title: Long-term phonatory instability in ataxic dysarthria.
abstract: OBJECTIVE
  Long-term phonatory instability can be quantified using cyclical and noncyclical measures. The objective of this study is to evaluate phonation in ataxic dysarthria and a control group of normal speakers to answer two main questions: (1) How common is elevated cyclical and noncyclical instability in ataxic dysarthria compared to that in a normal control group? (2) Is cyclical instability predictive of noncyclical instability?
  
  
  METHODS
  Vowel prolongations of ataxic-dysarthric and normal speakers were compared using the Motor Speech Profile module of the Computerized Speech Lab. Cyclical measures included tremor rate, amplitude and periodicity. Noncyclical measures included the coefficient of variation for loudness and frequency.
  
  
  RESULTS
  Noncyclical measures are elevated in a subset of speakers with ataxic dysarthria regardless of whether cyclical instability (vocal tremor) is present. Cyclical instability was detected in nearly half the patients. Interestingly, elevations in both types of measures also described phonation of a number of the participants in the control group.
  
  
  CONCLUSIONS
  Combined use of cyclical and noncyclical measures can document aspects of phonation in ataxic dysarthria that have clinical implications.
authors.affiliation: University of Oklahoma Health Sciences Center, Oklahoma City, 73117-1215, USA. Frank-Boutsen@ouhsc.edu
authors.forename: Frank
authors.initials: F
authors.lastname: Boutsen
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Duffy
authors.forename: Hani
authors.initials: H
authors.lastname: Dimassi
authors.forename: Sarah S
authors.initials: SS
authors.lastname: Christman
mesh_terms: D000328:Adult; D000368:Aged; D002524:Cerebellar Ataxia / Q000150:complications* / Q000503:physiopathology; D002908:Chronic Disease; D004401:Dysarthria / Q000209:etiology*; D055154:Dysphonia / Q000209:etiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007821:Laryngeal Muscles / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010507:Periodicity; D010700:Phonetics; D013018:Sound Spectrography; D013061:Speech Acoustics; D014202:Tremor / Q000209:etiology* / Q000503:physiopathology; D014833:Voice Quality