Analysis of factors influencing the effective dose of intratympanic steroid injection of dexamethasone in idiopathic sudden sensorineural hearing loss

Currently, Intratympanic steroid injection (ITSI) has been identified as a common method for delivering dexamethasone to the inner ear in idiopathic sudden sensorineural hearing loss (ISSNHL). This study analyzed factors influencing dexamethasone effective dose in ITSI, aiming to optimize injection protocols and efficacy assessment. A total of 251 ISSNHL patients received ITSI with 5 mg dexamethasone, and drug leakage from the external auditory canal was quantified. The effects of Eustachian tube function (assessed via taste method), injection speed (5 vs. 10 s), and injection site (anteroinferior, posteroinferior, anterosuperior tympanic membrane) on the effective dose were evaluated. The pretreatment and posttreatment audiological examination results were collected, and the relationship between the effective dosage and the efficacy was analyzed. Significantly higher median leakage (1.90 mg vs. 0.75 mg, p < 0.01) was showed in patients with bitter taste, indicating passive eustachian tube opening. However, injection speed and site had no significant impact on leakage (p > 0.05). No significant differences in hearing outcomes were observed between high (>3.5 mg) and low (≤3.5 mg) effective dose groups (p > 0.05). ITSI effective dose primarily depends on eustachian tube function, and low-dose dexamethasone (sufficient to fill the tympanic cavity) is equally efficacious, suggesting simplified clinical protocols.