Hi. My Husband Had A Medtronic Strata 11 Installed 9

Hi. My husband had a Medtronic Strata 11 installed 9 days ago replacing a medium pressure shunt as a lumbar drain indicated he might benefit from a revision to a lower pressure. There was a baseline ct prior to the revisison. A couple of days after the procedure, the programable shunt was adjusted downward to 1 from a setting of 1.5. A couple of days later, a ct revealed no reduction in ventricle size. A day later, the setting was moved down to .5 which is the lowest setting. 2 days later another ct with no decrease in ventricle size again. This brings us to the present with no improvement in clinical signs or decreases in ventricle size. I am of the mind that nothing happened - the programable shunt pressure of 0.5 seems to be the same as the medium pressure shunt that was replaced. Is this possible? If so, is there a solution?