The injection of botulinum toxin into the buccinator muscle yielded improved symptoms in patients with facial synkinesis.

The current prospective cohort study included 84 patients who received multiple treatment cycles of botulinum toxin over a 1-year period at a tertiary referral center.

Clinicians used the Synkinesis Assessment Questionnaire to assess subjective scores before injection and 2 weeks after injection. They also compared pre- and post-injection scores among patients who received buccinator injections with those who did not.

Thirty-three of the 84 patients received injections in the buccinator muscle, according to the results. The researchers reported on 23 patients from this group who met inclusion criteria.

There were 82 treatment visits recorded in the current data set. Buccinator injections were involved in 53.6% of those visits, while 46.4% had no buccinator injections.

Vestibular schwannoma was the most common etiology of facial paralysis at 43.5%, followed by Bell Palsy (39.1%).

Synkinesis Assessment Questionnaire scores between the pre-injection and post-injection surveys improved in all patients, regardless of buccinator muscle treatment status. However, post-injection scores on this questionnaire were 45.9 (95% CI, 38.8-46.8) during cycles when buccinators were addressed and 42.8 (95% CI, 41.3-50.4) when they were not addressed (P = .43). Also, the difference between pre-Botox injection outcomes (18; 95% CI, 16.2-21.8) and post-Botox injection outcomes (19; 95% CI, 14.2-21.8) was greater during cycles when buccinator muscles were addressed.

In buccinator-specific analysis, the addition of buccinator injections yielded significantly improved post-Botox injection scores (5.7 vs. 4.1; P = .004), corresponding with a greater difference between pre- and post-botulinum injection scores (3.3 vs. 2; P = .02).