This study aims to compare the efficacy of steroid nasal drops targeting the olfactory cleft versus traditional intranasal steroid sprays in improving olfactory function in patients with chronic rhinosinusitis (CRS) with olfactory cleft obstruction. The main questions this clinical trial aims to answer are:

1. Efficacy Comparison: Is olfactory improvement greater with olfactory cleft-targeted steroid nasal drops compared to standard nasal steroid sprays in CRS patients?
2. Mechanism Exploration: How do changes in inflammatory markers, obstruction severity, and olfactory test results explain the potential benefits of this treatment approach?

Olfactory dysfunction is one of the most common clinical symptoms in patients with chronic rhinosinusitis (CRS), affecting approximately 60%-80% of individuals with CRS. This condition significantly impairs quality of life and is associated with systemic health issues such as depression and nutritional imbalances. The olfactory cleft, a critical anatomical region housing the olfactory neuroepithelium, is often obstructed in CRS patients due to nasal polyps or mucosal hypertrophy, leading to conductive olfactory dysfunction.

Current first-line treatments for CRS, including oral or intranasal corticosteroids, have limitations. Oral steroids pose systemic side effects, while standard nasal sprays often fail to deliver adequate drug concentrations to the olfactory cleft. In contrast, targeted hormone nasal drops may achieve higher efficacy by directly addressing localized inflammation and edema in the olfactory cleft. Preliminary studies suggest that fluticasone nasal drops can reduce the need for sinus surgery in patients with CRS unresponsive to conventional sprays. However, no randomized controlled trials have systematically evaluated the efficacy of olfactory cleft-targeted hormone drops in improving olfactory function in CRS patients with confirmed olfactory cleft obstruction.

In this study, investigators planned to enroll 54 patients with olfactory cleft obstruction and assign them to one of two treatments: olfactory cleft-targeted steroid nasal drops or conventional nasal sprays. This study aims to investigate the efficacy and underlying mechanisms of olfactory cleft-targeted steroid nasal drops in improving olfactory function.

Inclusion Criteria:

1. Prospective enrollment of otolaryngology clinic patients aged 18-65 years with olfactory dysfunction. Diagnosis of chronic rhinosinusitis-related olfactory dysfunction is based on the EPOS 2020 guidelines. Participants must demonstrate olfactory impairment via Sniffin' Sticks testing, with TDI scores (sum of Threshold, Discrimination, and Identification) meeting:(1) Hyposmia: 16 < TDI < 30.75; (2) 3.Anosmia: TDI < 15.
2. Sinus CT scans confirming obstruction in the olfactory cleft region.
3. Willingness to participate and signed informed consent.

Exclusion Criteria:

1. Use of systemic corticosteroids within 4 weeks or intranasal steroids within 2 weeks prior to enrollment.
2. Severe nasal septum deviation, nasal tumors, acute upper respiratory infections, or uncontrolled allergic rhinitis.
3. Severe cardiovascular disease, hepatic/renal insufficiency, uncontrolled diabetes, or immune system disorders.
4. Current or planned pregnancy.
5. Investigator-determined inability to comply with study requirements (e.g., memory/behavioral disorders, depression, heavy alcohol use, prior non-compliance).

We will decide whether to share the individual participant data after the study.