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Pseudo-conductive Hearing Losses. Bastaninejad , Shahin , MD, Assistant Professor of ORL, TUMS, Amir’Alam Hospital. Definition. of Pseudo-conductive Hearing Loss. A pparent conductive hearing loss on audiometric testing, that is not due to pathology in the external or middle ear.

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pseudo conductive hearing losses

Pseudo-conductive Hearing Losses

Bastaninejad, Shahin, MD, Assistant Professor of ORL, TUMS, Amir’Alam Hospital

definition
Definition

of Pseudo-conductive Hearing Loss

Apparent conductive hearing loss on audiometric testing, that is not due to pathology in the external or middle ear

case presentation
Case Presentation
  • 10yr old boy
  • CHL in Left ear, found during a routine school-hearing test
  • Left side Rinne’s test was negative
  • AR in Left ear: Ipsi.neg., Contra.Pos.
  • CTnl.
  • No history of trauma and…
slide4

Hamad Al Muhaimeed, et al. Conductive hearing loss: investigation of possible inner ear origin in three cases studies. The Journal of Laryngology & Otology November 2002, Vol. 116, pp. 942–945

case cont
Case Cont.
  • The provisional diagnosis was ossicular disruption medial to the neck of the stapes (to explain the presence of the contralateral stapedial reflex)
  • Exploration performed  all ossiceles were mobile, FP was mobile, but Round window reflex was negative
importance
Importance

Some causes of these pseudo-conductive hearing losses can be diagnosed without resorting to surgery

bibliography
Bibliography
  • The concept of inner ear conductive hearing loss was proposed as early as the 1960s by Gloris and Davis and by Nixon and Glorig. They proposed stiffness of the cochlear partition as a possible cause
proposed mechanisms for a true pseudo chl
Proposed Mechanisms for a True Pseudo-CHL
  • Third window effect
  • lesions in the:
    • Scala vestibuli
    • Helicotrema
    • Scala tympani
    • Basilar membrane
  • Obliterated round window membrane

Transmission Problem

Inner ear conductive hearing loss

key discriminating features
key discriminating features
  • Presence of AR in the ear with CHL
    • Exception:crossed or may be a normal stapedial reflexes can be present if there is fracture in the stapes crura or footplate medial to the insertion of the stapedius tendon
key discriminating features1
key discriminating features
  • Round window reflex findings:
    • Presence When Otosclerosis is suspected
    • Absence  In the presence of an obviously mobile footplate
differential diagnosis
Differential Diagnosis
  • Poor Masking andPoor Audiometry:
    • Perhaps the most common cause of pseudoconductivehearing loss is the presence of a unilateral or asymmetric sensorineural hearing loss in which the better hearing inner ear is poorly masked  perform tuning fork test in all subjects
    • Collapsing ear canals
ddx cont
DDx Cont.
  • Functional Hearing Loss:
    • Must be considered in any patient with an unusual conductive hearing loss pattern:
      • Some subjects who are exaggerating their hearing loss have difficulty estimating the loudness level of the two different stimuli  different CHL in two consecutive assessments…
      • Also they may have an inverse air–bone gap!
ddx cont1
DDx Cont.
  • Third Window  can arise from a fistula into the cochlea or the labyrinthine portion of the inner ear
    • Semicircular Canal Dehiscencies (Superior, Inferior and Lateral)
    • LVA
    • X-Linked Deafness With Stapes Gusher
    • Dehiscence Between the Cochlea and Carotid Canal
    • Paget Disease of the Temporal Bone
    • Some inner Ear Malformations
slide17

Saumil N. Merchant and John J. Rosowski. Conductive Hearing Loss Caused by Third-Window Lesions of the Inner Ear. Otol Neurotol. 2008 April ; 29(3): 282–289

ddx cont2
DDx Cont.
  • Round Window Obliteration
  • Inner Ear Mechanical Conductive Loss
    • One of the types of presbycusis (CHL with Mixed loss at 4k and 8k)
    • Changes in BM pliability
    • Lesions in the scala vestibuli, helicotrema and scala tympani
    • Co-existed with some forms of the congenital hearing losses
ddx cont3
DDx Cont.
  • Missed Middle Ear Pathology
    • Otosclerosis with a flexible suprastructure
    • Malleus or incus fixation or stiffness
    • Pathology at the lenticular process of the incus
    • Floppy tympanic membrane
    • Adhesions lysed during the approach for exploration
    • Transient pathology at the time of audiogram
conclusion
Conclusion

Think about plausibility of Pseudo-conductive hearing loss and include it’s possibility in your pre-operative evaluation and patient consent before proceeding to the middle ear exploration