ENT · Otology
The facts most likely to be tested
Otosclerosis is characterized by abnormal bony remodeling of the otic capsule, most commonly resulting in stapes fixation at the oval window.
Patients typically present with progressive conductive hearing loss in a young adult, often with a positive family history.
The classic audiometric finding is the Carhart notch, which is a dip in bone conduction thresholds specifically at 2000 Hz.
Physical examination often reveals a pinkish hue behind the tympanic membrane, known as the Schwartz sign, indicating increased vascularity of the promontory.
Otosclerosis is frequently exacerbated by pregnancy, likely due to hormonal influences on bone metabolism.
The tympanogram in otosclerosis typically shows Type As (shallow), reflecting reduced middle ear compliance.
Definitive management for symptomatic patients is stapedotomy or stapedectomy with the placement of a prosthesis.
Vignette unlocked
A 32-year-old woman presents to the clinic complaining of a 2-year history of gradually worsening hearing loss in her left ear. She reports no history of ear infections, trauma, or ototoxic medication use, but notes that her mother underwent ear surgery in her 30s. On physical examination, the tympanic membranes are intact and mobile, but a subtle reddish blush is noted over the promontory. Audiometry demonstrates a conductive hearing loss with a characteristic dip in bone conduction at 2000 Hz.
What is the most likely diagnosis?
Otosclerosis
The patient's presentation of progressive conductive hearing loss, family history, and the pathognomonic Carhart notch and Schwartz sign are diagnostic for otosclerosis.
Full handout
High yield triage
Etiology / Epidemiology
Common in young Caucasian females with a strong autosomal dominant family history.
Clinical Manifestations
Presents with progressive conductive hearing loss and the Schwartz sign.
Diagnosis
Confirmed via audiometry showing a Carhart notch at 2000 Hz.
Treatment
Managed with stapedectomy; avoid stapedotomy in patients with active disease.
Prognosis
Excellent outcomes with surgical intervention; recurrence is rare.
Full handout
Epidemiology & Etiology
Otosclerosis is a primary disorder of the bony otic capsule. It is most prevalent in Caucasian women aged 20–40. A strong autosomal dominant inheritance pattern is frequently observed.
Pertinent Anatomy
The disease involves abnormal bone remodeling of the stapes footplate. This fixation prevents the stapes from vibrating against the oval window, effectively blocking sound conduction.
Pathophysiology
Excessive bone resorption followed by disorganized bone deposition leads to stapes ankylosis. This mechanical fixation results in conductive hearing loss. Over time, the process may extend to the cochlea, causing sensorineural hearing loss.
Clinical Manifestations
Patients report slowly progressive hearing loss, often exacerbated by pregnancy. The Schwartz sign, a reddish hue behind the tympanic membrane, indicates hypervascularity. Sudden vertigo or tinnitus may occur if the inner ear is involved.
Diagnosis
The gold standard is clinical diagnosis supported by audiometry. A hallmark finding is the Carhart notch, a specific dip in bone conduction thresholds at 2000 Hz. Tympanometry typically reveals a Type As (shallow) curve.
Treatment
Initial management includes hearing aids for those who decline surgery. The definitive treatment is stapedectomy with prosthesis placement. Avoid surgery during active, progressive phases to prevent inner ear damage.
Prognosis
Surgical success rates for restoring hearing are >90%. Long-term audiometric monitoring is required to ensure the prosthesis remains stable and to screen for late-onset sensorineural decline.
Differential Diagnosis
Cholesteatoma: presence of keratin debris/retraction pocket
Ossicular chain disruption: history of trauma
Meniere disease: episodic vertigo and fluctuating hearing loss
Tympanosclerosis: scarring from chronic otitis media
Congenital stapes fixation: present from birth