Objective: To examine the relationship between objective markers of speech motor control, disease severity and ataxia.

Background: Mild dysarthria is a common symptom of Multiple Sclerosis and frequently co-occur with limb tremor and ataxia. Yet, the relationship between speech characteristics, MS disease severity and cerebellar manifestations (such as tremor) is poorly understood.

Methods: Participants with upper limb tremor and limb ataxia were recruited along with non-tremor controls. The Scale for Assessment and Rating of Ataxia (SARA) and the Expanded Disability Status Scale (EDSS) score were determined by a neurologist. Acoustic analysis of speech was used in three seconds-long speech samples to investigate: 1) stability of vocal pitch, in sustained utterance of the vowel /a/; 2) stability of loudness, in the same vocal task and 3) alternating motion rate (speech diadochokinesis, /pa/ta/ka/ used as token). After adjustment for multiple comparisons, p<0.016 was considered for statistical significance.

Results: 33 participants with Multiple Sclerosis and upper limb tremor (46.9±12.3years, 75% female, EDSS=3.8 IQ=2.5) were matched with 33 people with Multiple Sclerosis but without tremor (47.7±10years, 75% female, EDSS=3.6 IQ=3.5). Diadochokinetic rate was 0.62 syllable/second slower in the tremor group (95%CI=0.17 to 1.07, p=0.007) and inversely correlated with SARA (Spearman’s rho=.612, p<0.001) and EDSS scores (rho=.370, p=0.002). Stability of pitch inversely correlated with SARA (rho=0.555, p<0.001) and EDSS scores (rho=0.404, p=0.001) but no significant differences between groups were observed. No significant relation between loudness stability values and other variables was observed.

Conclusions: automated analysis of speech can be used to assess cerebellar disfunction in short samples of speech from people with Multiple Sclerosis. Longitudinal studies are needed to understand the potential for monitoring disease progression.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/under-three-seconds-objective-speech-markers-of-ataxia-in-multiple-sclerosis/