Restoration of Function in the Paralyzed Rabbit Orbicularis Oculi Muscle by Direct Functional Electrical Stimulation

Abstract

Restoration of the ability to blink and protect the eye in the patient with facial paralysis remains a challenge. Although many treatments exist, no one approach corrects all the deficits associated with the loss of orbicularis oculi function. In this study, the author investigated the feasibility of restoring function by direct electrical stimulation of the paralyzed orbicularis oculi muscle in the rabbit model. Using a pacing device developed by the author, functional restoration of a normal-appearing blink was produced throughout 30 days of continuous pacing in six rabbits with transected facial nerves. Histologic evaluations of the paced tissues demonstrated no evidence of detrimental effects attributable to the electrical stimulation. The findings of this study support the feasibility of employing direct electrical stimulation to restore the function of paralyzed orbicularis oculi muscles. Potential applications may also exist in other areas in which peripheral denervation creates functional impairment.

A Rodent Model of Dynamic Facial Reanimation Using Functional Electrical Stimulation

“…No signs of pain (flinching, blinking, or vocalizing) were observed in our experiments. A prior study observed that rabbits initially flinched in response to orbicularis oculi stimulation, but signs of pain diminished over time (Otto, 1997). There is evidence that FES paradigms including interferential stimulation (McDonnall et al, 2009) and low-intensity multichannel stimulation (Somia et al, 2001) render facial muscle stimulation functional but not painful.…”

“…Importantly for FES, denervation also causes a transient increase in excitability, due in part to increased sensitivity to acetylcholine, followed after a few days by decreased excitability due to Wallerian degeneration of the axons distal to the injury (Sunderland, 1978). Nevertheless, prior animal studies of facial FES have elicited functional movement (e.g., complete eyelid closure) for several months after paralysis (Salerno et al, 1991; Otto, 1997; Sachs et al, 2007). This may be explained in part by demonstrations that FES can prevent and even reverse the effects of denervation, both in facial muscles (Salerno et al, 1991) and non-facial muscles (Eberstein and Eberstein, 1996).…”

“…The effectiveness of FES in activating paralyzed facial muscles, in particular the orbicularis oculi to restore eye blink, has been demonstrated in rabbits and dogs (Rothstein and Berlinger, 1986; Salerno et al, 1991; Otto, 1997; Somia et al, 2001; Sachs et al, 2007; Jie et al, 2016). Since many facial movements including eye blink are symmetric, a natural closed-loop FES control signal in unilateral facial paralysis can be derived from the intact side of the face.…”

Differential cellular FGF-2 upregulation in the rat facial nucleus following axotomy, functional electrical stimulation and corticosterone: a possible therapeutic target to Bell’s palsy

“…To our knowledge, functional electrical stimulation has not been applied in rodents, despite some reports have evaluated its efficacy for neurofunctional restoration after facial nerve lesions in rabbits [97][98][99]. We can not exclude the possibility of retrograde signals may have triggered the increases of FGF-2 in the neuronal cells of facial nucleus after the functional electrical stimulation performed in our works, however it seems possible that proprioceptive reflexes might have exerted an important role in that process.…”

Comparative studies on the implantation of nano platinum black and pure platinum electrodes in the rabbit orbicularis oculi muscle

“…A biocompatible polymer parylene film, made with a plasma-enhanced chemical vapour deposition system, was used to cover the electrode and platinum wire (0.02 mm in diameter), acting as a flexible insulator. 7 Photolithography and oxygen deep reactive ion-etching techniques were applied to the exposed electrode.…”