Causes of olfactory impairment include sinus diseases, post-viral olfactory dysfunction, neurological diseases, and post-traumatic lesions of the olfactory nerve. Since the outbreak of the COVID-19 in 2019, there has been a significant increase in the number of patients suffering from olfactory disorders, and the duration of loss of smell and taste varies. According to follow-up studies, nearly 46% of those patients still have symptoms of olfactory impairment one year after diagnosis, and nearly 7% have even completely lost their ability to smell. In recent years, injecting platelet-rich plasma into the nasal cavity has been a new method to improve the sense of smell. The effects of platelet-rich plasma can reduce chronic inflammation and cell-related damage and promote regeneration of olfactory tissue, while hyaluronic acid can promote the release of growth factors from platelets.
The purpose of this study is to explore the efficacy of injecting high-concentration platelet plasma combined with hyaluronic acid into the nasal olfactory mucosa in the treatment of traumatic anosmia. A total of 80 patients with olfactory dysfunction were collected from otolaryngology, head and neck outpatient clinics. Selection criteria are 18 years of age or older, and loss of olfactory function for more than 6 months after head trauma. Exclusion criteria are pregnant or lactating women, patients with compromised immune function, patients with acute or chronic sinus infection, patients with nasal polyps, patients with a history of sinonasal cancer, and patients with low platelets or hemophilia and other blood and blood cell-related diseases.
This study will establish experimental groups and control groups according to random distribution. Subjects in both groups received zinc tablets and olfactory training for 12 weeks. The experimental group additionally received an injection of platelet-rich plasma combined with hyaluronic acid. After treatment, patients return to the clinic to track the olfactory condition.
Before treatment, the subjects evaluated their olfactory function using a Visual Analogue Scale (VAS) and performed the phenyl ethyl alcohol odor detection threshold test and the traditional Chinese version of the University of Pennsylvania Olfactory Identification Test. In the experimental group, 10cc of blood will be drawn from the subjects in the experimental group, the drawn blood will be centrifuged, the centrifuge tube will be inverted 20 times to mix the plasma and hyaluronic acid, and finally 5cc of the plasma mixed with hyaluronic acid will be drawn out using an empty syringe. The project investigator injects plasma mixed with hyaluronic acid into the nasal septum and the medial side of the middle turbinate of the patient's nasal cavity under a nasal endoscope. The two groups will undergo the same olfactory tests three months later to compare the changes in olfactory function of the two groups of patients before and after treatment to explore the efficacy of injecting high-concentration platelet plasma combined with hyaluronic acid into the nasal olfactory mucosa to treat traumatic anosmia.
