Speech therapy in the treatment of Parkinson’s disease

Speech disorders are key elements in the diagnosis and management of individuals with Parkinson’s disease (PD). In this chapter, we review the symptoms of speech disorders in PD, their etiology, and treatment. The neural mechanisms underlying speech abnormalities in PD are not well understood. Tentative explanations for these abnormalities include deficits in any or a combination of the following: (1) scaling and maintenance of movement amplitude, (2) temporal processing, (3) sensory processing, (4) internal cueing, and (5) vocal vigilance. The effects of medical intervention (neuropharmacological and neurosurgical) are shown to be minimal, adverse, or inconclusive. Behavioral therapy of parkinsonian speech is described with special emphasis on LSVT® LOUD, a vocal training regimen with Level 1 evidence for treatment efficacy. This efficacious treatment is delivered in a manner consistent with principles of neuroplasticity and is designed to address the aforementioned deficits underlying the speech disorder in PD. The importance of early referral for optimal speech rehabilitation in PD is emphasized.