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 interval between wave I and V |
Normal interval between wave I and V |
Wave V delayed or absent |
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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