Ocular-oral synkinesis caused by partial injury of the zygomatic and buccal branches of the facial nerve after mid-face trauma

Facial nerve paralysis induced by acute traumatic facial nerve injuries limited to the zygomatic and buccal branches shows unique complications, such as strong co-contractions of the lower facial muscles around the lips during voluntary blinking (ocular-oral synkinesis). We investigated the characteristics of facial complications after facial nerve injury in the mid-face area and reported the treatment results. A total of 21 patients with facial nerve injuries to the zygomatic and/or buccal branches were evaluated for the degree of facial synkinesis and mouth asymmetry. Patients with mild-to-moderate symptoms were treated using physical rehabilitation therapy combined with botulinum toxin (Botox) injection, and patients with severe or uncontrolled symptoms were treated using surgical therapy. Initial/final mean synkinesis scores and mouth asymmetry degrees were 2.17/1.75 and 0.85/0.66 in the physical therapy group and 3.11/0.78 and 2.41/−0.31 in the surgery group, respectively. Physical therapy with Botox injection alone did not show significant improvements in synkinetic symptoms of the patients with mild-to-moderate synkinesis (p > 0.05), whereas surgical therapy resulted in significant improvements in synkinesis and mouth asymmetry (p