Hearing Loss Associated with Neurologic Disorders Flashcards
What is ANSD operationally defined as?
Intact otoacoustic emissions (although sometimes they may disappear later in the condition) because OAEs measure OHC function
Or present cochlear microphonic (CM) with absent emissions
Grossly abnormal/absent ARTs, electrocochleography (ECochG), and ABR responses
Are OHCs intact in ANSD?
Yes
Is neural synchrony affected in ANSD?
Yes
Therefore, you will see intact emissions (OHCs are fine) and ABR and reflexes abnormal
Will anything that has to do with the 8th nerve be abnormal for ANSD?
Yes
ABR generated by neural structures
Neural integrity of VIII and lower brainstem pathways affected
ARTs also abnormal/absent because of VIII nerve involvement
Is there typically severe impairment of speech perception especially in noise because of disruption of synchronous 8th nerve firing in ANSD?
Yes
What percent of the deaf population has ANSD?
10% to 15%
How many babies in the NICU have ANSD?
Around 40%
Do the majority of NICU babies with ANSD have a bilateral loss?
Yes
Some unilateral
Are OAEs for ANSD babies normal?
Yes
Because they are coming from the OHCs
Can ANSD be genetic or environmental?
Yes
What are characteristics of genetic-based ANSD nonsyndromic?
Observed in families or
No other family member may be affected
Autosomal recessive mode of inheritance
Synapsis of IHC and 8th nerve fibers affected
What are some characteristics of genetic based ANSD syndromic?
Often associated with peripheral neuropathies (nerve function abnormal)
Charcot-Marie-Tooth syndrome and Friedreich’s ataxia
What are some characteristics of genetic based mitochondrial ANSD?
Mitochondrial inheritance indicates that affected females will have affected off-spring but affected males will not
What are some characteristics of environmental based ANSD?
Infectious disorder due to viral involvement
E.g., mumps and measles (can be unilateral)
Immune disorders can be accompanied by deafness typical to ANSD
For example, Guillian-Barre syndrome
Affects proximal nerve roots and proximal portions of VIII N
Deafness and paralysis with a lengthy period of recovery
If arterial blood supply affected, OHCs will be affected
Are thresholds variable for ANSD?
Yes
They don’t give you a lot of information
Can people with ANSD benefit from hearing aids?
They can provide limited benefits, but current recommendations include trial amplification if there is residual hearing
Is it usually recommended for people with ANSD to trial an FM device?
Yes
To reduce effects of noise distance, and reverberation especially in the classroom
Could manual communication also be helpful for someone with ANSD?
Yes
Cued speech or ASL
What is the current most successful treatment for ANSD?
CIs
Is charcot marie tooth common?
Yes
It is one of the most common inherited neurological disorders
What is the most common form of charcot marie tooth?
Type 1A
Deletion or point mutation
What is the transmission of charcot marie tooth?
Variable
Inherited as AD, AR, or X-linked recessive
What is charcot marie tooth?
A progressive neurodegenerative disease characterized by polyneuropathy
What are some characteristics of charcot marie tooth?
It affects both motor and sensory nerves
Absent limb reflexes
Chronic degeneration of peripheral nerves causing muscular atrophy
Muscle wasting seldom seen above elbows or mid-thighs
What is the typical onset of charcot marie tooth?
12 to 20 years
Full blown condition by 30 years
Is charcot marie tooth life threatening?
No
Does charcot marie tooth have 100% penetrance?
Yes
What are the audiological findings of charcot marie tooth?
SNHL with onset either in childhood or adulthood
Hearing loss is slowly progressive
Hearing loss maybe caused by auditory neuropathy due to demyelination of CN VIII
What is ataxia?
An inability to coordinate voluntary muscular movements
Is friedreichs ataxia common?
Yes
One of the most common forms of AR ataxia
Is friedreichs ataxia AR?
Yes
When does friedreichs ataxia manifest?
Before adolescence
What is friedreichs ataxia characterized by?
Incoordination of limb movements
Dysarthria
Nystagmus
Diminished or absent tendon reflexes and Babinski sign
Impairment of position and vibratory senses
Scoliosis, pes cavus (abnormally high foot arch), and hammertoe
Cardiomyopathy
Abnormalities in motor and sensory nerve conduction, including CN VIII and CN II, which cause hearing loss and visual impairment
What triad of clinical manifestations is commonly regarded as sufficient for diagnosis of friedreichs ataxia?
Hypoactive knee and ankle reflex
Progressive cerebellar dysfunction
Preadolescent onset
What kind of transmission does Hereditary Sensory and Autonomic Neuropathy type 1 have?
AD
Is Hereditary Sensory and Autonomic Neuropathy type 1 rare?
Yes
What is Hereditary Sensory and Autonomic Neuropathy type 1 characterized by?
Adult-onset (~ 37 yrs.) of progressive SNHL progressing to deafness
Early-onset dementia
Sensory neuropathy by 20 to 35 years resulting in lack of feelings in toes and ulceration, in some cases requiring amputation
Generally, an early death by the 4th to 5th decade, is reported
What transmission does neurofibromatosis (NF) have?
AD
Does NF have high penetrance and variable expressivity?
Yes
Because it’s AD
What is NF 1 known as?
The peripheral form
What is NF 2 known as?
The central form
Is NF1 or NF2 more common?
NF1
What are characteristic features of NF1?
Cafe-au-lait spots
Cutaneous & subcutaneous fibromatous tumors
Lisch nodules in the eye
About 5% have VIII nerve tumors
How many tumors do people with NF1 typically have?
Increase in number throughout life
Usually first appear around puberty
What are lisch nodules around the eye in NF1?
Looks like spots in iris
What is the transmission of NF2?
50% AD and 50% spontaneous mutation
Does NF2 have complete penetrance?
Yes
When is the disease onset of NF2?
Young adulthood
What is NF2 characterized by?
Characterized by a progressive disabling/disfiguring course
Bilateral vestibular schwannomas
Does NF2 typically have audiological symptoms and not NF1?
Yes
Do NF2 patients also have café au lait spots?
No
Less than half have them
What other symptoms does NF2 have besides bilateral vestibular schwannomas?
Progressive visual loss is common
Intelligence is not impaired
Emotional consequences and devastating communication disorder
How is NF2 diagnosed?
CT scans and MRI with contrast
What is the differential diagnosis for NF2?
NF1 and vestibular schwannoma
How do you treat NF2?
Surgery to remove the tumors
Destroy VIII nerve, which results in deafness in both ears
Tumors can come back
Are cochlear implants an option for NF2 patients?
No
No nerve to stimulate
What is the current device option for someone with NF2?
Auditory brainstem implant (ABI)
An ABI bypasses the damaged auditory nerve and connects directly to the brainstem to detect sound
Provides sound awareness and very limited speech understanding
