Spatiotemporal movement variability in ALS: Speaking rate effects on tongue, lower lip, and jaw motor control.
Mili Kuruvilla-Dugdale, Antje Mefferd
PMID 28528293WHAT IT FOUND
Talkers with mild to moderate ALS had less variable tongue dorsum and lower lip movements during typical speech than controls.
Slow speech increased variability in ALS; fast speech did not. These are group differences, not treatment effects.
Key findings
01During typical speech, talkers with mild to moderate ALS had lower movement variability than controls for tongue dorsum, lower lip, and jaw.
02Slow speech yielded higher tongue dorsum and lower lip variability than typical or fast speech in ALS; tongue tip and jaw variability did not change significantly with rate.
03Movement variability during typical speech was associated with intelligibility and speaking rate, but the severity association was preliminary because two severely impaired talkers had a heavy influence on it.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
Read the rest of this summary
You get three full summaries a month, free, and we do not ask for a card. Search, the TL;DRs and your library stay unlimited either way.
What it does not show
The study analysed only eight people with mild to moderate ALS for speaking rate effects, so it does not show how people with severe ALS manage rate changes. The severity associations included only two severely impaired talkers, and the authors said these two had a heavy influence on the results. Statistical power was low; the paper reported only 26% power for one tongue tip comparison and said at least 37 ALS talkers would be needed for that comparison. Tongue and lower lip movements were not separated from jaw movement, so the observed variability may partly reflect jaw contribution. The target sentence was vowel-heavy and lacked stop consonants, which may have affected the variability results. Critical p-values were not adjusted for multiple comparisons. The study compared ALS and control groups at one time point and did not test whether variability changes as ALS progresses. Sensor tracking errors meant the number of usable participants varied slightly within groups.
The easy way to misread this
Do not conclude that slow speech is a helpful treatment for ALS dysarthria. This study did not test a treatment, and in mild to moderate ALS slow speech increased tongue and lip movement variability rather than making movements more consistent.