|Precipitators (triggers)||Exercise, extreme temperatures, airway irritants, emotional stressors||Exercise, extreme temperatures, airway irritants, emotional stressors, allergens|
|Number of triggers||Usually one||Usually multiple|
|Breathing obstruction location||Laryngeal area||Chest area|
|Timing of breathing Noises||Stridor on inspiration||Wheezing on exhalation|
|Pattern of dyspneic event period||Sudden onset and relatively rapid cessation||More gradual onset and longer recovery|
|Nocturnal awakeningwith symptoms||Rarely||Almost always|
|Response to broncho- dilators and/or systemic corticosteroids||No response||Good response|
|Flow-volume loop||Inspiratory cut-off, perhaps some expiratory limb reduction *||Reduced expiratory limb only|
|Bronchial provocation test||Negative||Positive|
|Laryngoscopic observartions||Inspiratory adduction of anterior 2/3 of vocal folds; posterior diamond-shaped chink; perhaps medialization of ventricular folds; inspiratory adduction may carry over to expiration||Vocal folds may ad-duct during exhalation|
|* When patient is symptomatic|
|Adapted from the following journal article:
Barbara A. Mathers-Schmidt. (2001). Paradoxical Vocal Fold Motion (PVFM):.
A Tutorial on a Complex Disorder and the Speech-Language Pathologist’s Role.
American Journal of Speech-Language Pathology, Volume 10, issue 2, pages 111-125