Computed Tomography in 15 Patients with Congenital Aural Atresia Treated with Floating Mass Transducer on the Round Window

Abstract

Objective: Illustrate preoperative (to assess radiological landmarks useful for diagnosis and surgery) and postoperative (to visualize complications and evaluate the correct positioning of the FMT) imaging features in patients with congenital aural atresia (CAA) treated with the floating mass transducer (FMT) of the Vibrant Soundbridge on round window (RW).

Method: Fifteen patients, aged from 2 months to 54 years, treated with FMT on the RW for bilateral (11 patients) and monolateral (4 patients) CAA, underwent high resolution computed tomography (HRCT) scans and/or cone-beam CT scans (CBCT) preoperatively and postoperatively at 12-to-60-month follow-up times. The first 4 patients had plain-film X-rays.

Results: The tympanic cavity was reduced in size in 20 out of 26 ears (76.9%). Ossicular chain abnormalities were present in all ears. These consisted most frequently of a fusion of the malleus to the incus, as observed in 15 ears (61.5%). The RW area was normal in all patients, while the oval window (OW) was stenotic in 7 ears (26.9%). The facial nerve had an abnormal course and/or caliber in 15 ears (61.5%). The mastoid was reduced in size in 9 ears (34.6%). Correct positioning of the FMT on the RW was observed in all patients at the last follow-up.

Conclusion: Plain-film x-rays are not adequate. HRCT and CBCT scans permit a complete understanding of the CAA anatomy and a precise determination of the location of the FMT on RW. CBCT has a lower administered radiation dose: a very important feature as the FMT is fitted on RW in infancy.