Use of Magnetic Resonance Imaging to Evaluate Children with Bilateral Hear ing Loss Before Receiving Cochlear Implant
Date Issued
2001-07-31
Date
2001-07-31
Author(s)
黃國茂
DOI
892314B002275M08
Abstract
Cochlear implant in profoundly deaf children was
not commonly performed due to the complex process
involving surgery, imaging work-up, auditory
functional evaluation and rehabilitation. Not much
information about the results of cochlear implantation
in children was available. Since there is no widely
acceptable classification of malformation of the
cochlea based on embryology and imaging findings,
the results of pediatric cochlear implantation from
various centers are not usually comparable. In addition,
cochlear malformation is frequently associated with
aberrant course or bifurcation of the facial nerve. The
anatomic landmarks are usually absent in patients with
cochlear malformation. One of the major concern
during operation is to prevent incidental injury to the
facial nerve. Thorough knowledge of the morphologic
changes of cochlear malformation can not be
overemphasized for the surgical approach of cochlear
implantation.
Due to recent advances of magnetic resonance
imaging include three-dimensional Turbo-spin echo
(3DTSE) and constructive interference in the steady
state (CISS), imaging with thin section and high
spatial resolution is possible. The goal of the study was to apply CISS and 3DTSE to demonstrate the
morphologic changes of the cochlear malformation,
associated semicircular canals and the diameter of
facial as well as eighth nerves.
Thirty children suffering from bilaterally profound
deafness and younger than 16 years old will be
included in the study. Another ten children with
normal hearing acuity will also be included as control
group. By using 1.5 T Magnetom Plus scanner
(Siemens, Erlangen, Germany), these children will
undergo 2D TSE, CISS pulse sequences. MIP images
deriving from CISS images will also be obtained. In
addition, these children will receive high-resolution
temporal CT examinations on a spiral CT PQ 6000
scanner (Picker, Ohio). The four sets of images will be
read by two radiologist to determine: the number of
turns of cochlea, the signal intensity of endolymph
within the cochlea, deformity of the cochlea,
anomalies of the vestibule and semicircular canals, the
vestibular aqueduct fistula, narrowing of the internal
auditory canal, the diameter of the 8th nerve within the
internal auditory canal, and the course of the facial
nerve near the inner ear and middle ear. We will
correlate these findings with what will be found
during operation. Much attention will paid to the
presence of calcification or fibrosis within the
implanted cochlea, deformity of the cochlea and
aberrant course of the facial nerve. Those congenital
anomalies of the inner ear will be classified according
to the Jackler’s classification. Whether the patient can
hear will be recorded during postoperative follow-up.
We intended to compare four kinds of images(2DFSE,
CISS, CISS MIP and HRCT) find out the most
conomic way to evaluate those bilaterally deaf
children. With use of high-resolution images, we also
want to cut down the failure rate resulting from
implantation in the unsuitable side of ear. We believe
that the risk of facial palsy after cochlear implantation
will be less if high-resolution images of the inner ear
are meticulously read.
Subjects
cochlear implant
mangetic resonance
imaging
imaging
hearing loss
cochlea
Publisher
臺北市：國立臺灣大學醫學院放射線科
Type
journal article
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