Differential Diagnosis

Patient History for establishment of pathology
  • Normal, Conductive, Mixed, Sensorineural, Retrocochlear
  1. Reason for visit
  2. Onset
    1. ​gradual or sudden
    2. sickness
    3. pregnancy
  3. ​Speech in Noise
    1. ​one on one; in direction
  4. Middle Ear Infections
    1. ​possibility of mixed if not treated in childhood that could have grown into a sensoryneural
    2. history of surgeries
  5. ​Noise Exposure
    1. ​Weapons firing
    2. Working in a noisy environment
    3. Motorcycles
    4. Concerts
    5. Hearing protection?
  6. Medications
    1. ​Ototoxic medications
    2. Cancer treatments
    3. Vestibular Medications
  7. ​Tinnitus
    1. ​one or both ears
    2. sounds like
    3. constant, intermittent
    4. bothersome
  8. Balance, Dizziness, Vertigo
    1. ​history of ear infections
    2. drainage, pressure, pain, fullness
  9. ​Family History
    1. ​Cause
    2. Age
  10. ​Previous Hearing Test
    1. ​Results
    2. Hearing aids?
  11. ​History of surgeries?

Otoscopy
  1. Visual inspection of the auricle, ear canal and tympanic membrane
  2. Insert otoscope with speculum while bracing and pulling superiorly and posteriorly of auricle
  3. Results
    1. Verification of proper anatomical landmarks, assessment of cerumen impaction, presence of fluid, scarring or other anomalies
  4. ​Food For Thought
    1. ​Can determine history and evolution of TM and ear canal
    2. Visual anomalies that would interfere with hearing or hearing testing
      1. ​cerumen; conductive component
      2. collapsed canals
      3. otitis media
      4. If clear and healthy looking can have
        1. ​ossicular chain discontinuity
        2. SNHL
        3. normal hearing or sensory neural hearing loss
      5. ​Cloudy ear drum, reddish ear drum, possible conductive

Tympanometry
  1. Instruction
    1. Pressure test of tympanic membrane and verification of canal size and function
    2. Be still and remain quiet
  2. Insert probe tip and pressurize canal
  3. Results
    1. Verification of function of tympanic membrane, pressure difference of outer and inner ear and ossicular chain action
  4. Food For Thought
    1. ​Type A is normal
      1. ​normal volume, compliance, pressure (normal ME function)
    2. Type As is shallow but not flat (fluid or ossicular fixation that decreases mobility; otitis media, otosclerosis)
    3. Type Ad is hypercompliant (overly mobile tympanic membrane usually caused by disarticulation, or perforation that is healed but thinner and more compliant than expected)
      1. ​conductive component
    4. Type B is flat
      1. ​ear canal volume normal possible OM
      2. ear canal volume low
        1. ​misplaced probe
        2. cerumen impaction
    5. Type C is negative pressure
      1. ​consistent with allergies, colds or end of infection
    6. ​https://www.aafp.org/afp/2004/1101/p1713.html

Acoustic Reflex Thresholds - need enough hearing in the stimulating ear and intact responding mechanism; is there enough hearing there to elicit the response, if not loud enough will not get a response. Ex: L HL, may not get L Ipsi but R Contra. Is there a conductive component that would obliterate. is there a facial nerve issue. of course, brainstem issues might wipe out reflexes. SNHL will always get reflexes, may get them lower due to sensitivity to loudness. 

  1. ​Keep in mind that ART results should be analyzed in combination with the patient history, audiogram, speech and tympanometry findings for differential diagnosis.
  2. Instruction
    1. Tones in both ears to measure reflexes
  3. Insert probe and foam tips
  4. Results
    1. Verification of acoustic stapedial reflex arc functionality ipsilaterally and contralaterally
    2. Determination of cranial nerve and brainstem function
  5. ​Food For Thought
    1. Normal
      1. ​Ipsilateral and Contalateral will be present at all frequencies
    2. Conductive
      1. ​Acoustic Reflexes will be absent when a probe is placed in an ear with a middle ear disorder
      2. ​Middle ear disorders typically prevent the probe from measuring a change in compliance when the stapedius muscle contracts. reflexes will be absent even in the case of a mild conductive hearing loss​​
      3. Examples: L/I & R/C absent (pathological ear); L/I, R/C & L/C (not loud enough to elicit response)
      4. Likely won't get reflexes
    3. ​Cochlear
      1. ​Sensation levels can be determined
        1. ​Example: 1kHz threshold is 50dB and ART is 90dB, sensation level is 50dB
        2. May look normal when thresholds are below 50dB, above this level, the chance of recording raised or absent reflexes increases
      2. ​Severe to profound cochlear loss in left ear, normal hearing in right
        1. ​R/I normal, L/C absent, L/I absent, R/C present
          1. ​right side works, left side cannot cross to right, left side doesn't work, right crosses but elevated
    4. ​​​Retrocochlear (CNVII/Facial Nerve)
      1. ​Usually elevated, often absent at maximum stimulus levels
      2. Ears with retrocochlear pathology and normal hearing do not have reflexes 30% of the time
      3. With a mild 30dB hearing loss, the likelihood of absent reflexes increases
      4. The absence of reflexes at 500, 1kHz, 2kHz in the presence of normal/near normal hearing must be considered suspicious unless proven otherwise
      5. The affected ear will show absent acoustic reflexes when a stimulus is presented to it in the case of CNVIII lesions
      6. Example: Retrocochlear lesion in left ear, normal hearing in both ears
        1. ​R/I normal, L/C elevated, absent, L/I elevated/absent, R/C normal
        2. Raised or absent acoustic reflexes with presentation to the left ear
      7. ​Example: Retrocochlear/CNVIII lesion in the left ear; mild hearing loss in the left ear & normal hearing in the right ear
        1. ​R/I normal, L/C Absent, L/I Absent, R/C normal
        2. Absent acoustic reflexes with presentation to the left ear
    5. ​​Facial Nerve/CN VII Involvement
      1. ​Acoustic reflexes mainly absent when measured on the affected side in the case of a facial nerve disorder. This is because the stapedius muscle is innervated by CN VII.
      2. Example: Bell's Palsy: R/I present, L/C present, L/I absent, R/C absent​
        1. ​Acoustic reflexes are absent when probe is coupled to the affected ear
        2. This is a similar pattern of results for CN VIII lesion
    6. ​​​Inter-axial Brainstem Lesion
      1. ​Very rare, about 1 in 10 million
      2. Acoustic reflexes are normal ipsilaterally and absent contralaterally
      3. The left and right pathways are disrupted by a lesion involving the auditory fibers
    7. ​See images at bottom of page

TEOAE/DPOAE - Conductive will not get emissions if above 40dB
  1. Instruction
    1. ​Test of ear hair cells, the sensory organ of hearing transduction
  2. ​Insert probe tip, remove and replace twice for each ear
  3. Results
    1. ​Verification of outer hair cell function

Speech Reception Threshold
  1. Instructions
  2. Familiarization with spondees
  3. Initial and test phase for the descending technique
  4. Calculation of threshold
  5. Results
    1. cross validation for pure-tone thresholds
    2. measurement of communication disability
    3. reference for supra-threshold measures
    4. estimation of performance at PBMax
  6. ​Food For Thought
    1. ​SRT - PTA agreement (500, 1kHz, 2kHz; or best frequency if sloping)
      1. ​SRT match within 7 to 10 dB
    2. ​Should mask if there is a 40dB difference or IA difference

Most Comfortable Listening Level (MCL)
  1. Instructions
  2. Calculation of threshold
  3. Usefulness of results
  4. estimation of presentation thresholds for word recognition

Uncomfortable Listening Level (MCL)
  1. Instructions
    1. ​Looking for loudest level that you can tolerate, where the sound will become unbearable.
  2. Calculation of thresholds
  3. Usefulness of results
    1. estimation of presentation thresholds for word recognition for conductive hearing loss

Pure Tone Audiometry - Looking for severity of hearing loss, looking for asymmetries. Looking for shadow curve for Interaural attenuation of transducer. Mask at difference of IA of transducer.
  1. Instructions
  2. Calculation of thresholds using pulsed or warbled tones
    1. ​250Hz, 500Hz, 1kHz, 2kHz, 3kHz, 4kHz, 6kHz, 8kHz
  3. Ensure proper masking
    1. ​If difference between Air thresholds is >/= to interaural attenuation
  4. Usefulness of results
    1. estimation of severity of hearing loss

Word Recognition Scores
  1. Instructions
  2. Estimation of PBMax
    1. highest score obtainable is the PBMax
    2. listeners on average achieve maximal performance on a speech recognition task at 30 to 40dB SL
    3. assessing only a single level may provide limited diagnostic or rehabilitative information
    4. assessing performance at multiple presentation levels for individuals with sensory/neural hearing loss provides greater diagnostic information
  3. Usefulness of results
    1. The influence of presentation levels on psychometric functions determines type and severity of hearing loss
  4. ​​Food For Thought
    1. ​For most individuals with normal auditory function or purely cohchlear hearing loss, maximum word recognition performance is maintained at high intensity levels. The term rollover is used to describe phenomenon of decreased word recognition ability with increasing intensity levels. This phenomenon often is observed in cases of retrocochlear pathology, and therefore can be used as a diagnostic indicator. Plotted as a performance intensity function

QuickSIN - Lists; Practice + 1, 2, 6, 8, 10, 11, 12, 15 and 17
  1. ​Instructions
  2. Test binaurally, unless there is a significant hearing loss asymmetry between ears
  3. Test presentation criteria:
    • For PTAs </= 45 dB HL = test at 70 dB HL
    • For PTAs > 45 dB HL = test at UCL - 10
  4. Perform a total of 3 lists; do not score the first practice list
  5. Usefulness of results
    1. ​Evaluation of the patients ability to hear in noise for determination of hearing aid choice or possible cognitive deficits

Bone Conduction - represents the better cochlea regardless of where you are putting it on, possible for ear to be better at certain frequencies. Masking over 15dB
  1. Test at 250, 500, 1kHz, 2kHz, 4kHz
  2. Instructions
  3. Calculation of thresholds
  4. Ensure proper masking
  5. Usefulness of results
    1. Establishment of conductive versus sensory/neural/mixed hearing loss

Synthesis of information from the battery of tests to diagnose pathology.

Middle Ear Pathology

Cochlear Pathology/VIIIth Nerve Pathology

Facial Nerve Pathology

Intraxial Brainstem Pathology

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