Changes in vocal loudness following intensive voice treatment (LSVT) in individuals with Parkinson's disease: a comparison with untreated patients and normal age-matched controls. Speech therapy in Parkinson's disease: a study of the efficacy ad long term effects of intensive treatment. Speech therapy and Parkinson's disease: a review and further data.
This study assessed the impact of the Lee Silverman Voice Treatment (LSVT) on vocal loudness [sound pressure level (SPL)] in a group of dysarthric individuals with idiopathic Parkinson's disease (IPD). Pre- to post-treatment changes in SPL in the treated group were compared with changes in voice SPL during the same time in two control groups: individuals with IPD not treated with the LSVT and in non-disordered individuals, age-matched to the patients. All subjects produced the same voice and speech tasks--sustaining vowel phonation, reading the "Rainbow Passage," producing a short monologue, and describing a picture. These tasks were recorded at three different occasions: just prior to treatment, just after treatment, and 6 months following treatment. The individuals treated with LSVT increased voice SPL from baseline to post-treatment by an average of 8 dB and from baseline to 6 months follow-up by an average of 6 dB. These changes were statistically significant and perceptibly audible. No significant changes in SPL were observed in the control groups during the time corresponding to the treatment and follow-up. Differences in SPL between the treated and untreated patients at post-treatment and follow-up were statistically significant for all voice and speech tasks. These findings, along with others, provide additional support for the efficacy of the LSVT. nan A review is undertaken of recent experimental studies of the effects of speech therapy offered to patients with Parkinson's disease. In contrast to earlier opinions based upon clinical impressions, the results of these studies indicate that the immediate gains from therapy measured within the clinical setting are readily detected, that these are perceived by patient's relatives and that there is reasonable evidence that benefits persist for some period after treatment. A further study is reported which tests the effects of a less intensive treatment regimen. This also gave positive results. Although questions remain regarding the most efficient form of treatment and the extent of its benefits outside the clinic, the existing results warrant greater optimism about the benefits of speech therapy offered to patients with Parkinson's disease.
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.