Oral and Laryngeal Diadochokinetic Rate in Multiple Sclerosis: Relationship to Disease Progression

The first purpose of this study was to investigate the rate of oral and laryngeal Diadochokinesis (DDK) in Multiple Sclerosis (MS) patients in comparison with healthy people. The second goal was to determine if DDK rate has any relationship with the disease progression.
In this cross-sectional study, two groups were enrolled: MS patients (n=31) and healthy subjects (n=14) . The samples of DDK tasks were collected. The scores of Expanded Disability Status Scale (EDSS) and duration of disease were considered as the indices of disease progression.
There were significant differences between the two groups in the rates of all DDK tasks (P≤0.001). Significant correlations were found between laryngeal DDK tasks and disease progression (r = - 0.488, r = -0.396, r = -0.444, r = - 0.667, P ≤ 0.027). Two oral DDK tasks were in correlation with EDSS and the disease duration (r = -0.403, r = -0.446, r =-0.521, r = -0.465, p≤0.025). There were high correlations between functional systems of EDSS (pyramidal, cerebellar and brainstem) and DDK tasks (r = - 0.448, r = -452, r = -0.458, r =-0.379, P ≤ 0.036).
In the present study, poor performance in DDK tasks provided evidence for insufficient motor control over related speech subsystems in MS. These findings suggest that DDK rate is a sensitive beneficial speech motor control assessment in MS. Moreover, DDK tasks might be introduced as additional prognostic parameters for detecting disease progression and evaluating treatment achievements.