Hypoglossal-facial nerve anastomosis in the rabbits using laser welding

The aim of this study is to compare laser nerve welding of hypoglossal-facial nerve to microsurgical suturing and a result of immediate and delayed repair, and to evaluate the effectiveness of laser nerve welding in reanimation of facial paralysis of the rabbit models. The first group of 5 rabbits underwent immediate hypoglossal-facial anastomosis (HFA) by microsurgical suturing and the second group of 5 rabbits by CO2 laser welding. The third group of 5 rabbits underwent delayed HFA by microsurgical suturing and the fourth group of 5 rabbits by laser nerve welding. The fifth group of 5 rabbits sustained intact hypoglossal and facial nerve as control. In all rabbits of the 4 different groups, cholera toxin subunit B (CTb) was injected in the epineurium distal to the anastomosis site on the postoperative sixth week and in normal hypoglossal nerve in the 5 rabbits of control group. Neurons labeled CTb of hypoglossal nuclei were positive immunohistochemically and the numbers were counted. In the immediate HFA groups, CTb positive neurons were 1416 +/- 118 in the laser welding group (n = 5) and 1429 +/- 90 in the microsurgical suturing group (n = 5). There was no significant difference (P = 0.75). In the delayed HFA groups, CTb positive neurons were 1503 +/- 66 in the laser welding group (n = 5) and 1207 +/- 68 in the microsurgical suturing group (n = 5). Difference was significant (P = 0.009). There was no significant difference between immediate and delayed anastomosis in the laser welding group (P = 0.208), but some significant difference was observed between immediate and delayed anastomosis in the microsurgical suturing group (P = 0.016). Injected CTb in intact hypoglossal neurons (n = 5) were labeled 1970 +/- 165. No dehiscence was seen on the laser welding site of nerve anastomosis in all the rabbits as re-exploration was done for injection of CTb. This study shows that regeneration of the anastomosed hypoglossal-facial nerve was affected similarly by either laser welding or microsurgical suturing in immediate repair; however, the welding was more effective especially in delayed repair.