Many people with Parkinson's disease suffer from disorders of speech. The most frequently reported speech problems are weak, hoarse, nasal or monotonous voice, imprecise articulation, slow or fast speech, difficulty starting speech, impaired stress or rhythm, stuttering and tremor. People with the condition also tend to give fewer non-verbal cues, such as facial expressions and hand gestures. These disabilities tend to increase as the disease progresses and can lead to serious problems with communication.
This review compared the benefits of speech and language therapy versus placebo (sham therapy) or no treatment for speech disorders in Parkinson's disease. Relevant trials were identified by electronic searches of 16 medical literature databases, various registers of clinical trials and an examination of the reference lists of identified studies and other reviews.
Only randomised controlled trials were included in this review. These were studies where two groups of patients were compared, one group had speech and language therapy, the other did not receive any therapy intended to improve speech. The patients were assigned to each of the groups in a random fashion so as to reduce the potential for bias.
Three trials with a total of 63 patients were found comparing speech and language therapy with an untreated group. The quality of the methods used in these trials was variable, with all studies failing in at least one critical area. All three of the controlled trials reported a positive effect of speech and language therapy for speech disorders in Parkinson's disease. Many of the outcome measures examined appeared to improve by a clinically significant amount after therapy. However, it should be noted that there were flaws in the methods used in these studies and only a small number of patients with Parkinson’s disease were examined. This means that there is insufficient evidence to absolutely prove or disprove the benefit of speech and language therapy for the treatment of speech disorders in Parkinson's disease patients, but lack of evidence does not mean lack of effect.
A large well designed placebo-controlled randomised trial is needed to assess the effectiveness of speech and language therapy for speech disorders in Parkinson's disease. Outcome measures with particular relevance to people with Parkinson’s disease should be chosen and the patients followed for at least six months to determine the duration of any improvement.
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.
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.
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.
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.
Only randomised controlled trials (RCT) of speech and language therapy versus placebo or no intervention were included.
Data were abstracted independently by CH and CT and differences settled by discussion.
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.