(1218) CT Identification of Static and Dynamic Internal Nasal Valve Collapse

Introduction: When performing surgery to improve the nasal airway it is necessary to distinguish between static and dynamic internal nasal valve collapse (INVC) so that the proper procedure is performed. Coronal CT images can distinguish between both types of internal nasal valve collapse with a high degree of reliability.

Methods: The modified Cottle maneuver is used to distinguish between static and dynamic INVC by performing it two different ways. As initially described, the upper lateral cartilage is elevated with a curette, allowing the airway to be assessed during inspiration. If positive, a diagnosis of static INVC is made. The second method is to use the curette to support the upper lateral cartilage during inspiration, preventing collapse. If positive, a diagnosis of dynamic INVC is made.

Results: Because CT scanning requires static images, they are obtained during the resting phase between breaths. Nasal occlusion at that moment is consistent with static collapse, whereas maintenance of airway patency suggests dynamic collapse. Our approach is to view the images from anterior to posterior. Initially a single air channel is identified on each side. Prior to the nasal bones appearing, if the caudal aspect of the upper lateral cartilage contacts the septum criteria are met to establish a diagnosis of static INVC. Two air chambers are seen, a smaller superior one and a larger inferior one. Lateral nasal wall contact with the septum, not solely attributable to the septum, confirms the diagnosis. The face of the inferior turbinates usually appear after the two air chambers have appeared. Posterior to the internal nasal valve, a single air channel re-appears. Axial images often correlate well but are less demonstrative.

Conclusions: Coronal CT images identifying a single anterior chamber that becomes two distinct channels in the vicinity of the anterior aspect of the nasal bones, that subsequently becomes one chamber, is pathognomonic of static internal nasal valve collapse.