The Rates and Clinical Characteristics of Pneumolabyrinth in Temporal Bone Fracture

Abstract

Background: Pneumolabyrinth is a rare inner ear clinical manifestation. To date, only about 50 cases have been reported—all as case reports. Consequently, the rate and clinical characteristics of pneumolabyrinth have not been evaluated.

Methods: Of the 38, 568 patients who visited our emergency department for head trauma, 466 underwent temporal bone computed tomography (CT). One hundred seventy-five patients had temporal bone fracture (13 bilateral temporal bone fractures; 188 ears with temporal bone fractures), and 14 patients had pneumolabyrinth (15 ears with pneumolabyrinth; 1 bilateral case). A retrospective review of their medical records and radiologic findings was performed. Temporal bone fractures were classified by two different systems: the traditional classification and an otic capsule-based classification.

Results: Pneumolabyrinth occurred in 8.0% of all temporal bone fractures, 4.0% of longitudinal temporal bone fractures, 16.1% of transverse or mixed temporal bone fractures, and 48.4% of otic capsule-violating temporal bone fractures. In all cases, pneumolabyrinth was found on CT, which was performed within 3 days, but not on follow-up CT performed 5 days or longer after head trauma. All patients complained of hearing loss and dizziness. Hearing in most patients (83.3%) did not improve, whereas dizziness improved in 91.7% of patients. Air was located only in the vestibule or semicircular canal in 53.3% and in the vestibular or semicircular canal and cochlea in 46.6% of ears with pneumolabyrinth. The initial hearing threshold and recovery rate using pure-tone audiometry were not different according to the air location in the inner ear.

Conclusion: Pneumolabyrinth was more common than expected; we believe that the timing of evaluation affects its rarity. Pneumolabyrinth was detected in nearly 50% of patients with otic capsule-violating temporal bone fractures when CT scanning was performed early after trauma.