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Submitted by Jennifer Anderson, MD MSc FRCS(C)
A 46 year old woman who was a housekeeper at a regional Ontario hospital for 17 years presented with recurrent episodic shortness of breath. These episodes would occur while in the workplace after exposure to cleaning products. The most troublesome product was Lemon Quat, a cleaning product used on the obstetrical unit.
Within seconds of exposure, the patient complained of chest tightness, shortness of breath, throat clearing, dry cough and husky voice. At the time of the first episode she was taken to the emergency department and treated with nebulized bronchodilator, intravenous steroids and antihistamines. Her symptoms resolved over several hours.
The patient returned to work after a week but continued to experience similar symptoms to varying degrees. Over the following few months, exposure to perfume, second-hand smoke, other cleaning products and exhaust fumes also provoked similar symptoms. Symptoms could last minutes to hours depending on the degree of exposure.
Her past medical history was significant for a history of gastroesophageal reflux (treated with proton-pump inhibitor) and a remote history of smoking (5 pack-year history).
The patient was started on bronchodilators by her family doctor and referred to a local respirologist. The work up revealed normal spirometry and a mildly positive methacholine challenge. The patient was tried on various bronchodilators and inhaled corticoid steroid without benefit. Extensive allergy testing was entirely negative.
Subsequent referral was made to a tertiary centre, the Voice Disorders Clinic, at St. Michael’s Hospital for multidisciplinary consultation and provocation testing.
After a detailed history regarding the initial onset, triggers, symptoms, review of prior test results and response to treatment was collected, the patient was examined with a routine otolaryngology exam. The upper airway was further assessed using video-endoscopy with provocation testing.
The detailed history revealed that the symptoms first occurred after an accidental exposure to the cleaning fluid which contained respiratory irritants (ammonium chloride, dimethyl-amine oxide and ethylenediamine) at a tenfold increased concentration than usual in an enclosed space.
Provocation testing during laryngeal endoscopy showed that after exposure, the patient showed increased laryngeal tension with supraglottic partial constriction, partial adduction (closure) of the vocal folds along with onset of dry cough within seconds of exposure to perfume, hand sanitizer and cologne. The voice quality also drastically altered and became strained, husky and dysphonic. The patient was diagnosed with irritable larynx syndrome (ILS) synonymous with the term irritant-associated vocal cord dysfunction (VCD).
This breathing disorder is clinically diagnosed based on episodic shortness of breath due to laryngeal/vocal cord adduction causing dyspnea and noisy breathing. Other common symptoms are voice change (dysphonia) and cough.
Morris and Kent reviewed 355 published reports concerning VCD and described their classification system in 20101. Broadly, the authors subcategorized VCD into Irritant Associated, Psychogenic and Exertional. In general, these three patterns are often seen in patients with a symptom complex consistent with episodic upper airway obstruction and reflect our 20-year experience at the Voice Disorders Clinic at St. Michael’s Hospital, a tertiary referral centre at the University of Toronto.
The etiology of VCD has several theories including Irritant Associated causes and neurogenic via altered sensorimotor pathways resulting in laryngeal hyper-responsiveness after exposure to airborne irritants. VCD is commonly diagnosed in patients who have other central hypersensitivity disorders such as irritable bowel syndrome and fibromyalgia2.
Psychogenic causes have also been postulated in VCD. A recent study3 described formal psychological testing in newly diagnosed VCD patients and demonstrated that VCD patients show elevated scores on hypochondriasis and hysteria compared to normal population on the MMP-2 (validated personality questionnaire). Also, female patients had higher levels of negative stress. Interestingly, approximately 27% of VCD patients had normal results on the psychological testing. In another report4, up to 73% of VCD patients will have a previous or current psychiatric diagnosis.
Exertional VCD may be associated with structural pathology in some patients wherein the supraglottis (epiglottis and aryepiglottic folds approximating) shows partial collapse during maximal exertion and is more commonly identified in young female athletes5. The European Laryngological Society formed a consensus group and has described this as exertional induced laryngeal obstruction (EILO). Flexible nasendoscopy performed during exercise shows laryngeal airflow obstruction observed at the supraglottis during maximal inhalational effort. Behavioural therapy or respiratory retraining is often beneficial with a smaller subset showing improvement after a surgery (supraglottoplasty)5 to reduce collapse of the epiglottis.
Other associated morbidities include asthma (up to 30%) rhinitis/sinusitis (post-nasal drip), gastroesophageal reflux (20-50%) and migraine headache.
The investigations performed in the patient group are the common respiratory assessment tools since most patients are initially treated for possible reactive airway disease. Spirometry, methacholine challenge, allergy testing and occasionally chest Computerized Tomography (CT) scan are done in this patient population, usually prior to being evaluated by a laryngoscopy provocation test.
Other useful investigations include CT of the sinuses in those with prominent rhinosinusitis, and sputum analysis and/or serum for Immunoglobulin E (IgE).
The majority of patients diagnosed and treated at our centre are ILS or irritant-associated VCD after asthma has either been excluded or treated without sufficient improvement.
The principles for management include:
Level 1: Minimize sensory stimuli:
Level 2: Behavioural:
Level 3: Medical:
In general, with the treatment of comorbidities and the management principles above applied, it is our experience that in compliant patients the majority of individuals improve, but rarely do the symptoms entirely resolve. Behavioural therapy has been a keystone for treatment wherein the patient gains understanding of their symptoms and contributing factors. Therapy focuses on awareness, exercises and strategies to reduce frequency and severity of symptoms. This typically reduces isolation and anxiety around their triggers. If the patient has not been working due this condition, 75% of our patients diagnosed with ILS/VCD have been able to return to work, although commonly there have been modifications to the workplace.
Figure 1. Widely abducted vocal cords during inspiration
Figure 2. Partial adduction of vocal folds during inspiration while undergoing provocation testing with perfume.