Preliminary study of microsurgical repairs of the inferior alveolar nerve in rats using primary suturing and laser weld techniques

Overview on the Evolution of Laser Welding of Vascular and Nervous Tissues

Laser welding presents a core position in the health sector. This process has had an outstanding impact on the surgical procedures from many medical areas, such as on vascular and nervous surgeries. The aim of the present research is to present an overview on the evolution of laser welding of vascular and nervous tissues. These surgeries present many advantages, such as an absence of foreign-body reactions and aneurysms and good tensile strengths. However, despite the sutureless nature of the process, complementary sutures have been applied to support the procedure success. An important concern in vascular and nervous laser welding is the thermal damage. The development of temperature-controlled feedback systems has reduced this concern with a very precise control of the laser parameters. The bonding strength of vascular and nerve laser welds can be enhanced with the application of solder solutions, bonding materials, and laser-activated dyes. Alternative techniques to laser welding, such as photochemical tissue bonding and electrosurgical high-frequency technologies, have also been tested for vascular and nervous repairs.

Effectiveness of fibrin adhesive in facial nerve anastomosis in dogs compared with standard microsuturing technique

PURPOSE

Epineural suturing is the most common technique used for peripheral nerve anastomosis. In addition to the foreign body reaction to the suture material, the surgical duration and difficulty of suturing in confined anatomic locations are major problems. We evaluated the effectiveness of fibrin glue as an acceptable alternative for nerve anastomosis in dogs.

METHODS

Eight adult female dogs weighing 18 to 24 kg were used in the present study. The facial nerve was transected bilaterally. On the right side, the facial nerve was subjected to epineural suturing; and on the left side, the nerve was anastomosed using fibrin adhesive. After 16 weeks, the nerve conduction velocity and proportion of the nerve fibers that crossed the anastomosis site were evaluated and compared for the epineural suture (right side) and fibrin glue (left side). The data were analyzed using the paired t test and univariate analysis of variance.

RESULTS

The mean postoperative nerve conduction velocity was 29.87 ± 7.65 m/s and 26.75 ± 3.97 m/s on the right and left side, respectively. No statistically significant difference was found in the postoperative nerve conduction velocity between the 2 techniques (P = .444). The proportion of nerve fibers that crossed the anastomotic site was 71.25% ± 7.59% and 72.25% ± 8.31% on the right and left side, respectively. The histologic evaluation showed no statistically significant difference in the proportion of the nerve fibers that crossed the anastomotic site between the 2 techniques (P = .598).

CONCLUSIONS

The results suggest that the efficacies of epineural suturing and fibrin gluing in peripheral nerve anastomosis are similar.

Comparison of microsuture, interpositional nerve graft, and laser solder weld repair of the rat inferior alveolar nerve

PURPOSE

Intraosseous repair of nerves involves difficulty of access and there is concern that bone healing may interfere with repair outcomes. The present report describes the effect of 3 separate repair techniques on recovery from section of the rat intraosseous inferior alveolar nerve, with reference to the mental nerve distal and the trigeminal ganglion proximal to the nerve section.

MATERIALS AND METHODS

Unilateral exposure of the inferior alveolar nerves of 28 rats was achieved through bone windows. Nerves were sectioned and rats were assigned to 1 of 4 groups (n = 7): untreated controls, microsuture repair, interpositional nerve grafts from the femoral nerve, or laser solder weld repair. Animals were sacrificed 1 year after surgery for histologic evaluation of the mental nerve, inferior alveolar nerve, and trigeminal ganglion compared with unoperated contralateral nerves.

RESULTS

Compared with the unoperated contralateral nerves, nerve section substantially decreased mental nerve fiber number, mental nerve myelination, mental nerve fiber diameter, inferior alveolar nerve vascularity, trigeminal neuron number, and trigeminal neuron horseradish peroxidase tracer uptake and increased trigeminal ganglion degenerate neurons (P < .001). All 3 forms of repair substantially decreased these effects (P < .05). Interpositional nerve graft was least effective (P < .05). Nonetheless, mental nerve fiber diameter was significantly decreased compared with unsectioned nerves after microsuture and laser solder weld repair (P < .05).

CONCLUSIONS

Intraosseous repair of the inferior alveolar nerve decreases peripheral and central signs of degeneration. Clinical hyperesthesia after repair may reflect a predominance of small fibers after recovery.