Hi and welcome to the Chiari forum.
Kerri is the best person to respond to you since she has and is dealing with something similar.....I do not have personal experience but if there is anything I can do for you please let me know.
Hi. I had my second decompression January,2019 so close to a year. About 2 months post op began experiencing severe neurological issues and horrible headaches. At that time imaging showed a “fluid collection” but they originally called it a seroma. It remained unchanged and then they said it was a pseudo. Still there and small according to them.....
Recently I had a spinal tap to rule in/out hydrocephalus. Turns out the pressure is low which indicates a leak and probably the reason for the pseudo formation. Waiting to see my next step
Have you gotten in touch with your NS? Seems like they should be looking into this for you