Chapter 4: Allergy and Immunology

CASE 4.1

A 15-year-old girl has a history of acute difficulty breathing when playing basketball. Her symptoms include inspiratory wheezing/stridor, increased respiratory rate, throat tightness, and chest discomfort. Premedication with adequate doses of albuterol has no effect.

Question 4.1.1 What is the most likely diagnosis?

A) Exercise-induced asthma.

B) Gastroesophageal reflux disease.

C) Musculoskeletal chest pain.

D) Hyperventilation.

E) Vocal cord dysfunction.

Answer 4.1.1 The correct answer is "E." Vocal cord dysfunction (VCD) is one of the most common asthma mimics. Patients with VCD present with hoarseness, coughing, dyspnea, and loud inspiratory wheezing/stridor, along with other symptoms mentioned above. Pulmonary function testing indicates airway obstruction due to an extrathoracic component. It appears that paradoxical inspiratory vocal cord adduction causes airflow restriction at the level of the larynx, resulting in a flattened inspiratory loop on flow–volume diagram. VCD presents a diagnostic challenge, and often leads to unnecessary treatment of asthma. In this patient, a β₂-agonist was ineffective, even though she displays symptoms with exertion. This argues against answer "A." The distinction between VCD and asthma may be less clear in other patients, since the two disorders sometimes coexist. The clinical history does not support the diagnoses of gastroesophageal reflux disease, musculoskeletal chest pain, or hyperventilation.

You make the diagnosis of VCD. However, the patient also complains of rhinorrhea, itchy eyes, sneezing, and itchy nose. Because you realize that we need to discuss it in this book, you kindly refer her for allergy testing (thank you!).

Question 4.1.2 With regard to radioallergosorbent testing (RAST) for allergic rhinitis, which of the following is true?

A) RAST is less expensive than traditional skin testing.

B) RAST is more sensitive than traditional skin testing.

C) RAST has a limited role in testing those with allergic rhinitis.

D) Antihistamine use is a contraindication to the use of RAST.

Answer 4.1.2 The correct answer is "C." RAST will be negative in up to 25% of those with a positive skin test, has poorly reproducible results, and is more expensive. Thus, skin testing remains the procedure of choice for identifying allergens. RAST can be used if skin testing is unavailable.

Question 4.1.3 Which of the following medications does NOT need to be discontinued prior to aeroallergen skin testing?

A) Intranasal steroid spray.

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