Use of a Y-tube conduit after facial nerve injury reduces collateral axonal branching at the lesion site but neither reduces polyinnervation of motor endplates nor improves functional recovery.

Background: Despite increased understanding of peripheral nerve regeneration, functional recovery after surgical repair remains disappointing. A major contributing factor is the extensive collateral branching at the lesion site, which leads to inaccurate axonal navigation and aberrant reinnervation of targets.

Objective: To determine whether the Y tube reconstruction improved axonal regrowth and whether this was associated with improved function.

Methods: We used a Y-tube conduit with the aim of improving navigation of regenerating axons after facial nerve transection in rats.

Results: Retrograde labeling from the zygomatic and buccal branches showed a halving in the number of double-labeled facial motor neurons (15% vs 8%; P < .05) after Y tube reconstruction compared with facial-facial anastomosis coaptation. However, in both surgical groups, the proportion of polyinnervated motor endplates was similar (≈ 30%; P > .05), and video-based motion analysis of whisking revealed similarly poor function.

Conclusion: Although Y-tube reconstruction decreases axonal branching at the lesion site and improves axonal navigation compared with facial-facial anastomosis coaptation, it fails to promote monoinnervation of motor endplates and confers no functional benefit.