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STEP > Ear, Nose and Throat > Flashcards

Ear, Nose and Throat Flashcards

1
Q

Outer ear properties

A
  • Visible portion of ear (pinna)
  • Includes auditory canal and eardrum
  • Transfers soundwaves via vibration of eardrum
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2
Q

Middle ear properties

A
  • Air filled space with three bones called ossicles (malleus, incus and stapes)
  • Ossicles conduct and amplify sound from eardrum to inner ear
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3
Q

Inner ear properties

A
  • Snail-shaped, fluid filled cochlea.
  • Contains basilar membrane that vibrates secondary to sound waves
  • Vibration is transduced via specialized hair cells
  • Send auditory nerve signaling to brainstem.
  • Each frequency leads to vibration at a specific location on the basilar membrane called tonotopy
  • Low frequency is heard at apex near helicotrema (wide and flexible)
  • high frequency is heard at the base of cochlea (thin and rigid)
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4
Q

Conductive hearing loss rinne and weber test results?

A

Rinne test: Abnormal result ( bone > air )

Weber test: Localizes to the affect ear

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5
Q

Sensorineural hearing loss rinner and weber test results?

A

Rinne test: Normal result (air > bone)

Webber test: Localizes to unaffected ear

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6
Q

What is noise induced hearing loss and what causes it?

A
  • Damage to stereociliated cells in organ of Corti
  • Loss of high frequency hearing first
  • Sudden extremely loud noises can produce hearing loss due to tympanic membrane rupture
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7
Q

What is presbycusis hearing loss and what causes it?

A
  • Aging-related sensorineural hearing loss
  • Often of high frequencies
  • Due to destruction of hair cells at the cochlear base
  • Preserved low frequency hearing at apex
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8
Q

What is a cholesteatoma?

A
  • An overgrowth of desquamated keratin debris within the middle ear space behind the ear drum
  • May erode the ossicles, mastoid air cells and lead to conductive hearing loss
  • Rinne test is abnormal (bone > air) and weber test goes to affected ear
  • Due to repeated infections or tear/pulling inward of the eardrum from poor eustachian tube function.
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9
Q

What is vertigo?

What are the two types?

A
  • Sensation of spinning while stationary
  • A subtype of dizziness
  • Distinct from lightheadedness
  • Peripheral and central are the two types
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10
Q

What is peripheral vertigo?

A
  • The most common form
  • Inner ear etiology
  • Due to semicircular canal debris, vestibular nerve infection, Meniere disease, benign paroxysmal positional vertigo
  • Positional testing shows delayed horizontal nystagmus
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11
Q

What is central vertigo?

A
  • Brain stem or cerebellar lesion
  • Due to stroke affecting vestibular nuclei or posterior fossa tumor
  • Findings include directional or purely vertical nystagmus, skew deviation, diplopia or dysmetria
  • Positional testing leads to nystagmus in any direction, it may change direction
  • There are also focal neurological findings
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12
Q

Cranial nerve I

  • Passes through?
  • Action
  • Sensory or motor?
A
  • Olfactory nerve
  • Passes through the cribriform plate in the anterior cranial fossa
  • Responsible for smell
  • Sensory nerve
  • Only cranial nerve without thalamic relay to cortex
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13
Q

Cranial nerve VIII

- Passes through?

A
  • Vestibulocochlear nerve
  • Passes through the internal auditory meatus in the temporal bone of the posterior cranial fossa.
  • Located laterally to cranial nerve VII
  • Responsible for hearing and balance
  • Sensory nerve
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14
Q

What are the causes of otitis externa?
What are the properties of the cause?
How is it treated?

A

Pseudomona Areguinosa (swimmers ear)
- Gram negative rod, non lactose fermenting, oxidase positive, produces blue green pigment (pyocyanin), has grape like odor
- Produces endotoxin (fever/shock), exotoxin-A (inactivates EF-2), phospholipase C (degrades cell membranes) and pyocyanin (reactive oxygen species)
- Treat with CAMPFIRES
Carbapenims
Aminoglycosides
Monobactams
Polymyxin
Fluoroquinolones
ThIRd and fourth generation cephalosporins
Extended spectrum penicillins

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15
Q

What is a major complication of otitis media?

A
  • Can lead to temporal lobe brain abscess
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16
Q

What organism produces biofilms and contains IgA protease and causes otitis media?

A
  • Hemophilus influenzae
  • Type B is encapsulated
  • Capsule serves as antiphagocytic virulence factor
  • Capsule polysaccharide + protein conjugate serves as antigen in vaccines
17
Q

Define otitis media

A
  • Infection of the middle ear between the eustachian tube and the tympanic membrane
18
Q

What are the most common causes of otitis media?

A
  1. Streptococcus pneumonia (35-40%)
  2. Hemophylus influenzae (25-30%
  3. Moraxella catarrhalis (15-20%)
  4. Viral upper respiratory infections
19
Q

Clinical presentation of otitis media?

A
  • Symptoms include ear pain, fever and decreased hearing
  • Physical exam reveals a red, bulging tympanic membrane with loss of the light reflex
  • There may be immobility of the membrane on insufflation of the ear with air.
  • Perforation of the tympanic membrane with discharge (otorrhea) may also occur.
20
Q

How is otitis media usually treated?

A
  1. Amoxicillin is best initial therapy
  2. Amoxicillin clavulanate is used if there has been recent amoxicillin use or patient does not respond to initial therapy
  3. Second generation cephalosporins may be used instead of amox-clav such as cefuroxime, loracarbef or cefprozil
  4. Third generation cephalosporins such as cefdinir or cefixime may also be used
  5. Macrolides such as azithromycin or clarithromycin should be used in those with penicillin allergies
  6. New fluoroquinolones such as levofloxacin, moxifloxacin or gatifloxacin can be used but have broader coverage than necessary and should not be used in children due to arthropathy.
  7. Sulfamethoxazole/Trimethoprim may be used but it is poorly active against Streptococcus Pneumoniae
21
Q

Define sinusitis

A
  • Infection of the sinuses

- Most common is the maxillary sinus, followed by the ethmoid, frontal and sphenoid sinus

22
Q

What are the most common causes of sinusitis?

A
  1. Viruses are the most common cause
  2. Streptococcus pneumonia (35-40%)
  3. Hemophylus influenzae (25-30%
  4. Moraxella catarrhalis (15-20%)
23
Q

How does sinusitis typically present?

A

Facial pain, headache, postnasal drainage and purulent nasal discharge

  • Headache is worse when the patient leans forward
  • Fever may occur
  • Tooth pain may occur because of the proximity of the teeth to the sinuses
24
Q

What is done for complicated cases of sinusitis?

A
  • CT of the sinuses is test of choice
  • If patient does not respond to therapy or there is recurrence, a sinus puncture may be necessary to confirm specific bacteriologic etilogy
25
Q

What is the treatment for sinusitis?

A
  • Decongestants such as pseudophedrine or oxymetazoline sprays
  • For more severe pain with discolored nasal discharge, antibiotic treatment is necessary
  • Just as with otitis media, begin with amoxicillin, then add amoxicillin + clavulanic acid and so on
  • For viral sinusitis, most cases resolve in 7-10 days, use antihistamines, NSAIDs and decongestants, if symptoms persist then antibiotics may be necessary.
26
Q

Most common causes of pharyngitis?

A
  • Viruses
  • Group A beta hemolytic Streptococci (S. Pyogenes) (15-20%)
  • ## May progress to rheumatic fever or glomerulonephritis
27
Q

How does pharyngitis typically present?

A
  • Sore throat with cervical adenopathy and inflammation of the pharynx with an exudative covering is highly suggestive of S. pyogenes
  • Mild S. pyogenes may not give exudate
  • Hoarseness and cough are not suggestive of pharyngitis
  • Most viruses do not give an exudate, Epstein-Barr can however
28
Q

How is pharyngitis diagnosed?

A
  • Rapid strep test is 80% sensitive but >95% specific
  • Positive test is equivalent to positive culture
  • Negative test should be confirmed with a culture
29
Q

How is pharyngitis treated?

A
  • Penicillin is best choice

- Macrolides and oral second generation cephalosporins are alternatives in the penicillin allergic patient

30
Q

What is Rhinosinusitis?

What are the causes and complications?

A
  • Obstruction of sinus drainage into the nasal cavity
  • Leads to inflammation and pain over the affected area
  • Typically the maxillary sinuses, become filled with fluid which then drain into the middle meatus
  • Most commonly caused acutely by viral URI
  • May lead to superimposed bacterial infection by S. pneumoniae, H. influenzae and M catarrhalis
31
Q

What is epistaxis?

A

Nose bleed

  • Most commonly occurs in the anterior segment of the nostril ( Kiesselbach plexus)
  • Life threatening hemorrhages occur in the posterior segment ( Sphenopalatine artery, a branch of the maxillary)
  • Caused by foreign bodies, trauma, allergic rhinitis and nasal angiofibromas
32
Q

What is Meniere’s disease?

A
  • A disorder of the inner ear that causes Increase volume and pressure of endolymph
  • It is thought to be due to defective resorption of endolymph
  • Distention of the endolymph system causes damage to the vestibular and cochlear components of the inner ear
  • Includes Triad of:
    1. Low-frequency tinnitus or ringing, accompanied by a feeling of fullness
    2. Vertigo the subjective sensation of spinning or motion in the absence of actual motion
    3. Sensorineural hearing loss, variable severity but worsening overtime
  • Treatment may be managed with diuretics or salt restriction
33
Q

Meniere’s disease
Cause?
Features?

A 
- A common cause of vertigo
Caused by
- Increased pressure and volume in endolymph
Features
- Recurrent vertigo
- Ear fullness/pain
- Unilateral hearing loss and tinnitus
34
Q

Benign Paroxysmal Positional Vertigo

A 
- A common cause of vertigo
Caused by
- Otoliths in semicircular canals
Features
- Brief episodes brought on by head movement
- No auditory symptoms
35
Q

Vestibular neuritis (Labarynthitis)

A 
- A common cause of vertigo
Caused by
- Inflammation of vestibular nerve 
Features
- Single episodes that can last days
- Severe vertigo with no hearing loss
36
Q

Describe how the transduction of mechanical sound waves into nerve impulses occurs in the Organ of Corti?

A
  1. Sound reaches middle ear by vibrating tympanic membrane
  2. Vibration is transferred to the oval window by ossicles
  3. Vibration of the oval window causes the basilar membrane to vibrate, which causes bending of hair cell cilia against tectorial membrane
  4. Hair cell bending causes oscillating hyperpolarization and depolarization of the auditory nerve, thereby creating nerve impulses from sound
37
Q

Noise induced hearing loss

A
  • Results from trauma to stereociliated hair cells of the organ of corti.
  • Prolonged noise exposure can cause distortion or fracture of the stereocilia due to the shearing forces against the tectorial membrane
  • High frequency hearing is lost first, regardless of the frequency of the sound causing the damage.

STEP (28 decks)

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