What is obliterative otosclerosis?
What is obliterative otosclerosis?
Obliterative otosclerosis involves total obscuration of the oval window and its margins (Fig. 11–1). It is thought to be evidence of very advanced otosclerosis. Young patients are especially at risk, particularly when active, aggressive otosclerosis develops around puberty.
What is a normal audiogram?
The average human can hear between 20 and 20,000 Hz. Audiograms typically test frequencies between 250Hz and 8000Hz. Human speech usually falls between 250Hz and 6000Hz.
How many Hertz should I hear?
The ‘normal’ hearing frequency range of a healthy young person is about 20 to 20,000Hz. Though a ‘normal’ audible range for loudness is from 0 to 180dB, anything over 85dB is considered damaging, so we should try not to go there. As we age, it’s the upper frequencies we lose first.
Can otosclerosis be seen on a CT scan?
We classified a CT scan as positive for otosclerosis when a hypodense focus was seen around the otic capsule. Preoperative and postoperative air- and bone-conduction thresholds were collected. Results: Of 209 HRCT scans, 84.2% were classified positive, 8.6% doubtful, and 7.2% negative.
What is the audiometric diagnosis of otosclerosis?
The audiometric diagnosis of otosclerosis is based largely on interpretation of the air-bone gaps that establish the presence of a conductive component to hearing loss. Other measures such as tuning fork tests or more sophisticated behavioral tests may be used along with objective audiometric measurements for this purpose.
Can we measure DPOAEs with otosclerosis?
When measuring DPOAEs, the increased stiffness of the ossicular chain in otosclerosis may lead to artifac-tual distortions at sound levels for which they do not normally occur. Moreover, clinical DPOAE systems cannot differentiate such artifactual distortion products from those biologically generated within the inner ear.
What are the acoustic consequences of otosclerosis?
The primary acoustic consequence of otosclerosis in its early stages is the increase in the stiffness reactance component of the total middle ear impedance. This results in a reduction of transmission effectiveness for low frequencies, as seen in elevated thresholds.
What is the range of pure conductive hearing loss from cochlear otosclerosis?
In the absence of cochlear involvement, the pure conductive hearing loss produced by the complete stapes fixation is limited to 60 to 65 dB, with a maximum air-bone gap across the frequency range. Figure 4–1 Pure tone audiogram of a patient suffering from cochlear otosclerosis.
