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Background: In tertiary Airways services, patients with a confirmed diagnosis of vocal cord dysfunction (VCD) can report symptomatic nocturnal wakening. Nocturnal wakening with breathlessness is typically associated with uncontrolled asthma or sleep apnoea. However, VCD can co-occur with, or be misinterpreted as, asthma. Although VCD is usually only considered as a diagnosis during awake states, previous case reports have suggested possible nocturnal symptoms of VCD. Aims and Objectives: To replicate and describe symptoms of nocturnal breathlessness and stridor in two patients, and assess whether symptoms correspond with VCD. Methods: Intravenous midazolam was administered to induce sedation during nasendoscopy in two patients with severe confirmed VCD who reported nocturnal stridor and frequent nocturnal wakening. Neither patient had uncontrolled asthma or reflux, and both responded well to respiratory speech and language therapy intervention (rSLT) to control daytime symptoms. Results: Prior to sedation, normal baseline laryngeal movement was evident. Following sedation, both patients developed inspiratory vocal cord adduction with stridor, as seen on nasendoscopy. There was very limited generalisation of daytime control of VCD symptoms (with rSLT techniques) to nocturnal presentation. Conclusions: Differential diagnosis can be challenging yet important to reduce inappropriate medical treatment and morbidity. These cases highlight the need for further understanding of VCD in complex breathlessness management. We suggest consideration of investigation of nocturnal VCD symptoms via full video sleep studies to improve understanding of potential mechanistic drivers.

Background: Differential diagnosis of asthma and VCD can be challenging. Previous research (e.g. Newman, Mason & Schmaling, 1995) has suggested a number of risk factors for VCD. Aims and Objectives: To compare co-morbidity characteristics of patients with complex breathlessness referred to a tertiary Airways service. To analyse whether specific factors are associated with an increased likelihood of confirming a diagnosis of VCD. Methods: Descriptive and correlational statistics were used to analyse patient characteristics and co-morbid factors in a sample of 155 patients, of whom 83 had confirmed VCD. A logistic regression analysis was used to identify significant predictor variables for VCD. Results: The majority of patients diagnosed with VCD were female (72%). A high proportion of these patients had reflux (49%), rhinitis (41%) and/or co-morbid asthma (33%). Partial correlations showed that Forced Vital Capacity percent (FVC%) within lung function tests was significantly correlated with a diagnosis of VCD (rs= 0.329, n=73, p=0.005). Age, gender, reflux, rhinitis and Forced Expiratory Volume 1 percent were not significantly correlated with VCD diagnosis. A logistic regression was performed to assess the impact of FVC% on diagnosis of VCD. The model was significant: χ 2 (1, N=73) =10.38, p=0.001. The model explained between 13.3% and 21.8% of the variance in VCD diagnosis, and correctly classified 83.6% of cases. Conclusions: A number of possible co-morbid factors were identified. Lung function, as described by FVC%, was found to be a significant predictor for VCD diagnosis in a sample of patients with complex breathlessness. This measure may be useful in the differential diagnosis of asthma and VCD.