A MAGNETIC EVALUATION OF PERIPHERAL-NERVE REGENERATION - I - THE DISCREPANCY BETWEEN MAGNETIC AND HISTOLOGIC DATA FROM THE PROXIMAL SEGMENT

Histologic techniques can quantify the number of axons in a nerve, but give no information about electrical conductibility. The number of fu nctional myelinated neuronal units in a nerve can be quantified based on a magnetic recording technique. When studying reconstructed periphe ral nerves a significant difference between the results found with the se two techniques can be observed. A comparison was made between the l ongterm changes in the number of histologically and magnetoneurophysio logically measured neuronal units proximal to a nerve reconstruction. This study was performed on 6 New Zealand White rabbits, 20 weeks afte r the peroneal nerve had been reconstructed. The contralateral nerves were used as a control. Histologic examination demonstrates a statisti cally significant decrease of approximately 5% in the number of myelin ated fibers. The magnetoneurophysiological results demonstrate a decre ase which is estimated to be caused by the loss of approximately 50% o f the functional myelinated neuronal units in the nerve. Therefore we conclude that of the initially available myelinated neuronal units, 5% degenerate completely, 45% are vital but lose their signal conducting capability, and the remaining 50% are vital and continue to conduct s ignals. Apparently, only this latter group of 50% of the initially ava ilable functional neuronal units appears to remain available for funct ional recovery. (C) 1998 John Wiley & Sons, Inc.