Speech profile in different clinical PSP phenotypes: an acoustic-perceptual study

Progressive supranuclear palsy (PSP) is a neurodegenerative disease with pathological hallmarks and different clinical presentations. Recently, the Movement Disorder Society (MDS) promoted a new classification; specific combinations of the core clinical features identify different phenotypes, including PSP with Richardson's syndrome (PSP-RS) and PSP with predominant parkinsonism (PSP-P). Since speech disorders are very common in PSP, they were included in the MDS-PSP criteria as a supportive clinical feature in the form of hypokinetic, spastic dysarthria. However, little is known about how dysarthria presents across the different PSP variants. The aim of the present study is to evaluate the presence of differences in speech profile in a cohort of PSP-RS and PSP-P patients diagnosed according to the MDS-PSP criteria. Each patient underwent a neurological evaluation and perceptual and acoustic analysis of speech. Disease severity was rated using the Natural History and Neuroprotection in Parkinson plus syndromes-Parkinson plus scale (NNIPPS-PPS), including global score and sub-scores. Twenty-five patients (mean disease duration [standard deviation] = 3.32 [1.79]) were classified as PSP-RS, while sixteen as PSP-P (mean disease duration [standard deviation] = 3.47 [2.00]). These subgroups had homogeneous demographical and clinical characteristics, including disease severity quantified by the NNIPPS-PPS total score. Only the NNIPPS-PPS oculomotor function sub-score significantly differed, being more impaired in PSP-RS patients. No significant differences were found in all speech variables between the two groups. Speech evaluation is not a distinguishing feature of PSP subtypes in mid-stage disease.