Effect of botulinum toxin injection on speech outcomes among patients with synkinetic facial nerve palsy: an assessment of speech intelligibility and quality of life

Background Facial nerve palsy (FNP) considerably impairs functional outcomes and quality of life. For patients with synkinetic FNP, physiotherapy and botulinum toxin A (BTX) are commonly used to reduce hyperkinesis and improve facial expression. This study assessed the effect of BTX administration on oral competence in patients with FNP. Methods Patients referred for BTX for management of their synkinetic FNP were recruited from the Sydney Facial Nerve Service. BTX was administered by a single surgeon. Their oral competence was measured using clinician and patient-rated outcome measures before and 4 weeks after BTX administration. This included a consonant analysis of a recorded reading sample, a subjective intelligibility rating by the clinician and patient, as well as 3 validated patient-reported questionnaires: the Speech Handicap Index (SHI), the Facial Disability Index (FDI), and the Oral Competence Questionnaire (OCQ). Results Twenty participants were recruited for analysis. Patients were administered an average of 31.5 u of BTX on the ipsilateral side, and 9.25 u on the contralateral side. This resulted in statistically significant improvements in the percentage of correct consonants (p < 0.001), particularly post-alveolar/alveolar fricative sounds (s, z, and sh; p < 0.001). This corresponded with significantly better speech-related quality of life (SHI p = 0.003). There was no significant change in the OCQ or FDI scores. Conclusions BTX administration for patients with synkinetic FNP showed improved speech-related quality of life and speech intelligibility.