Effect of manual stimulation on functional recovery after hypoglossal-facial anastomosis over a y-tube-conduit

(transection and suture) is usually poor. To test whether manual stimulation afterdirect suture or entubulation of the hypoglossal nerve into a Y-tube conduitconnecting it with the zygomatic and buccal facial nerve branches would improveaxonal pathfinding at the lesion site, quality of muscle reinnervation and recoveryof vibrissal whisking.Ninety six young adult female inbred rats were used. For hypoglossal-facialanastomosis (HFA) over a Y-tube (HFA-Y-tube) the proximal stump of thehypoglossal nerve was entubulated and sutured into the long arm of a Y-tube(isogeneic abdominal aorta with its bifurcation). The zygomatic and buccal facialbranches were entubulated and sutured to the short arms of the Y-tube. Forhypoglossal facial coaptation the proximal stump of the hypoglossal nerve wasdirect sutured to the distal stump of facial nerve. After HFA-Y-Tube, restorationof vibrissal motor performance, degree of collateral axonal branching at the lesionsite and quality of neuro-muscular junction (NMJ) reinnervation of the manualstimulated or non stimulated animals were compared to animals receiving HFACoaptation(no entubulation) after 4 months.HFA-Y-tube reduced collateral axonal branching (from 21% to 11%). However itfailed to reduce the proportion of polyinnervated NMJ and did not improvefunctional outcome when compared to HFA-Coaptation.