Why Flushing the Valve Cannot Be A Reliable Method to Evaluate the Ventriculoperitoneal Shunt Function?

Most neurosurgeons or physicians are used to pump the shunt valve whenever they want to examine a patient with previous hydrocephalus having a kind of shunt system. If the patient is assessed during a regular follow up without any complaint we may find good emptying and filling or delayed filling. Even delayed filling is found at a normal functioning shunt in an asymptomatic patient, this finding does not confirm any abnormal situation. In a patient with symptoms of shunt malfunction the situation is different; if pumping is abnormal it only confirms the clinical status and should be proved with shunt tap and neuroimaging. Actually there is currently no practical way to clinically measure detailed shunt performance (e.g., flow rate) in vivo. The current commonly used methods for evaluation of shunt function include computed tomography and magnetic resonance imaging, radioisotope injection, and plain radiographs [1] .