The course of aberrant reinnervation following nerve repair with fresh or denatured muscle autografts.
Denatured muscle grafts obtained by freeze thawing have been proposed to replace losses in the peripheral nerves. In the present report, we compare the performance of such grafts with fresh grafts in the rat median nerve. A long-term effect of muscle interposition on reinnervation was studied by behavioral assessment, muscle ATPase histochemistry, and retrograde labeling of motoneurons. There was no difference in grasping strength recovery between fresh and denatured 10-mm-long muscle grafts. Recovery was delayed and incomplete. Twelve months after surgery, only 50% of the normal grasping strength was attained. Grasping recovery was not observed in the 20-mm-long graft groups. Pathway reinnervation was non-specific with a huge amount of motor fiber misdirection. A decrease in the number of misdirected motor fibers occurred with time and activity recovery. Muscle reinnervation was not specific with disturbance of the mosaic pattern and type-grouping formation. Preference of type I axons for reinnervating deeper zones was observed. Type I aberrant reinnervation was demonstrated in the muscle periphery. The mosaic distribution of type I and II muscle fibers was not stable, and readjustments were observed with time, correlating with grasping improvement. During grasping strength recovery, there was a decrease in the number of type I fibers peripherally located and an increase of those deeply disposed. A time- and activity-related recovery was associated with readjustment in the pathways and muscle fiber rearrangement. We suggest that muscle activity generates specificity.
Bertelli
Jayme A
JA
Universidade do Sul de Santa Catarina Unisul, Centro de Ciências Biológicas e da Saúde CCBS, Tubarão, SC, Brazil. bertelli@matrix.com.br
Taleb
Madjid
M
Mira
Jean-Claude
JC
Ghizoni
Marcos F
MF
D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D001572:Benzofurans / Q000378:metabolism; D002452:Cell Count; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008475:Median Nerve / Q000378:metabolism / Q000502:physiology* / Q000637:transplantation*; D009121:Muscle Denervation / Q000379:methods; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D009132:Muscles / Q000294:innervation / Q000502:physiology / Q000637:transplantation*; D009416:Nerve Regeneration / Q000502:physiology*; D016900:Neurofilament Proteins / Q000378:metabolism; D011597:Psychomotor Performance / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function / Q000502:physiology; D013997:Time Factors; D014182:Transplantation, Autologous / Q000379:methods*
D001572:Benzofurans; D016900:Neurofilament Proteins; C038675:true blue