The Rates and Clinical Characteristics of Pneumolabyrinth in Temporal Bone Fracture.

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.