Olfactory mucosal findings and clinical course in patients with olfactory disorders following upper respiratory viral infection.

Seventy patients with olfactory disorders following upper respiratory viral infection (URVI) were studied clinically, and the olfactory mucosa of 13 patients was biopsied using special biopsy forceps. The specimens were examined using immunohistochemical staining for neuron-specific enolase (NSE), S-100 protein (S-100), cytokeratin (CK), and proliferating cell nuclear antigen (PCNA). Although the clinical course of URVI-olfactory disorders was not very good, overall a high proportion of Alinamin intravenous injection test-positive patient's recovered their sense of smell. Immunohistochemical study of the biopsy specimens revealed a decrease in the number of olfactory receptor cells and nerve bundles. In a few cases the olfactory neuroepithelium was replaced by metaplastic squamous epithelium. Sometimes different types of degeneration were found in the same specimen. No PCNA-immunoreactivity was detected in the olfactory epithelium. The result generally correlated with the degree of degeneration of the olfactory mucosa, because regeneration of the olfactory receptor cells is suspected to be extremely slow or rare in humans. Alinamin test-positive patients had many olfactory receptor cells. These findings suggest that olfactory mucosal biopsy and the Alinamin intravenous injection test are useful methods of determining the prognosis in post-URVI olfactory disorders.