Diagnose
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I now have all the information needed to give a comprehensive answer. Let me analyze the audiogram first and then synthesize the full response.
Audiogram Analysis:
Looking at the audiogram carefully:
- RIGHT ear (circles = air conduction, brackets = bone conduction): Air conduction thresholds are around 25–35 dB across frequencies with a Carhart notch at 2000 Hz. Bone conduction is near 0–10 dB (normal). → Air-bone gap present = Conductive Hearing Loss (CHL)
- LEFT ear (X = air conduction, < = bone conduction): Air conduction thresholds around 25–40 dB across frequencies, with similar air-bone gap. Bone conduction near normal. → Bilateral CHL
- Both ears show normal bone conduction with depressed air conduction
- The pattern is bilateral, flat/low-frequency predominant CHL with a characteristic dip at 2000 Hz on bone conduction (Carhart notch)
Case-6: Bilateral Otosclerosis
1) Diagnosis
Bilateral Otosclerosis (Stapedial otosclerosis)
The audiogram shows:
- Bilateral conductive hearing loss — significant air-bone gap in both ears
- Normal bone conduction thresholds (indicating intact cochlear function)
- Carhart notch at 2000 Hz on bone conduction (a mechanical artifact of stapes fixation, not true SNHL)
- Normal tympanic membrane (no perforation, normal middle ear pressure implied)
- Bilateral symmetric pattern
This is the classic audiometric signature of otosclerosis: progressive bilateral CHL in a young adult with an air-bone gap greatest in the low frequencies and a Carhart notch at 2 kHz.
2) Clinical Features
| Feature | Detail |
|---|---|
| Age of onset | Late teens to 20s; becomes symptomatic by age 30–40 |
| Sex | 2:1 female predominance |
| Laterality | ~75% bilateral (though often asymmetric) |
| Hearing loss | Progressive, insidious CHL — worse with low frequencies initially |
| Paracusis of Willis | Patient hears better in noisy environments — pathognomonic of CHL (people speak louder in noise) |
| Tinnitus | Common; pulsatile (active/vascular phase) or continuous |
| Autophony | May be present |
| Schwartz sign | Reddish/flamingo-pink blush seen through the tympanic membrane on otoscopy — signifies active otospongiotic lesion over the promontory |
| Tuning forks | Weber lateralizes to the more affected ear; Rinne negative (BC > AC) bilaterally |
| Stapedial reflex | Absent on tympanometry — key finding confirming stapes fixation |
| Family history | ~60–66% positive; autosomal dominant, 25–40% penetrance |
| Hormonal acceleration | Often worsens during or after pregnancy |
| Tympanic membrane | Normal appearance (no perforation, no retraction) |
Histopathologically, the lesion starts at the fissula ante fenestram (anterior to the oval window), causing progressive fixation of the stapes footplate.
3) Most Commonly Affected Frequency
Low frequencies are most commonly and earliest affected — the air-bone gap is typically greatest at 250–500 Hz initially. The Carhart notch at 2000 Hz is the hallmark bone-conduction dip (a mechanical artifact of stapes fixation, not true cochlear damage).
As the disease progresses, higher frequencies become involved. If the disease extends to involve the cochlear endosteum → mixed or purely sensorineural loss (cochlear otosclerosis).
4) Management
Surgical (definitive):
- Stapedotomy (preferred) — a small fenestra (0.6–0.8 mm) is made in the stapes footplate and a piston prosthesis is inserted to restore sound transmission from the incus to the oval window
- Stapedectomy (total footplate removal) — older technique, now largely replaced by stapedotomy
- Performed under local anesthesia (MAC); outpatient procedure
- Surgery is indicated when air-bone gap ≥ 20–25 dB and the patient has binaural difficulty
- Contraindications: only hearing ear, active infection, poor general health
Medical (non-surgical / adjunct):
- Sodium fluoride (Florical) — stabilizes active otospongiosis by promoting re-mineralization; may slow progression, especially for cochlear involvement
- Bisphosphonates — third-generation agents (e.g., pamidronate) studied for sensorineural component
- Hearing aids — effective alternative for patients who refuse or are not surgical candidates
Outcome of surgery: ~90% of patients achieve closure of the air-bone gap to within 10 dB. The Carhart notch typically resolves postoperatively because it was mechanical, not cochlear.
5) Hearing Loss with Complete Ossicular Disruption + Intact TM
55–60 dB conductive hearing loss (maximum CHL).
From Cummings Otolaryngology: "Ossicular disruption behind an intact TM resulted in a maximal conductive hearing loss of 55 to 60 dB. In the absence of functional impedance matching, the intact eardrum reflected sound energy back into the EAC, which caused an additional 17-dB conductive loss above what was expected from removal of the hydraulic and catenary/ossicular lever action."
This is the maximum possible air-bone gap for a purely conductive lesion. The intact TM paradoxically worsens the loss compared to a perforated TM with ossicular disruption (which causes ~50 dB loss) because it reflects rather than transmits sound energy to the oval/round windows.
Sources: Cummings Otolaryngology Head and Neck Surgery, Chapters 145–146
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