Analysis of Preoperative Factors Influencing Hypoglossal-facial ‘Side’-to-side Neurorrhaphy for Facial Paralysis after Excision of Acoustic Neuroma

Objective Hypoglossal nerve-facial nerve‘side’-to-side neurorrhaphy is a new method for the treatment of potential incomplete facial paralysis after acoustic neuroma.However,there are differences in postoperative outcomes among patients.This study analysed preoperative factors that may influence the treatment outcomes of neurorrhaphy.Methods We performed a retrospective study of 53 patients who were treated by neurorrhaphy for facial paralysis after acoustic neuroma resection.After a one-year follow-up period,the patients were divided into two groups according to facial functional outcome:better recovery or ordinary recovery.We analysed the following factors:gender,age,tumour size,and characteristics,tumour adhesion to the facial nerve,the duration of facial paralysis(DFP)and F wave appearance prior to neurorrhaphy(F wave).Results Univariate analysis showed significant differences between the two groups in DFP(P=0.0002),tumour adhesion to the facial nerve(P=0.0079)and F waves(P=0.0048).Logistic regression analysis of these factors also showed statistical significance with P values of 0.042 for the DFP,0.043 for F waves,and 0.031 for tumour adhesion to the facial nerve.Conclusions Tumour adhesion to the facial nerve,F waves appearance and DFP prior to neurorrhaphy are the predominant factors that influence treatment outcomes.

An Experimental Study on the Optimal Timing for the Repair of Incomplete Facial Paralysis by Hypoglossal-facial‘Side'-to-side Neurorrhaphy in Rats

Objective To investigate the optimal timing for the repair of persistent incomplete facial paralysis by hypoglossal-facial ‘side＇-to-side neurorrhaphy in rats. Methods A total of 30 adult rats with crushed and bulldog-clamped facial nerve injury were randomly divided into 5 groups（n = 6 each） that were subjected to injury without nerve repair or with immediate repair, 2-week-delayed repair, 4-week-delayed repair, or 8-week-delayed repair. Three months later, the effects of repair in each rat were evaluated by facial symmetry assessment, electrophysiological examination, retrograde labeling, and axon regeneration measurement. Results At 3 months after injury, the alpha angle significantly increased in the group of rats with 4-week-delayed repair compared with the other four groups. Upon stimulation of the facial nerve or Pre degenerated nerve, the muscle action potentials MAPs were recorded in the whisker pad muscle, and the MAP amplitude and area under the curve in the 4-week-delayed repair group were significantly augmented at 3 months post-injury. Similarly, the number of retrograde-labeled motor neurons in the facial and hypoglossal nuclei was quantified to be significantly greater in the 4-week-delayed repair group than in the other groups, and a large number of regenerated axons was also observed. Conclusion The results of this study demonstrated that hemi HN-FN neurorrhaphy performed 4 weeks after facial nerve injury was most effective in terms of the functional recovery of axonal regeneration and activation of facial muscles.

Comparison of the Nerve Regeneration Capacity and Characteristics between Sciatic Nerve Crush and Transection Injury Models in Rats

Objective To provide useful information for selecting the most appropriate peripheral nerve injury model for different research purposes in nerve injury and repair studies,and to compare nerve regeneration capacity and characteristics between them.Methods Sixty adult SD rats were randomly divided into two groups and underwent crush injury alone(group A,n=30)or transection injury followed by surgical repair(group B,n=30)of the right hind paw.Each group was subjected to the CatWalk test,gastrocnemius muscle evaluation,pain threshold measurement,electrophysiological examination,retrograde neuronal labeling,and quantification of nerve regeneration before and 7,14,21,and 28 days after injury.Results Gait analysis showed that the recovery speed in group A was significantly faster than that in group B at 14 days.At 21 days,the compound muscle action potential of the gastrocnemius muscle in group A was significantly higher than that in group B,and the number of labeled motor neurons in group B was lower than that in group A.The number of new myelin sheaths and the g-ratio were higher in group A than in group B.There was a 7-day time difference in the regeneration rate between the two injury groups.Conclusion The regeneration of nerve fibers was rapid after crush nerve injury,whereas the transection injury was relatively slow,which provides some ideas for the selection of clinical research models.