4yr old daughter with enlarged brain ventricles

My lil girl is 4yrs old and was diagnosed with CP and mild MR at 6 mos.  Just recently doctors found a huge tumor in the rear of her brain and it was successfully removed however she has large ventricles which haven't gone back to normal and it's been a month since the tumor was removed.  Post surgery she had 2 drains in her head to alleviate the fluid build up from the brain and to alleviate the fluid from the surgery area *1 in front right part of head and other in back of head where surgery was done. Doctors removed the drains after the front one topped off at 23 with lil fluid drainage and the other behind head topped off at 15 with same results.  Her front area healed well with stitches but back area was repeatedly being tapped due to fluid leakage which kept stitches from healing properly. She had a drain put back in which was not in the skull but just under her scalp and continues to drain CSF fluid between 30ccs - 80ccs a day.  Doctors strongly suggest on inputting a shunt and I just want some outside professional opinions.  Someone please let me know what they think.  The current drain was inserted on Friday, 10/22 and was raised from 0 to 5 on that drain thing and shes still putting out csf...should we wait to see if the ventricles get smaller or not?  I've seen the CT scans from day 1 till now and the ventricles dont seem to becoming smaller...