Gate control theory of pain
The basic premises of the gate control theory of pain are that activity in large (nonnociceptive) fibers can inhibit the perception of activity in small (nociceptive) fibers, and that descending activity from the brain also can inhibit that perception.
Given this construct, it is easy to understand why deafferentation may cause pain.
If the large fibers are preferentially injured, the normal inhibition of pain perception does not occur.
