported in about 2.1% of adult and 10-40% of paediatric patients after posterior fossa surgery. There is no consensus concerning prophylactic external ventricular drainage (EVD) placement that is frequently used before posterior fossa lesion removal, as well in those cases without clear evidence of hydrocephalus. The aim of the study was to define the most correct management for patients who undergo posterior fossa tumour surgery, thus identifying cohorts of patients who are at risk of persistent hydrocephalus prior to surgery. A systematic review of literature has been performed, following PRISMA guidelines. Most of the studies reported CSF shunt only in the presence of hydrocephalus, whereas only a few authors suggested its prophylactic use in the absence of signs of ventricular dilatation. Predictive factors for postoperative hydrocephalus has been identified, including young age (< 3 years), severe symptomatic hydrocephalus at presentation, EVD placement before surgery, FOHR index > 0.46 and Evans index > 0.4, pseudomeningocele, CSF leak and infection. The use of pre-resection CSF shunt in case of signs and symptoms of hydrocephalus is mandatory, although it resolves in the majority of cases. As reported by several studies included in the present review, we suggest CSF shunt also in case of asymptomatic hydrocephalus, whereas it is not indicated without evidence of ventricular dilatation.