Accelerating functional recovery after rat facial nerve injury: Effects of gonadal steroids and electrical stimulation

Abstract

Electrical stimulation may decrease cell death or promote sprouting to accelerate early recovery. Testosterone may affect the actual rate of axonal regeneration and produce acceleration in functional recovery. By targeting different stages of neural regeneration, the synergy of electrical stimulation and testosterone appears to have promise as a neurotherapeutic strategy for facial nerve injury.

Single session of brief electrical stimulation immediately following crush injury enhances functional recovery of rat facial nerve

“…Electrode assemblies were constructed as previously described [5][6]. During the same surgery as the crush procedure, the base of the electrode assembly was sutured onto the paraspinous muscles of each animal.…”

“…The animals were divided into seven groups (n = 6 in all groups): one group that received no ES; one group that received one 30 min session of ES immediately following the injury (1 session); groups receiving one 30 min session of ES immediately following the injury along with additional sessions either 1 d later (2 sessions), 1 d to 3 d later (4 sessions), or 1 d to 6 d later (7 sessions); and a group that was stimulated daily until complete recovery as previously described [5][6][7]. The onset of recovery for both vibrissae orientation and eye blink reflex occurred within a few days.…”

“…The eye blink reflex, vibrissae movement, and orientation of the vibrissae relative to the rostrocaudal axis of the animal were measured. These parameters were chosen because they are dependent on the facial nerve and have been used in previous studies of facial nerve recovery [5][6][12][13]. The time to complete recovery of all measured parameters was also recorded and analyzed.…”

“…Therefore, ES has been explored as a therapeutic strategy for improving the outcome of peripheral nerve injury. Over the course of several studies, our laboratory has shown that daily ES applied to the facial nerve proximal to the site of injury affects early events in the nerve regeneration process, and therefore functional recovery, in rats by initiating axon sprout formation [5][6][7]. Pockett and Gavin reported that administering ES following sciatic nerve crush injury in rats accelerates the appearance of the toe-spreading reflex, a sensitive indicator of the onset of motor recovery [8].…”

“…Our previous studies demonstrating the effectiveness of ES in enhancing recovery from facial nerve crush injury have used daily stimulation beginning the day after injury [5][6]. However, given the evidence that ES acts on early events in the regenerative process, one of the objectives of the current study was to determine the effectiveness of ES administered immediately following crush injury.…”