How do you know she has neurological damage? What was the course of corid that you gave her? I recently had a 2 1/2 year-old hen I thought was dying in my lap. I put her on a 14 day course of antibiotics and she recovered. She also went immediately into molt. I assume the molt is a stress reaction from an illness, but cannot be totally sure it wasn’t a molt all long. My point is, you might not want to give up on her yet. If you are going to give up on her (no judgement here), and she is suffering, the kindest thing may be to end it for her instead of letting her die a slow painful death. Only you can decide that. So sorry.