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.