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This study examined the effects of intensive voice treatment (the Lee Silverman Voice Treatment [LSVT(R)]) on ataxic dysarthria in a woman with cerebellar dysfunction secondary to thiamine deficiency. Perceptual and acoustic measures were made on speech samples recorded just before the LSVT program was administered, immediately after it was administered, and at 9 months follow-up. Results indicate short- and long-term improvement in phonatory and articulatory functions, speech intelligibility, and overall communication and job-related activity following LSVT. This study's findings provide initial support for the application of LSVT to the treatment of speech disorders accompanying ataxic dysarthria. Potential neural mechanisms that may underlie the effects of loud phonation and LSVT are addressed.
Key Words: ataxia, dysarthria, voice treatment, voice disorders, neurologic disorders
Ataxic dysarthria is a motor speech disorder associ- ated with cerebellar dysfunction. The dysarthria appears to be related to a disturbance in the neural mechanisms that underlie the coordination, temporal regulation, and quasi-automatic control of respiratory, phonatory, and articulatory movements for speech. The symptoms of ataxic dysarthria vary, and may include any, or a combination, of the following abnormalities: imprecise articulation, momentary irregular articulatory breakdowns, slow rate of speech, excess and equal stress, monoloudness, monopitch, prolonged syllables, irregular intrasyllabic voice fundamental frequency (F0) inflections, and breathy, weak, or unstable voice. Physiologic studies of ataxic dysarthria have documented slow movements, temporal dysregulation, errors of direction and range of movements, impaired ability to increase muscular forces in order to produce rapid movements, and reduced or exaggerated range of movements involving the respiratory, phonatory, or articulatory systems. These abnormalities may be accompanied by other signs of cerebellar dysfunction, such as hypotonia, broad-based stance and gait, truncal instability, dysmetria, tremor, and dysdiadochokinesis (Duffy, 1995; Kent et al, 2000).
Past studies of the treatment of ataxic dysarthria have reported only modest or limited improvement in speech intelligibility or naturalness when treatment was geared toward teaching the patient to change and monitor specific parameters such as articulatory precision, rate, stress patterning, or pitch inflection (Duffy, 1995; Yorkston, Hammen, Beukelman, & Traynor, 1990). This lack of improvement may be related to the important role the cerebellum plays in motor learning and control. Based on recent studies (e.g., Blakemore, Frith, & Wolpert, 2001; Topka, Massaquoi, Benda, & Hallett, 1998), it appears...