Laser-Two-Focus Measurement of Cerebrospinal Fluid Flow Rate in a Hydrocephalus Shunt Tube Using Indocyanine Green Fluorescence

Hydrocephalus is a disease in which excess cerebrospinal fluid (CSF) accumulates in the brain, causing symptoms such as headache, vomiting, and disturbance of consciousness. The typical treatment is a shunt system in which a surgically implanted shunt tube drains the excess CSF from the brain to the abdominal cavity, etc. The shunt incorporates a valve which can control the flow of CSF. However, only invasive or indirect methods have been proposed to monitor the flow [1], [2], making it difficult to set the appropriate value of the valve.