Vulnerability of the gradually elongated nerve to compression injury.

The purpose of this study is to clarify the vulnerability of the gradually elongated peripheral nerve. Rabbit's sciatic nerves were gradually elongated to 30 mm at the rate of 2.0 mm/day and 4.0 mm/day. Immediately after elongation, the sciatic nerve was exposed and compressed for 30 minutes at various forces, 15, 30 and 60 g/0.1 cm(2). Immediately after elongation and compression, 2, 4 and 8 weeks after compression, each group was electrophysiologically and histologically estimated--15 g/0.1 cm(2) caused no damage to the control group, neurapraxia to the 2.0 mm/day group, and axonotmesis to the 4.0 mm/day group; 30 g/0.1 cm(2) caused neurapraxia to the control group and axonotmesis to the 2.0 mm/day group; 60 g/0.1 cm(2) caused axonotmesis to the control group and slowly recovered axonotmesis to the 2.0 mm/day group. This study shows that though mild compression, does not cause nerve injury to the intact nerve, it can sometimes cause severe damage to the gradual elongated nerve.