Chronic Facial Nerve Palsy with Aberrant Regeneration

This is a 35-year-old woman who was diagnosed with right sided Bell's palsy six months prior. Contrast-enhanced MRI at that time was normal. This video demonstrates the phenomenon of aberrant regeneration (synkinesia) of the facial nerve. Due to aberrant regeneration, at rest the right palpebral fissure (PF) is narrower than the left contrary to what would be expected with an acute right facial palsy, where the PF should be wider due to orbicularis oculi weakness. The lower face can also be more contracting, making the nasolabial fold on the normal side look relatively flattened. However, when asking the patient to smile, it's apparent that less teeth are visible on the right; when asking the patient to raise the eyebrows, there's right frontalis weakness; when asking the patient to close her eyes, there's orbicularis oculi weakness. Aberrant regeneration is demonstrated by the following: when activating the lower face by smiling or pursing the lips together, the right eye closes (some fibers that originally innervated the o. oris now innervate the o. oculi); when activating the upper face by closing the eye or lifting the eyebrows, the right side of the mouth contracts (some fibers that originally innervated the o. oculi now innervate the o. oris). Additionally, patients can have miswiring of the lacrimal and salivary glands, causing symptoms such as ‘crocodile tears' where a patient who is salivating (e.g., thinking about or eating food) will experience ipsilesional tearing.