Autotomy following limb denervation: effects of previous exposure to neurectomy.

Neurectomy, dorsal rhizotomy or spinal cord lesions can evoke self-attack and autotomy of portions of insensate limbs. This behavior has been attributed to dysesthesia and/or pain. However, the majority of animals subjected to these lesions do not exhibit self-mutilation. This study was designed to test for individual predisposition to self-mutilative behaviors by effecting two sequential limb denervations. In susceptible animals, denervation of the first limb induced circulatory, trophic and inflammatory reactions and/or autotomy. Inflammation developed slowly in one or two digits of some animals and then spontaneously resolved. Other animals attacked the tips of inflamed digits effecting local autotomy. Still other animals aggressively attacked multiple digits, rapidly developed diffuse inflammation and produced extensive autotomy. Denervation of a second limb, following complete healing of all tissue injury, induced by the first denervation, produced several dramatic responses. Nearly 90% of those responding with autotomy to the first denervation responded with autotomy to the second denervation. In contrast, only 11% of the non-attackers showed autotomy following the second denervation. The inflammatory and autotomy responses to the second denervation were markedly reduced in latency and increased in intensity. The pattern of autotomy was stereotyped, initiated at the digit tips, progressed proximally, lead by advancing inflammation. It is suggested that a strong host-response component is involved in the autotomy response.