Conduction velocity of the rabbit facial nerve: a noninvasive functional evaluation

Abstract

The aim of this study was to evaluate standardized conduction velocity data for uninjured facial nerve and facial nerve repaired with autologous graft nerves and synthetic materials. An evaluation was made measuring the preoperative differences in the facial nerve conduction velocities on either side, and ascertaining the existence of a positive correlation between facial nerve conduction velocity and the number of axons regenerated postoperatively. In 17 rabbits, bilateral facial nerve motor action potentials were recorded pre- and postoperatively. The stimulation surface electrodes were placed on the auricular pavilion (facial nerve trunk) and the recording surface electrodes were placed on the quadratus labii inferior muscle. The facial nerves were isolated, transected and separated 10 mm apart. The gap between the two nerve ends was repaired with autologous nerve grafts and PTFE-e (polytetrafluoroethylene) or collagen tubes. The mean of maximal conduction velocity of the facial nerve was 41.10 m/s. After 15 days no nerve conduction was evoked in the evaluated group. For the period of 2 and 4 months the mean conduction velocity was approximately 50% of the normal value in the subgroups assessed. A significant correlation was observed between the conduction velocity and the number of regenerated axons. Noninvasive functional evaluation with surface electrodes can be useful for stimulating and recording muscle action potentials and for assessing the functional state of the facial nerve.

Anastomose do nervo facial de coelhos com cola de fibrina: estudo da velocidade de condução nervosa

“…Surface electrodes are able to record the nerve's functional status after the trauma or surgery, in a non-invasive fashion 31 .…”

“…The use of surface electrodes allows for a very precise and non-invasive functional evaluation, thus avoiding another surgical procedure (required by the internal electrodes). It also precludes the possibility of muscle or nerve injury and infection at the implantation site, which may occur when one uses needle electrodes 31,44,45 . Despite the low number of regenerated axons, nerve conduction speed showed a good facial nerve recovery with fibrin glue, reaching a value close to 81% of the normal value at the end of the period.…”

“…We then calculated the conduction velocity difference (reduction) between the preoperative test and the postmortem test (postop). The surgical procedure and the functional evaluation (nerve conduction velocity) were carried out only on the left side, since there are no statistically significant differences between nerve conduction velocity of the right and left facial nerves in rabbits 31 . For histology purposes we obtained cross sections from the distal portion of the facial nerve (near the anastomosis region).…”

“…In order to check the results attained in the studies about reinnervation dynamics, we can do histologic and functional evaluations. The functional evaluation obtained through recording nerve conduction velocity through electromyography with surface electrodes may be useful to stimulate and record muscle action potential and evaluate facial nerve functional status after an injury or surgery 31 . The present investigation aims at using nerve conduction velocity with surface electrodes to assess fibrin glue as an alternative to conventional nerve anastomosis methods.…”

Histopathological analysis of gangliosides use in peripheral nerve regeneration after axonotmesis in rats

“…Such damage may be caused by traumatic, neoplastic or iatrogenic agents. The consequences of a nerve fibre injury depend on its nature, site and intensity 1 .…”