Arachnoid cysts are developmental anomalies that represent 1% of all intracranial space occupying lesions. Treatment of symptomatic cases may include shunting of the cyst or an open fenestration of it, among other less acceptable surgical procedures. Each procedure has its own pros and cons. We present a case of the development of an acute intracranial hypertension during cysto-peritoneal shunt malfunction in a child. We describe the possible mechanism of these phenomena and, based on this report and by reviewing other case series in the literature, we raise the possibility that acute increase in intracranial pressure and the development of shunt dependency, although rare, are important complications of shunting an arachnoid cyst.