title: Validity and Reliability of Surface Electromyography in the Assessment of Primary Muscle Tension Dysphonia.
abstract: OBJECTIVE
  The study aims to evaluate the reliability and the discriminative validity of surface electromyography (sEMG) in the assessment of patients with primary muscle tension dysphonia (MTD).
  
  
  METHODS
  The study design is cross-sectional.
  
  
  METHODS
  Fifteen patients with primary MTD (mean age: 34.07 ± 10.99 years) and 15 healthy volunteers (mean age: 34.53 ± 10.63 years) were included. All participants underwent evaluation of sEMG to record the electrical activity of the thyrohyoid and cricothyroid muscles. The outcome measures were the root mean square (RMS), activity peak, duration, and time to the peak activity, which were obtained during /a/ and /i/ prolongation for test-retest reliability.
  
  
  RESULTS
  The test-retest reliability was good to excellent for the RMS and peak activity measures (intraclass correlation coefficient [agreement] [ICCagreement] = 0.49-0.98). The reliability for the activity duration was poor to excellent (ICCagreement= 0.19-0.9). Poor test-retest reliability was found for the time to peak measure (ICCagreement= 0.15-0.37). The standard error of measurement for all sEMG measures was between 0.41 and 2.05. The smallest detectable change (SDC) was calculated between 1.13 and 5.66. The highest SDC values were obtained for the peak and the lowest SDCs were documented for the duration (5.66 and 1.13, respectively). All sEMG measures were not able to discriminate between the MTD patients and healthy subjects (P > 0.05).
  
  
  CONCLUSIONS
  The sEMG is a reliable tool to measure the RMS, the peak activity, and the activity duration in primary MTD. However, it is not able to discriminate the patients with primary MTD from healthy subjects.
authors.affiliation: Department of Speech therapy, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Seyyedeh Maryam
authors.initials: SM
authors.lastname: Khoddami
authors.affiliation: Department of Physiotherapy, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran. Electronic address: talebian@tums.ac.ir.
authors.forename: Saeed
authors.initials: S
authors.lastname: Talebian
authors.affiliation: Department of Ear, Nose, Throat, Head and Neck Research Center, Hazrat-e-Rasoul Hospital, Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Farzad
authors.initials: F
authors.lastname: Izadi
authors.affiliation: Department of Physiotherapy, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Noureddin Nakhostin
authors.initials: NN
authors.lastname: Ansari
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D055154:Dysphonia / Q000175:diagnosis* / Q000503:physiopathology; D004576:Electromyography; D005260:Female; D006801:Humans; D007821:Laryngeal Muscles / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010699:Phonation; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013061:Speech Acoustics; D013997:Time Factors; D014833:Voice Quality; D055815:Young Adult
keywords: Assessment; Muscle tension dysphonia; Reliability; Surface electromyography; Validity