Facial-Hypoglossal End-To-Side Neurorrhaphy: Exploration of the Source of Axonal Sprouting

Abstract

Background The clinical application of end-to-side (ETS) neurorrhaphy is under debate partly due to a lack of consensus on the source of axonal sprouting. Methods In this study, 24 rats were divided into three groups: sham operation, facial-hypoglossal ETS neurorrhaphy, and end-to-end (ETE) neurorrhaphy. Electrophysiological tests were employed to detect the evoked compound muscle action potentials (CMAPs) in different situations, and the latencies and maximal amplitudes of the CMAPs recorded were compared. Fluorescence retrograde tracing studies, hematoxylin and eosin (HE) staining, and immunohistochemical staining of growth-associated protein 43 (GAP-43) were performed. The number and the diameter of myelinated axons proximal and distal to the coaptation sites were measured. Results Twelve weeks after the surgeries, reinnervation of whisker pad muscles by hypoglossal nerves in both the ETS and ETE groups were confirmed via electrophysiological study. The maximal amplitudes of the CMAPs recorded in different situations and the quantification of myelinated axons supported the coexistence spontaneous collateral sprouting and regenerative sprouting of axons. Double-labeled neurons were found within the hypoglossal nuclear areas in the ETS neurorrhaphy group and HE staining illustrated the axons crossed the coaptation site into the facial acceptor nerve. Although immunohistochemical staining of GAP-43 revealed different timeframes between ETS and ETE neurorrhaphy groups, no significant difference on latency or diameters of the myelinated axons distal to the coaptation sites was noted between ETE and ETS groups. Conclusion Both spontaneous collateral sprouting and regenerative sprouting of axons coexisted following ETS neurorrhaphy, which represents an alternative approach to peripheral nerve reconstruction.

The effects of FK1706 on nerve regeneration and bladder function recovery following an end-to-side neurorrhaphy in rats

“…NBD has been treated by intradural End-to-side (ETS) neurorrhaphy of lumbar and sacral nerve, ameliorating urination dysfunction and hydronephrosis for these patients [ 2 ]. ETS neurorrhaphy is a nerve rerouting surgery which sutures the distal stump of an injured nerve to the side of an adjacent healthy nerve to promote nerve regeneration and functional reconstruction with preserving adjacent nerve function simultaneously [ 3 ]. One important advantage of ETS neurorrhaphy is the donor nerve function could be preserved well.…”

Dynamic Quantitative Assessment of Motor Axon Sprouting after Direct Facial–Hypoglossal End-To-Side Neurorrhaphy in Rats

“…5,6 Retrograde labeling is often applied to trace axon sprouting in studies concerning ETS nerve repair. Despite collateral sprouting, as indicated by the observation of double-labeled neurons, some studies still support the idea that axon regeneration originates from terminal sprouting of donor axons injured during the repair procedure, [7][8][9][10][11][12] which is especially apparent in case of motor axons. 13 Although many labeling studies have provided qualitative evidence of the reinnervation type after ETS neurorrhaphy, very few works attempted to conduct analysis quantificationally and dynamically.…”