INNER EAR Flashcards
What is homeostasis
he ability of an organism or a cell to maintain internal equilibrium by adjusting its physiological processes
what is inner ear homeostasis
he process by which chemical equilibrium of inner ear fluids and tissues is maintained”
For proper inner ear function, a tight control of what is necessary
ion movement across the cell membranes
what could be disrupted if you do not have inner ear homeostasis
hair cell fxn
regulation of extracellular endolymph and perilymph
conduction of nerve impulses
The major ions involved in inner ear homeostasis include
Sodium (NA+)
Potassium (K+)
Significant roles also are played by
Chloride (Cl-)
Calcium (CA2+)
which ion channels are disrupted in connexins
potassiu
Before sound can be perceived it has to be converted to______, a process mediated by the cilia of the inner ear hair cells
electrical impulses in the auditory nerve
bring about transduction mechanism and allows nerves to integrate the signal
ihc
The sound-induced excitatory deflection of the stereocilia causes a mechanoelectrical transduction (MET) current to depolarize the hair cells and initiate _______ in the auditory nerve or vestibular nerve in response to acceleration/gravity changes
action potentials
The endolymph and perilymph are the ________ support system for hair cell function just as the cochlear partition traveling wave and tectorial membrane are the ______ support system for hair cell function
metabolic
mechanical
where is EP at its highest
it is higher at basilar end than apical end
higher in cochlear than vestibular system
high K+ concentration in the endolymph creates a +80 mV endocohlear potential (EP) that couples with a -80 mV hair cell intracellular potential to create a differential potential of +160 mV
80 mV – (-80mV) = 160 mV
Stereocilia are laterally displaced either by
Shearing movement of the tectorial membrane (outer hair cells) or
Motion of the endolymphatic fluid (inner hair cells)
what if eno and perino EP had the same ion composition?
no EP becuase there is no difference
endolymphatic hydrops - causes excessive endolymph causing the two to mix and causes the fluctuating HL in Meneire’s
specialized intercellular connection between a multitude of animal cell-types. It directly connects the cytoplasm of two cells, which allows various molecules and ions to pass freely between cells.
gap junction or nexus
Any cochlear disorder that disrupts the strial cell layers, channels, transporters, or gap or tight junctions will reduce the EP and result in a
permanent snhl
proteins embedded in the cell membrane that regulate the flow of water
aquaporins
part of the blood-brain barrier and probably the blood-labyrinth barrier
aquaporins
Active water transport b/w cells occurs through
aquaporin channels
Hearing loss can result from
increased or decreased activity of the strial process
Increased K+ transport in the endolymph or increased endolymph production
endolymphatic hydrops (too much endolymph - Meneire’s - progressive fluctuating snhl)
Decreased K+ transport in the endolymph or decreased endolymph production
endolymphatic xerosis (decrease in endolymph - connexin, JLNS - permanent snhl)
Genetic disorders associated with ion transport and pathways are often associated with
permanent hearing loss
Majority of non-syndromic genetic hearing loss is due to alteration of
proteins that prevent movement of K+ from the organ of corti to the lateral wall and into the stria
which condition are KCNE1 KCNQ1?
jlns
connexin genes
abnormalities result in abnormal connexin gap junction proteins
responsible for itself for >50% of nonsyndromic HL
Several cochlear and vestibular disorders are transient and recover spontaneously, such as
Sudden-onset hearing loss
Diuretic otoxicity (e.g., Furesmide) recovery after stopping drugs
Autoimmune labyrinthitis, which can have transient symptoms
Meniere’s disease, which exhibits intermittent symptoms
The fact that these disorders manifest temporary hearing loss and recovery indicates that the damage is not to the hair cells but to
the ion homeostatic process
generally, if it is the inner ear involvement, HL type is always
SNHL
what are symptoms of cochlear disorders
usually SNHL
speech perception difficulties
loudness recruitment
aural fullness
tinnitus
Sound tolerance conditions – abnormal/excessive response to sounds
inner ear nerves or synapse is affected = neural involvement or severe sensory you have issues with speech perception
why
because you do not hear with your ears you understand with your brain and it isnt getting to the brain correctly
especially in noise
what can tinnitus be in cochlear disorders
ringing that sounds like roaring, hissing, buzzing, music (mysophonia)
soft, loud, high, low pithed
unilateral or bilateral
constant or intermittent
can change in pitch, loudness, frequency
unilateral tinnitus clinically
alert to this
pathology because bilateral is more systemic, aging etc. but uni is looking more at pathology
Sound tolerance conditions – abnormal/excessive response to sounds
hyperacusis
physical discomfort/pain when a sound is loud but would be tolerable for most people
hyperacusis
Intense emotional reactions to certain sounds (e.g., body sounds like chewing and sniffing) that are not perceived as loud
misophonia
increased reactivity to sounds including general discomfort and annoyance regardless of its loudness
noise sensitivity
Anticipatory fear of sound. Can cause a comorbid condition (e.g., tinnitus) to get worse
phonophobia
most common causes of SNHL
Aging (presbycusis)
Exposure to toxic levels of noise – Noise-induced hearing loss
other causes of SNHL
Genetic syndromic and non syndromic SNHL
Ototoxicity
Infections of the inner ear
Autoimmune conditions that affect the inner ear
Most infections of the inner ear are caused by
viruses
Bacteria also can cause serious diseases such as
meningitis
what are two types of viruses
RNA and DNA viruses
rna in their genome
rna viruses
example of rna viruses
covid 19 and flue
why is it hard to make effective long lasting vaccines
not as stable as dna viruses
viruses mutate quickly and the vaccines no longer work because they change
more stable and dna in their genome
dna viruses
examples of dna viruses
smallpox
herpes
chicken pox
how can viruses cause irreversible HL in vitro
through transmission in the placenta or during infancy
how did we come up with covid vaccine so fast?
because of HIV vaccines they had the tech and used it to make this
without hiv we wouldn’t have had a covid vaccine as fast
what does the virus do to the cochlea?
destructs cochlea at the basal turn and would see hf snhl
hair cells damaged
issues with potassium and affects homeostasis
tectorial membrane is shriveled or rolls up
Reissner’s membrane is collapsed
what is the biggest rna virus
rubella virus
what is rubella responsible for
german measles
Rubella has a greater effect on the auditory system if contracted by the mother during the ________ when the auditory system is developing
1st or initial part of the 2nd trimester
rubella can lead to
congenital hearing loss
congenital cataracts
cardiovascular cataracts
possible intellectual disability
responsible for mumps
paramyxovirus
inflammation of carotid glands
boys - can cause infertility because it affects the sperms
mumps
infection of salivary glands, primarily parotid gland
paramyxovirus
what is the hl seen in paramyxovirus
Acquired permanent SNHL, typically unilateral
common double-stranded DNA virus that belongs to the herpes virus family
cytomegalovirus (CMV)
what does cmv stand for
cytomegalovirus
what can cmv result in
result in decreased life expectancy
It can cause hepatomegaly & splenomegaly
It can result in a rash – “blueberry muffin” (reddish blue to magenta) rash
found in other mammals as well such as chimpanzees
It is one of the most common viral diseases of the human race
It is common all-over North America
cmv
CMV can result in decreased immunity, like immunity to flue vaccine, because
it has a very large genome
immune system uses energy to fight this virus all of our lif
most common viral disease among the newborn
cmv
do all newborns with cmv have a hl
no
the risk is very high,
About 20% of newborns diagnosed with CMV will develop hearing loss
75% babies born with CMV can manifest delayed onset SNHL even as adults
what is teratogenic
impacts development of the fetu
if cmv goes through the placenta to the fetus,
mother shows common cold/flu symptoms
In 2023, Minnesota became the first state to screen ____ newborns for CMV
ALL
CMV causes a ________ HL with the final stage generally being reached by ~ 3 to 5 years
progressive profound permanent SNHL
many children with progressive profound permanent SNHL from cmv are candidates for
CI
Many newborns with CMV are not detected for congenital SNHL through newborn screening because of
later-onset or progressive SNHL
In infants, older children, and adults, CMV infection maybe “silent” or symptoms may mimic a common cold and cause no permanent damage
true
infected newborns are generally considered contagious
true
CMV may cause only a hearing loss, or it may cause significant neurological and other complications depending on when the infection occurred in vitro, such as
Cardiovascular problems
Neurological and motor deficits
Blindness
Intellectual disability
can cmv be passed through breastmilk? can it cause snhl?
yes
no evidence that it produces snhl past 3 weeks of age
how can cmv be diagnosed
Urine polymerase chain reaction (PCR) is the gold standard
histologic exam
CT scan
what can ct reveal for cmv
intracranial calcification
what is gold standard for cmv diagnosis
urine PCR
where are human cmv inclusion bodies commonly seen
salivary glands and lung tissue
what is PCR
look at dna of virus, urine sample is taken and run through this, machine produces millions copies of dna and you study to see if it is from the CMV virus and can tell if child has it or not
are inclusion bodies only seen in cmv
NO
shown in many viruses
proteins that stain pink
inclusion bodies
what does aids stand for
acquired immunodeficiency syndrome
caused by the microbe human immunodeficiency virus (HIV)
aids
retrovirus
HIV
what is a retrovirus
rely on reverse transcriptase to perform reverse transcription of its genome going from RNA to DNA
disease & virus of AIDS & HIV
disease is aids
virus is HIV
why can HIV not be removed
RNA goes to DNA
DNA embeds itself into the cell of the host’s genome
replicates as it is a part of your cell’s system which is why you cannot get rid of it because you would remove your own cells
Retroviruses rely on their enzyme
reverse transcriptase
patient may be HIV+ and not express signs/symptoms of AIDS
true
HIV is neurotropic
true
attacks the nervous sytem
HIV also is lymphotropic and immunotropic
true
It attacks the lymph glands, both T and B cells, and the immune system
For populations at risk for HIV, the condition must be considered in all cases of
sudden bilateral or unilateral HL
also adult pt that has a lot of otitis media otitis externa because they cannot fight off these infections
older medications for hiv used to be
ototoxic
what are some otologic signs/symptoms with AIDS
OME with or without CHL; SNHL (during later disease stages)
Otalgia
Vertigo
Tinnitus
Aural fullness
Reduced OAEs (OHCs affected)
Delayed ABR interwave latencies (central effects)
Auditory symptoms also may be secondary to
Ototoxic effects of the AIDS drugs
Recurrent/chronic OME and other opportunistic infections that attack the ear due to the suppressed immune system
how can pediatric aids occur
HIV can be transmitted through the placenta
why is pediatric aids increasing
cases of AIDS in women is increasing
anytime you see adult with chronic otitis externa or media, there is an underlying pathology that is causing the issue. why?
not common for adults to have these infections
There is no latent or dormant period for the virus with congenital or early-appearing encephalopathy/encephalitis that can damage the brain and CNS why
with adults it takes awhile for disease to manifest itself
have it but not full blown
different for newborns because it is in their bloodstream and immune system is not developed
born very sick
Greater incidence of otitis media with poorer prognosis in children with AIDS due to
compromised immune system
how can aids in children affect their innume system
Higher rate of recurrence of infection
Higher failure rate of response to treatment
will see full blown hl and recurrent otitis media in kids with PAIDS
true
what is meningites
inflammation of meninges that surrounds brain and spinal cord
where are meninges
duramater, arachnoid mater, and pia mater) surrounding the brain and spinal cord
where does meningitis come from
various virus
bacterial, including mycobacterium tuberculosis
mycobacterium tuberculosis
Haemophilus influenza; most common cause
Pneumococcus pneumoniae
meningitis
purulent (pus filled) otomastoiditis that can lead to secondary meningitis
Pneumococcus pneumoniae
two ways to get meningitis
primary
secondary
primary meningitis
disease starts in meninges
secondary meningitis
OME leads to mastoiditis/labyrinthitis then meningitis
cholesteatoma that spreads to the meniinges
what does Pneumococcus pneumoniae look like
stained dark purple, looks like chromosomes
what does Mycobacterium tuberculosis look like
looks like rice
stained green, yellow
vacuum cleaners of the cell
macrophage cell
what does Haemophilus influenza look like
look like blackberries
symptom of meningitis
fever
neck rigidity
head ache
malaise
sick & vomiting
malaise
feeling unwell
severe and untreated meningitis can lead to
blindness
paralysis because motor centers of brain is damaged
HL/deafness
vertigo & balance problems
One of the most significant causes of acquired sensorineural hearing loss
meningitis
can cause permanent abnormal cochlear bone formation
meningitis
what is treatment of meningitis
antibiotics that are appropriate to the organism so start with broad spectrum
mastoidectomy if infection relates to middle ear disease and antibiotics dont resolve
amplificcatioin or CI if severe/profound HL occurs
what decreaes success rate of CIs
the bony growth continuing after CI that can compromise the implant
what is important for post meningitis CI candidates
make sure there is enough space in cochlea for the implant due to the abnormal bony growth
