One-Way Valve of the CSF Drainage

Figure hydr_26_n.jpg: A shunt consists of three parts $$hydr_25??(see alternate figure). The important middle part is a one-way valve. This older pressure-driven Holter Haussner valve illustrates the working mechanism clearly: The white arrow corresponds to the ventricular CSF under pressure; the fine spring within a container is compressed and lets the CSF enter through a lateral opening into the chamber of the valve. A back-flow is impossible due to the pressure gradient and the construction of the valve. Modern valves contain silicone slits instead of a spring, and most important, some antisiphon mechanism against the effect of the errect position of the body, and a tool with a programmable flow resistance from the outside.