Due to lesions in the basal ganglia, individuals with PD may experience hypokinetic dysarthria
, a term that describes a group of speech characteristics pertaining to phonation and respiration; articulation; prosody; and resonance (Pinto et al.
Ratings indicated abnormally low tone, but only for a single task, for two participants in the flaccid group (unilateral), three in the flaccid-spastic group (bilateral), and one in the hypokinetic dysarthria group (bilateral).
Tissue stiffness values tended to be higher in individuals with flaccid dysarthria than in those with spastic or hypokinetic dysarthria.
Instead, the data from study 1 suggested the opposite; individuals with spastic and hypokinetic dysarthria, typically considered to have abnormally high tone, had lower orofacial stiffness values on average than did individuals with flaccid dysarthria, which is characterized by abnormally low tone.
Speech disorders associated with PD are known as Parkinsonian dysarthria or hypokinetic dysarthria (Schulz & Grant, 2000).
At present, speech therapy programs for patients with PD who exhibit hypokinetic dysarthria mainly target vocal loudness, following the Lee Silverman Voice Treatment (LSVT) protocol (Ramig, Countryman, Thompson, & Horii, 1995; Ramig, Pawlas, & Countryman, 1995).