Otology and opthamology Flashcards
Where are low frequencies best heard?
apex (near helicotrema)
Where are high frequencies best heard?
base of cochlea
what is damaged in noise-induced hearing loss?
sterociliated cells in the organ of corti
what is damaged in presbycusis?
hair cells at cochlear base
what is cholesteatoma?
the overgrowth of desquamated keratin debris within the middle ear space - may erode ossicles, mastoid air cells, leading to conductive hearing loss
how does cholesteatoma present?
painless otorrhea
what is benign paroxysmal positional vertigo?
Benign cause of vertigo - caused by problem in inner ear
benign paroxysmal positional vertigo diagnosis ?
Dix-Hallpike Maneuver
How do you perform the dix-hallpike maneuver
extend and turn seated patients head then have them rapidly lay down - symptoms will appear after 5-10 seconds if it is benign paroxysmal positional vertigo
what is peripheral vertigo?
Caused by inner ear etiology
what type of vertigo is Meniere disease?
peripheral vertigo
what is the triad seen in meniere disease?
sensorineural hearing loss, vertigo, tinnitus
what causes menieres disease?
increased endolymph within the inner ear due to endolypmphatic hydrops
treatments for peripheral vertigo?
antihistamines anticholinergics, antiemetics
what additional treatments are used for menieres disease?
low salt diet and diuretics
how do you treat BPPV?
epley maneuver
what is central vertigo?
vertigo caused by a brain stem or cerebellar lesion
findings of central vertigo
directional or purely vertical nystagmus, skew deviation, diplopia, dysmetria
where in the eye do extraocular muscles insert?
sclera
what is scleritis?
inflammation of sclera that presents with a red eye and severe boring pain on movement
Associated with RA and can cause blindness
What is the treatment for episcleritis?
its self limitied
what is keratitis?
corneal inflammation more common in contact lens weareres that presents with pain and photophobia and can cause blindness
what is conjuctivitis?
inflammation of the conjunctiva
what are the different causes of conjunctivitis?
Allergic - will be bilateral
Bacterial - will have pus
Viral - will have swollen preauricular node
What is the most common cause of viral conjuctivitis?
adenovirus
Most common causes of bacterial conjunctivits in adults?
S. aureus, S. pneumo
Most common causes of bacterial conjunctivits in children?
H. influenza, S. pneumo
What bacteria are you worried about if you get a corneal abrasion?
pseudomonas
what antibiotic do you give for a corneal abrasion?
aprafloxacin
most refraction in the eye occurs where?
retina (but the lens adjusts)
what type of collagen is in the capsule that surrounds the lens?
type IV
what is hyperopia?
‘farsightedness’ - near objects are blurry
-eye too short for refractive power - light focuses behind retina
how do you correct hyperopia?
a convex (converging lens)
what is myopia?
‘nearsightedness’ - far objects are blurry - eye too long for refractive power - light focuses in front of retina
how do you correct myopia?
concave lens (divering) lens
what is astigmatism?
abnormal curvature of cornea - different refractive power at different axes
how to correct astigmatism?
cylindrical lens
what is presbyopia?
age-related impaired accomodation (focusing on near objects) caused by decrease in lens elasticity, changes in lens curvature and decreased strenght of the ciliary muscle
how to treat presbyopia?
reading glasses ‘magnifiers’
Risk factors for cataracts?
Older age, smoking, excessive alcohol, excessive sunlight, prolonged corticosteroid use, DM, trauma, infetion
what drugs decrease aqueous humour production?
B-blockers, A2-agonists, carbonic anyhdrase inhibitors
what is ectopia lentis?
Dislocation of lens - can be from trauma or associated with systemic disorder (Margrans, homocystinuria, etc)
What are the causes of secondary open-angle glaucoma?
A blocked trabecula meshwork from WBCs (uveitis), RBCs, retinal elements (such as retinal detachment)
what causes primary open-angle glaucoma?
unknown
closed angle glaucoma PRIMARY cause
enlargment or anterior movement of lens against central iris - > obstruction of normal aqueous flow through pupil - fluid builds up and pushes iris against cornea - obsturction of flow
closed angle glaucoma SECONDARY cause
hypoxia from retinal disease (DM, vein occlusion) induces vasoproliferation in iris that contracts angle
How does chronic closure closed angle glaucoma present?
often asymptomatic but causes damage to optic nerve and peripheral vision
how does acute closed angle glaucoma present?
painful, red eye with sudden vision loss. Halos around lights, frontal headache, fixed and mid-dilated pupil, nausea and vomiting
medical treatments of glaucoma?
acetazolamide, mannitol, timolol, pilocarpine
treatment of acute closed angle glaucoma?
SURGERY - MEDICAL EMERGENCY
what is uveitis?
inflammation of the uvea
what is inflamed in anterior uveitis?
iris
what is inflamed in posterior uveitis?
choroid and or retina
what is a hypopyon?
accumulation of pus in antior chamber that may be seen in uveitis
what disorders is uveitis associated with ?
sarcoidosis, RA, juvenile idiopathic arthritis, HLA-B27 associated conditions
pathophys of age-related macular degeneration
Degeneration of macula that casues distortion and eventual loss of central vision
what are the two types of age-related macular degeneration?
dry - nonexudative - deposition of yellow extracellular material between bruch membrane and retinl pigment epithelium with gradual vision loss
how to prevent progression of dry age related macular degeneration?
multivitamins and antioxidants
What is wet age-related macular degeneration?
rapid vision loss due to bleeding secondary to choroidal neovascularization
how to treat wet age-related macular degeneration?
anti-VEGF injections (bevacizumab, ranibizumab)
What are the two types of diabetic retinopathy?
nonproliferative and proliferative
nonproliferative diabetic retinopathy pathophys
damaged capillaries leak blood leading to hemorrhages and macular edema
proliferative diabetic retinopathy pathophys
chronic hypoxia results in new blood vessel formation causes traction on retina
how to treat nonproliferative diabetic retinopathy
blood sugar control
how to treat proliferative diabetic retinopathy
anti-VEGF injections, peripheral retinal photocaugulation surgery
what causes hypertensive retinopathy?
retinal damage due to chronic uncontrolled HTN
findings in hypertensive retinopathy
flame shaped retinal hemorrahges, arteriovenous nicking, microaneurysms, macular star, cotton-wol spoots
pathophys of retinal vein occlusion
blockage of central or branch retinal vein, often due to compression of vein by atherosclerotic artery
pathophys of retinal detachment
sepration of neurosensory layer of retina and pigmented epithelium -> degeneration of photoreceptios -> vision loss
fundoscopy findings of retinal detachment
crinkling of retinal tissue and changes in vessel direction
presentation of retinal detachment
‘curtain drawn down’ vision loss
risk factors for retinal detachment
high myopia and history of head trauma
presentation of central retinal artery occlusion
acute, painless monocular vision loss
what causes central retinal artery occlusion?
Embolus (may occur with a PDA, carotid artery atherosclerosis, etc.)
Findings in central retinal artery occlusion
Cherry red spot and cloudy retina
what causes the cherry red spot in tay sachs disease
accumulation of sphinolipids
What is retinitis pigmentosa?
inherited retinal degeneration
presentation of retinitis pigmentosa
begins with night blindness (rods in peripheral vision affected first)
fundoscopy findings in retinitis pigmentosa
bone spicule-shaped deposits around macula
pathophys of papillodeama
optic disc swelling due to increased ICP
presentation of papillodema
enlarged blind spot and elevated optic disc with blurred margins
what is leukocoria
loss (whitening) of the red reflex
which patients commonly have retinitis
AIDs patients with CD4 less than 50
Miosis neuro pathway
VIA parasympathetic
1st neuron goes from idenger-westphal nucleus to ciliary ganglion via CNIII and synapses
2nd neuron sends short ciliary nerves to sphinctor pupillae muscles and constrcts pupil
How does the pupillary light reflex work?
light in either retina send signal via CNII to pretectal nuclei which signals to bilateral edinger-westphal nuclei to contstrict both pupils
Neuron pathway for mydriasis
1st neuron: hypothalamus to ciliospinal center of budge
2nd neuron: exits at T1 to superior cervical ganglion
3rd neuron: travels along internal carotid through cavernous sinus and enters orbit as long ciliary nerve to pupillary dilater muscles and inervates SM of eyelids, sweat glands of forehead and face as well
what spinal level is the ciliospinal center of budge found?
C8-T2
Marcus Gunn Pupil
Normal eye causes constriction of both pupils upon light, but damaged eye (optic nerve damage) results in dilation of both pupils due to light (or they constrict less than they should)
what causes horner syndrome?
sympathetic denervation of face
Common presentation of CN III palsy
down and out eye, ‘blown’ pupil
which direction does the superior oblique move the eye?
down and medial
findings with CN IV damage
eye is higher in affected side
patient tilts head towards unaffected side to compensate
how does CN VI damage present
cannot abduct eye, it will be medially displaced
what is estropia?
misalignment of the eyes
is meyner loop responsible for upper or lower quadrant vision?
upper
is the dorsal optic radiation responsible for upper or low quadrant vision?
lower
where is meyer loop?
temporal lobe
where is the dorsal optic radiation?
parietal lobe
what is contained in the cavernous sinus?
internal carotid artery
CN III, IV, Va, Vb and VI and sympathetic fibers (CN III)
what is medial in the cavernous sinus?
internal carotid artery and CN VI
what is just below the sella tursica?
sphenoid sinus
what is amacrosis fugax?
painless transient vision loss commonly presents as symptom of TIA (due to ischemia)
which two nerves does the medial longitudinal fasciculus coordinate?
CN III, CN VI
what is internuclear opthalmoplegia?
lesion in MLF that results in a conjugate gaze palsy
how does internuclear opthalmoplegia present?
CNVI activates ipsilateral lateral rectus, which moves eye laterally. BUT CNIII nucleus does not stimulate redial rectus in contralateral eye and thus it does not adduct. This causes nystagmus in the ipsilateral eye.
how would right INO present?
right refers to the eye that cannot ADDuct - right eye cannot adduct and left eye will have nystagmus
what is the PPRF?
the part that initiates lateral gaze from the brainstem. (whereas the medial LF will mediate the opposite eye). If you get a lesion here you cannot look towards the side of the lesion (ipsilateral gaze palsy)
