Here is what you should look for:

  1. Check the case history or notes about age of the patient, their complaint, and other information that might provide you with a clue about the site of lesion. Patients administered ototoxic drugs, exposed to noise, hereditary factors and complain of difficulties hearing clearly in noise or trouble hearing children may suggest cochlear pathologies. Tinnitus, intermittent hearing loss, dizziness, paralysis, fatigue complaints may suggest neural lesions. Young children are more likely to have conductive hearing losses while adults are more likely to present with SNHL. The elderly may experience auditory processing disorders along with SNHL.
  2. Look at the tympanograms: Type A means there should be either normal hearing or sensorineural (SNHL). (So check the audiograms to determine whether there is normal hearing or SNHL.
  3. Look at the acoustic reflex thresholds (ARTs): ARTs will probably be absent unless the tympanograms are type A or some type C (in other words, if there is a conductive or mixed loss, the ARTs are usually absent). For normal audiograms and cochlear lesions, the ARTs generally do notexceed the 90th percentile. For neural lesions, the ARTs are often absent or exceed the 90th percentile.
  4. Look for the OAE: OAEs are generally absent when there is a conductive loss (and mixed loss). OAEs are generally absent when the loss is cochlear specific to damage to the outer hair cells (OHCs). Most ototoxic drugs, noise exposure, etc., result in damage to the OHCs, however, there are a few instances of cochlear lesions with normal OAEs (OHC functioning), but result in pathology to the inner hair cells (IHCs) such as hypoxia (in adequate supply of oxygen) in infants, administration of carboplatin (cancer drug), auditory neuropathy, etc., while leaving the OHCs intact.

Fig 8-1

Child with history of OM, conductive loss, type B tympanograms, absent ARTs, no rollover, PB-max=100%, no APD as indicated by PSI, expect normal OHC function, but OAE would be absent because of the OM, absolute latencies for ABR would be elongated, but interwave would be normal

Fig 8-2

Otosclerosis which is more common in females and onsets around 20 or during pregnancy, conductive loss, As tymps, absent ARTs, probably normal OHCs, but OAE may be absent because of the abnormal tymp, static compliance is below normal, no rollover, PB-max near 100 %, no auditory processing problem with high DSI scores, ABR absolute latencies elongated with normal interwave latencies

Fig 8-3

Cisplatin ototoxicity damaging hair cells, precipitous high frequency SN loss, high PB-MAX, no rollover, no APD as indicated by DSI, normal tymps, ARTs within normal range, OAE may be abnormal if OHCs damaged by noise and drugs, ABR, normal.

Fig 8-4

45 year old woman with unilateral SNHL secondary to endolymphatic hydrops (Meniere’s), tinnitus, fluctuating hearing loss, ear fullness sensation, and severe vertigo. Tympanograms normal suggesting SN, AS. ART’s within normal range suggesting cochlear lesion for left ear. Normal right ear, normal speech recognition ability. Left ear, reverse slope audiogram with very poor speech recognition ability…below lower limits. OAEs not evaluated, but should be normal for right ear, and abnormal for left ear. OHCs should be normal right, abnormal left. ABRs normal…absolute and interwave latencies all within normal range. Results suggest cochlear damage despite the very poor speech recognition ability which often occurs with Meniere’s.

Fig 8-5

Tympanograms normal indicating SNHL for left ear. Ski slope audiogram left. Acoustic reflexes present when right ear stimulated in ipsilateral (uncrossed) and contralateral (crossed) and absent when left ear stimulated suggesting neural lesion. Significant rollover, AS, suggesting neural lesion. Normal DSI suggesting no auditory processing disorder in cerebrum. ABR abnormal…absolute wave V latency and interwave I-III elongated suggesting neural lesion for left ear. Pt has acoustic tumor on left auditory nerve. Though OAEs not conducted, OHC should be normal with normal OAEs. Exception is whether cochlear artery integrity compromised for left ear resulting in lesion to cochlea.

Fig 8-6

34 year old woman with episodes of diplopia, tingling sensation and weakness in left leg. Normal tympanograms indicating SNHL. Reverse slope audiograms, AU. Acoustic reflexes with crossed stimulation absent suggesting neural lesion. Normal WRS, BUT poor SSI with rollover suggesting neural lesion. DSI suggests cerebrum level and corpus calosum functioning normally. ABR elongated, AD, and absent, AS suggesting neural lesion. Patient diagnosed with MS.

Fig 8-7

57 year old male exposed to excessive noise. Tympanograms and ARTS within normal range suggesting cochlear SNHL. Notch at 4000 Hz typical of noise induced SNHL. No rollover. Normal DSI suggesting normal cerebral auditory function. OAEs in higher frequency will be abnormal with OHC in apical turn damaged.

Fig 8-8

78 year old female complaining her hearing aids are not providing benefit compared to early use when listening in noise. Tympanograms and acoustic reflexes within normal range suggestive of cochlear SNHL. Rollover present in both ears but not a significant rollover. DSI abnormal for the left ear with a right ear advantage…suggesting cerebrum auditory processing problem likely for her age. Suggest directional microphones, FM use with HA and quiet listening environ.

Fig 8-12(8-10)

A four year old child with cytomegalovirus (CMV). Tympanograms normal suggesting a SNHL. ARTs within the normal range suggesting cochlear lesion. OAEs are absent also suggesting cochlear lesion involving pathology to the OHCs. No speech recognition tests were reported.

Fig 8-14 (Case 8-11)

A six year old girl with a history of chronic OM. Tympanograms are normal (type A)…and the audiogram shows normal hearing sensitivity, too. ARTs are within the normal range. OAEs were not evaluated, but are probably normal suggesting normal OHC function. But note the rollover for the right ear and very poor word recognition scores. The PSI-CCM (dichotic test) shows poor results for the left ear. These interesting speech recognition results most likely suggest auditory processing problems. An ABR was normal. The chronic OM may have played a role during the development of language. This child will probably experience difficulty in noisy classroom/learning environments.

Fig 8-15 (Case 8-12)

A 30 year old male complains of hearing loss in his right ear following an automobile accident. He reported head and neck injuries resulting from the accident. Tympanograms are within the normal range. ARTs are approximately the same or better than the hearing threshold (AND NOTE the mixed loss!!!). Be ware, the patient’s responses may not be reliable! ARTS should be absent with this degree of A-B gap. The OAEs are present for the right ear…oops!!!...look at the severity of the loss and the supposed conductive loss…not possible…another alert to unreliable patient responses. In the left ear, note bone results are significantly worse than the air results…oops!!! ARTs are in the expected range for the left ear. OAEs for the left ear are in the expected range for normal hearing. Patient did not return for ABR. This person was most likely not reliably responding to pure tone stimuli—malingering.