disorders of the auditory nervous system
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Disorders of the Auditory Nervous
SystemOzarks Technical Community College
HIS 120
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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
Disorders of the Auditory Nervous System
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Acoustic Neuroma Auditory Neuropathy Spectrum Disorder
Disorders of the Auditory Nerve
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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
Acoustic Neuroma
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Audiogram of Patient w/ Acoustic Neuroma (Right ear)
Image from: f1000prime.com
Right
Left
WRS(%)
76 100
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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
Diagnosis of Acoustic Neuroma
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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
Treatment for Acoustic Neuroma
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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
Hearing Aids in Patient’s with Acoustic Neuroma
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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).
Auditory Neuropathy Spectrum Disorder (ANSD)
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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
Audiometric Configuration of ANSD
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Hearing aids may help Often hearing aids are of very limited
benefit, and cochlear implants are recommended in these situations
Treatment for ANSD
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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
Disorders of the Cochlear Nuclei
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Minimal Auditory Deficiency Syndrome Central Deafness Auditory Processing Disorder
Disorders of the Higher Auditory Pathways
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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
Minimal Auditory Deficiency Syndrome (MADS)
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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
Central Deafness
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Auditory Processing Disorder (APD)
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
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What causes an APD? 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
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Behaviors of Individuals at Risk for APD
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
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Behaviors of APD…. 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
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Criterion for APD Diagnosis The individual MUST have:
◦ Normal hearing◦ Normal intelligence
May co-exist with: AD/HD* Learning disabilities Speech/language delays Reading disorder Autism spectrum disorder
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APD Diagnosis 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
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Treatment of APD 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
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Accommodations for Kids with APD 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
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You are not responsible for the following slides. They contain “nice-to-know” information about APD tests. Feel free to stop reviewing
the powerpoint now
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APD Evaluation: 7 Years+
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)
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Dichotic Digits
• Requires BINAURAL INTEGRATION• “Tell me all four numbers”
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Staggered Spondaic Words (SSW)
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Dichotic Listening
Musiek, Weihing. Brain and Cognition 76 (2011)
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Competing Sentences Test◦ BINAUR
AL SEPARATION “Tell
me the sentence in your left ear”
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(C)APD Evaluation: 7 Years+
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
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Gap Detection
*Greater than 20 msec is abnormal
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Time-Compressed Speech
60 %
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30 %
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