Utility of maximum phonation time in the diagnosis of spasmodic dysphonia (laryngeal dystonia)

Abstract

Abstract Objectives Maximum phonation time is a simple test used to assess glottic competency. Our objective was to evaluate any correlation between maximum phonation time and spasmodic dysphonia as adductor spasmodic dysphonia and abductor spasmodic dysphonia have an adductor and abductor overdrive, respectively. Methods A 3-year data-review was performed for patients diagnosed with adductor spasmodic dysphonia, abductor spasmodic dysphonia and mixed spasmodic dysphonia. Maximum phonation time was noted on the first visit and compared with a control group. Results Average maximum phonation time in adductor spasmodic dysphonia, abductor spasmodic dysphonia and control group was 25 seconds, 9 seconds and 16 seconds. A significant difference was found for adductor spasmodic dysphonia and abductor spasmodic dysphonia. A receiver operating characteristic curve analysis between adductor spasmodic dysphonia and control groups showed a positive predictive value of 81.3 per cent, negative predictive value of 83.9 per cent, sensitivity of 79.6 per cent and specificity of 85.2 per cent. Level of evidence = 4. Conclusion We recommend that maximum phonation time be added to the diagnostic armamentarium of spasmodic dysphonia. This correlation between maximum phonation time and spasmodic dysphonia has not been previously published.