Nasal Obstruction and Nasal Valves

Nasal obstruction is a common complaint in the practice of Otolaryngology. Billions of dollars are spent on the surgical treatment of this complaint.

Nasal obstruction is a symptom, not a diagnosis, and there are a range of medical and structural conditions that can cause such symptoms.

There are four nasal valves or flow limiting segments: external valve, internal valve, septal valve, and inferior turbinates.

Either a narrow or a very wide nasal passage can affect the air column. When the normal, turbulent air flow pattern is disturbed, it is perceived as nasal obstruction. This helps explain the few patients that complain of persistent nasal obstruction in the postoperative period even with a widely patent nasal passage.

Airflow within the nose is both smooth and turbulent. Each flow component is important in the perception of "normal" nasal function. Smooth airflow provides movement of air toward the lower respiratory tract. Turbulent airflow causes eddied currents within the nostril. This allows for the distribution of the air column across a larger surface area for conditioning and for the air to reach the olfactory area.

The paired external valves consist of the lower lateral cartilage, the columella, and the nasal floor. Active dilatation of this valve occurs with each inspiration by action of the nasalis muscles. Malfunctions in this area can be the result of trauma, facial nerve palsies or congenital anomalies of the alar cartilage.

The paired internal valves consist of the caudal end of the upper lateral cartilage, the nasal septum, and the soft tissue surrounding the piriform aperture. This valve is located at the anterior end of the inferior turbinate. The aging process can adversely affect the internal valve function by decreasing tissue elasticity and causing further collapse.

The nasal septal valve is composed of the perpendicular plate of the ethmoids posteriorly, the quadrangular cartilage anteriorly, and the vomer inferiorly.

The maxillary crest and palatine bones complete the septal floor. The septum is uniquely constructed to absorb direct trauma. The quadrangular cartilage articulates directly with the bone posteriorly and inferiorly. Direct cartilage-bone articulation is rare without intervening ligaments and it is this unique construction that allows more lateral mobility.

Studies show that anterior deflections of the septum account for most of nasal symptoms associated with septal deformities. Smaller, anterior deflections are much more important in the perception of nasal airflow than larger posterior deformities.

The inferior turbinates contain special erectile tissue consisting of venous sinusoids surrounded by smooth muscle. There is a normal nasal cycle in which this erectile tissue vasodilates and vasoconstricts. The cycle occurs approximately every four hours, first one side then the other. Although the nasal cycle is a normal phenomenon, this pattern can sometimes be confused as obstructive symptoms.