Autotomy following limb denervation: effects of sparing selected afferents.

Lesions of the brachial plexus are often followed by inflammation, self-inflicted scratching and autotomy of the denervated extremity. If innervation of the shoulder girdle muscles was spared, this denervation syndrome was decreased in incidence and intensity as compared to a full brachial plexus section. Spared innervation increased the latency between the appearance of inflammation and autotomy, revealing a strong linkage between the site of inflammation and the site of autotomy attack. Plexus lesions, which spared one of the nerves of the distal limb, also decreased the incidence and intensity of autotomy and shifted self-attack from autotomy to scratching wounds. Subsequent section of this nerve produced a two-stage brachial plexus denervation, and the cumulated autotomy was markedly less than that produced by a single-stage brachial plexus denervation. Scratching wounds and autotomy exhibited similar latencies. Scratching was directed towards areas of partial innervation and autotomy towards areas of total denervation. The results are discussed in terms of the possible contributions of dysesthesia inflammation and ischemia in scratching behavior and autotomy.