Speech disorders in Parkinson’s disease: early diagnostics and effects of medication and brain stimulation

Abstract

Hypokinetic dysarthria (HD) occurs in 90% of Parkinson's disease (PD) patients. It manifests specifically in the areas of articulation, phonation, prosody, speech fluency, and faciokinesis. We aimed to systematically review papers on HD in PD with a special focus on (1) early PD diagnosis and monitoring of the disease progression using acoustic voice and speech analysis, and (2) functional imaging studies exploring neural correlates of HD in PD, and (3) clinical studies using acoustic analysis to evaluate effects of dopaminergic medication and brain stimulation. A systematic literature search of articles written in English before March 2016 was conducted in the Web of Science, PubMed, SpringerLink, and IEEE Xplore databases using and combining specific relevant keywords. Articles were categorized into three groups: (1) articles focused on neural correlates of HD in PD using functional imaging (n = 13); (2) articles dealing with the acoustic analysis of HD in PD (n = 52); and (3) articles concerning specifically dopaminergic and brain stimulation-related effects as assessed by acoustic analysis (n = 31); the groups were then reviewed. We identified 14 combinations of speech tasks and acoustic features that can be recommended for use in describing the main features of HD in PD. While only a few acoustic parameters correlate with limb motor symptoms and can be partially relieved by dopaminergic medication, HD in PD seems to be mainly related to non-dopaminergic deficits and associated particularly with non-motor symptoms. Future studies should combine non-invasive brain stimulation with voice behavior approaches to achieve the best treatment effects by enhancing auditory-motor integration.

Communication changes in Parkinson’s disease

“…Easily usable instrumental methods provide objective acoustic measurements to quantify performance,27 bearing in mind that the key articulatory–acoustic variables to measure may differ between languages.…”

Towards robust voice pathology detection

“…Next, conventional and clinically interpretable [10]) acoustic features were usually computed prior to pathology detection [43,14,51]. The acoustic features such as multidimensional voice program parameters (MDVP) [4], mel-frequency cepstral coefficients (MFCC) [52], glottalto-noise excitation ratio (GNE) [42], etc.…”

Changes in Phonation and Their Relations with Progress of Parkinson’s Disease

“…As reported by the recent studies, acoustic analysis of HD can provide clinicians with non-invasive and reliable methodology of PD diagnosis, assessment and monitoring [9,15]. Moreover, this methodology has also been used to monitor the efficiency of PD treatment [10,[16][17][18].…”

“…Up to 90% [7] of patients with PD develop a multi-dimensional speech disorder named hypokinetic dysarthria (HD) [8], which is manifested in phonation, articulation, and prosody [9][10][11]. In the area of phonation, insufficient breath support, reduction in phonation time, increased acoustic noise, instability of articulatory organs, microperturbations of frequency/amplitude, and harsh breathy voice quality has been observed [9,12]. HD leads to serious complications in daily communication of patients with PD [13].…”

“…Moreover, this methodology has also been used to monitor the efficiency of PD treatment [10,[16][17][18]. In the field of acoustic analysis of PD phonation, the authors mostly focused on the sustained vowel /a/ [9]. Conventional phonatory features such as jitter, shimmer, harmonic-to-noise ratio, degree of unvoiced segments, and formant-based parameters extracted from this vowel have been widely used to diagnose PD [12,[19][20][21][22][23].…”