What's VCD? I didn't even know it existed until last week, so don't feel embarrassed. Also known as laryngeal dysfunction, paradoxical vocal cord motion, laryngeal dyskinesia, vocal cord malfunction and a number of medicalese terms, this tricky little guy masquerades most commonly as the everyman of respiratory conditions, asthma. (And from the dawn of the 20th century to today, occasionally it's diagnosed as hysteria. It's all in your head, person who can't breathe, it's all in your head.)
First, a quick anatomy lesson. Your larynx has two main functions: protect your trachea by preventing aspiration during both respiration and swallowing, and allow vocal communication (through your vocal cords).
So, what is VCD? According to this paper, it is "a condition where the larynx exhibits paradoxical vocal cord adduction during inspiration, resulting in any of a number of symptoms that would be expected from extrathoracic airway obstruction, including, wheezing, dyspnea, cough, and shortness of breath." Or more clearly, "The adduction of vocal cords with an open glottic chink in a patient experiencing dyspnea. In VCD the vocal cords adduct anteriorly from the vocal process, and the posterior glottic chink remains open. The adduction occurs during inspiration or in both the inspiratory and expiratory phases."
Ok, maybe not so clear. Translation: when you breathe, your vocal cords are open (see A in the figure), allowing air to pass through. But in people with VCD, when they breathe, their vocal cords paradoxically (hence paradoxical vocal cord motion) constrict (see B in the figure, encircled), leaving a small "chink" or diamond space that severely restricts airflow.
You can actually see the characteristic "chink" via the gold standard for diagnosis, laryngoscopy (also called videostroboscopy) - a physician sticks a mini telescope through your mouth or nose and asks you to talk/make sounds. The telescope magnifies and records your vocal cords working in slow motion. (Check out this 2 minute video of a videostroboscopy in action. Seriously cool.)
The problem: while some physicians know about the disease, it's often not on the tip of their tongue when someone comes in with symptoms mimicking asthma. But you can't blame them - the symptoms are pretty much the same:
- Shortness of breath
- Chronic cough and/or throat clearing
- Chest and/or throat tightness
- difficulty inhaling (most common)
- difficulty exhaling (less common; usually irritant-induced)
- panic, anxiety, fear of suffocating
- insufficient oxygen in the blood
- feeling like something is stuck in the throat
More problems: sometimes VCD can be secondary to underlying conditions like GERD, ALS, brainstem compression, myasthenia gravis and others.
A clue for physicians is a patient's response to asthma medication. A patient with asthma will respond to bronchodilators and/or steroids; patients with VCD often will have reduced or no response.
What do we know?
At first, not much. But the National Jewish Medical and Research Center did some pioneering work starting in the 1980s and since then researchers have been plugging away.
An example of a study exploring misdiagnosis of VCD is Boris et al. Allergy Asthma Proc. 2002 Mar-Apr;23(2):133-9.The researchers evaluated 158 patients referred to an allergy practice with a diagnosis of asthma. The patients were separated in four groups by their pulmonary function as assessed with flow volume loops. 32 percent had asthma alone, 16 percent had asthma and laryngeal dysfunction, 26 percent had laryngeal dysfunction alone, and 25 percent didn't meet study criteria. The patients were treated with antireflux meds (a common concomitant condition in asthmatics) and inhalers. In the laryngeal only group, 73 percent had trouble breathing in (and 71 percent had trouble breathing out), compared with only 2 percent in the asthma only group (7 percent breathing out) (p < 0.0001). The
laryngeal dysfunction group only had a 29 percent beneficial response to Albuterol inhalation compared with a 92 percent response in the asthma group (p < 0.0001). The laryngeal dysfunction group responded significantly less to both inhaled and oral steroids (p = 0.002).
A number of case studies and reviews have been published - see Ibrahim et al., Postgrad Med J. 2007 Mar;83(977):164-72, for a recent overview.
What can we do?
This is the tricky part. Unlike asthma, you can't aerosolize a therapy for VCD. At this point we just have speech therapy and in some cases psychotherapy (for patients whose condition is accompanied by panic attacks and hysteria). Speech therapy techniques are aimed at focusing attention on exhalation and breathing with your abdomen rather than inhaling and breathing with your throat/lungs. Relaxation techniques are important too, helping to relax the neck, shoulder and chest muscles to promote "normal" breathing. Physician education - both educating the physician, and the physician educating the patient - is part of the management.
If you're in or near Colorado, you're in luck: the National Jewish Medical and Research Center is a leader in the field, both in research and treatment.