Autotomy following peripheral nerve lesions: experimental anesthesia dolorosa

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Abstract
When hindlimb peripheral nerves are cut across in rats and mice, there is a tendency for the animal to attack the anesthetic limb. This attack was called autotomy. The time course and degree of autotomy following various types of nerve injury was described. Different types (4) of lesion were applied to the sciatic nerve of rats. The most serious autotomy was produced by section of the nerve and encapsulation of its cut end in a polythene tube. Section followed by immediate resuturing also produced serious autotomy. Simple ligation of the nerve end was followed by less autotomy than encapsulation or cut and resuture. A crush lesion caused only minimal attack. Section of the saphenous branch of the femoral nerve produced no autotomy. If the saphenous and sciatic nerves were ligated at the same time so that the entire foot became anesthetic, there was a great increase of autotomy over that seen when the sciatic nerve alone was ligated. This increase with the double lesion occurred even if the saphenous nerve was ligated > 100 days after the sciatic nerve had been cut. Mice showed autotomy very similar to that seen in rats but the onset was somewhat faster. Autotomy may be triggered by an abnormal afferent barrage generated in the cut end of the nerve. Autotomy from peripheral nerve lesion is a different phenomenon from that seen after dorsal root section. Autotomy occurs under conditions which produce anesthesia dolorosa in man. This simple model may be suitable for studies of the prevention of irritations originating from chronic lesions of peripheral nerves.