Discussion
The use of a VSB in patients with unilateral hearing loss is known to improve the ability of speech understanding in noise and sound localization 6, 10. We have consistently observed that VSB implantation results in significantly greater hearing ability without impairing auditory function in the case of UCAA. Compared to the VSB, BC devices transfer auditory information to both cochleae, indicating that the monaural benefit provided by the VSB is lost4. Also, there is general consensus that congenital and early childhood hearing loss should be treated as soon as possible4. Taken together, the above findings indicate that it is ideal to address conductive hearing loss in children with UCAA via VSB, which means intervention prior to the plastic reconstruction of the ear which is generally performed at age 10 or older.
However, since the temporal bone, middle ear structures and facial nerve are often affected to varying extents in UCAA children, preoperative evaluation via CT scans is needed11. In this case, the stapes as well as adequate middle ear and mastoid pneumatization were identified, allowing us to place the FMT on the stapes superstructure. Even if the malformation was markedly more severe, a BC device or a cartilage conduction hearing aid12, which are approved in Japan, might have been an alternative solution to restore auditory function.
Plastic reconstruction of the auricle follows a standard procedure with autologous rib cartilage in two operative steps based on the technique of Nagata 13. Although some modifications have been reported9, 14, 15, these operations predominantly include (1) costal cartilage harvest and implantation of the sculpted framework in a subcutaneous pocket and (2) elevation of the auricle with skin grafting. When performing VSB implantation in advance of the auriculoplasty, otologists must ask plastic surgeons to design the proposed ear preoperatively. Additionally, both the skin undermined around the proposed ear for creation of the ear and the temporoparietal and mastoid fascia potentially utilized in the second step must be preserved during VSB implantation. Therefore, we selected a retroauricular incision through “all” layers at about 20 mm from the outline of the prospective ear, leaving the tissues used in the auriculoplasty intact. Hence, our surgical procedure will not interfere with the future plastic reconstruction.