Chemodenervation of the Posterior Belly of the Digastric Muscle in Facial Synkinesis.

Patients with facial synkinesis may have jaw tightness and swallow discomfort despite chemodenervation of facial mimetic musculature, and the posterior belly of the digastric (PBD) muscle is a logical target to treat these symptoms. To compare patient-reported outcomes of botulinum toxin (BT) chemodenervation of the posterior belly of digastric muscle in patients with postparalytic facial synkinesis. Retrospective review. Patients with facial synkinesis who underwent electromyography (EMG)-guided PBD BT chemodenervation in addition to their baseline therapeutic regimen were included. Pre- and post-treatment Synkinesis Assessment Questionnaires (SAQ) and a two-question survey regarding jaw tightness and swallow discomfort were administered. Twenty-nine patients were included. An average of 5 U of BT-A was injected into the PBD, and 46.5 U across all facial muscles. From pre- to post-injection, patients demonstrated improvement in jaw tightness at rest (3.02 vs. 1.98/5.0,  < 0.001), with swallow (2.78 vs. 1.94/5.0,  < 0.001), and total SAQ (64.3 vs. 51.2/100,  < 0.001). Patients rated subjective benefit from PBD injection compared with prior treatments without PBD injection as 4.5/5.0. Synkinesis patients with jaw tightness or swallow discomfort may benefit from the addition of PBD injections to the therapeutic regimen.