The Effect of Botulinum Toxin Type A on Speech Intelligibility in Oromandibular Dystonia
Abstract
Speech intelligibility of 10 individuals with OMD was measured before and after receiving BoNT-A injections. Intelligibility was assessed using the PIT (single-word intelligibility), SIT (sentence intelligibility), and a conversational speech task. Five listeners rated the speech intelligibility of these three intelligibility tasks via orthographic transcription and visual analogue scaling (VAS) techniques. BoNT-A was not associated with significant differences in speech intelligibility. Further analysis revealed a significant difference on the PIT VAS intelligibility ratings based on order of presentation, suggesting that listeners rated the first half of words on the PIT (words 1-29) as more intelligible than the second half of words (words 30-57). There was also a significant difference in SIT transcription intelligibility scores based on sentence length, suggesting that listeners rated shorter sentences with higher intelligibility than longer sentences. This research will contribute to a small body of literature on speech intelligibility in OMD.