Restoration of paralyzed orbicularis oculi muscle function by controlled electrical current

Area of Science:

• Neurosurgery
• Regenerative Medicine
• Biomedical Engineering

Background:

• Facial nerve paralysis results in significant loss of orbicularis oculi muscle function.
• Restoring function to denervated muscles is a critical challenge in treating facial paralysis.

Purpose of the Study:

• To investigate the efficacy of controlled electrical stimulation in restoring function to peripherally denervated orbicularis oculi muscles using a canine model.
• To assess the electrophysiological changes in stimulated versus non-stimulated denervated muscles.

Main Methods:

• Unilateral facial nerve neurotmesis was performed in eight dogs.
• Four dogs received daily electrical stimulation (40 min/day) to the denervated orbicularis oculi muscle for 75 days.
• Electrophysiological studies compared denervated treated, denervated untreated, and normal orbicularis oculi muscles.

Main Results:

• Electrical stimulation evoked minimum muscle closure with stimulus strength not significantly different from controls.
• Between days 10-30, maximum muscle closure required significantly less pulse strength in stimulated denervated muscles compared to non-stimulated ones.
• This improvement in stimulated muscles was comparable to normal muscles during the same period but not sustained beyond day 40.

Conclusions:

• Daily electrical stimulation can transiently reverse denervation-induced changes in paralyzed orbicularis oculi muscle.
• Controlled electrical current shows feasibility for restoring orbicularis oculi muscle function following facial nerve injury.