Otosclerosis Part 2 - Symptoms, Signs, Investigations, Differential diagnosis

👂 Otosclerosis - Clinical Features, Investigations & Differential Diagnosis

Continued from Part 1 - Otosclerosis Causes, Pathogenesis, Types, Pathology.

This is Part 2 of the Otosclerosis series.

In this section, we will cover:

• How a patient with otosclerosis presents
• Key symptoms and signs
• Audiological and radiological investigations
• Important differential diagnoses

📍 Common Sites of Otosclerotic Focus

🚨 MCQ Alert - The most common site of otosclerosis is:

• Fissula ante fenestram
  • Located anterior to the oval window
  • ⭐ Most common MCQ answer

What are the other sites of Otosclerosis?

🧠 History taking in Otosclerosis

✅ Classical History

• Progressive bilateral hearing loss

• Onset in early adulthood (20–30 years)

• Female predominance

• Hearing loss worsens during pregnancy

• Usually painless and slowly progressive

👉 Typical MCQ question:

Middle aged woman with progressive bilateral conductive hearing loss worsened during pregnancy

❌ History NOT Suggestive of Otosclerosis

• Onset before 10 years or after 40 years

• Non progressive hearing loss

• Ear discharge

• Ear trauma

• Prominent vertigo as the main symptom

🔊 Symptoms of Otosclerosis

• Hearing Loss (Most Common) - Usually Bilateral

What is the type of hearing loss seen in Otosclerosis?

What % of Otosclerosis patients have Unilateral hearing loss?

What are the Mechanisms of Conductive Hearing Loss in Otosclerosis?

When does Sensorineural Hearing loss occur in Otosclerosis?

• 🩸 Circulatory Theories in Cochlear Otosclerosis - Otto Mayer’s Theory & Ruedi’s Theory

What is Otto Mayer’s Theory in Otosclerosis?

What is Ruedi’s Theory in Otosclerosis?

• Paracusis Willisii - Seen in 20-78% of patients - ⭐ Classic symptom of otosclerosis

What is Paracusis Willisii?

• Tinnitus

What is the type of tinnitus seen in Otosclerosis?

• Vestibular Symptoms

  • Vertigo is uncommon
  • Rarely the sole presenting symptom

What is the cause behind the vestibular symptoms in Otosclerosis?

• Speech Pattern

  • Soft, monotonous, well-modulated speech
  • Patient hears own voice via bone conduction

👁️ Signs of Otosclerosis

🔍 Otoscopy

• Tympanic membrane usually normal

• May show Schwartz sign

What is Schwartz sign? What is its other name?

🔧 Tuning Fork Tests

• Rinne negative
  • First at 256 & 512 Hz
  • Later at 1024 Hz
• Weber lateralized to worse ear
• Absolute bone conduction: Normal (↓ if cochlear involvement)

What is Bezold’s Triad?

🎧 Investigations of Otosclerosis

📊 1. Pure Tone Audiometry

• Conductive hearing loss
• Greater loss at lower frequencies
• Carhart’s notch

What is Carhart's Notch? What are the causes of Carhart's Notch?

• Cookie Bite Audiogram

What is Cookie Bite Audiogram? When is it seen?

📈 2. Tympanometry

• Type As (stiffness)

• Acoustic reflex absent

🧠 3. HRCT Temporal Bone

Findings in active otosclerosis:

• Hypodense lucent areas
• Thickened stapes footplate
• Narrowed oval & round windows

Inactive lesions → hard to detect

What is Symons & Fanning CT Grading system of Otosclerosis?

🧲 4. MRI

• Used mainly for cochlear implant planning

🔄 Differential Diagnosis of Otosclerosis

• Ossicular Chain Discontinuity
• Congenital Stapes Fixation
• Tympanosclerosis
• Secretory Otitis Media

📘 In my detailed notes, I’ve discussed an exhaustive list of Differential Diagnosis of Otosclerosis.

How would you rule out each of the Differential Diagnosis of Otosclerosis.

📌 Key Exam Pearls

• Female + pregnancy + Conductive Hearing Loss = Otosclerosis
• Most common site: Fissula ante fenestram
• Carhart’s notch at 2000 Hz
• Schwartz sign = active lesion
• Tympanometry: Type As
• Paracusis Willisii = classic symptom

📘 Next Part:
Treatment of Otosclerosis — medical, surgical & indications.