Hydrocephalus and occipital encephaloceles: presentation of a series and review of the literature.

Introduction: Encephaloceles are rare congenital malformations of the central nervous system in which brain tissue is extruded from a defect in the skull. Hydrocephalus can occur in 60 to 90% of patients with posterior encephaloceles when compared to other types of this malformation. This article aims to present a series of posterior encephaloceles and its association with hydrocephalus as well as promote a review of the pertinent literature.

Material And Methods: A retrospective study of our series based on hospital charts of 50 patients with posterior encephaloceles was performed. Data on sex, location of encephalocele, presence of associated malformations, presence of neural tissue within the malformation, presence of hydrocephalus and microcephaly were recorded.

Results: There were 29 females and 21 males. There were 25 (50%) supratorcular, 8 (16%) torcular, and 17 (34%) infratorcular lesions. Mean age of encephalocele primary repair was 8 days (range 2-120 days). Hydrocephalus was diagnosed in 25 (50%) of the cases. Ventriculoperitoneal shunt was inserted in 24 patients. The mean age at VP shunt insertion was 1.3 months (range 0.3-9 months). Endoscopic third ventriculostomy was successfully performed in one patient. Dandy-Walker malformation and ventriculomegaly prior to encephalocele surgical correction were positively associated with hydrocephalus (p values 0.05 and 0.01, respectively). Chiari III malformation was found in 2 cases, both requiring CSF shunt for treatment of hydrocephalus and are stable in follow-up. Microcephaly was present in 9 cases. The known mortality rate was 8%.

Conclusions: Hydrocephalus is common in patients with posterior encephaloceles, being more frequent in the supratorcular type, especially when associated to Dandy-Walker, Chiari III malformation, and pre-existing ventriculomegaly. The severity of giant encephaloceles, when associated to torcular types and microcephaly, is a limiting factor for development of hydrocephalus, due both to the rapid evolution of natural history and the structural changes in microcephaly.