PANDORA: Evaluation of Platelet-rich Plasma in Non-tumoural Odour Disorders: a Descriptive Pilot Study.

Prospective consecutive recruitment in an ENT department at Hôpital Lyon Sud (Hospices Civils de Lyon). Eligible participants are enrolled into one of two diagnostic cohorts (DOD or DOPT), and analyses are performed separately by cohort. PRP is prepared from autologous venous blood using a standardized preparation system and injected under endoscopic guidance in the olfactory cleft area (superior nasal septum mucosa). Follow-up assessments are performed at baseline and at Months 3 and 6 after the first injection.

• Autologous Platelet-Rich Plasma (PRP) Injection (Biological): At 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.

Primary outcomes

• Proportion of participants with clinically meaningful improvement in olfactory function (Sniffin' Sticks Test TDI score) [Baseline (Visit 1, prior to first injection) to Month 6 follow-up (Visit 5)]: 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).

Secondary outcomes

• Occurrence of treatment-related adverse events [From first injection (Day 0) to Month 6 follow-up visit]: 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) [Baseline (Visit 1) to Month 3 follow-up (Visit 4)]: 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) [Baseline (Visit 1) to Month 6 follow-up (Visit 5)]: 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) [Baseline (Visit 1) to Month 6 follow-up (Visit 5)]: 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.
• Change in patient-reported olfactory impairment (Visual Analog Scale) [Baseline (Visit 1) to Month 6 follow-up (Visit 5)]: Change in patient-reported olfactory impairment assessed using a Visual Analog Scale (VAS) ranging from 0 (no discomfort) to 10 (unbearable discomfort) between baseline and Month 6.

Sex: All, ages: 18 Years to 99 Years

Inclusion Criteria

* 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.
* Affiliated to a social security system (or equivalent).
* Written informed consent.

Exclusion Criteria

* 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).
* History of sinus or skull base surgery (except septoplasty/turbinoplasty/rhinoseptoplasty).
* Therapeutic-dose anticoagulants.
* Refusal to discontinue chronic NSAID use if applicable.
* Pregnancy/labor/breastfeeding.
* Vulnerable persons (deprived of liberty; legal protection; etc.).
* Participation in another interventional study with ongoing exclusion period.