Ear, Nose and Throat

Question 1

Outer ear properties

Answer 1

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

Question 2

Middle ear properties

Answer 2

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

Question 3

Inner ear properties

Answer 3

• 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)

Question 4

Conductive hearing loss rinne and weber test results?

Answer 4

Rinne test: Abnormal result ( bone > air )

Weber test: Localizes to the affect ear

Question 5

Sensorineural hearing loss rinner and weber test results?

Answer 5

Rinne test: Normal result (air > bone)

Webber test: Localizes to unaffected ear

Question 6

What is noise induced hearing loss and what causes it?

Answer 6

• 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

Question 7

What is presbycusis hearing loss and what causes it?

Answer 7

• 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

Question 8

What is a cholesteatoma?

Answer 8

• 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.

Question 9

What is vertigo?

What are the two types?

Answer 9

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

Question 10

What is peripheral vertigo?

Answer 10

• 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

Question 11

What is central vertigo?

Answer 11

• 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

Question 12

Cranial nerve I

• Passes through?
• Action
• Sensory or motor?

Answer 12

• 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

Question 13

Cranial nerve VIII

- Passes through?

Answer 13

• 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

Question 14

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

Answer 14

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

Question 15

What is a major complication of otitis media?

Answer 15

• Can lead to temporal lobe brain abscess

Question 16

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

Answer 16

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

Question 17

Define otitis media

Answer 17

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

Question 18

What are the most common causes of otitis media?

Answer 18

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

Question 19

Clinical presentation of otitis media?

Answer 19

• 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.

Question 20

How is otitis media usually treated?

Answer 20

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

Question 21

Define sinusitis

Answer 21

• Infection of the sinuses

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

Question 22

What are the most common causes of sinusitis?

Answer 22

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

Question 23

How does sinusitis typically present?

Answer 23

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

Question 24

What is done for complicated cases of sinusitis?

Answer 24

• 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

Question 25

What is the treatment for sinusitis?

Answer 25

- 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.

Question 26

Most common causes of pharyngitis?

Answer 26

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

Question 27

How does pharyngitis typically present?

Answer 27

- 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

Question 28

How is pharyngitis diagnosed?

Answer 28

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

Question 29

How is pharyngitis treated?

Answer 29

- Penicillin is best choice | - Macrolides and oral second generation cephalosporins are alternatives in the penicillin allergic patient

Question 30

What is Rhinosinusitis? | What are the causes and complications?

Answer 30

- 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

Question 31

What is epistaxis?

Answer 31

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

Question 32

What is Meniere's disease?

Answer 32

- 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

Question 33

Meniere's disease Cause? Features?

Answer 33

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

Question 34

Benign Paroxysmal Positional Vertigo

Answer 34

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

Question 35

Vestibular neuritis (Labarynthitis)

Answer 35

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

Question 36

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

Answer 36

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

Question 37

Noise induced hearing loss

Answer 37

- 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.