In the peripheral nervous system of rats, a wide-variety of toxins has been studied to selectively target neurons projecting through a particular nerve. We employed 54 adult male rats to create a neuroma-in-continuity and to evaluate the effect of the immunotoxin OX7-saporin to inhibit neuroma-in-continuity formation. Materials and Methods: The left common peroneal, tibial or sciatic nerves were crushed by one 10-second application of a microforceps. At 3 and 6 weeks after nerve crush, the respective nerve was cut distal to the site of nerve crush, and microinjection of 2 μl of natural saline or 2 μl of the OX7-saporin was done.

In all nerve specimens of the control group and the saline-injection experimental subgroups, gross observation showed a thickened area at the site of nerve crush. Histology showed features consistent with a neuroma-in-continuity. In 11 of the 14 nerve specimens of the OX7-saporin injection experimental subgroups, gross observation showed a narrowed area at the site of nerve crush. Histology showed prevention of neuroma-in-continuity formation as seen by wiping out of almost all nerve fibers, leaving an empty tube encasing by connective tissue.

This study supports the hypothesis that intraneural injection of the OX7-saporin may inhibit neuroma-in-continuity formation