Abstract: Objective To study the influence of the facial nerve crimping ischemia injury on the recruitment of macrophage in rats, and to provide theoretical basis for clinical application of traumatic facial paralysis. Methods Sixty SD rats were randomly divided into 3 groups: 20 in ischemia (extrusion+ischemia) group; 20 in extrusion (extrusion only) group;20 in control group. Rats in ischemia group received an operation that extruding the left facial nerve, cutting off the surface nutrition blood vessels of the facial nerve and stripping epineurium under operating microscope (ischemia completely); The rats in extrusion group just received the extrusion on the left facial nerve but the nutrition blood vessels were preserved; The control group rats served as sham group. At 3 days, 7 days,14 days after operation, behavioral observation and electrophysiological detection were given to each group. After assessment, 5 rats were sacrificed in every group for immunohistochemistry (using macrophage specific antibody CD68), in order to study macrophages further. Results 1. Behavioral observation: At 3 days after operation, all rats in ischemia group and extrusion group showed facial paralysis. Then, at 7 days after operation, part of the rats' facial paralysis were aggravated, the other rats had recovery performance; At 14 days after operation, facial paralysis recovery was observed in experimental groups. However, the recovery rate of the ischemia group is significantly slower. 2. Electrophysiological detection: With the extension of time, orbicularisoris muscles compound action potential maximum amplitude and latency period in ischemia group and extrusion group were gradually approached to the control group. But didn’t achieve the normal level. The recovery rate in ischemia group was relatively lower than in extrusion group. 3. Histological observation: Immunohistochemical results showed that the macrophages gradually increased in ischemia group, until reached a peak at 7 days after operation; The result in extrusion group was similar but the number of macrophages was more than in ischemic group; No significant positive expression was observed in control group. Conclusion Facial nerve crush injury and ischemia can hinder the recruitment of macrophages, eventually hinder the process of nerve repair.

Key words: Facial nerve, Crush Injury and Ischemia, Macrophages, Recruitment