Arrested hydrocephalus is defined as adequately shunted hydrocephalus while all other forms of hydrocephalus are at various levels of compensation. Compensation occurs at some cost to the child. Weighing the cost of compensation versus the risk of a shunt is used to decide which course to follow. Close observation with objective data is mandatory if the decision is made not to shunt the young child. In the very young, less than 3 years of age, one should probably err on the side of inserting a shunt.