Idiopathic Sudden Sensorineural Hearing Loss: Is Hyperbaric Oxygen Treatment the Sooner and Longer, the Better?

(1) Background: We aimed to evaluate hearing benefits from hyperbaric oxygen (HBO) therapy in patients with Idiopathic Sudden Sensorineural Hearing Loss (ISSHL). (2) Methods: We performed a retrospective analysis of chart reviews on patients with ISSHL between Jan 2016 and Dec 2021. All patients were referred to receive HBO therapy by the department of Ear, Nose and Throat (ENT). Hearing gain was assessed based on pure-tone audiometry (PTA). Data were analyzed for 102 patients after 1 to 5 therapy sessions, and for 46 patients after 6 to 10 therapy sessions. (3) Results: After 1–5 HBO sessions, patients (N = 102) showed an improvement in 45 (44.1%) of the patients (p < 0.000). Also, improvements were found with patients showing different grades of ISSHL: 11 (26.8%) with slight-moderate, 11 (40.7%) with severe, and 23 (67.6%) with profound ISSHL. Significant treatment effects were found at different affected frequencies, especially the low frequency range. After 6–10 HBO sessions, patients (N = 46) showed similar treatment effects as after 1–5 HBO sessions, but no additional improvement. Moreover, patients who received HBO treatment within 12 days showed improvement effects 6.484 times greater (p < 0.000) compared with those who received treatment after 13 days. (4) Conclusions: The improvement of HBO therapy on ISSHL was significant after 1–5 sessions, with larger improvements for those suffering more serious symptoms. Further adding more HBO treatment sessions to 6–10, no further improvement was found. Patients starting HBO therapy within 12 days of ISSHL showed 6.484 times greater improvements compared with those starting HBO therapy later.