Household magnets can change the programmable shunt valve in hydrocephalus patients

We found that external household magnets can change the pressure settings of programmable shunt valves. We compare two popular, adjustable, shunt valves used to regulate the cerebral-spinal fluid (CSF) of hydrocephalus patients: the Codman/spl reg/Hakim/spl trade/ Programmable Valve (CHPV), and the PS Medical/spl reg/STRATA/spl trade/ Valve. We measured the threshold magnetic fields required to change the settings of these two valves at different initial settings. Both types were susceptible to setting changes, with the actual threshold magnetic field strength needed depending on the valve setting and also having some valve variability. The magnetic fields required to increase the valve settings were similar for the two valves, but the fields required for reducing the settings were lower for the STRATA valve than for the CHPV.