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Abstract & Commentary
Source: Ramig LO, et al. Intensive voice treatment (LSVT) for patients with Parkinson’s disease: A 2 year follow up. J Neurol Neurosurg Psychiatry. 2001;71:493-498.
Among the difficulties facing Parkinson patients, speech disorders are particularly vexing. Unlike bradykinesia and rigidity, parkinsonism affecting the voice usually only partially responds to treatment with dopaminergic agents. Hoarseness, hypophonia, impaired articulation, tachyphemia, and vocal freezing can markedly impair patients’ personal and professional lives, and are not uncommonly a major source of disability. The standard approach used by most neurologists is to refer these patients for speech therapy. However, once the treating neurologist writes the prescription for speech therapy, he or she usually has no way of knowing whether the therapy worked or whether benefits were maintained. In the current era of evidence-based medicine, neurologists need to know that the nonpharmacologic treatments they recommend are effective.
The current paper describes a longitudinal study of Parkinson patients treated with 1 of 2 forms of speech therapy, with follow-up over 2 years. The study asked 2 questions: is the Lee Silverman vocal technique (LSVT) superior to Respiratory Therapy (RET), and are benefits sustained over a 2-year period? RET therapy targets increased inspiratory and expiratory muscle activity as a way of increasing speech volume. LSVT targets only the volume of speech, asking patients to produce a loud voice with maximum effort. Thirty-three patients were randomly assigned to receive either RET or LSVT therapy, each of which was performed 4 times per week for 4 weeks. Patients were then expected to continue practicing the exercises on their own. They were assessed immediately after completing the therapy, and again at the end of 2 years using a standard set of speech tests (phonation, repetition, recitation of a passage). An examiner blinded to the patients’ therapeutic assignment scored them at 4 weeks and 2 years.
The LSVT significantly improved measures of vocal loudness and inflection immediately after treatment, and benefits were maintained (with slight drop-off) at 24 months. By contrast, RET therapy did not significantly improve either measure of vocal function immediately after treatment or at 2-year follow-up.
Ramig and colleagues propose that the LSVT improves speech in Parkinson’s disease by rendering speech production more efficient. Another possibility is that in addition to an underlying tendency to be hypophonic, Parkinson patients may underestimate the volume of speech that they produce. Proprioceptive and motor learning deficits are well described in Parkinson’s disease, and it is possible that the effectiveness of the LSVT results from the continuous reinforcement of the need to overcompensate for perceived softness. Whatever the mechanism, this study (and others as well) shows that the LSVT is an effective treatment for speech disorders in Parkinson patients. Neurologists who refer Parkinson patients for speech therapy are encouraged to specify LSVT on the prescription in order to maximize their patients’ outcomes. —Steven Frucht
Dr. Frucht, Assistant Professor of Neurology, Movement Disorders Division, Columbia-Presbyterian Medical Center, is Assistant Editor of Neurology Alert.