The most effective diagnostic strategy is to perform laryngoscopy during an episode, at which time abnormal movement of the<unk> s, if present, can be observed. If the endoscopy is not performed during an episode, it is likely that the vocal folds will be moving normally, a 'false negative' finding. Spirometry may also be useful to establish the diagnosis of<unk>  when performed during a crisis or after a nasal provocation test. With spirometry, just as the expiratory loop may show flattening or concavity when expiration is affected in asthma, so may the Inspiratory loop show truncation or flattening in<unk> . Of course, testing may well be negative when symptoms are absent. Differential diagnosis The symptoms of<unk>  are often inaccurately attributed to asthma, which in turn results in the unnecessary and futile intake of corticosteroids, bronchodilators and leukotriene modifiers, although there are instances of comorbidity of asthma and<unk> . The differential diagnosis for<unk>  includes vocal fold swelling from allergy, asthma, or some obstruction of the vocal folds or throat. Anyone suspected of this condition should be evaluated and the vocal folds (voice box) visualized. In individuals who experience a persistent difficulty with inhaling, consideration should be given to a neurological cause such as brain stem compression, cerebral palsy, etc. The main difference between<unk>  and asthma is the audible stridor or wheezing that occurs at different stages of the breath cycle:<unk>  usually causes stridor on the inhalation, while asthma results in wheezing during exhalation. Patients with asthma usually respond to the usual medication and see their symptoms resolve. Clinical measures that can be done to differentiate<unk>  from asthma include: * rhinolaryngoscopy: A patient with asthma will have normal vocal<unk>  movement, while one with<unk>  will display vocal<unk>  abduction during inhalation * spirometry: A change in the measure following the administration of a bronchodilator is suggestive of asthma rather than<unk>  * chest radiography: The presence of hyperinflation and peribronchial thickening are indicative of asthma, as patients with<unk>  will show normal results
Vocal cord dysfunction
Vocal cord paresis
Velopharyngeal insufficiency
Laryngotracheal stenosis
Pulmonary hypoplasia
Tracheomalacia
Congenital limb deformities
Tracheal agenesis