A Case of Pneumolabyrinth Induced by Eustachian Tube Air Inflation

Objectives: Here, we report a case of pneumolabyrinth induced by Eustachian tube air inflation (ETAI) with a catheter and present evidence that multiple air bubbles entered the perilymphatic space through a preexisting oval window fistula. Setting: Tertiary referral center. Patient: Sixty-six-year-old woman. Intervention(s): None. Main Outcome Measure(s): Air bubbles in the perilymphatic space revealed by cone beam computed tomography (CT) volume rendering imaging. Results: The patient was referred to us because of vertigo, unsteadiness, and right hearing loss after ETAI using a Eustachian tube catheter. On Day 2, an audiogram showed right total deafness, and the perilymphatic space could not be identified on T2-weighted magnetic resonance imaging. Ahigh-resolution cone beam CT scan obtained on Day 3 showed multiple air bubbles in the labyrinth. The volume rendering images clearly revealed a larger air bubble in the vestibule inside the footplate of the stapes and small air bubbles in the horizontal semicircular canal, superior semicircular canal, and basal and second turns of the cochlea. This finding indicates that the air bubbles entered the perilymphatic space through an oval widow fistula caused by a sudden elevation in intratympanic air pressure. Two months later, the air bubbles had disappeared, and the patient's high tone hearing had improved slightly. Conclusion: ETAI can cause a pneumolabyrinth if the intratympanic pressure rises beyond a certain critical level. In this situation, volume rendering imaging of high-resolution cone beam CT can be used to quantify and identify the air bubbles present. The images taken in this study suggest that air bubbles entered the perilymphatic space through a perilymphatic fistula.