Topical Versus Injection PRP for Olfactory Dysfunction
Trial statusRecruiting
Trial phasePhase 3
Trial typeInterventional
Biological sexAll
Age18-80
SponsorTaipei Veterans General Hospital, Taiwan
About this trial
The goal of this clinical trial is to determine whether two different delivery methods of autologous platelet-rich plasma (PRP) can improve olfactory function in adults with persistent olfactory dysfunction lasting more than three months. The main questions it aims to answer are:
1. Does carrier-assisted topical application of PRP lead to comparable or better improvement in smell function than intranasal injection of PRP? 2. Which method provides greater patient comfort and fewer adverse effects?
Researchers will compare carrier-assisted topical PRP application to intranasal PRP injection to see if one approach is more effective in restoring olfactory function.
Participants will:
1. Receive a single PRP treatment delivered either by injection or via a PRP-soaked carrier placed into the olfactory cleft. 2. Continue daily olfactory training for three months following the intervention. 3. Undergo smell testing (Sniffin' Sticks) before and after treatment and complete quality-of-life questionnaires.
Eligibility criteria
This trial does not accept healthy volunteersQualifiers
Aged between 18 and 80 years, regardless of sex
Subjective complaint of olfactory dysfunction with confirmed hyposmia or anosmia based on standardized olfactory testing
History of at least 3 months of prior olfactory training but with persistent olfactory complaints
Disqualifiers
Congenital anosmia
Diagnosed neurological or structural brain abnormalities (e.g., brain tumor, major head trauma, stroke) with low likelihood of olfactory recovery
Inability or unwillingness to comply with study procedures or follow-up assessments
Trial design
Design model
Parallel
Treatments tested in this trial
Intranasal Injection of Autologous PRP
Procedure/SurgeryUnder topical anesthesia and decongestion, approximately 1 mL of freshly prepared autologous platelet-rich plasma will be injected into multiple sites of the olfactory cleft mucosa bilaterally using a 25-gauge needle under endoscopic guidance. Single treatment session.
Carrier-Assisted Topical Application of Autologous PRP
Procedure/SurgeryFour pieces of sterile, bioabsorbable carrier (Gelfoam sponge) will be soaked with approximately 5 mL of freshly prepared autologous platelet-rich plasma. Under endoscopic guidance, two pieces will be placed gently into each olfactory cleft, ensuring contact with the olfactory mucosa. Carriers will remain briefly to allow PRP diffusion before dissolving naturally or being removed. Single treatment session.
platelet-rich plasma
Combination productThis study adopts a fully automated, closed-system PRP preparation technique to ensure the stability of the blood product. A total of 60 mL of whole blood is drawn and processed using the Phoenix Q1 centrifuge (TFDA Medical Device Manufacturing License No. 004461) for blood component separation in a closed, sterile environment. An optical sensor identifies and automatically collects the buffy coat layer (rich in platelets and monocytes), yielding approximately 6 mL of autologous platelet-rich plasma (PRP). The centrifugation and PRP collection process takes about 5 minutes. Compared with traditional methods requiring manual identification and collection, this approach enhances the precision and safety of centrifugation-based preparation.
olfactory training
DeviceParticipants will perform olfactory training for 12 weeks following the PRP intervention. Training is conducted twice daily using four odor bottles containing standardized odorants from Sigma-Aldrich (Germany): lemon (citronellal, #27470), rose (phenylethanol, #77861), clove (eugenol, #W246700), and eucalyptus (eucalyptol, #C80601). Each odor is sniffed gently for about 20 seconds, with a 20-second pause between bottles. Participants will record the perceived intensity of each odor in a training diary after every session.
Treatment groups
60 Participants
are divided into 2 treatment groupsGroup A: Intranasal PRP injectionExperimental treatment 3 interventions
Group B: Topical PRP application armExperimental treatment 3 interventions
Trial outcomes
Primary outcomes
1
Sniffin' Sticks Olfactory Test
The Sniffin' Sticks test (Burghart Messtechnik GmbH, Holm, Germany) comprises three subtests for odor detection threshold (T), odor discrimination (D), and odor identification (I). This test employs odor-containing felt-tip pens, which are presented to participants to evaluate their olfactory performance. In the detection threshold subtest, we employed an adaptive staircase procedure based on a three-alternative forced-choice format. Participants were tasked with differentiating a stick with a rose-like aroma (phenylethyl alcohol) from two blank sticks. Odor discrimination was assessed using 16 pen triplets, two of which contained identical odors and one stick contained a different odor. Participants were tasked with identifying the odd one out. In the odor identification subtest, participants were tasked with naming 16 common odors by selecting appropriate terms from a set of four descriptors per odor. The scores from each subtest were combined into a composite TDI score.
Time frame
pre-intervention and at 1 and 3 months (may extend to 6 and 12 months) post-interventionSecondary outcomes
1
Procedure-related pain evaluation
Visual analogue scale for pain (0-10) immediately after procedure.
Time frame
during the procedure and up to 2 weeks post-intervention2
Retronasal Olfactory Test
Retronasal olfactory testing was performed using standardized odorized powders/capsules presented in the oral cavity, with participants instructed to exhale through the nose and rate the perceived odor. It specifically evaluates olfactory function via the retronasal route.
Time frame
pre-intervention and at 3 months post-intervention3
Visual Analogus Scale for olfaction
Visual Analogus Scale for olfactory function from 0 to 10. (0 means inability of smelling and 10 means super good smell function)
Time frame
pre-intervention and at 1 and 3 months (may extend to 6 and 12 months) post-intervention4
Questionnaire of Olfactory Disorders (QOD)
A questionnaire on olfaction-related quality of life status
Time frame
pre-intervention and at 1 and 3 months (may extend to 6 and 12 months) post-interventionSponsors and contacts
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Source ClinicalTrials.gov