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Keywords:

  • Spasmodic dysphonia;
  • laryngeal resistance;
  • airflow interruption;
  • mean flow rate;
  • subglottal pressure

Abstract

Objectives/Hypothesis:

To measure the laryngeal resistance (RL), subglottal pressure (Ps), and mean flow rate (MFR) of adductor (ADSD) and abductor (ABSD) spasmodic dysphonia patients using the airflow interrupter.

Methods:

The RL of six ABSD and seven ADSD patients was measured using the airflow interrupter, a noninvasive device designed to measure MFR and Ps via mechanical balloon valve interruption. Subjects performed 10 trials at each of two intensity levels, with each trial consisting of a sustained /a/ during which phonation was interrupted for 500 ms. Laryngeal resistance was calculated as subglottal pressure divided by airflow.

Results:

Mean RL for the ADSD and ABSD subtypes at 65 dB were 24.78 cmH2O/L/s and 14.51 cmH2O/L/s, respectively (P = .04). Mean RL at 70 dB were 40.02 cmH2O/L/s and 15.84 cmH2O/L/s (P = .014). Ps for the ADSD and ABSD subtypes at 65 dB were 10.23 cmH2O and 8.32 cmH2O, respectively (P = .582). At the 70 dB level, Ps were 12.39 cmH2O and 11.78 cmH2O (P = .886). MFR for the ADSD and ABSD subtypes at 65 dB were 435 mL/s and 746 mL/s (P = .205). Mean MFR at 70 dB were 518 mL/s and 848 mL/s (P = .198).

Conclusions:

Noninvasive measurements of RL may be useful for differentiating between ADSD and ABSD. This simple objective test, which produces a quantitative output, could be used to evaluate laryngeal function in patients with spasmodic dysphonia. Laryngoscope, 2009