Semicircular canal dysfunction in profound sudden sensorineural hearing loss and its prognostic value: implications for the proper indication of hyperbaric oxygen therapy.

Vestibular involvement in sudden sensorineural hearing loss (SSNHL) is regarded as an indicator of poor prognosis. This study aimed to investigate the prognostic significance of semicircular canal dysfunction in profound SSNHL and evaluate the effectiveness of hyperbaric oxygen therapy (HBOT) accordingly. From October 1, 2020 to August 15, 2025, patients diagnosed with profound SSNHL (≥ 80 dB) and with available video head impulse test results were assessed. A total of 85 patients were included and divided into two groups based on HBOT compliance: the HBOT group (≥ 5 sessions, n = 39) and the non-HBOT group (< 5 sessions, n = 46). Semicircular canal function and treatment outcomes were compared. PSCC dysfunction was independently associated with about 14 dB poorer post-treatment mean hearing thresholds (76.00 ± 3.43 dB vs. 62.26 ± 3.75 dB, p = 0.011). In these patients with PSCC dysfunction, HBOT was associated with improved post-treatment mean hearing thresholds (74.32 ± 2.90 dB vs. 89.22 ± 3.17 dB; p = 0.002), with significant improvements at 0.5, 1, 2, and 4 kHz (all p < 0.05). PSCC dysfunction is associated with poorer hearing recovery in patients with profound SSNHL and may help identify a distinct clinical phenotype that is more likely to benefit from HBOT.