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how awful. There is hope yet. Our Oreo used to take off on our island and be gone 2 or 3 days. It used to flip me out. She doesn't do that anymore, but has been gone one full day recently. Usually she does this when my husband leaves for home to work. This upsets her, and she goes looking for HIM and gets lost. (now that she is 6 this is getting better, but still is very worrysome).

Put something with scent outside, in case he is lost. His litter box, or some bedding.

Being so cute, someone could have taken him in. He may have become disoriented after a chase or whatever. (since he has neuro issues).
Also a minor injury...like a pulled nail, may keep him from trying to come down if he were treed by a predator. That happened to a cat of ours once. We walked around when she didnt come home, and she was up a tree 3 doors down, and we could barely hear her crying she was so tired. She had ripped one of her toe sheathes and it hurt too much to try and come back down.

It has been our experience that even neutered males will wander. I won't get a male cat because of this...we had two broken hearts over this issue over the years.

Have you seen stray or wandering cats on your property? If so watch them, from which direction they come, and follow that track. If he found a female, she may be in that direction.

It there is a vet nearby, check that out. If he were found, someone may have taken him there. You can call them first. Shelters too.
I was really hoping he'd be back today. With your warmer weather, it makes it easier for him to stay out. The way it is here now, he'd be on someone's doorstep begging to be let in.

Hang in there... still...
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