MYELINATED SENSORY AND ALPHA MOTOR AXON REGENERATION IN PERIPHERAL-NERVE NEUROMAS

Histochemical staining for carbonic anhydrase and cholinesterase (CE) activities was used to analyze sensory and motor axon regeneration, re spectively, during neuroma formation in transected and tube-encapsulat ed peripheral nerves. Median-ulnar and sciatic nerves in the rodent mo del permitted testing whether a 4 cm greater distance of the motor neu ron soma from axotomy site or intrinsic differences between motor and sensory neurons influenced regeneration and neuroma formation 10, 30, and 90 days later. Ventral root radiculotomy confirmed that CE-stained axons were 97% alpha motor axons. Distance significantly delayed axon regeneration. When distance was negligible, sensory axons grew out so oner than motor axone, but motor axons regenerated to a greater quanti ty, These results indicate regeneration differences between axon subty pes and suggest more extensive branching of motor axons within the neu roma. Thus, both distance from injury site to soma and inherent motor and sensory differences should be considered in peripheral nerve repai r strategies. (C) 1998 John Wiley & Sons, Inc.