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Type:
Educational Exhibit
Keywords:
Pathology, Congenital, Screening, Normal variants, Computer Applications-3D, MR, CT-High Resolution, Ear / Nose / Throat, Anatomy
Authors:
P. Digge1, R. K. N. Solanki2, S. M. Paruthikunnan3, D. S. Shah2; 1Manipal, Karnataka/IN, 2Ahmedabad/IN, 3Manipal/IN
DOI:
10.1594/ecr2015/C-0867
Background
Congenital deafness is present in approximately 1 in 1000 births,
while the incidence of profound hearing loss in infants may be as high as 1 in 250 (1).
Of these,
it has been estimated that half are due to a hereditary cause.
Mutations in the gene GJB2,
with a carrier frequency of approximately 3% to 4%,
have been established as the most common cause of nonsyndromic hearing loss,
responsible for up to 20% of cases of childhood deafness (2).
Impairment of hair cell function induces profound deafness in approximately 0.3% of children younger than 5 years.
Congenital inner ear malformations are a result of the arrest or aberrance of inner ear development due to the heredity,
gene mutation,
or the other factors.
The malformations can exist in any part of the inner ear,
of which 20% are bony structure malformations.
The remaining 80% are membranous malformations,
which cannot be detected by any standard method because the bony structure of the inner ear is normal,
and the pathology is at the cellular level (3).
However,
patients with bony malformations can readily be diagnosed by CT and magnetic resonance imaging (MRI).
Ever since the availability of cochlear implants,
pre-operative evaluation by imaging of temporal bone has gained much attention.
Precise selection of the candidate for cochlear implant dependent on preoperative radiological investigation.
Only the CT and MRI can provide a better picture of anatomy and pathology.
Owing to the tiny and multiple structures in temporal bone where important structures like middle ear,
vestibulo-cochlear apparatus,
facial nerve etc are present,
because all of these structures present in small area with different combination of soft tissues and bony structures,
poses a special challenge to radiologist.