Kidney trouble with chiari?

My 9 year old son was diagnosed in July 2012 with Chiari Malformation with a syrinx. another MRI will be done in November and we will know then if he will have surgery. He also has scoliosis that will require growing rods once we know more about the progression of the Chiari and syrinx ( his neurosurgeon doesn't think the syrinx is causing the scoliosis b/c the curve is pretty bad and the syrinx is not "large enough to cause that big of a curve") . Now he has to see a urologist b/c his kidneys appear to be enlarged. I am curious if the kidney problem is related to the Chiari. Has anyone else had this experience? Any info is greatly appreciated !!!!! Thanks so much !