Reliability of speech assessments in spinocerebellar ataxia type 3/Machado-Joseph disease

Abstract Background: Spinocerebellar ataxia type 3/Machado-Joseph Disease (SCA3/MJD) is a genetic disorder characterized by ataxic manifestations. Although dysarthria is the main symptom, validated assessments of speech and voice are lacking. Objectives: We aimed to evaluate reliability of auditory-perceptual and acoustic assessments, collected in-person and by telephone calls, and to raise data on their external validity. Methods: Symptomatic individuals were studied. Arm 1 studied test-retest reliability of in-person speech assessments; arm 2 studied reliability of in-person and remote evaluations. Friedreich's Ataxia Rating Scale (FARS)-adl, demographic, and molecular data were also obtained. The minimum kappa for the five perceptual variables under study to be considered reliable was set at 0.8. The minimum intraclass correlation coefficients (ICC) for the 45 acoustic-instrumental assessments under study to be considered reliable was 0.70, for a p <0.05. Results: 17 and 20 subjects were included in arms 1 and 2, respectively. All five auditory-perceptual assessments and 30 acoustic-instrumental assessments were considered reliable for the standard in-person use. Four auditory-perceptual and four acoustic assessments have also achieved reliability for use in-person and/or by telephone. Three auditory-perceptual assessments (subsystems: phonation, respiration, and resonance) and two acoustic-instrumental assessments (subsystems: respiration and articulation) correlated with age and disease duration; phonation also correlated FARS-adl. Discussion: A substantial number of assessments of speech were considered reliable for the standard in-person use in SCA3/MJD. Moreover, eight of them were also reliable when used either in-person or remotely. Our results support their use in future studies on this disease.