ABSTRACT
Stretch injuries to peripheral nerves are often associated with poor recovery, which
may relate to both the character and the extent of structural alterations in the nerve
trunk. Previous biomechanical studies have provided insight into such structural changes;
however most of these investigations have involved the testing of specirhens after
removal from the body. This investigation presents an in vivo model of nerve stretch injury and correlates functional recovery with different regions
of the stress-strain relationship described in previous biomechanical studies.
Functional recovery was measured for 8 weeks using the Sciatic Functional Index of
de Medinaceli. Nerves stretched prior to reaching mechanical failure demonstrated
excellent recovery within 2 to 3 weeks, with acute histologic features including variable
amounts of degenerating axons. Nerves stretched through the point of mechanical failure
were permanently deformed, with widespread degeneration and ruptures in the epineurium
and perineurium. Despite these severe pathologic changes, a significant degree of
recovery was observed by the end of the study period. These results suggest that if
continuity is preserved, a substantial amount of recovery is possible following severe
nerve stretch lesions in the rat. Preservation of continuity may create an optimal
alignment for regenerating neurons.
