Unblocking cerebrospinal fluid shunts using low frequency ultrasonic cavitation

Cerebrospinal fluid (CSF) shunts for reducing potentially damaging intracranial pressure have been used for almost 50 years. Unfortunately, shunts frequently become blocked, and this often requires a replacement through a subsequent surgical procedure. We have investigated an alternative approach that uses ultrasonic cavitation to unblock a catheter and have conducted in vitro and animal experiments using a prototype system. Low-frequency (20 kHz) extensional waves are transmitted along a fine wire to the tip where cavitation is produced in a highly localized volume. Our experiments indicate that the system is capable of unblocking catheters and, as a result, the technique may be a viable alternative to surgical replacement.