What is synkinesis and why does it occur?

Facial nerve injuryLoss of normal activationAxonal regrowthPathways may be impreciseLinked movementFor example, eye closure with smiling

After substantial facial nerve injury, regenerating axons can enter unintended pathways, so one group of fibers activates several muscles together. Postparalytic facial synkinesis is involuntary movement linked to a voluntary facial action.

Common examples are eye closure during smiling, mouth movement during blinking, cheek tightness or platysma bands during speech and smiling. This differs from pure paralysis: movement has returned, but it is not isolated or coordinated.

Assessment

Examination records rest and smile, eye closure, speech, tooth show, cheek and platysma tension, symmetry and excursion. Standardized video and photographs aid follow-up. Eye safety, speech, eating and social impact are also assessed.

In the supplied article, synkinesis severity is described as + mild, ++ moderate and +++ severe. This is descriptive; treatment is not selected by one sign alone.

PPFS classification by smile and severity

Type	Smile quality	Synkinesis
Type I	Good smile, more than 4 teeth visible	+
Type II-to-III	Good smile, more than 2 teeth	++ to +++
Type III-to-II	Acceptable smile, fewer than 2 teeth	++ to +++
Type III	Poor smile, 0–1 teeth	+++

The classification supports description and discussion but does not mandate one treatment.

Nonoperative treatment

Specialist neuromuscular retraining: slow, precise movement, mirror feedback and reduction of excessive effort to improve control.
Botulinum toxin: selective injections can reduce excessive eye closure, mouth pull or neck tightness. The effect is temporary and dosing is individualized.
Eye, pain and soft-tissue care: according to symptoms and safety.

These approaches may remain the main treatment in mild and moderate synkinesis.

Selected surgical options

Severe, functionally and aesthetically limiting synkinesis that remains uncontrolled may lead to selective neurectomy, myectomy, nerve transfer or dynamic smile reconstruction. The existing movement and muscles that should be preserved guide the plan.

The article describes a strategy for severe cases: extensive selective removal of aberrant nerves and synkinetic muscles followed by creation of an independent smile unit with a free functioning gracilis, most often powered by a cross-face nerve graft. This complex and irreversible approach is not appropriate for every patient and is not the only consensus treatment for every grade.

Movement mappingViable muscles and unwanted activationSelective planWhat to preserve, weaken or reconstructLong rehabilitationLearning the reconstructed smile unit

Illustration of aberrant motor reinnervation patterns after facial palsy.

Surgical illustration from the paper on reconstruction in complex synkinesis.

Evidence limits and individual decision-making

For severe synkinesis, a cross-face nerve graft–powered free gracilis transfer is one option for dynamic smile reconstruction. Selection depends on the smile pattern, viable muscle function, co-contraction severity, prior treatment and the patient’s goals.

Clinical evidence is based mainly on retrospective series and highly specialized practice. It supports reconstruction in selected cases but cannot promise an individual result or displace facial rehabilitation, botulinum toxin or selective procedures when those are appropriate.

Reference

Chuang DC-C, Tay JQ, Khoury A, Lu JC-Y, Chang TN-J. Motor Aberrant Reinnervation Sequelae in Postparalytic Facial Synkinesis: A 35-year Evolution of Surgical Strategy. Plastic and Reconstructive Surgery – Global Open. 2026;14:e8051. doi:10.1097/GOX.0000000000008051

The figures are taken from the paper co-authored by Dr Khoury and are presented for education.