Frontal sinus disease. II. Development of the frontal sinus model: Occlusion of the nasofrontal duct

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Abstract
The history of the surgical treatment of frontal sinusitis and mucocele is a reflection of the uncertainty surrounding its pathogenesis. Since the pioneer work of Coates, Hilding, Proetz, and Walsh over three decades ago, two principal etiologic factors are usually accepted: obstruction of the nasofrontal duct, and mucosal inflammation; however, no one has been able to obstruct reliably the nasofrontal duct in an experimental model (e.g., canine) to see whether such a blockage would actually incite infection or a mucocele. In addition, all previous work was performed from within the sinus cavity.We have been able to obstruct reliably the nasofrontal duct in the dog by manipulating the ethmoturbinates via a lateral rhinotomy, thereby creating a blocked frontal sinus without using a foreign body or voiding the integrity of the sinus cavity itself.Preliminary results show that mucus builds up under pressure within the closed sinus cavity. In this first report, in addition to the surgical method, we present the anatomical, histological, and ultrastructural changes in six experimental dogs at three months, six months and one year. X‐rays show the radiographic changes at various lengths of obstruction.At this point blocking the nasofrontal duct itself does not result in either mucocele formation or infection in our experimental model. A mucocele has been produced in a frontal sinus denuded of its mucoperiosteal lining. We postulate two distinct types of mucocele: one, a “pressure” mucocele in an obstructed sinus, and the second, a “trauma” mucocele which results from regeneration after infection or blunt trauma to the sinus mucosa.This model should allow us to analyze the role of the nasofrontal duct in the pathogenesis of frontal sinus disease. Future application in the investigation of obliterative surgery and frontal sinus trauma is discussed.