Cerebrospinal Fluid Volume Monitoring for Hydrocephalus Therapy

Hydrocephalus is a disease in which cerebrospinal fluid (CSF) accumulates in the ventricular system of the brain. Clinical therapy involves surgically implanting a catheter system to drain this fluid. These systems typically use a pressure-regulated valve system that diverts CSF into a cavity within the body for patients with chronic hydrocephalus. While the treatment is implanted into patients worldwide, its success is unsatisfactory, often requiring numerous revisions due to shunt malfunction. We have recently suggested that a continuous volume sensor may be an alternative approach for use in hydrocephalus treatment. This article highlights advancement of our novel device, which consists of parylene coated sensors with openings for electrode contacts. The instrumentation is miniaturized with the use of surface mount technology. In order to demonstrate the working principle of the technology, the feasibility of acute volume measurements was assessed in an animal model. $250μl$ of CSF was removed from a hydrocephalic rat, and measurements are shown. Our vision of an improved therapy consists of incorporating this impedance based volume sensor with a controller and micropump for feedback control of CSF volume.