Clinical speech impairment in Parkinson's disease, progressive supranuclear palsy, and multiple system atrophy

Speech abnormalities are common to the three Parkinsonian syndromes, namely Parkinson's disease (PD), progressive supranuclear palsy (PSP) and multiple system atrophy (MSA), the nature and severity of which is of clinical interest and diagnostic value.

To evaluate the clinical pattern of speech impairment in patients with PD, PSP and MSA and to identify significant differences on quantitative speech parameters when compared to controls.

Cross-sectional study conducted in a tertiary medical teaching institute.

Twenty-two patients with PD, 18 patients with PSP and 20 patients with MSA and 10 age-matched healthy controls were recruited over a period of 1.5 years. The patients were clinically evaluated for the presence and characteristics of dysarthria. This was followed by quantitative assessment of three parameters: maximum phonation time (MPT), semantic fluency and reading speed. The outcome measures were compared between the patient groups and with controls.

Patients with PD had hypophonic monotonous speech with occasional rushes of speech while patients with MSA and PSP had mixed dysarthria with ataxic and spastic elements respectively. All quantitative parameters were affected when compared to controls (P values<0.001, 0.012 and 0.008 respectively). Maximum phonation time was significantly less in PSP when compared to MSA and PD (P=0.015). Reading speed also showed a similar trend which was not statistically significant. Semantic fluency was comparable in all three groups.

Dysarthria in PD, PSP and MSA have many overlapping but certain distinctive features as well which could serve as a diagnostic clue. Patients with PSP had profound speech impairment probably indicative of the more severe frontostriatial pathology.