In Detail: When the CSF needs a permanent diversion, doctors place an internal drainage system called a shunt. The principles of managing the CSF remain the same as in the acute phase; but instead of draining the fluid into an outside collection system, the catheter sends it to places where it can be absorbed within the body. In most cases the CSF is delivered into a cavity within the abdomen (see illustration), but sometimes the system directs the CSF to an upper chamber of the heart. In both cases an adjustable, one way valve maintains a therapeutic flow rate, and the system can be monitored and regulated with minimal care. The shunt is likely to stay in place for the duration of the patient’s life