Selective neurectomy of the zygomatic branches for oro-ocular synkinesis: A targeted approach to improve eye aperture.

[BACKGROUND] Oro-ocular synkinesis is a common sequela of facial paralysis, characterized by involuntary eyelid closure during oral movement. Although botulinum toxin (BTX) is the first-line therapy, its transient effect necessitates repeated treatments. Selective neurectomy (SN) of the synkinetic ocular branches from the zygomatic-buccal nerves has emerged as an adjunct to BTX, though objective outcome data remain limited.

[METHODS] A retrospective cohort study was performed on patients with post-paralytic synkinesis treated with either BTX exclusively (BTX, n=13) or targeted SN of the synkinetic ocular branches (SN, n=11). Objective facial metrics were quantified using Emotrics Plus software, comparing the brow height and exposed eye aperture at rest, during smiling and puckering. Outcome assessment was performed before and after treatment.

[RESULTS] The median time from treatment to outcome evaluation was 1.6 months in the BTX group and 7.5 months in the SN group. Preoperatively, both groups demonstrated significant asymmetry in exposed eye aperture from at rest to facial expression. Post-treatment, the SN group showed no significant asymmetry during smiling or puckering, whereas the asymmetry was still evident in the BTX group. Six of the 11 SN patients required low-dose BTX touch-ups with longer intervals between the injections.

[CONCLUSIONS] SN of the synkinetic ocular branches reduces involuntary eye closure in oro-ocular synkinesis and improves ocular symmetry for more than 6 months after surgery. Although nearly half of the patients required additional chemodenervation, SN provided an alternative option to BTX alone with reduced dependence on ongoing injections and prolonging the injection intervals.

[LAY SUMMARY] Involuntary eye closure during oral movement is a distressing sequela of facial paralysis. Although BTX offers temporary relief, SN may provide a more lasting improvement in ocular symmetry for appropriately selected patients.