Adductor laryngeal dystonia (AdLD, formerly called adductor spasmodic dysphonia) is the most common type of laryngeal dystonia, but even so, it’s rare. Evidence is sparse and conflicting about which outcome measures best capture disease severity and which outcome measurement tools track well with each other.
A recent systematic review, published in the Journal of Voice, recommends that any core set of measurement tools for AdLD should include three domains: perceptual measures, acoustic measures, and patient-reported outcome measures (PROMs).
Christopher D. Dwyer, MD, a laryngologist now practicing in the Division of Otolaryngology–Head and Neck Surgery at Brigham and Women’s Hospital, Sarah L. Schneider, MS, CCC-SLP, at the University of California San Francisco (UCSF), and colleagues hypothesized that a single patient rating of treatment outcome might compare well with perceptual and acoustic outcomes, which would greatly simplify clinical trials of novel treatments.
However, in a paper also published in the Journal of Voice, they say this approach was unsuccessful. What’s more, instruments in the three separate domains infrequently correlated with each other.
At UCSF, the research team studied 26 patients with AdLD who responded favorably to at least two injections of botulinum toxin A. Their mean age was 58 (range, 25–85), and 77% were female.
Before the next injection, the patients:
- Participated in a videoconference with the clinical research coordinator in which they recorded six standardized sentences, three to five seconds of sustained /i/, /a/ and /ooh/, and spontaneous voicing of how the patient felt about their current voice state
- Downloaded the VoiceEvalu8 app onto their mobile phones and made a second voice recording that included sustained /a/ repeated three times, the sentence “We were away a year ago,” and the first four sentences of the rainbow passage
- Completed four PROMs: the abbreviated Voice Handicap Index (VHI-10), the OMNI–Vocal Effort Scale (OMNI-VES), the Communicative Participation Item Bank General Short Form (CPIB-10), and a set of three visual analog scales (VASs) developed at UCSF that were used to rate vocal effort required for face-to-face conversation, effort required for telephone conversations, and overall severity of voice breaks
Four weeks after treatment, the participants repeated the videoconference and completed the same PROMs. They answered a global-rating-of-change (GROC) question: “Compared to before your most recent Botox injection, how would you describe your voice?” on a scale of −5 to +5 and rated the effectiveness of the injection on a VAS of 0% to 100%.
Four voice-specialized speech–language pathologists used the Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V) for perceptual voice analysis of the videoconference recordings; they were blinded as to whether each sample was collected pre- or post-treatment. The VoiceEvalu8 software analyzed acoustic measures.
The key findings were:
- The only outcome measure that significantly correlated with the GROC question was the patient’s perception of injection effectiveness (r=0.535; P=0.022)
- Overall AdLD severity and vocal strain, as measured with the CAPE-V, were highly correlated (r=0.900; P<0.001), and for overall severity, there were high inter-rater and intra-rater reliabilities among the speech–language pathologists (r=0.81 and r=0.98, respectively)
- However, none of the CAPE-V perceptual ratings correlated significantly with the PROM scores or acoustic measures
- There were no correlations between the subjectively evaluated perceptual measures and the objectively evaluated acoustic measures
- PROMs that incorporate a VAS or linear pictograph (i.e., the OMNI-VES) were highly correlated with each other, which is encouraging since these questionnaires are easiest to complete
Outcomes Measurement Needs Further Attention
Clinicians perception of vocal strain and overall severity in AdLD are sensitive to the treatment effect of botulinum toxin A. Still, the magnitude of change doesn’t necessarily align with the patient’s perception of how their voice impairment affects their quality of life. Which outcome measures should be used in AdLD is still an open question.