Background: Increasing numbers of acute sensorineural hearing loss (SNHL) are recently experienced in irradiated nasopharyngeal carcinoma (NPC) survivors.
Aim: This study adopted MR imaging to differentiate between post-irradiation sudden deafness (PISD) and post-irradiation endolymphatic hydrops (PIEH) in long-term NPC survivors with acute SNHL.
Methods: From 2012 to 2021, consecutive 10 irradiated NPC survivors with acute SNHL were enrolled. All patients underwent an inner ear test battery and MR imaging using HYDROPS-Mi2 technique. Six patients (11 ears) with positive cochlear hydrops on MR images were diagnosed as PIEH, while another 4 patients (4 ears) without cochlear hydrops on MR images were referred to PISD.
Results: The interval from the onset of NPC to acute SNHL did not significantly differ between the PIEH (10 ± 6 years) and PISD (8 ± 2 years). No significant difference was found between the two disorders from any of the symptomatic, radiotherapeutic, audiological, or vestibular perspective. Interestingly, most (5/6) patients with PIEH had bilateral involvement, while all (4/4) patients with PISD showed unilateral affliction. A significantly declining sequence of abnormality rates in the inner ear test battery was noted in the PIEH patients, running from the audiometry (100%), cervical vestibular-evoked myogenic potential (VEMP) test (100%), ocular VEMP test (73%), to the caloric test (36%). However, such declining trend was not observed in patients with PISD.
Conclusion: When facing an NPC survivor who had acute SNHL over a prolonged period after irradiation, MR imaging using HYDROPS-Mi2 technique should be performed to differentiate the PIEH from the PISD, since both disorders have various treatment modalities and hearing outcome.
Keywords: Acute sensorineural hearing loss; HYDROPS-Mi2 technique; MR imaging; Nasopharyngeal carcinoma (NPC); Post-irradiation endolymphatic hydrops (PIEH); Post-irradiation sudden deafness (PISD).
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