Shunt dependency in shunted arachnoid cyst: a reason to avoid shunting.

Cystoperitoneal (CP) shunting is minimally invasive and achieves a high rate of resolution on neuroimaging. However, in the absence of definite symptoms, shunting should be reconsidered, because some patients can experience shunt dependency after CP shunting. In this study, the risk of shunt dependency in patients with arachnoid cysts treated with CP shunting and the management of these patients are described. Eight patients (7 boys and 1 girl) were diagnosed as shunt dependent following CP shunting. At the time of the first operation (mean age at first shunting 6.1 years, range 1-11 years), a causal relationship between symptoms and the arachnoid cyst was evident in only 2 cases. Clinical manifestations, neuroimaging (computed tomography and/or magnetic resonance imaging) and intracranial pressure (ICP) data were reviewed retrospectively. The mean age of the patients at the time of shunt dependency was 9.8 years (range 6-13 years), and the mean time between the first shunt operation and shunt dependency was 41 months (range 17-80 months). Although neuroimaging demonstrated a collapsed cyst and small ventricles in most patients, ICP monitoring revealed significant intracranial hypertension. The release of shunt ligation, revision or additional shunting, such as ventriculoperitoneal shunting or lumboperitoneal shunting, resulted in the complete resolution of symptoms except in one patient who lost vision. This study shows that shunt dependency after CP shunting is a real problem and requires more attention. ICP monitoring can demonstrate the presence of intracranial hypertension when clinical and radiological analyses do not.