I got my hand with a belt sander in high school, back in 1974. Ripped all the nerves and soft tissue off the first knuckle of the left hand index finger, exposing it to the bone. I remember seeing the joint to this day. I didn't lose any motor function of the left index finger, but if I rub the scar lightly on that knuckle, I feel it at the finger tip. It feels like it's wired backwards as far as tactile sense is concerned.
I worked at a McDonald's long before they had the clam-shell cookers for the meat, and worked an open hot grill. I got very 'calloused' to the heat from constantly touching the grill (unintentionally) and getting minor burns. It took a couple years before I had fully restored feeling in the finger tips of both hands.
The WORST problem though, is compression of the nerves at C5/C6. Numbness is one thing, but when the muscles start tying themselves in knots and it feels like lightning has struck me on the elbow, I can't begin to describe that pain. Couple that with desiccated disks at L2/L3 and L4/L5, and bulging disk at L3/L4, which basically makes it feel like someone took a blowtorch down the inside of my leg, under my foot, and stopped on my big toenail (still holding it there), yeah, I got some experience with numbness in the extremities.
I've also had two rotator cuff repairs on my right shoulder, and one on the left. Not being able to use my arms for nearly two years has only aggravated the inability to do therapeutic exercises, and escalated pains I was living with. I'm living proof if you stop moving, you start hurting.