The diagnosis of a conductive olfactory loss

Two of the most common causes of olfactory loss include upper respiratory infection (URI) and nasal or sinus disease. The etiology of most URI-related losses is thought to be viral and, as yet, there is no available treatment. In contrast, nasal or sinus disease produces an obstructive or conductive loss that often responds dramatically to appropriate therapy. Therefore, the distinction is important but in many cases may be difficult because such patients often present with no other nasal symptoms, and routine physical findings may be nonspecific. The purpose of this report is to characterize those aspects of the history and physical examination that will help to substantiate the diagnosis of a conductive olfactory loss.

A retrospective, nonrandomized study of consecutive patients presenting with a primary complaint of olfactory loss.

This study reviewed 428 patients seen at a university-based taste and smell clinic from July 1987 through December 1998. Of this total, 60 patients were determined to have a conductive olfactory loss. All patients were referred specifically because of a primary chemosensory complaint. The University of Pennsylvania Smell Identification Test (UPSIT; Sensonics, Inc., Haddon Heights, NJ) was administered in all cases.

The most commonly diagnosed etiologies of olfactory loss were head injury (18%), upper respiratory infection (18%), and nasal or sinus disease (14%). Of the 60 patients with a conductive loss, only 30% complained of nasal obstruction, whereas 58% described a history of chronic sinusitis. Only 45% reported that their olfactory loss at times seemed to fluctuate in severity. Anterior rhinoscopy failed to diagnose pathology in 51% of cases, whereas nasal endoscopy missed the diagnosis in 9%. Systemic steroids elicited a temporary reversal of conductive olfactory loss in 83% of patients who received them, offering a useful diagnostic maneuver, whereas topical steroids did so in only 25%.

The etiology for olfactory loss can in many cases be difficult to determine, but it is important to establish prognosis and to predict response to therapy. Diagnosis requires a thorough history, appropriate chemosensory testing, and a physical examination that should include nasal endoscopy. A trial of systemic steroids may serve to verify that the loss is indeed conductive.