Conductive Hearing Loss

Introduction to Hearing Loss
Anatomy and Physiology of Hearing
Conductive Hearing Loss
Sensorineural Hearing Loss
Sudden Sensorineural Hearing Loss
Other Types of Hearing Loss

Table of Contents

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Conductive hearing loss

Is caused by a disorder of the external & middle ear

Usually does not excess 60 dB



  • Occlusion of EAC
  • Perforated of the TM
  • Occlusion of eustachian tube
  • Fixation of the ossicular chain c or s fixation of ear drum
  • Discontinuty of the drum ossicle chain mechnism
  • Congenital malformation


Occlusion of EAC

Occlusion of EAC may be result from

  • Congenital atresia
  • Acquired atresia from External otitis or trauma,FB or Impactcerumen,Furuncle, Polyp,exostosis,Neoplasm

Restoration of normal hearing can be expected after removal of the obstruction


Perforated of the TM

Degree of HL depend on size,location & nature of perforation

Caused by trauma,after an acute necrotic OM

Usually low frequency loss


Occlusion of eustachian tube

Hypertrophy of nasopharyngeal adenoid tissue

Allergic tubutympanitis,scars of tube orifice

Acute viral or bacterial nasopharyngitis

Descent in plane,train,deep sea diving->barotrauma or aero-otitis

Cleft palate,both before and after surgical repair

Tumor of nasopharynx

Malocculsion of mandibular jt (Costen’s syndrome)


Fixation of the ossicular chain c or s fixation of ear drum

Decreased of mobility of ossicular chain from fixation

Otosclerosis, tympanosclerosis, scar after sergery or infection

Can evaluated by pneumotic otoscope

Reconstruction ex Stapesdectomy in otosclerosis


Discontinuty of the drum ossicle chain mechnism

Infection or trauma

Incudostapedial joint floating in middle ear à increased risk of devascularized of its

Evaluated by pneumatic otoscope or tympanogram

Occurs maximum CHL by normal TM




Physical examination

  • Otoscope (Diagnosis,Pneumatic)
  • Tuning fork test (Rinne, Weber test)
  • Audiometry
  • Tympanometry


History and physical examination for hearing loss


Age at onset

Abrupt versus gradual

Progressive, intermittent, or continuous

Antecedent illness

Duration of symptoms

Associated symptoms

  • Tinnitus
  • Dizziness or vertigo
  • Aural fullness
  • Pain
  • Allergy symptomatology
  • Actions that change intensity of symptoms
  • Distorted auditory perception
  • Worsening with pregnancy or oral contraceptive use

Family history of hearing loss

Occupational noise exposure

Recreational noise exposure


Surgical history

Previous or current draining from ear

  • Quality of drainage

Systemic infections and treatments

  • Meningitis
  • Syphilis

Previous use of a hearing aid

Ototoxic medications

  • Cancer chemotherapy
  • Antibiotics

Recent air travel

Recent underwater diving


Tuning fork test

False negative Rinne test

  • When there is total or severe SNHL in one ear
  • The vibrations of the tuning fork are transmitted across the bone of the skull and are sensed by the opposite and healthy cochlea




Table 147-2. Degree of hearing loss estimated by Rinne testing

Rinne test result

Estimated conductive loss

Negative, 256 Hz

Positive, 512 and 1024 Hz

Mild conductive loss of 20-30 dB
Negative, 256 and 512 Hz

Positive, 1024 Hz

Moderate conductive loss of 30-45 dB
Negative, 256, 512, 1024 Hz Severe conductive loss of 45-60 dB


Summarized By Thirayost Nimmanon

โดย ธีรยสถ์ นิมมานนท์


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