title: Inhaled Mannitol as a Laryngeal and Bronchial Provocation Test.
abstract: OBJECTIVE
  Timely diagnosis of vocal cord dysfunction (VCD), more recently termed "inducible laryngeal obstruction," is important because VCD is often misdiagnosed as asthma, resulting in delayed diagnosis and inappropriate treatment. Visualization of paradoxical vocal cord movement on laryngoscopy is the gold standard for diagnosis, but is limited by poor test sensitivity. Provocation tests may improve the diagnosis of VCD, but the diagnostic performance of current tests is less than ideal. Alternative provocation tests are required. This pilot study demonstrates the feasibility of using inhaled mannitol for concurrent investigation of laryngeal and bronchial hyperresponsiveness.
  
  
  METHODS
  Consecutive patients with suspected VCD seen at our institution's asthma clinic underwent flexible laryngoscopy at baseline and following mannitol challenge. VCD was diagnosed on laryngoscopy based on inspiratory adduction, or >50% expiratory adduction of the vocal cords. Bronchial hyperresponsiveness after mannitol challenge was also assessed. We evaluated the interrater agreement of postmannitol laryngoscopy between respiratory specialists and laryngologists.
  
  
  RESULTS
  Fourteen patients with suspected VCD in the context of asthma evaluation were included in the study. Mannitol provocation demonstrated VCD in three of the seven patients with normal baseline laryngoscopy (42.9%). Only two patients had bronchial hyperresponsiveness. There was substantial interrater agreement between respiratory specialists and laryngologists, kappa = 0.696 (95% confidence interval: 0.324-1) (P = 0.006).
  
  
  CONCLUSIONS
  Inhaled mannitol can be used to induce VCD. It is well tolerated and can evaluate laryngeal and bronchial hyperresponsiveness at the same setting.
authors: Department of Allergy, Immunology and Respiratory Medicine, The Alfred Hospital, Melbourne, Victoria, Australia. Electronic address: tunn_ren_tay@cgh.com.sg.
authors: Tunn Ren
authors: TR
authors: Tay
authors: Department of Allergy, Immunology and Respiratory Medicine, The Alfred Hospital, Melbourne, Victoria, Australia.
authors: Ryan
authors: R
authors: Hoy
authors: Department of Otolaryngology, Head and Neck Surgery, The Alfred Hospital, Melbourne, Victoria, Australia.
authors: Amanda L
authors: AL
authors: Richards
authors: Department of Otolaryngology, Head and Neck Surgery, The Alfred Hospital, Melbourne, Victoria, Australia.
authors: Paul
authors: P
authors: Paddle
authors: Department of Allergy, Immunology and Respiratory Medicine, The Alfred Hospital, Melbourne, Victoria, Australia.
authors: Mark
authors: M
authors: Hew
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D001249:Asthma / Q000175:diagnosis* / Q000503:physiopathology; D016535:Bronchial Hyperreactivity / Q000175:diagnosis* / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D016084:Bronchoconstriction; D003937:Diagnosis, Differential; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007826:Laryngismus / Q000175:diagnosis* / Q000503:physiopathology; D007828:Laryngoscopy; D008297:Male; D008353:Mannitol / Q000008:administration & dosage* / Q000009:adverse effects; D008875:Middle Aged; D015588:Observer Variation; D010036:Otolaryngology; D010865:Pilot Projects; D011237:Predictive Value of Tests; D000072106:Pulmonologists; D015203:Reproducibility of Results; D013038:Specialization; D064706:Vocal Cord Dysfunction / Q000175:diagnosis* / Q000503:physiopathology; D014827:Vocal Cords / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D008353:Mannitol
keywords: Asthma; Larynx; Mannitol; Paradoxical vocal fold motion; Vocal cord dysfunction