This is a prospective, single-center, single-arm, non-comparative descriptive pilot study evaluating autologous platelet-rich plasma (PRP) injections in adults with persistent (\>6 months) non-tumoural olfactory dysfunction, either age-related degenerative olfactory dysfunction (DOD) or post-traumatic olfactory dysfunction (DOPT). Participants receive three PRP injections over 4 weeks (Day 0, Day 14, Day 28), with follow-up visits at Month 3 and Month 6 after the first injection. Olfactory function is assessed using the Sniffin' Sticks Test (TDI score). Patient-reported outcomes include SNOT-22 and a visual analog scale (VAS) for perceived olfactory impairment. Safety is assessed through adverse event collection.
Adults with persistent (>6 months) non-tumoural olfactory dysfunction: age-related degenerative olfactory dysfunction (DOD) or post-traumatic olfactory dysfunction (DOPT).
Objective olfactory impairment confirmed by Sniffin' Sticks Test (TDI ≤ 30.5/48).
MRI within the last 6 months after onset excluding tumoural etiology or central cause.
Normal nasal endoscopy.
Inflammatory rhinosinus disease (e.g., nasal polyposis) or granulomatosis with polyangiitis.
Coagulation disorder.
Brain radiotherapy history or ongoing chemotherapy.
Olfactory disorder temporally linked to SARS-CoV-2 infection (delay <1 month).
Single group
Autologous Platelet-Rich Plasma (PRP) Injection
Biological/VaccineAt each injection visit (Day 0, Day 14 ±1, Day 28 ±1), venous blood is collected and processed to obtain autologous PRP using a standardized preparation system. PRP is injected under endoscopic guidance into the superior nasal septum mucosa near the olfactory cleft, up to a total volume of 4 mL per visit. Participants are monitored after each injection and adverse events are recorded.
Proportion of participants with clinically meaningful improvement in olfactory function (Sniffin' Sticks Test TDI score)
Proportion of participants whose change in olfactory function, measured using the Sniffin' Sticks Test (Threshold, Discrimination, Identification score - TDI), between baseline (Visit 1, prior to the first PRP injection) and the 6-month follow-up visit reaches or exceeds the minimal clinically significant difference (MCID) of 5.5 points on the 48-point TDI scale. The TDI score combines three components: olfactory threshold (T), odor discrimination (D), and odor identification (I).
Occurrence of treatment-related adverse events
ccurrence and type of adverse events during the study period. Adverse events will be classified according to the Common Terminology Criteria for Adverse Events (CTCAE v5.0). For each adverse event, the investigator will assess severity and relationship to the experimental treatment.
Change in olfactory function at Month 3 (TDI score)
Change in olfactory function measured by the Sniffin' Sticks Test (TDI score) between baseline (Visit 1, before the first injection) and the Month 3 follow-up visit.
Change in olfactory function at Month 6 (TDI score)
Change in olfactory function measured by the Sniffin' Sticks Test (TDI score) between baseline (Visit 1, before the first injection) and the Month 6 follow-up visit.
Change in quality of life (SNOT-22 score)
Change in quality of life assessed using the Sino-Nasal Outcome Test (SNOT-22) questionnaire between baseline and Month 6. The SNOT-22 score ranges from 0 to 110, with higher scores indicating greater symptom burden. A minimal clinically significant difference is considered to be 8.9 points.
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