Speech and language therapy for dysarthria in Parkinson's disease

Abstract

Background: Dysarthria is a common manifestation of Parkinson's disease which increases in frequency and intensity with the progress of the disease (Streifler 1984). Up to 20% of Parkinsonian patients are referred for speech and language therapy (S & L T), its aim being to improve the intelligibility of the patient's speech.

Objectives: To compare the efficacy of speech and language therapy versus placebo or no interventions in patients with Parkinson's disease.

Search strategy: Relevant trials were identified by electronic searches of MEDLINE, EMBASE, CINAHL, ISI-SCI, AMED, MANTIS, REHABDATA, REHADAT, GEROLIT, Pascal, LILACS, MedCarib, JICST-EPlus, AIM, IMEMR, SIGLE, ISI-ISTP, DISSABS, Conference Papers Index, Aslib Index to Theses, the Cochrane Controlled Trials Register, the CentreWatch Clinical Trials listing service, the metaRegister of Controlled Trials, ClinicalTrials.gov, CRISP, PEDro, NIDRR and NRR; and examination of the reference lists of identified studies and other reviews.

Selection criteria: Only randomised controlled trials (RCT) were included.

Data collection and analysis: Data were abstracted independently by KD and RW and differences settled by discussion.

Main results: Three randomised controlled trials were found comparing speech and language therapy with placebo for speech disorders in Parkinson's disease. A total of 63 patients were examined. The loudness of the patients' voices were increased by between 7-18%, depending on the speaking task being performed. It is likely that this is a clinically significant improvement. After six months the degree of improvement was reduced but was still statistically significant. Overall measures of dysarthria were measured in two trials and also improved. The clinical significance of these improvements was less clear cut as intelligibility of speech was not measured in any of these studies.

Reviewer's conclusions: Considering the small number of patients examined, the methodological flaws in many of the studies, and the possibility of publication bias, there is insufficient evidence to support or refute the efficacy of speech and language therapy for dysarthria in Parkinson's disease. A Delphi-style survey is needed to develop a consensus as to what is 'standard' S< for dysarthria in Parkinson's disease. Then a large well designed placebo-controlled RCT is needed to demonstrate speech and language therapy's effectiveness for dysarthria in Parkinson's disease. The trial should conform to CONSORT guidelines. Outcome measures with particular relevance to patients should be chosen and the patients followed for at least 6 months to determine the duration of any improvement.