path ch 31 disorders of hearing/balance/vision

structures within ear

Hear and interpret sounds, provide information about position and movement of

head in space

receptors within eye

Shapes and colors conveyed in light energy

impairments of eyes/ears

Disease, aging, medications, environmental factors, genetics; alter information available to cortex to process

Children born with hearing or vision deficits

Developmental, communication, mobility delays

Adults with vision or hearing loss

Problems with mobility, nutrition, stress, coping, mood, affect, increased susceptibility to environmental issues

hearing process

sounds waves transformed into neural impulses; pitch, loudness, timing preserved at each step, allowing brain to perceive sound accurately

pathologies of auditory system

Disrupt normal sound transmission process

types of hearing loss

sensorineural, conductive, mixed

auricle (pinna)

Collects sound pressure waves; directs them into external auditory canal. Generates cues about timing and intensity of sounds to localize them

largest ossicle

malleus

3 ossicles

malleus, incus, stapes

ossicles

Attached oval window, which leads to fluid-filled inner ear

external acoustic meatus

Ends at tympanic membrane (TM), or eardrum; Lined with hairs and glands that secrete cerumen to protect the rest of hearing system from dust/debris

tympanic membrane

sound receptor & transmitter, vibrations transmitted to ossicles

neural signal pathway

Along auditory portion of the vestibulocochlear nerve→Exits cochlea via internal auditory canal→Travels through multiple nuclei in brainstem.→thalamus→primary auditory cortex (located in temporal lobe)

components of bony labyrinth

cochlea (hearing), the vestibule (acceleration), and the three semicircular canals (balance)

bony labyrinth

System of canals in temporal bone; fluid-filled membranous labyrinth

cochlea canals

scala vestibuli, scala media, scala tympani; Filled with perilymph (similar to CSF)

cochlea

pressure “windows”

utricle & saccule in vestibule

Sensitive to position of head in relation to gravity (movement forward/backward, up/down)

static labyrinth/otolith organs

utricle & saccule in vestibule

Possible effects of loss of peripheral balance function

vertigo, feelings of unsteadiness, visual blurring, hearing sensitivity

causes of balance disruption

certain disease & conditions, central vestibular disorders, some medications

conductive hearing loss

Sound unable to travel normally to inner ear; reflects audibility problem

types of conductive hearing loss

outer ear disorders, otitis media, otosclerosis

characteristics of outer ear disorders

most are highly treatable & do no involve hearing loss

cases where outer ear disorders DO cause hearing loss

congenital outer ear malformations

common outer ear disorders

cerumen impaction, collapsed ear canal, external otitis, stenosis of ear canal, microtia or anotia

otitis media

inflammation of middle ear space associated w/ eustachian tube dysfunction; commonly diagnosed in children

otitis media clinical manifestations

cold like symptoms, upper respiratory problems

acute otitis media

moderate to severe bulging of TM & middle ear effusion

complications of acute otitis media

TM rupture, temporary conductive hearing loss

acute otitis media treatment

antibiotics

recurrent acute otitis media

3+ episodes in 6 months or 4+ episodes in 12 months

factors that increase recurrence of acute otitis media

male, passive exposure to smoking, winter season

chronic otitis media

infection longer than six weeks with persistent effusion in middle ear space

chronic otitis media

mild to moderate conductive hearing loss

chronic otitis media treatment

topical antibiotics/steroids, frequent cleaning of ear canal

treatment for severe cases of chronic otitis media

surgical intervention, systemic antibiotics, ventilation/pressure equalization (PE) tubes

otosclerosis

abnormal bone growth in middle ear space

hearing loss associated w/ otosclerosis

slowly progressive, bilateral, conductive (can be mixed if otic capsule involved)

etiology & pathogenesis of otosclerosis

alternating bone resorption & formation, genetic components (autosomal dominant), viral factors, autoimmune disorders

otosclerosis diagnosis

pt hx, otoscopy, audiologic results, radiologic study

otosclerosis treatment

annual hearing tests to monitor hearing loss, surgical procedures, hearing aids, fluoride, calcium, vitamin D

presbycusis

hearing loss due to aging, most common form of hearing loss

4 types of presbycusis

sensory, neural, metabolic/strial, mechanical/cochlear conductive

etiology & pathogenesis of presbycusis

no widely accepted etiology, various contributing factors

clinical manifestations of presbycusis

progressive decrease in hearing thresholds, decreased ability to understand speech

presbycusis diagnosis

hx & complete audiologic assessment

presbycusis treatment

hearing aids, assistive listening devices, cochlear implants

meniere disease

inner ear disorder with both auditory and vestibular symptoms; excess endolymph within membranous labyrinth of inner ear

meniere disease clinical manifestations

vertigo w/ nausea & vomiting, tinnitus, pressure or fullness in the ear, fluctuating hearing loss

ototoxicity

Side effect of some medications, damage sensory cells of inner ear

chocleotoxic medications

Damage sensory cells of cochlea, cause sensorineural hearing loss (Typically bilateral)

vestibulotoxic medications

Damage sensory cells of peripheral balance system (typically bilateral)

Factors affecting extent of ototoxic effects

age, comorbidities, genetic predisposition, drug in use/dosage/schedule

most widely used ototoxic medications

Aminoglycoside antibiotics, platinum-based antineoplastic medications

genetic hearing loss

one of the most common birth defects; caused by genetic mutation

nonsyndromic genetic hearing loss

hearing loss only

syndromic hearing loss

hearing loss accompanied by pattern of other clinical abnormalities

genetic hearing loss diagnosis

physical attributes related to syndrome, genetic testing

genetic hearing loss treatment

regular audiologic monitoring; sensorineural: hearing aid/cochlear implant; conductive: hearing aid or osseointegrated hearing implant

vision pathway

light enters thru cornea→crosses anterior→pupil→image inverted in lens→retina→optic nerve exits at optic disc

myopia

Nearsightedness, image focused in front of the lens

hyperopia

Farsightedness, eyeball is too small, image focused behind the retina

presbyopia

Farsightedness associated with aging, lost elasticity reduces accommodation, ciliary muscles weakening & the eye's lens becoming less flexible with age

astigmatism

Irregular curvature in the cornea or lens

strabismus

Result from deviation of one eye, double vision (diplopia). May cause by weak or hypertonic muscle, short muscle or neurological defect—should be treated immediately in children to prevent neurological defect

nystagmus

Rapid, involuntary eye movement. Develops in some individuals with amblyopia and strabismus. May result from neurological causes, inner ear or cerebral disturbance, drug toxicity

inhered

result from neurological causes (stroke), paralysis of extraocular muscle, loss depth perception

color blindness

congenital or acquired problem w/ cones, red/green, blue/yellow, or achromotopsia

most common type of color blindness

red/green

most severe type of color blindness

achromotopsia

hordeolum (stye)

bacterial infection in oil glands at base of eyelash case tender, red, often pus-filled bump along edge of eyelid; resolves in a week w/o treatment

conjunctivitis (pinkeye) symptoms

Redness, discharge, itching, burning of eyes, increased tearing, blurred vision, light sensitivity

viral conjunctivitis (most common)

adenoviruses, HSV, resolves in 7-21 weeks

bacterial conjunctivitis

chalmydia; resolves within 1 week but symptoms last up to 3, treat w/ topical antiobiotics

allergic conjunctivitis

not contagious, treated w/ saline/oral & topical medications

pterygium

Benign growth on conjunctiva; may extend to cornea

pterygium risk factors

High levels of exposure to UV light, wind, airborne irritants

causes for pterygium removal

unsightly, interferes w/ vision, causes discomfort

keratitis

Severe pain and photophobia develops when cornea is infected or irritated, possibly due to transfer from herpes lesion at mouth or scare formation damaging the cornea; increases risk of ulceration eroding cornea

keratitis causes

Damage from chemicals, splashes and fume

corneal abrasion

scratch or cut on cornea

causes of corneal abrasion

foreign body/chemical irritant, rubbing eye too forcefully, being poked in eye

symptoms of corneal abrasion

eye redness, tearing, pain, blurred vision, light sensitivity

corneal abrasion treatmen

flush w/ water or sterile saline solution, topical antibiotics, antiinflammatories

cataracts

Cloudy or opaque discoloration of lens

cataract causes

Age-related changes, trauma, congenital anomalies, systemic disease, pharmacologic triggers

cataract diagnosis

Ophthalmologic exam

cataract treatment

limit exposure to UV light, surgery, ultrasonic vibrations, artificial lens, capsulotomy (cut the lens in a way that does not affect vision)

glaucoma

increase in IOP leads to slow, painless progressive vision loss, possibly causing blindness; numerous risk factors

glaucoma signs & symptoms

Halos around the eye at night, loss of peripheral vision, possible pain

is acute glaucoma narrow or open angle?

narrow angle

is chronic glaucoma narrow or open angle?

open-angle

acute glaucoma

angle between cornea & iris is decreased

cause of acute glaucoma

aging developmental abnormalities, trauma or infection

glaucoma treatment

surgery

chronic glaucoma

Thickness of trabecular network which allows for resorption of fluid, pressure increases over time possibly causing damage to retina or optical nerve; irreversible & may cause blindness

chronic glaucoma risk factor

age over 50