Disorders of the auditory nervous system


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Disorders of the auditory nervous system

  1. 1. Ozarks Technical Community College HIS 120
  2. 2.  Can be broken up into three categories: ◦ Disorders of the auditory nerve ◦ Disorders of the cochlear nuclei ◦ Disorders of the higher auditory pathways  Pathology of the auditory nervous system is often referred to as a RETROCOCHLEAR pathology, meaning a disorder occurring after the cochlea
  3. 3.  Acoustic Neuroma  Auditory Neuropathy Spectrum Disorder
  4. 4.  A benign (non-cancerous) tumor that grows on the auditory nerve (CN VIII)  Also referred to as an acoustic tumor or vestibular schwannoma ◦ Occur at a rate of 1/100,000 every year ◦ In 95% of cases, tumors are unilateral (one ear only)  Classic signs of acoustic neuroma ◦ Asymmetrical, sensorineural hearing loss in the high frequencies ◦ Poorer word recognition score in affected ear ◦ Unilateral tinnitus ◦ May also be associated with dizziness ◦ If the tumor is big enough to press on the facial nerve (CN VII), may report facial weakness/numbness
  5. 5. Image from: f1000prime.com Right Left WRS(%) 76 100
  6. 6.  It is important that you refer patients to an ENT physician if they exhibit an asymmetrical hearing loss and unilateral ear symptoms  Auditory brainstem response (ABR) testing may be performed by an audiologist  Magnetic resonance imaging (MRI) of the internal auditory canals is the gold standard for diagnosis, as ABR testing may miss small tumors
  7. 7.  Do nothing ◦ If the tumor is small enough, it will be monitored for growth  Surgical removal ◦ Usually results in total hearing loss in affected ear  Narrow-beam radiation (Gamma Knife) to stop tumor growth, which preserves hearing
  8. 8.  May wear a hearing aid in the affected ear, but hearing should be tested regularly to monitor for changes in hearing sensitivity and speech understanding
  9. 9.  I will refer to ANSD as auditory neuropathy  Auditory neuropathy refers to a condition in which there is normal cochlear function, but the transmission of electrical information along the auditory nerve, from the cochlea to the brainstem, is dys-synchronous (not smooth).
  10. 10.  Varies from patient-to-patient, which is why it is referred to as a spectrum disorder  Will exhibit a range from normal hearing to profound SNHL ◦ Most often will find a mild to moderate SNHL that is progressive (getting worse)  Great difficulty understanding speech, especially in the presence of fairly good hearing thresholds  Diagnosed based on audiometric findings, absence of an ABR response, normal MRI
  11. 11.  Hearing aids may help  Often hearing aids are of very limited benefit, and cochlear implants are recommended in these situations
  12. 12.  Nearly impossible to diagnose with certainty, but there may be abnormalities along the auditory brainstem that results in sensorineural hearing loss  Usually due to disease, toxicity, irritation, pressure, trauma ◦ Stroke, anoxia, syphilis, congenital malformation, aging, multiple sclerosis
  13. 13.  Minimal Auditory Deficiency Syndrome  Central Deafness  Auditory Processing Disorder
  14. 14.  The presence of language and learning disabilities due to auditory deprivation in young children  The auditory deprivation is often due to the slight/mild conductive hearing losses that accompany undiagnosed/untreated otitis media
  15. 15.  Characterized by: ◦ No response to puretone testing on the audiogram ◦ These patient’s cannot “hear”, but they have normal acoustic reflexes and ABRs  Usually due to several compromise of both brain hemispheres due to a vascular lesion ◦ Very rare
  16. 16.  A deficit in the neural processing of auditory stimuli that is not due to higher order language or cognitive factors  Difficulty identifying and interpreting auditory information in the absence of peripheral HL ◦ The ear and the brain do not coordinate well ◦ Auditory information breaks down somewhere between the ear and the brain
  17. 17.  Delay in development ◦ Auditory deprivation secondary to otitis media, much like MADS  Disordered development of the auditory nervous system  Specific central lesion  May be acquired in adults due to head injury, stroke, brain tumor, or multiple sclerosis ◦ More prevalent in males
  18. 18.  Behaves like they have a hearing loss ◦ Says “huh” or “what” frequently ◦ Inconsistent response to auditory stimuli ◦ Often misunderstands what is said ◦ Constantly requests that information be repeated  Poor listening skills ◦ Inattentive ◦ Easily distracted ◦ Restless  Difficulty understanding speech in noise  Poor academic performance
  19. 19.  Difficulty with phonics and auditory discrimination ◦ confuses words that sound alike ◦ Has problems with reading, spelling, and vocabulary  Poor auditory memory ◦ Difficulty following oral directions ◦ Learns poorly through auditory channel  Poor receptive and expressive language  Gives slow or delayed response to verbal stimuli  Difficulty understanding rapid speech or unfamiliar dialect  Issues with gross and/or fine motor skills  Poor musical abilities ◦ Does not recognize sound patterns or rhythm ◦ Poor vocal prosody
  20. 20.  The individual MUST have: ◦ Normal hearing ◦ Normal intelligence  May co-exist with:  AD/HD*  Learning disabilities  Speech/language delays  Reading disorder  Autism spectrum disorder
  21. 21.  Educational Assessment ◦ Psychological/IQ testing ◦ Speech/language assessment  Audiology Assessment ◦ Puretone and speech testing ◦ Tympanometry and reflexes ◦ OAEs ◦ Electrophysiology  APD Battery ◦ Monaural tasks in background noise ◦ Auditory pattern recognition ◦ Binaural separation and integration  Dichotic vs. Diotic stimuli  Includes verbal and non-verbal stimuli
  22. 22.  Based on the results of the APD evaluation ◦ Where is the weakness?  Specific skill training  Modify the listening environment  Assistive Listening Devices ◦ increase the signal-to-noise ratio  Speech-Language Therapy  Environmental modifications to reduce noise and reverberation
  23. 23.  Extended time on assignments ◦ Format adaptations on homework questions  Classroom VISUALS  Classroom accommodations  Written notes/note buddy  Study guide  Set of texts at home/books on tape  Test-taking adaptations ◦ Quiet area ◦ Modified format ◦ Extended time ◦ Segmented testing over multiple days
  24. 24. Feel free to stop reviewing the powerpoint now 
  25. 25.  Dichotic Tests(Simultaneous & Different Stimuli): ◦ Binaural Integration  Dichotic Digits (DD)  Dichotic Sentence Identification (DSI)  Staggered Spondaic Word (SSW) Test ◦ Binaural Separation/Selective Auditory Attention  Synthetic Sentence Identification (SSI-CCM)  Competing Sentences Test (CST)
  26. 26. • Requires BINAURAL INTEGRATION • “Tell me all four numbers”
  27. 27. Musiek, Weihing. Brain and Cognition 76 (2011)
  28. 28. CompetingSentencesTest ◦BINAURALSEPARATION “Tellmethesentenceinyourleftear”
  29. 29.  Diotic (Simultaneous and Same Stimuli): ◦ Auditory Patterning/Temporal Ordering  Pitch Pattern Sequence (PPS)  High vs. low pitch  Duration Patterns (DP)  Long vs. short  Gap Detection
  30. 30. *Greater than 20 msec is abnormal
  31. 31. 60%TimeCompression 30%TimeCompression