Effect of Pulsed and Continuous Ultrasound Therapy on the Degree of Collateral Axonal Branching at the Lesion Site, Polyinnervation of Motor End Plates, and Recovery of Motor Function after Facial Nerve Reconstruction

The aim of the present study is to test whether ultrasound therapy of muscles denervated by nerve injury would improve the quality of their reinnervation by reduction of the collateral axonal branching at the lesion site and poly-innervation degree at the neuromuscular junctions. After transection and suture of the buccal branch of the facial nerve, pulsed or continuous type of ultrasound therapy was applied to the paralyzed whisker pad muscles of rats in the course of 2 months. Instead of reduction, we found a significant increase in the collateral axonal branching after continuous ultrasound therapy when compared to the branching determined after pulsed or sham ultrasound therapy. Both types of ultrasound therapy also failed to reduce the proportion of polyinnervated end plates in the reinnervated facial muscles. Accordingly, continuous ultrasound therapy failed to restore any parameter of the motor performance of the vibrissal hairs. Application of pulsed ultrasound therapy promoted slight improvements of the functional parameters angular velocity and acceleration. The inhomogeneous structural and functional results achieved after both types of ultrasound therapy let us conclude that further studies are required to evaluate its effects on peripheral nerve regeneration. Anat Rec, 302:1314-1324, 2019. (c) 2019 Wiley Periodicals, Inc

Assessment of axonal sprouting and motor performance after hypoglossal-facial end-to-side nerve repair: experimental study in rats

Hypoglossal-facial nerve anastomosis (HFA) aims to reanimate denervated mimic muscles with hypoglossal axons when the transected facial nerve is not accessible. The aim of this study was to evaluate the recovery of HFA using a Y tube in two variants: (1) the proximal stump of the hypoglossal nerve was entubulated to the Y tube (classic Y tube HFA) and (2) the Y tube was sutured to an epineurial window of a slightly damaged hypoglossal nerve (end-to-side Y tube HFA). A total of 48 adult female rats were divided into four groups: intact controls (group 1), sham operated (group 2), classic Y tube HFA (group 3) and end-to-side Y tube HFA (group 4). The abdominal aorta with both common iliac arteries of isogeneic male rats served as the Y-tube conduit. Animals from group 4 recovered better than those from group 3: the degree of collateral axonal branching (3 +/- 1%) was significantly lower than that determined in group 3 (13 +/- 1%). The mean deviation of the tongue from the midline was significantly smaller in group 4 (6 +/- 4 degrees) than that measured in animals from group 3 (41 +/- 6 degrees). In the determination of vibrissal motor function in group 3 and group 4, a decrease in amplitude was found to be - 66% and - 92%, respectively. No differences in the reinnervation pattern of the target muscles were detected. As a result, these surgical models were not determined to be able to improve vibrissal movements. It was concluded that performance of end-to-side Y tube HFA diminishes collateral axonal branching at the lesion site, which in turn, promotes better recovery of tongue- and vibrissal-motor performance