Direct or Objective Evaluation of Nasal Function: Nasal Mucosal Microscopy, Mucociliary Transport, Flow Rhinometry, Acoustic Rhinometry and Olfactory Assessment

Abstract

Anterior rhinoscopy, nasal endoscopy, skin prick test, nasal cytology, specific IgE analysis, rhinomanometry, acoustic rhinometry, olfactory screening, mucociliary transport, and imaging studies comprise the tools readily available to the otolaryngologist and allergist to use to clarify/confirm a diagnosis of rhinitis and/or rhinosinusitis.

Nasal cytology functions as an aid in differentiating allergic, nonallergic and infectious rhinitis, viral and bacterial infections, and inflammatory and noninflammatory formats of rhinitis. The in-office methods for obtaining a sample of nasal secretions are nose blowing or lavage. Nasal mucous, mucosa, and submucosa are obtained by swabbing, brushing, or scrapping the nasal surface or through a biopsy. Wright-Giemsa is an easy and accurate staining method for all nasal cytologic specimens. Hansel stain is the simplest to perform if only the identification of eosinophils is desired. The presence of squamous epithelial cells suggests that the specimen was taken from the nasal vestibule or anterior tip of the inferior turbinate and has no diagnostic value. The presence of non-squamous epithelial cells suggests a properly obtained specimen. Non-squamous cells are ciliated and non-ciliated columnar cells, goblet cells, and basal cells. The identification of neutrophils, intracellular bacteria, eosinophils, mast cells, basophils, monocytes, and lymphocytes each denotes a format of immune-mediated activity when sampled with a scrapping technique and stained with Wright-Giemsa.

Trapped noxious chemicals, particulates, and pathogens are removed from the airway before they can invade the mucosa by a mechanism termed mucociliary clearance, mucociliary transport, or mucociliary escalator. Functional screening assays of mucociliary transport include the saccharine granule test, charcoal tablet test, and rhinoscintigraphy.

Objective measures of nasal airway patency can be useful in assisting the clinician by assessing airway patency at baseline using pre- and post-decongesting evaluation and assessing airway patency in serial fashion over time to track a patient’s response to therapy and to monitor for early signs of disease recrudescence. For measuring nasal patency, two forms of measurement are commonly used: rhinomanometry and acoustic rhinometry. Rhinomanometry describes airway patency based on nasal airflow and airway resistance measurements. Acoustic rhinometry estimates patency based on the measurement of reflected sound waves (echo) that emerge from various portions of the nasal cavity. In patients where there is a question of etiology for nasal congestion or when trying to delineate which patient may be a candidate for a surgical intervention, rhinometry can provide additional data that confirms and localizes an obstruction.

Derangement of sense of smell is associated with a myriad of nasal/sinus/and other pathologies as well as topical and systemic medication use. Odor molecules bind an “odor-presenting intermediary,” and this complex activates olfactory neurons, with signal propagation to olfactory bulb, then on to the cerebrum, and ultimately the conscious “experience” of olfaction. A variety of scratch and sniff screening smell tests are commercially available for office use.