The Role of Speech-Language Pathology (SLP) in the Management of Parkinson’s Disease

Lindsey A. Unger, M.S., CCC-SLP

Communication is a basic human need, and is vital to our ability to express our wants and needs, gain and maintain employment, engage socially, and maintain relationships. In other words, functional communication significantly contributes to our sense of quality of life. 

PD is a progressive neurodegenerative disorder that leads to a wide range of deficits, and affects approximately 1-2% of the world’s population (1). Researchers estimate that 89% of individuals with PD have speech and voice disorders of laryngeal, respiratory, and articulatory function, though only 3-4% of these individuals receive intervention for these impairments (3). Changes in communication can be subtle, and symptoms of speech and voice disorders can be missed or attributed to other processes such as aging, especially in the earlier stages of the diagnosis (2). When these subtle early signs are missed, the opportunity for early intervention is lost, consequently making management/improvement of speech and voice impairments more challenging as the disease progresses. Alternatively, when effective behavioral speech-language therapy is prescribed early, upon diagnosis, evidence suggests it may help slow or halt symptom progression (8). 

The speech disorders in PD are collectively known as hypokinetic dysarthria, which is characterized by a gradual deterioration in speech intelligibility (speech clarity) along with decreased voice loudness, prosodic variation/monotone voice, breathy and hoarse vocal quality, short rushes of speech that can lead to reduced speech fluency, lessened facial expression, and reduced breath support for voicing (4). Dysarthria can be one of the main components of the disease that leads to feelings of social isolation in PD (5), and researchers believe there is a link between the decline of speech intelligibility and cognitive functioning (6). Hypokinetic dysarthria in PD can result from reduced feedback and motor output from the basal ganglia, an important center for the control and regulation of speech movements, resulting in inadequate muscle activation (9). Additionally, reduced/altered internal cueing and sensory processing are common in PD, as is reduced amplitude of output (hypokinesia), which can collectively lead to communication impairment (10). It is easy to see how this ability can be taken for granted, however, for the individual diagnosed with PD, a gradual change in speech clarity, voice, cognition and facial expressiveness can occur, making communication more challenging. 

Progression of the disease can also lead to problems with swallowing (also known as dysphagia), and a decline in nutrition/hydration status, airway protection, and saliva management While neurosurgical interventions (such as Deep Brain Stimulation) and pharmacological treatments for PD such as dopaminergic therapy have shown beneficial effects on the motor manifestations of PD, its effect on speech and voice impairments remains inconclusive with mixed and contradictory findings (7). However, a combination of medical therapy (optimal medication) with behavioral speech therapy provided by a qualified Speech-Language Pathologist (SLP) appears to offer the greatest improvement for speech dysfunction (3). 

According to the American Speech-Language Hearing Association (ASHA) 2016 Scope of Practice Guidelines, a SLP is defined as the “professional who engages in professional practice in the areas of communication and swallowing across the life span. Communication includes speech production and fluency, language, cognition, voice, resonance, and hearing” (11). There are several therapeutic methods and techniques used by SLPs in the clinical setting with patients with PD. 

Lee Silverman Voice Treatment® (LSVT-LOUD®) has level I efficacy which has been found to be highly effective for improving dysarthria in PD, and more effective than traditional motor speech therapy in this population (12). An SLP must have specialized training and certification in LSVTLOUD in order to provide this treatment. The program is organized around a simple therapeutic principle: increasing vocal loudness to retrain the sensory motor processes involved in disordered speech communication (13). It is an intensive, repetitive, and cognitively non-demanding one-month behavioral speech treatment based on the principles of motor learning, and can result in improvements in facial expressiveness, voice intensity, voice quality, speech intelligibility, prosody, and respiratory-phonatory coordination (10). Interestingly, LSVT® cultivates a system-wide spread of effects known to help alleviate dysphagia in PD, as the program may help activate better neuromuscular control over the aerodigestive tract, improving both oral and pharyngeal stages of swallowing which can lessen aspiration risk (12). To find an LSVT-LOUD® certified provider, visit the LSVT Global website by clicking here.

Parkinson Voice Project® has created another popular and highly effective intensive voice retraining program called SPEAK OUT!® Parkinson Voice Project® based out of Richardson, Texas is the only 501(c)(3) nonprofit organization in the world solely dedicated to helping people with Parkinson’s improve their speech and swallowing. SPEAK OUT!® is a two-part therapy approach emphasizing the use of “Intentional” speech as opposed to automatic speech, which has been scientifically proven to significantly improve the speech and voice impairments in Parkinson’s Disease. The protocol involves participation in 2-3 individual treatment sessions per week for a total of 12 sessions, followed by transition to ongoing/weekly group therapy called The LOUD Crowd® which helps maintain skills over time. Together, the patient and speech-language pathologist complete speech, voice and cognitive exercises using a specialized workbook that Parkinson Voice Project® provides to every person with Parkinson’s in the U.S. who is receiving SPEAK OUT!® To find a SPEAK OUT!® certified provider near you, visit the Parkinson Voice Projects ® website by clicking here.

References:

1. De Lau LM, Giesbergen PC, de Rijk MC, Hofman A, Koudstaal PJ, Breteler MM. Incidence of parkinsonism and Parkinson disease in a general population: the Rotterdam Study. Neurology. 2004; 63(7):1240–1244.

2. Ciucci M, Grant L, Rajamanickam E, Hilby B, Blue K, Jones C, Kelm-Nelson C. Early Identification and Treatment of Communication and Swallowing Deficits in Parkinson Disease. Semin Speech Lang. August 2013; 34(3): 185–202.

3. Ramig LO, Fox C, Sapir S. Speech Treatment for Parkinson’s Disease. Expert Review of Neurotherapeutics. Feb 2008; 8(2):297-309.

4. Atkinson-Clement C, Sadat J, Pinto S. Behavioral treatments for speech in Parkinson’s disease: meta-analyses and review of the literature. Neurodegenerative Disease Management. 2015; 5(3), 233–248.

5. Hirsch MA, Farley BG. Exercise and neuroplasticity in persons living with Parkinson’s disease. Eur. J. Phys. Rehabil. Med. 45, 215–229 (2009).

6. Sapir S, Pawlas AA, Ramig LO et al. Voice and speech abnormalities in Parkinson disease: relation to severity of motor impairment, duration of disease, medication, depression, gender, and age. J. Med. Speech Lang. Pathol. 9, 213–226 (2001).

7. Sapir S, Ramig L, Fox C. Intensive voice treatment in Parkinson’s disease: Lee Silverman Voice Treatment. Expert Rev. Neurotherapeutics. 11(6), 815-830 (2011).

8. American Speech-Language-Hearing Association. (2016). Scope of practice in speech-language pathology [Scope of Practice]. Available from www.asha.org/policy/.

9. Sharkawi, Ramig, Logemann, Pauloski, Rademaker, Smith, Pawlas, Baum, Werner. Swallowing and Voice Effects of Lee Silverman Voice Treatment (LSVT): a Pilot Study. J Neurol Neurosurg Psychiatry, 2002; 72: 31-36.

10. Narayana, Fox, Zhang, Franklin, Robin, Vogel, Ramig. Neural Correlates of Efficacy of Voice Therapy in Parkinson’s Disease Identified by Performance—Correlation Analysis (2010). Hum Brain Mapp, February 31(2): 222-236.

11. Hely M, Morris J, Traficante R, Reid W, O’Sullivan D, Williamson P. The Sydney Multicentre study of Parkinson’s disease: progression and mortality at 10 years. J. Neurol. Neurosurg. Psychiatry 67(3) (Sep 1999), 300-307.

12. Bine J, Frank E, McDade H. Dysphagia and dementia in subjects with Parkinson's disease, Dysphagia 10 (3) (1995) 160e164. Summer.

13. Lieberman A, Horowitz L, Redmond P, Pachter L, Lieberman I, Leibowitz M. Dysphagia in Parkinson’ s Disease. Am J Gastroenterol.1980;74(2):157-60.

14. Raja A, Ashtray F, Azargoon S, Chitsaz A, Nilforoush H, Taheri M, Sadegh S. The association between saliva control, silent saliva penetration, aspiration, and videofluoroscopic findings in Parkinson’s disease patients. Advanced Biomedical Research. 2015 May 29;4:108.

15. Karlsen KH, Tandberg E, Arsland D, Larsen JP. Health related quality of life in Parkinson’s disease: a prospective longitudinale study. J. Neurol. Neurosurg. Psychiatry 69, 584–589 (2000).

16. Miller N, Noble E, Jones D, Allcock L, Burn DJ. How do I sound to me? Perceived changes in communication in Parkinson’s disease. Clin. Rehabil. 22, 14–22 (2008).

17. Schulz GM, Grant MK (2000) Effect of speech therapy and pharmacologic and surgical treatments on voice and speech in Parkinson’s disease: a review of the literature. J Commun Disord 33:59–88.