Disorders of the Auditory Nervous

SystemOzarks Technical Community College

HIS 120

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

Acoustic Neuroma Auditory Neuropathy Spectrum Disorder

Disorders of the Auditory Nerve

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

Audiogram of Patient w/ Acoustic Neuroma (Right ear)

Image from: f1000prime.com

Right

Left

WRS(%)

76 100

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

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

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

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)

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

Hearing aids may help Often hearing aids are of very limited

benefit, and cochlear implants are recommended in these situations

Treatment for ANSD

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

Minimal Auditory Deficiency Syndrome Central Deafness Auditory Processing Disorder

Disorders of the Higher Auditory Pathways

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)

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

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

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

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

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

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

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

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

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

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

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)

Dichotic Digits

• Requires BINAURAL INTEGRATION• “Tell me all four numbers”

Staggered Spondaic Words (SSW)

Dichotic Listening

Musiek, Weihing. Brain and Cognition 76 (2011)

Competing Sentences Test◦ BINAUR

AL SEPARATION “Tell

me the sentence in your left ear”

(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

Gap Detection

*Greater than 20 msec is abnormal

Time-Compressed Speech

60 %

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30 %

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