Need advice regarding surgery

My 8yr old daughter had surgery a yr ago. Her headaches and pain went away but her syrinx is getting bigger (13mm pre-op to 18mm transversely on her MRI last week. Her new NS suggests another surgery. Here’s my problem…luckily, she has zero symptoms. She’s stronger than she’s ever been. I know we cant just ignore it and that if and when she starts having symptoms they could be irreversible. Has anyone else had such a big syrinx w/o symptoms? Thank you all.