Synkinesis in Bell's palsy in a randomised controlled trial.

Objectives: To study the development of synkinesis in Bell's palsy. Frequency, severity, gender aspects and predictors were analysed.

Design: Data from the randomised controlled Scandinavian Bell's palsy trial including 829 patients.

Main Outcome Measures: Frequency and severity of synkinesis at 12 months were the main outcome measures. Mean Sunnybrook synkinesis scores, voluntary movement scores and composite scores between 6 and 12 months were compared.

Results: In 743 patients with a 12-month follow-up, synkinesis frequency was 21.3%. There was no gender difference. Synkinesis was moderate to severe in 6.6% of patients. Those with synkinesis at 6 months had a synkinesis score of 4.1 (±2.8 sd), which increased to 4.7 (±3.2) (P = 0.047) at 12 months (n = 93). Sunnybrook composite score at 1 month was the best predictor for synkinesis development with receiver operating characteristics and area under the curve (AUC) 0.87. Risk for synkinesis increased with a lower Sunnybrook composite score. Furthermore, at 1 month, symmetry of voluntary movement had higher predictive value for synkinesis than resting symmetry with AUC 0.87 and 0.77, respectively. Gentle eye closure and open-mouth smile were the only independent significant predictive items (AUC 0.86).

Conclusions: Moderate-to-severe synkinesis was present in 6.6% of patients. The mean synkinesis score increased between 6 and 12 months, and outcome should therefore be evaluated after at least 12 months. Sunnybrook composite score and symmetry of voluntary movement at 1 month were good predictors for synkinesis.