Voice, speech, and swallowing disorders

Nearly 90% of individuals with Parkinson’s disease (PD) develop voice and speech disorders during the course of their disease (1,2). These disorders are characterized by reduced voice volume (hypophonia); a breathy, hoarse, or harsh voice quality (dysphonia); imprecise consonant and vowel articulation due to reduced range of articulatory movements (hypokinetic articulation), and a tendency of these movements to decay and/or accelerate toward the end of a sentence; reduced voice pitch inflections (hypoprosodia, monotone); and rushed, dysfluent, hesitant, or stuttered-like speech (palilalia). These disorders, collectively termed hypokinetic dysarthria (3), may be among the first signs of PD (1,2,4-6). The hypokinetic dysarthria in individuals with PD typically results in reduced speech intelligibility. Reduced facial expression (hypomimia) is also common in individuals with PD. Together these symptoms can result in an individual with PD being interpreted as cold, withdrawn, unintelligent, and moody (7,8). These factors may also impair the ability to socialize, convey important medical information, interact with family members, and maintain employment (7).