3D CT imaging is getting very useful in detecting middle ear and inner ear pathology. In patients who presents with conductive hearing loss due to middle ear abnormalities can be diagnosed by 3DCT imaging. When the tympanic membrane is intact, the only way to find out the state of the middle ear structures are by doing an operation called exploratory tympanotomy.
Exploratory tympanotomy is used when the diagnosis is in doubt and it is felt that direct microscopic visualization will significantly aid diagnosis and enhance planning of middle ear surgery.
To detect conductive hearing loss caused by ossicular fixation, incus discontinuity and otosclerosis is easier with 3D CT imaging.
No need of exploratory tympanotomy for diagnostic purpose alone, but can be useful if surgery is considered at the same time.
What is Otosclerosis?
Otosclerosis is a condition that affects the stapes, one of the tiny bony ossicles in the middle ear. To have normal hearing, the ossicles need to be able to move freely in response to sound waves. Otosclerosis causes abnormal bone material to grow in and around the stapes.
The condition usually starts at the foot of the stapes, where it attaches to the cochlea. Bone is continually being broken down and remodeled but the remodeling process of the stapes becomes faulty. New bone is not made properly and gradually abnormal bone forms. In time, more and more of the stapes becomes covered by the abnormal bone growth. This abnormal bone reduces the movement of the stapes, which reduces the amount of sound that is transferred to the cochlea. Eventually the stapes becomes ‘fixed’ which causes conductive hearing loss.
In most cases, only the stapes is affected. Sometimes the disease also affects the bony shell of the cochlea. Both ears are usually affected but sometimes only one.
Diagnosis of Otosclerosis
1-Audiogram and Tympanogram
2-3D CT middle and inner ear
3D CT proved valuable in detecting otosclerosis, foci of demineralization, and changes in bony texture and enables the easy recognition of subtle radiographic findings.
Otosclerosis (otospongiosis) is a primary focal disease of the labyrinthine capsule. The stapes footplate is fixed when the spongiotic focus expands and invades the oval window.
Persons with stapedial otosclerosis experience a progressive conductive hearing loss. In many cases, cochlear degeneration is observed, in which a mixed hearing loss occurs.
3D CT proved valuable in determining otosclerotic changes of the oval window and otic capsule. Spongiotic changes of the otic capsule are better appreciated by CT than tomogram.
left ear had stepedectomy before-showing Teflon piston in situ
Treatment
Hearing aids can be very helpful and it makes sense to try them before considering surgery. However, otosclerosis will continue to progress and hearing aids will not stop you developing profound deafness in the long term.
If you do need surgery, then an operation called a stapedectomy can be carried out. However, if you suffer from tinnitus, surgery may not relieve this and if your inner ear is also affected, surgery may not improve your hearing either.
A tinnitus masker may help.
