End-to-end and end-to-side neurorrhaphy between thick donor nerves and thin recipient nerves: an axon regeneration study in a rat model.

During nerve reconstruction, nerves of different thicknesses are often sutured together using end-to-side neurorrhaphy and end-to-end neurorrhaphy techniques. In this study, the effect of the type of neurorrhaphy on the number and diameter of regenerated axon fibers was studied in a rat facial nerve repair model. An inflow-type end-to-side and end-to-end neurorrhaphy model with nerve stumps of different thicknesses (2:1 diameter ratio) was created in the facial nerve of 14 adult male Sprague-Dawley rats. After 6 and 12 weeks, nerve regeneration was evaluated in the rats using the following outcomes: total number of myelinated axons, average minor axis diameter of the myelinated axons in the central and peripheral sections, and axon regeneration rate. End-to-end neurorrhaphy resulted in a significantly greater number of regenerated myelinated axons and rate of regeneration after 6 weeks than end-to-side neurorrhaphy; however, no such differences were observed at 12 weeks. While the regenerated axons were thicker at 12 weeks than at 6 weeks, no significant differences in axon fiber thickness were detected between end-to-end and end-to-side neurorrhaphy. Thus, end-to-end neurorrhaphy resulted in greater numbers of regenerated axons and increased axon regeneration rate during the early postoperative period. As rapid reinnervation is one of the most important factors influencing the restoration of target muscle function, we conclude that end-to-end neurorrhaphy is desirable when suturing thick nerves to thin nerves.

Combination of hypoglossal-facial nerve jump graft by end-to-side neurorrhaphy and cross-face nerve graft for the treatment of facial paralysis.

The cross-face nerve graft and the interpositional jump graft were performed simultaneously for 13 patients with facial paralysis. The period between the onset of paralysis and surgery ranged from 3 to 32 weeks. In nine patients, surgery was performed within 3 months of the onset of paralysis. The patients in whom reinnervation by both grafts succeeded could smile without closing their eyes by moving the tongue and could close the eye on the affected side without an accompanying oral movement. The expression was natural and included fine muscle movements. Spontaneous recovery of the facial nerve was observed in three patients. Among patients who showed functional recovery without spontaneous recovery, House-Brackman's palsy grade was II in one patient, III in five patients, and IV in one patient. Functional deficits of the tongue were not observed. We recommend that this surgery be performed within 3 months of onset of paralysis.