Perform a complete history and physical examination, evaluate the radiographic studies and their comparisons, and combine all of this information to make an accurate diagnosis.

VPSs are a relatively common device in pediatrics. As with any artificial device placed internally, the possibility of malfunctioning exists. Missing the diagnosis of shunt malfunction may lead to permanent neurologic injury or death. Unfortunately the diagnosis of shunt failure is not a simple task. Commonly used techniques to diagnose shunt malfunction are a combination of the patient’s history, clinical exam, and radiographic studies. Often, however, the ultimate decision is based on the head CT and “shunt series.” This chapter will explain how relying solely on those results will result in approximately one third of cases of shunt failure being missed.

Noninfectious shunt failure occurs due to obstruction, mechanical failure of the shunt (e.g., disconnection, fractured tubing, misplacement, or migration of the shunt), overdrainage, cerebrospinal fluid drainage other than from the shunt, loculations within the ventricular system, and abdominal causes. Timing of the malfunction may assist in diagnosing the type of shunt failure. Obstruction of the shunt system can occur at any time after shunt placement and at any point along the shunt. Early shunt malfunctions are usually due to misplacement, disconnection, or migration of the shunt components. Common causes for late shunt failure include tubing fractures, shunt overdrainage, ventricular loculations, and erosion of the distal tubing into a hollow viscus in the abdomen.