II. Experiments on the restoration of paralysed muscles by means of nerve anastomosis. Part II.―Anastomosis of the nerves supplying limb muscles

Abstract

In the Preface published with Part I of this research the historical development of the subject has been shortly detailed. As there stated, the first experiments on anastomosis of nerves were those conducted on the nerves of the muscles of the limbs, namely, on the wing of the cock. Although the functional restoration in the case of Flourens’ experiment was described as being so satisfactory, it apparently failed to convince investigators, and, subsequently, when the possibility of functional cross union came to be inquired into, various explanations of the result in Flourens’ experiment were put forward. Thus there was the objection that sufficient precaution was not taken to prevent confluent reunion of all four ends, and that this might have occurred and permitted restoration of the old paths. There was the allegation again of Schiff that the description of the extent of the recovery was deficient, and the suggestion of Cunningham (5) that the recovery might have been vicarious, due to the tensors of the patagium, whose supply remained intact. The next contribution to the subject in the form which is here under consideration was that by Rawa (2) in 1883-85. There are two parts in Rawa’s research, namely, the cross union of nerves of different function, namely, the vagus and hypoglossal, and the cross union of nerves of similar function in the limb in dogs. In the latter, which alone require consideration here, the nerves which he crossed were the posterior tibial and the peroneal. His idea here was to form a cross between the nerve supply of the flexor and that of the extensor muscles of the paw. He, however, found difficulty in getting isolated unions, and thus preventing confluent reunion of the nerve ends, with danger of reunion of corresponding ends. To avoid this he adopted a method of reunion which could not lead to functional restoration of the limb in any circumstances, namely, the laying down of but one crossing, the other central and peripheral segments being excised. Thus only one set of muscles remained in a position to recover function, while the other group was left to be permanently unsupplied. The consequence was that in all his animals contracture had of necessity to develop, and to become more pronounced with the recovery of the muscle group to which the nerve supply had been conducted. Rawa, however, deduced from his work that recovery of function of the group of muscles took place under the new conditions, as he found recovery of flexion in the case where the peripheral segment of the posterior tibial was united to the central segment of the peroneal, and of extension when the peripheral segment retained was that of the peroneal, and these conclusions were confirmed by physiological examination. One of his conclusions also was that a period was required for re-education to the altered conditions.