Cochlear versus Retrocochlear hearing loss

DIFFERENCE BETWEEN COCHLEAR AND RETROCOCHLEAR DEAFNESS
Test Normal Cochlear lesion Retrocochlear lesion
Pure Tone Audiogram Normal SNHL SNHL
Speech Discrimination 90-100% < 90% Very poor
Roll over phenomenon Absent Absent Present
Recruitment Absent Present Absent
SISI Score 0-15% >70% 0-20%
Threshold tone decay 0-15DB <25DB >25DB
Stapedial Reflex Present Present Absent
Stapedial reflex Decay Normal Normal Abnormal
BERA Normal intervalbetween wave I and V Normal intervalbetween wave I and V Wave V delayed orabsent
Exam Question

  • Recruitment phenomenon is seen in Presbyaccusis,Meniere's Disease(Cochlear lesion)
  • To distinguish between cochlear and post cochlear dam­age, test done is Brainsterm evoked response audiometry.
  • Stapedial Reflex Decay is absent in 8th nerve lesion.(suggestive of Retrocochlear lesion)

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