Inner-Ear Anomalies Revealed Using MRI

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Main Category: Hearing / Deafness
Also Included In: Ear, Nose and Throat;  Medical Devices / Diagnostics
Article Date: 19 Sep 2008 - 1:00 PDT

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Magnetic resonance imaging (MRI) can be used to identify defects in soft-tissue that contribute to hearing loss in children, according to a report released on September 15, 2008 in Archives of Otolaryngology -- Head & Neck Surgery, one of the JAMA/Archives journals.

Thousands of children each year are effected by sensorineural hearing loss, which is related to damage to the sensory nerves. Of these cases, approximately half are thought to be genetics, one quarter are acquired, and one quarter have an unknown cause. Evaluation of these problems is usually performed using plain file x-rays and computer tomography (CT). These work by evaluating the bones that form the parts of the inner-ear, but it is possible that soft-tissue defects within these bones could also be responsible for hearing loss.

To investigate the potential of magnetic resonance imaging in sensorineural hearing loss, John E. McClay, M.D., and colleagues at UT Southwestern Medical Center and Children's Medical Center Dallas examined medical records from 227 children between the ages of 1 month and 17 years, with an average age of 5.3 years who showed signs of sensorineural hearing loss. The children were examined by MRI between June 1996 and June 2002. Of the total, 170 children had enough clinical information be included in the study, and of these, 101 were affected in both ears while 69 were affected in one ear, making a total 271 years affected by sensorineural hearing loss.

Upon examination of the MRI readings:

• 40% showed inner ear abnormalities.
• 32% showed abnormalities of the cochlea, which contains the tiny hairs that are required for hearing. These were composed of 23% with mild abnormalities and 8% with moderate to severe abnormalities.
• 18% had missing or deficient cochlear nerves.
• More abnormalities were found in children with mild and moderate hearing loss (48% versus 29%).
• More inner ear abnormalities were seen in children with moderate, severe, or profound hearing loss in one ear in comparison to those with hearing loss of the same severity in both ears (62% versus 38%).

The authors indicate that this correlation could help lead to diagnosis of sensorineural hearing loss, depending on the specific circumstances for each patient. "Although the specific origin of sensorineural hearing loss may remain undiagnosed in many patients, a thorough workup to identify the cause of sensorineural hearing loss should be considered in each patient," they write. "Historically, high-resolution CT has been the imaging modality of choice in the initial workup of these patients. However, the soft tissue structures of the inner ear responsible for the electrochemical transfer of sound to the brain, such as the membranous labyrinth and the cochlear nerve, are not evaluated well with high-resolution CT."

They conclude, optimistic about the potential uses of this diagnosis technique. "With MRI, these soft tissue components of hearing from the cochlea to the auditory cortex can be elucidated, which should improve our ability to appropriately diagnose the location of the defect in these children with sensorineural hearing loss," they conclude.

Evaluation of Pediatric Sensorineural Hearing Loss With Magnetic Resonance Imaging
John E. McClay, MD; Timothy N. Booth, MD; David A. Parry, MD; Romaine Johnson, MD; Peter Roland, MD
Arch Otolaryngol Head Neck Surg. 2008;134(9):945-952.
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Written by Anna Sophia McKenney
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