Updated: 6/28/2020

Conductive vs. Sensorineural Hearing Loss

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Snapshot
  • A 30-year-old man presents with constant right ear pain and hearing loss for the last 3 months. He also states that at times he experiences ringing of the right ear. He was previously diagnosed with an ear infection that was treated with antibiotics. On physical examination, there is amorphous and white debris in the right middle ear. A tuning fork was placed on the mastoid process and sequently by the external auditory canal. Bone conduction was louder than air conduction on the right ear. When the tuning fork is placed in the middle of the patient's ear, the tone was louder in the right ear. It is explained to the patient that a non-contrast computer tomography (CT) scan of the temporal bone will be scheduled. (Conductive hearing loss secondary to a cholesteatoma)
Introduction
  • Hearing loss
    • basic principles
      • unilateral hearing loss can result from lesions affecting the
        • external auditory canal
        • middle ear
        • cochlear
        • cranial nerve VIII
        • cochlear nuclei
      • bilateral hearing loss suggests
        • a lesions after the auditory pathways enter the brainstem
          • this is because auditory information crosses bilateraly immediately after entering the brainstem
    • hearing loss is generally divided into
      • conductive hearing loss
        • secondary to lesions affecting the
          • external auditory canal
          • middle ear
      • sensorineural hearing loss
        • secondary to lesions affecting the
          • cochlea
          • cranial nerve VIII
  • Conductive hearing loss
    • etiologies include
      • otitis externa
      • squamous cell carcinoma
      • osteoma
      • cerumen
      • otitis media
      • cholesteatomoa
      • otosclerosis
      • tympanic membrane perforation
  • Sensorineural hearing loss
    • etiologies include
      • hereditary hearing loss
      • presbycusis
      • ototoxic drugs
      • Meniere disease
      • barotrauma
      • acoustic neuroma
      • multiple sclerosis
  • Physical exam maneuver
    • whispered voice test 
      • the examiner stands behind the patient at arm's length and one of the patient's ears are occluded 
        • the examiner whispers a series of letters and numbers, of which the patient must repeat
      • normal findings
        • patient should be able to repeat the whispered letters and number
      • pathology
        • hearing impairment, which will prompted further physical exam maneuvers, such as the Weber and Rinne test
    • Rinne test
      • compares air conduction to bone conduction
        • air conduction is tested by
          • placing the vibrating tuning fork by the outside of the ear
        • bone conduction is tested by
          • placing the tuning fork on the mastoid process
      • normal findings
        • air conduction is more than bone conduction
      • pathology
        • in conductive hearing loss
          • bone conduction is greater than air conduction
            • this is because bone conduction bypasses issues involving the external and middle ear
        • in sensorineural hearing loss
          • air conduction is greater than bone conduction bilaterally (just like in normal conditions)
          • there is decreased hearing in the affected ear
    • Weber test
      • the vibrating tuning fork is placed in the middle of the patient's forehead
        • the patient is subsequently asked to say which side is loudest
      • normal findings
        • sound is equally heard in both ears
      • pathology
        • in conductive hearing loss
          • the tone is louder on the affected side
            • this is because of compenstatory mechanism aimed at increasing the perceived volume of the affected side
        • in sensorineural hearing loss
          • the tone is decreased on the affected side
  • Diagnostic studies
    • audiogram
      • useful confirmatory diagnostic study in patients with hearing impairment that cannot be explained by obvious causes (e.g., cerumen imapaction) 

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Questions (2)

(M2.ET.17.0) A 72-year-old man presents to his primary care physician with progressively worsening hearing loss. He states that his trouble with hearing began approximately 7-8 years ago. He is able to hear when someone is speaking to him; however, he has difficulty with understanding what is being said, especially when there is background noise. In addition to his current symptoms, he reports a steady ringing in both ears, and at times experiences dizziness. Medical history is significant for three prior episodes of acute otitis media. Family history is notable for his father being diagnosed with cholesteatoma. His temperature is 98.6°F (37°C), blood pressure is 138/88 mmHg, pulse is 14/min, and respirations are 13/min. On physical exam, when a tuning fork is placed in the middle of the patient's forehead, sound is appreciated equally on both ears. When a tuning fork is placed by the external auditory canal and subsequently on the mastoid process, air conduction is greater than bone conduction. Which of the following is most likely the cause of this patient's symptoms?

QID: 109463
1

Accumulation of desquamated keratin debri

10%

(17/177)

2

Eustachian tube obstruction secondary to nasopharyngeal inflammatory edema

2%

(4/177)

3

Stapedial abnormal bone growth

6%

(10/177)

4

Cochlear hair cell degeneration

68%

(120/177)

5

Endolymphatic hydrops

12%

(21/177)

M 5 C

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