[Nerve coaptation using CO2 milliwatt laser]

The technique of laser tissue welding with a low-output CO2 laser has become popular due to the minimal amount of nerve tissue damage caused. The purpose of this study was to ascertain the efficacy of nerve coaptation by laser tissue welding in comparison to micro-sutures. In a first series of 15 rats, peripheral nerves were transsected. 24 nerves were coaptated by laser welding (LW) with different parameters in order to evaluate the optimal laser settings. For comparison, six nerves were coapted (NS) with four 10/0 nylon sutures. Finally, the nerves were removed and the tensile strength of the different coaptations determined. The best results of the laser welds were obtained at laser settings of 40 to 60 mW in the continuous mode resulting in a tensile strength of 9.5 +/- 2.2 g. The tensile strength was 39.3 +/- 7.3 g for the sutured coaptation. In a second series, one sciatic nerve was coapted in thirteen rats by laser welding (LW) (60 mW, cont. mode) and in eleven rats using four 10/0 nylon sutures (NS). After six months, the Sciatic Function Index (SFI) was evaluated and the nerves were harvested for histological examination of transverse and longitudinal sections. All animals showed good regeneration and none of the 24 nerve coaptations showed dehiscence. The SFI was for the NS-group -94 +/- 23 and for the LW-group -77 +/- 20. The mean number of myelinated nerve fibres (NS 10,170 +/- 2512 vs. LW 11,902 +/- 1649) and the fibre diameter (NS 4.30 +/- 0.14 um vs. LW 4.02 +/- 0.59 microns) of the nerves distal to the coaptation were similar in both groups and showed no statistical difference. We conclude that nerve coaptation by CO2-laser welds are as successful as the 10/0 nylon sutures in the animal model. Improvements of welding techniques may in the future reduce nerve damage even further and so yield even better functional results.