TUBULIZATION INCREASES AXONAL OUTGROWTH OF RAT SCIATIC-NERVE AFTER CRUSH INJURY

It is important to develop methods which increase nerve regeneration s ince restoration of function following injury to peripheral nerves oft en requires outgrowth of the injured axons over Song distances. In thi s study, axonal outgrowth after bilateral crush injury to the sciatic nerve of the rat was measured. One group with large-diameter nonpermea ble silicone tubes and one group with large-diameter permeable silicon e tubes applied around the crush site on one side had regeneration fol lowing nerve injury compared to controls on the other side. The length of regeneration of the regenerating axons were then measured 4, 5, an d 6 days following the crush injury using the ''pinch reflex test.'' T he presence of axons at the pinch level was confirmed by immunocytoche mical staining for neurofilaments. The length of regeneration for rats with nonpermeable tubes was significantly greater than that of the co ntralateral control side and was so at all times (p < 0.05). The effec t was present but not that pronounced where permeable tubes were used. We conclude that the outgrowth of regenerating sensory axons after sc iatic nerve crush injury in the rat can be increased by enclosing the regeneration site in a silicone tube. The observed effect may be due t o local mechanisms such as macrophage invasion or prevention of rapid wash-out of fluid from the crush zone. (C) 1996 Academic Press, Inc.