Speech and language therapy versus placebo or no intervention for speech problems in Parkinson's disease

Abstract

Background: Parkinson's disease patients commonly suffer from speech and vocal problems including dysarthric speech, reduced loudness and loss of articulation. These symptoms increase in frequency and intensity with progression of the disease). Speech and language therapy (SLT) aims to improve the intelligibility of speech with behavioural treatment techniques or instrumental aids. Objectives: To compare the efficacy of speech and language therapy versus placebo or no intervention for speech and voice problems in patients with Parkinson's disease. Search methods: Relevant trials were identified by electronic searches of numerous literature databases including MEDLINE, EMBASE, and CINAHL, as well as handsearching of relevant conference abstracts and examination of reference lists in identified studies and other reviews. The literature search included trials published prior to 11th April 2011. Selection criteria: Only randomised controlled trials (RCT) of speech and language therapy versus placebo or no intervention were included. Data collection and analysis: Data were abstracted independently by CH and CT and differences settled by discussion. Main results: Three randomised controlled trials with a total of 63 participants were found comparing SLT with placebo for speech disorders in Parkinson's disease. Data were available from 41 participants in two trials. Vocal loudness for reading a passage increased by 6.3 dB (P = 0.0007) in one trial, and 11.0 dB (P = 0.0002) in another trial. An increase was also seen in both of these trials for monologue speaking of 5.4 dB (P = 0.002) and 11.0 dB (P = 0.0002), respectively. It is likely that these areclinically significant improvements. After six months, patients from the first trial were still showing a statistically significant increase of 4.5 dB (P = 0.0007) for reading and 3.5 dB for monologue speaking. Some measures of speech monotonicity and articulation were investigated; however, all these results were non-significant. Authors' conclusions: Although improvements in speech impairments were noted in these studies, due to the small number of patients examined, methodological flaws, and the possibility of publication bias, there is insufficient evidence to conclusively support or refute the efficacy of SLT for speech problems in Parkinson's disease. A large well designed placebo-controlled RCT is needed to demonstrate SLT's effectiveness in Parkinson's disease. The trial should conform to CONSORT guidelines. Outcome measures with particular relevance to patients with Parkinson’s disease should be chosen and patients followed for at least six months to determine the duration of any improvement.