What's the chance (percentage) that an MRI will change the settings on a codman hakim programmable vp shunt? Can anything else change it?

High. The codman hakin programmable vp shunt does not have the newer "locks" like the codman certas or the sophysa that prevent changes in a high magnetic field like an mri. In fact, neurosurgeons are trained to be prepared to re-program the vp shunt any time the patient has an MRI scan. Any time these shunts are near a high magnetic field, there is a risk that the shunt will change its setting.
Good . The programmable shunt should be reprogrammed after exposure to a highly magnetic field such as mri.
Very high. Right after MRI you should have it reprogrammed to intended setting. Any strong magnetic field can alter the setting.