I imagine chickens can suffer seizures, since other animals can. I had a finch that was not acting right, and I thought when I heard a ruckus, she had fallen off the perch. But then I caught her seizing, fluttering, rolling around the cage, then stopping and acting like nothing had happened. I also have a dog who has seizures, and is dazed for a while afterwards.
I would not know the cause, or if there is one.