Gaming Keyboards

Hmm.. I have never heard of a keyboard that has the arrow keys in the middle of them, and I am terribly sorry to hear about your disability, My best guess would be to maybe move the keyboard to your left so the arrow keys are right in the middle and just get used to leaning? I don't know, it sounds uncomfortable to me.. I will try and look for you, but I don't think I will find anything.
*Edit*
I thought about it for a second, but I am very sure it is out of anyones price range for a keyboard, except maybe multi-millionares..

http://www.artlebedev.com/everything/optimus/ priced at about $1600 but you can customize any of those keys to do anything with just a little time. Because each key has a tiny lcd screen in them. Like I said, overpriced but still a possibility

I will keep looking

I can't find anything, I am sorry my friend, You could always try a speed pad but that would seriously reduce the amount of keys you can have. the one I use is the N52 Tournament Edition, you can see it here: http://www.n52te.com It works fine but its only built for your left hand, you can try the Logitech one, it might fit better to your need as it has more buttons and is in a circular setting as well as off of a slope.

Something like this:

http://www.xsreviews.co.uk/reviews [...] gamepad-2/

It has the arrow keys in the middle, but no qwerty keyboard, meaning you could have your keyboard on a tray under your desktop and the speed pad right where you need it, somewhere it could easiely be accessed and used.

Best of luck to you and maybe gives you some more ideas