By: Jack D. Sedwick M.D.
Nasal airway patency is greatly dependent on the physical structure of the nose. Many individual aspects of the nasal cavity collectively affect nasal function. One of the difficulties in effectively managing nasal airway obstruction is determining what factors — both anatomic and physiologic — are the primary cause of the airway obstruction.
Causes of nasal airway obstruction
Nasal airway resistance accounts for more than 50 percent of total airway resistance. Therefore, effective treatment of the nasal airway can have a major effect on overall airway obstruction. The causes of nasal airway obstruction are varied and include:
• Septal deviation
• Turbinate hypertrophy
• Rhinoplasty
• Septal perforation
• Valvular collapse
• Choanal atresia
• Neoplasm
• Polyposis
• Allergic rhinitis
• Septal hematoma
• Rhinitis medicamentosa
• Vasomotor rhinitis
• Sinusitis
A discussion of the work-up and management of all causes of nasal airway obstruction is beyond the scope of this review. It is important to keep all the above causes of nasal airway obstruction in mind when treating patients with complaints of nasal airway obstruction. Often, more than one of these causes of nasal airway obstruction may be affecting a patient’s breathing, and only by addressing each of these causes is the patient going to get maximum improvement.
 The nasal valves
Of all the causes of nasal airway obstruction the nasal valves may be the most often overlooked. This is unfortunate, as surgical treatment can frequently effectively treat a narrow nasal valve and give patients a lifetime of easy nasal breathing.
The nasal valve can be thought of as two distinct areas of obstruction: the internal nasal valve and the external nasal valve. The external nasal valve is the lateral wall of the nasal vestibule, the first component of nasal resistance. The nasal vestibule is composed of compliant walls that are liable to collapse from the negative pressures generated during inspiration. The lateral wall of the nasal vestibule is primarily supported by the lower lateral alar cartilage and its musculofibrous attachments. [figure 1]
Despite the tendency, airway collapse is prevented by activation of the dilator naris muscles during inspiration. During expiration, positive pressure is the driving force for nasal vestibule dilation. Weakening of this very delicate external nasal valve can lead to severe nasal airway obstruction.
A second area of major resistance occurs at the anterior tip of the inferior turbinate at the entrance to the piriform aperture (internal nasal valve). The floor of the internal nasal valve is the nasal floor; the roof the upper lateral cartilage, the lateral wall is the inferior turbinate and the medial wall is the septum. The internal nasal valve represents the narrowest segment of the airway.
Disorders: mucocutaneous and anatomic/structural
Further, the etiologies of nasal valve dysfunction can be thought of as mucocutaneous and anatomic or structural disorders.
The mucocutaneous component refers to the mucosal or nasal lining swelling due to allergic, vasomotor or infectious rhinitis. These problems with the nasal lining can significantly decrease the cross-sectional area of the nasal valve and thus reduce nasal airway flow.
The anatomic or structural component refers to any abnormalities in the structures that define the nasal valve. For the internal nasal valve this includes the nasal septum, upper lateral cartilage, piriform aperture, head of the inferior turbinate and floor of the nose. For the external nasal valve this would include the lower lateral cartilage and fibroareolar tissue of the nasal ala or the sidewall of the nasal vestibule.
The anatomic or skeletal components can be further divided into static and dynamic nasal dysfunction. Static dysfunction is secondary to continuous obstruction at the level of the nasal valve. This can be due to fixed problems such as a deviated septum, inferior turbinate hypertrophy, or inferomedially displaced upper lateral cartilage. Dynamic dysfunction is obstruction that varies in severity with respiratory effort and is usually related to deficiencies in the structural support of the lateral nasal wall (external nasal valve), including the cartilaginous, fibroareolar tissue, and muscular components. The lateral nasal wall caudal to the bony arch is mobile and responds variably to pressure changes.
Identifying nasal valve dysfunction
Identification of patients with nasal valve dysfunction can be difficult. Other more common causes of nasal airway obstruction should always be evaluated and treated as well. The classic maneuver in the evaluation of nasal valve collapse is the standard Cottle maneuver, which is used to assess nasal valve incompetence by judging improvement in nasal breathing with lateral distraction of the ipsilateral cheek. The problem with the standard Cottle maneuver is the results can be nonspecific. A straightforward narrowing of the nasal airway produced by septal deviation or turbinate hypertrophy is improved by the Cottle maneuver. Anterior rhinoscopy is also a poor means of accurately evaluating subtle changes in nasal valve anatomy; the dysfunctional nasal valve can be missed due to distortion from the nasal speculum.
 A more precise diagnosis can be made based on direct inspection of valvular support during quiet and forced inspiration. Collapse at the internal nasal valve is usually diagnosed based on the identification of medialization of the caudal margin of the upper lateral cartilages due to negative pressure created upon inspiration through the nose. A fine swab or cerumen curette may be used to lateralize the upper lateral cartilage to confirm the presence of internal valvular collapse. External nasal valve collapse can be diagnosed based on observation of the nostril margin to determine if the alar collapses with moderate-to-deep nasal inspiration. One nostril can be occluded to facilitate this maneuver. Next, a modified Cottle maneuver can be performed with a cerumen curette or cotton swab placed intranasally to support the external nasal valve to determine specifically if improvement in nasal airflow results. Minimal distraction of a collapsed internal valve or stabilization of the external valve during inspiration can dramatically increase airflow. [figure 2]
Treatment
 Once nasal valvular dysfunction is identified the physician should seek out any mucocutaneous component to the nasal obstruction and treat it aggressively with medication. In some cases, treatment of the mucocutaneous component will be enough to allow the patient to breath normally. The cross-sectional area of the nasal valve — and, thus, nasal airway patency — can be significantly increased if mucosal swelling is reversed.
Once nasal valvular dysfunction, secondary to mucocutaneous abnormalities, has been adequately treated, structural defects of the internal and external nasal valves can be considered for surgical repair. The anatomic sites of abnormalities include the septum, upper and lower lateral cartilage, floor of the nose, head of the inferior turbinate, or a combination of these sites. In most instances, functional rehabilitation requires reconstruction of the incompetent nasal valve with a cartilage implant. [figure 3]
Augmentation and reconstruction
Autologous cartilage continues to be the preferred material for nasal augmentation and reconstruction grafting. Because the tissue is autologous, it carries little risk of disease transmission, immunomodulation, rejection, or toxicity. Autologous tissue has a lower rate of infection as well.
Despite the free nature of these grafts, graft loss is very uncommon. Nasal septal cartilage is the first choice for use as grafting material; however, prior surgical excision or trauma may preclude the use of septal cartilage. The next choice of autologous graft material is ear conchal cartilage. Conchal cartilage is often brittle and difficult to sculpt and may be insufficient when significant dorsal augmentation is required. Costal cartilage can provide large amounts of donor cartilage for grafting but is used infrequently because of the attendant chest scar and the risk of pneumothorax. Split calvarial bone grafts can be used in some cases. Other alloplastic materials can be used but they have other increased risks of rejection and are usually a second choice.
Surgical management is tailored to the problems diagnosed and usually includes cartilage grafting, using spreader grafts, batten grafts and columellar strut grafts. (Fig. 1 shows placement of batten grafts; Figs. 2 and 3 show placement of spreader grafts.) Other techniques are used on a case-by-case basis.
The big picture
Most nasal airway obstruction can be effectively treated. Collapse of the nasal valve is a relatively uncommon — but important — cause of nasal airway obstruction. In cases where nasal valve collapse is suspected, referral to an otolaryngologist or facial plastic surgeon can be helpful.
 Jack Sedwick, M.D., practices in Anchorage with the Alyeska Center for Facial Plastic Surgery. He is board-certified in both facial plastic surgery and otolaryngology. He can be reached for new patients or referrals at 561-1421.
Published July 2006, Physician Practice.
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