Occupation vocal cord dysfunction due to exposure to wood dust and xerographic toner

Objectives: Vocal cord dysfunction is a poorly understood entity that is often misdiagnosed as asthma. Both irritant and nonirritant vocal cord dysfunction have been described. This report presents two cases of irritant vocal cord dysfunction secondary to specific environmental exposure, the first to iroko and western red cedar wood (a carpenter) and the second to xerographic printing toner (a secretary). Methods: Several tests were performed, including chest radiographs, measurements of total serum immunoglobulin E, skin prick tests with common pneumoallergens (as well as iroko and western red cedar in the first case), pulmonary function studies, methacholine challenge testing, specific inhalation challenge performed with suspected agents in a single-blinded fashion, and peak expiratory flow testing and fiberoptic rhinolaryngoscopy (in case 1). Results: During the specific inhalation challenge, the patients showed dysphonia, chest tightness, inspiratory stridor, and flattening of the inspiratory limb of the maximum flow-volume loop in spirometry, with no significant decreases in the level of forced expiratory volume in 1 second; fiberoptic rhinolaryngoscopy confirmed the diagnosis of vocal cord dysfunction in case 1. Conclusions: It is important to know that agents that can cause occupational asthma can also cause vocal cord dysfunction. The mechanisms by which these agents produce vocal cord dysfunction are unknown. The differences in the clinical presentation of the patients described relative to the reported cases suggest that more than one pathophysiological mechanism may be implicated in the genesis of this entity.