Characteristics of Adduct Spasmodic Dysphonia and Muscle Tension Dysphonia Using Spectrogram / 대한이비인후과학회지

ABSTRACT

BACKGROUND AND OBJECTIVES: Adduct spasmodic dysphonia (ADSD) is a neurogenic and focal laryngeal dystonia resulting in a strained voice quality with spastic voice breaks. While muscle tension dysphonia (MTD) is caused by functional voice disorders, its symptoms are similar to those of ADSD. Because the approaches of treatment for ADSD and MTD are radically different, accurate evaluations are necessary for precise diagnosis. A spectrogram analysis for differentiating ADSD from MTD provides differentiations on four spectral findings (abrupt voice breaks, irregular wide-spaced vertical striations, well-defined formants and high-frequency spectral noise). The aim of this study was to evaluate if the spectrogram could provide detailed information on the visual characteristics that distinguish ADSD and MTD. SUBJECTS AND METHOD: 11 female patients of ADSD and 13 female patients of MTD who were diagnosed by laryngoscope and stroboscope from 2009 through 2012 were selected for this study. The speech samples of subjects were obtained using Computerized Speech Lab. The two speech therapists evaluated a wide-band (300 Hz) spectrogram by blind test using 4 scales (0-3 point) for four spectral findings. RESULTS: Abrupt voice breaks and irregular wide-spaced vertical striations of ADSD were significantly higher than those of MTD. Well-defined formants and high-frequency spectral noise were not found significantly different between two groups. CONCLUSION: The spectrograms provided visual perceptual information needed to differentiate ADSD from MTD. Voice therapy to reduce hypertension could be considered for patients of ADSD with excessive formants and noise. If spectrogram analysis were used along with other assessments, it would be more useful in distinguishing ADSD from MTD.