Case report
The patient was a 9-year-old boy with congenital CAA and lobule-type microtia on the right ear (Fig. 1A). No associated symptoms were observed. He visited Shinshu University Hospital, Department of Otolaryngology and asked us to treat his conductive hearing loss as early as possible. Preoperative audiometry showed mean air conduction pure-tone thresholds of 70 dB HL at 0.5, 1, and 2 kHz with an air-bone gap of 50 to 90 dB (Fig. 3A). Plastic reconstruction of the auricle was scheduled to be undertaken at age 11. Therefore, we suggested to him and his parents that he undergo VSB prior to the atresiaplasty. We, otolaryngologists, consulted the plastic surgeons about the surgical planning so as not to interfere with the costal cartilage grafting associated with the auriculoplasty. This study was approved by the Ethics Committee of Shinshu University School of Medicine (jRCTs032190002).
Preoperatively, a film pattern was copied from the contralateral ear (Fig. 1B). With the film attached to his face, the ear position was determined by comparison with the contralateral ear from the frontal view and in a sitting position (Fig. 1C). Using glasses with a scale enabled us to design the ideal ear position (Fig. 1D). Surgery was performed under general anesthesia with facial nerve monitoring. First, we determined the position of the drill site for the mastoidectomy with the aid of a navigation system (Medtronic, Dublin, Ireland) and the outline of the desired position of the implant 1.5 cm from the edge of the intended mastoid cavity. An arc-shaped incision line was marked 2 cm away from the proposed ear (Fig. 2A). We incised the skin to the level of the periosteum and made a single layer flap. The temporal bone was exposed to allow access to the mastoid cavity. Mastoidectomy to the point where the atretic plate was visible was performed. The atretic plate was then gently drilled, and the incus and malleus were fused into a malformed complex which was strongly adhesive to surrounding structures (Fig. 2B). After removing the complex, the tympanic facial nerve and stapes were identified (Fig. 2C). In accordance with the manufacturer’s protocols, the implant (VORP 503) was placed in the prepared bone bed and fixed to the cortical bone with screws (Fig. 2E). A Vibroplasty-Clip-Coupler was attached to the FMT, and the Coupler-FMT assembly placed onto the head of the stapes superstructure (Fig. 2D) and secured with fascia. The skin flap was sutured with a drain (Fig. 2F) that was removed 2 days after the surgery.
Eight weeks post-surgery, the initial activation of the audio processor was performed. He has been able to comfortably wear the VSB all day. As a result, his hearing thresholds with the VSB at 6 months after activation indicated sufficient amplification. The mean aided pure-tone thresholds (at frequencies of 0.5, 1, and 2 kHz) was 25 dB HL, implying a functional gain of 25 dB to 45 dB (Fig. 3C,E). Additionally, bone conduction thresholds were stable between the pre- and post-operative evaluations. His score on the Japanese monosyllable test at 0, -5, -10 dB SNR was improved remarkably (Fig. 3F). The results of sound localization testing are described in Figure 3B,D showing the time course of the deviation (d ) score. The d scores showed improvement in this case from 18.75 to 7.92. He will receive the auriculoplasty with costal cartilage grafting at age 11.