Introduction The diagnosis of vocal cord dysfunction (VCD) is often difficult. Visualisation of the vocal cords using laryngoscopy is the current gold standard method of diagnosis, but may not be diagnostic if carried out when the patient is asymptomatic. An inspiratory flow volume manoeuvre performed during spirometry aids diagnosis, indicating inspiratory flow obstruction when flattened, but is subject to the same problem. Home serial spirometry (HSS), however, may improve diagnostic yield as it can be performed on demand, when the patient experiences symptoms.

Methods A retrospective review was performed of all patients referred to a District General Hospital with symptoms suggestive of VCD, between May 2005 and July 2010. Static spirometry was performed by a lung physiologist within the department. Patients were educated to perform HSS using a Jaeger Spiropro^@+ handheld spirometer immediately on experiencing symptoms. Results were downloaded when the machine was returned after a 2-week period. Direct visualisation of the vocal cords via laryngoscopy was performed by a respiratory physician.

Results 54 patients were investigated for possible VCD. A final diagnosis of VCD was made in 31 (57%) cases. Inspiratory loop flattening on static spirometry was present in 48/54 (88%) patients investigated and 28/31 (90%) confirmed cases of VCD. There was evidence of inspiratory loop flattening on HSS in 28/39 (71.7%) patients. 22/39 (56%) who had laryngoscopy were found to have evidence of VCD. 25 patients had both laryngoscopy and HSS performed: 14 of these had evidence of VCD on both tests. 3 of the positive laryngoscopy results were associated with normal HSS. There were eight cases with flattened inspiratory loops on HSS in patients in whom no abnormality was found on laryngoscopy.

Conclusion The nature of laryngoscopy, necessarily performed at one point in time, limits its value in the diagnosis of VCD. HSS is a useful non-invasive test that can increase diagnostic yield in VCD.