Otology Flashcards
What type of inheritance is aminoglycoside induced hearing loss?
Mitochondrial mutation
So passed through mom to all of her children
Schiebe aplasia
Membranous aplasia of cochlea and saccule (can’t see on CT scan)
Pendred Syndrome:
Mutation
Characteristics
AR
SNHL, Mondini malformation with enlarged vestibular aqueduct, euthyroid goiter (by age of 10)
SCL26A4 gene mutation for Pendrin - chloride/bicarb exhange protein, iodide exchange too
Most common infectious cause of congenital hearing loss
CMV - Associated with cerebral calcifications, hepatosplenomegaly, jaundice, intellectual disability
What does the inferior vestibular nerve control?
POSTERIOR SSC function + saccule
What does the superior vestibular nerve control?
Lateral and Superior SCC + Utricle
What do aminoglycosides damage?
OUTER hair cells (Amin-O for Outside)!
Medial wall of epitympanum?
Mostly the promontory
MRI findings of cholesterol granuloma
HYPERintense on T1 AND T2
MRI findings of cholesteotomas
HYPOintense T1, HYPERintense T2, diffusion restricted
Where does chorda tympani nerve pass through in the middle ear?
Between manubrium of malleus and long process of incus before exiting through the petrotympanic fissure.
ABR waveforms mnemonic
ECOLI
I+II - 8th nerve
III - Cochlear nucleus/Sup olivary complex
IV - Sup olivary complex
V - Lateral lemniscus
VI, VII - Inferior colliculus
What is Schwartze’s sign?
Red hue seen at the promontory, found in otosclerosis
Characteristics of CENTRAL vertigo etiology
Vertigo that does not extinguish with repeated stimulation, DOWN (vertical) beating nystagmus that does not improve with fixation, NOT associated with hearing loss usually, less severe.
Get MRI!
Most common cause of NON syndromic congenital SNHL?
Connexin 26 mutation, AR
Non functional gap junction protein, product of GJB2 gene
Most common cause of SYNDROMIC congenital SNHL?
Usher syndrome - AR
Usher Type I, Type II and Type III features?
AR
Type I: Congenital profound SNHL, NO vestibular fx (NO)
Type II: Normal vestibular fx, moderate-severe SNHL (YES)
Type III: Like type II but with variable vestibular fx, progressive HL (MAYBE)
Alport syndrome
X linked, mutation of type IV collagen (COL4A3), causes hearing loss and glomerulonephritis, eye lesions
What is directional preponderance and how do you measure it?
It’s the measure of the difference in total eye speeds between slow phases on each side.
Measured with caloric testing data.
What is speech detection threshold?
Level at which patient is aware of speech 50% of the time.
Explain 7 up Coch down!
Sup ant: FN
Sup Post (behind Bill’s bar): SVN
Inf ant: Cochlear nerve
Inf Post: IVN
Transvere crest is between the SVN and IVN
CHARGE Syndrome
Coloboma of eye, heart defects, atresia of nasal choanae, retardation, genital/urinary abnormalities, ear abnormalities (SCC aplasia, deafness)
-Autosomal DOMINANT
Most common cochlear malformation
Incomplete partition type 2 - arrest at 7th week, 1.5 turns of cochlea, associated with EVA, pendred syndrome, predisposition to SNHL
What % of pediatric HL is due to genetic?
50% are genetic
70% of those are NON syndromic
Most common syndromic cause - Usher
Most common NON syndromic cause - Connexin 26
NF-2
AD
Tumor suppressor gene 22
Bilateral acoustic neuromas, cafe au lait spots (less than NF-1), other cranial, etc. schwanommas, intracranial meningiomas, optic gliomas
Stickler Syndrome
AD
Mutation type II and XI collagen genes
Joint hypermobility, retinal detachment, SNHL, micrognathia
Waardenburg Syndrome
MITF gene/PAX3 gene, AD usually
4 types, SNHL, while forelock, iris pigment abnormalities, dystopia canthorum, broad nasal root
Type II - don’t have dystopia canthorum, SNHL more common
Type III - Type I + upper limb abnormalities
Type IV - Type I + Hirschprung’s disease
Treacher Collins Syndrome
AD
CHL secondary to ossicular abnormalities, can also have EAC stenosis
Hypoplastic mandible, cleft palate, downward slanting eyes, coloboma of lower eyelids (in Goldenhar its UNILATERAL)
AR syndromes with SNHL (3)
- Usher - most common syndromic cause of pediatric HL!
- Pendred
- JLNS
JLN Syndrome
AR, severe to profound HL
Cardiac conduction defect –> syncopal episodes and sudden death
Prolonged QT interval
Important to get EKG in infants with severe to profound SNHL!
-KCNQ1 Gene
Oto-palato-digital Syndrome
X linked, flat midace, cleft palate, short, broad fingers, CHL (ossicular malformation)
What age do you use Behavioral observational audiometry?
Visual response audiometry?
Conditioned play audiometry?
BOA - < 6 months
VRA - Ideal for 6 mo to 30 mo
CPA - > 30 months
Autosomal Dominant congenital HL syndromes (mnemonic)
WANT CBS
Wardenburg, Apert, Neurofibromatosis, Treacher Collins, Crouzon, Branchio-Oto-Renal, Stickler
Also Pfeiffer!
What does the cochlear aquaduct contain?
-The cochlear aqueduct connects the scala tympani to the subarachnoid space via perilymphatic (periotic) duct.
-Parralel to IAC on CT temporal bone
-Has PERILYMPH (Like CSF, NA NA NA)!
What type of fluid is found in the scala tympani and scala vestibuli?
The scala tympani contains perilymph (“Like CSF, NA NA NA - high NA+)
Perilymph vs Endolymph Composition
Perilymph: High Na+, LOW K+, resembles extracellular fluid and CSF. Found in Scala vestibuli and Scala Tympani.
Endolymph: Low Na+, HIGH K+, resembles intracellular fluid. Found in Scala MEDIA.
Characteristics of congenital cholesteotoma (location, mean age, gender ratio, etc).
Location: Most commonly anterior superior quadrant
Mean age: 5
Male to female preponderance (3:1)
Where do cochlear nerve Afferents recieve most input from?
INNER hair cells (90%)
What are the 5 types of tympanoplasties?
- All three ossicles present, involved repair of TM
- Malleus eroded/missing, graft placed over incus
- Malleus + incus removed, graft placed over stapes head.
- Absent or eroded suprastructure, graft placed over mobile foot plate stapes
- Fixed footplate - 5a = placing graft over fenestration made in horizontal SSC. 5b = stapdectomy + graft overlay.
Malignant Otitis Externa: risk factors, likely microorganism, imaging, TX
- Think uncontrolled diabetic or immunosuppressed
- Pseudomonas #1, fungal less likely
- Biopsy - rule out malignancy
- Imaging: CT (bony erosion), MRI to show soft tissue extent (usually 1st choice), Technetium scan (can diagnose bony activity and shows long term change), FOLLOW with gallium scan (and ESR)
- TX: IV antibiotics
Gradinego syndrome (3 things)
Suppurative OM, Retro-orbital pain/pain in distribution of trigeminal nerve, Ipsilateral abducens palsy (eye looking IN due to unopposed medial rectus)
MRI characteristics for Vestibular Schwanomma VS Meningioma?
VS
T1 - Isointense
T2 - Slightly hyperintense
Contrast - Enhances!!!
Meningioma:
T1 - Isointense
T2- Variable
Contrast - mild to moderate enhancement
HAS DURAL TAIL
What does SP/AP ratio relate to and what is considered pathologic?
ECG measures this.
Normal SP/AP ratio ~ 0.4
SP/AP ratio > 0.4 = suggestive of endolymphatic hydrops
What is one ototoxic drugs that affects INNER hair cells?
CARBOplatin. The rest usually affect the OUTER hair cells (of basal turn so starts with high frequency HL or stria vascularis). Use otoacoustic emmissions to monitor this!
What is speech recognition (reception) threshold?
Level at which patient can repeat 50% of speech material.
Reasons for hearing loss after stapedectomy
- Reparative granuloma (seen 1-6 weeks post op) –> usually SNHL
- Obliterative otosclerosis –> Immediate persistent HL post operatively
- Middle ear adhesions, displacement of prosthesis, necrosis of long process incus (recurrent CHL AB gap > 10 dB)
-MOST COMMON: Resorption of incus, followed by prosthesis displacement.
Exostoses vs Osteomata
Exostoses- broad base, often bilateral, multiple lesions along medial EAC. Harder to remove. Cold water exposure.
Osteomata - Pedunculated, single lesions along suture lines. Easier to remove.
What is crossover? When does it occur? What can you do to minimize the risk of it?
When sound presented to test ear stimulates contralateral ear. More likely to happen with external headphones vs internal ones.
Masking should be done when air conduction threshold for test ear exceeds non test ear by 40 dB for external headphones, 70 dB for internal headphones.
Do masking either way if bone conduction exceeds 10 dB in test ear vs non test ear.
OSHA limits for daily noise exposure?
8 hours at 90 dB. Half time for every 5 dB added (ex: 16 hours @ 85 dB. Half time for every 5 dB added)
Word discrimination definition
Amount of monosyllabic words repeated after hearing them at 50 dB above threshold
What is recruitment?
Increase in percieved loudness of sound in an ear with SNHL. Theory is that damaged hair cells recruit adjacent hair cells with normal function. Results in a narrowed range between softest and loudest sounds. Think retrocochlear lesion if you see this. Excessive tone decay suggests this too.
What is Donaldson’s line?
Imaginary line drawn posteriorly through plane of horizontal SCC, approximates location of endolymphatic sac (superior aspect of it).
What is the Stenger test used for?
To test for malingering.
What is the nerve excitability test and how to interpret?
Tests for FN function - thresholds to elicit facial movement are compared on both sides. Difference > 3.5 mA is considered significant weakness.
At the base of the cochlea, the __ ends at the __ window, while the __ terminates at the __ window, which opens to the middle ear
At the base of the cochlea, the scala vestibuli ends at the oval window, while the scala tympani terminates at the round window, which opens to the middle ear.
What is impedence matching and how is it accomplished?
Ensures acoustic energy is not lost as it transitions from air to fluid wave. This is accomplished mainly by the difference in surface area between the TM and the oval window (stapes footplate) - 60 mm sq vs 3 mm sq
Which two aminoglycosides are VESTIBULOtoxic?
Gentamycin and Streptomycin (affect sensory cells in crista ampullaris). Streptomycin is MOST vesibulotoxic.
NEOMYCIN = most COCHLEOtoxic
Acoustic Reflex
Contraction of stapedius muscles (innervated by FN) upon exposure to loud noise (~ 70-100 dB). Efferent limb is measured by changes in TM compliance.
ABSENT in otosclerosis
Histopath associated with vestibular schwanomma?
Spindle shaped cells arranged in Antoni A and B patterns
Type of HL, Acoustic reflex and cVEMP findings for SSCD?
CHL (worse in lower frequencies, also supranormal bone conduction), present acoustic reflexes, lower threshold and higher amplitude on cVEMP
Sensory innervation to external ear/TM?
TM - TATA
Tympanic membrane, Auriculotemporal nerve (anterior outer half), tympanic branch of IX (Jacobson’s, inner), Auricular branch of X (Arnold’s, posterior outer half)
External Ear:
Auriculotemporal nerve
Lesser occipital nerve
Auricular branch of X
Greater auricular nerve
Intensity of meningioma and paragangliomas on T1 and T2?
Both isointense on T1 and T2
Von Hippel Lindau Disease
AD
Multiple hemangioblastomas of retina and central nervous system, renal cysts, clear cell renal carcinoma, pheochromocytomas, endolymphatic sac tumor (10%).
What do utricle and saccule sense?
Utricle - senses linear acceleration in a horizontal plane.
Saccule - Senses linear acceleration in a vertical plane.
1st and 2nd most common etiologies for facial nerve injury and what segment is injured?
1: Bell’s (labrynthine)
2: Trauma (perigeniculate)
Which malignancy most commonly metastasized to temporal bone?
Adenocarcinoma of breast
Most common head and neck malignancy in pediatrics and what is the standard of care for T bone location?
Rhabdomyosarcoma - SOC if chemo, radiation therapy, debulk and/or complete resection.
Treatment modalities for T2-T4 temporal bone malignancies?
Surgery AND radiation therapy.
CHL expected with TM perforation + OCR discontinuity vs OCR discontinuity only?
TM perf + OCR discontinuity: 45-50 dB CHL
OCR discontinuity: 60 dB CHL (maximal)
Otosclerosis inheritance and most commonly affected site?
Autosomal dominant, fissula ante fenestrum (area of anterior crura of stapes footplate) = most common, round window = 2nd
Pittsburgh Staging System for Temporal Bone SCC?
T1 - Limited to EAC, no bony erosion or soft tissue
T2 - Limited bony erosion, limited soft tissue involvement
T3 - Full thickeness bony EAC erosion, middle ear or mastoid involved
T4 - Involvement of carotid canal, jugular bulb, medial middle ear, petrous apex, or facial nerve
Diagnostic criteria for definite Meniere’s?
Fluctuating aural symptoms of affected ear
Audiometric confirmation of low-mid frequency SNHL before, during or after episode
At least two episodes of rotational vertigo 20 min-12 hours
Causes excluded by other tests
What is the rollover phenomenon?
Sign of retrocochlear pathology (same goes for recruitment and excessive tone decay)
Occurs when SRT DROPS with increasing loudness
5 types of nerve injury in Sunderland classification?
Remember Wallerian degeneration starts at grade II (~ 3 days post injury).
Michel Aplasia?
Alexander Aplasia?
Michel: Complete agenesis of inner ear (petrous)
Alexander: Poor development of cochlear duct, organ of corti, ganglion (HF HL)
What is ototoxicity of cisplatin dependant on (two things)?
Age (<5 = more affected) and dose
What is the operculum?
The operculum is the opening of the vestibular aqueduct into the posterior fossa and lies along the posterior face of the petrous bone. It is enlarged in patients with EVA.
Operculum O’s - Opening to aquaduct, site on pOsterior petrous bone
Where do paragangliomas arise from and features of it?
Glomus tympanicum tumors arise from Jacobsen’s plexus on the cochlear promotory (CN IX). These tumors are often associated with succinate dehydrogenase (SDH) mutation and surgical removal is recommended, particularly while they are small.
Differential: glomus jugulare (would see connection to jugular bulb on CT), endolymphatic sac tumor (associated with VHL disease), glomus tumors (very vascular, feeding branch from ascending pharyngeal artery (ECA), can be embolized prior to surgery)
Name the structures in the picture
A - Scala vestibuli
B - Modiolis
C - Otic capsule bone
D - Organ of Corti
What is ENOG and when to do it?
This is an evoked electromyography (EMG), where the facial nerve is stimulated at the stylomastoid foramen and the response recorded with facial electrodes.
By 3 days, Wallerian degeneration has occurred, and neural integrity is more accurately reflected. A decrement in ENoG recording by > 90% compared to the normal side is considered an indication for surgical decompression. So do after 3 days but before 3 weeks.
Note this is recommended for COMPLETE facial paralysis only!
Definition of SSNHL?
30 dB loss over three contiguous frequencies over three days
Name the structures in the image below (ear histopathology)
A - external ear canal
B - middle ear
C - Reissner’s membrane (seperates cochlear duct from vestibular duct, endolymphtatic hydrops seen in Menniere’s affects this)
D - Vestibule
What is the characteristic MRI finding for cholesteatomas?
Restricted diffusion on non-echo planar diffusion weighted MRI
What does cVEMP test and what does oVEMP test?
cVEMP tests the saccule and inferior vestibular nerve while the oVEMP tests the utricle and superior vestibular nerve. The cVEMP response is an inhibitory response and is ipsilateral while oVEMP response is excitatory and contralateral (inferior oblique muscle).
Acoustic Reflex Pathway?
Unilateral CN VIII Stim –> Cochlear nucleaus –> BILATERAL superior olive complex –> BILATERAL CN VII nerve motor comples –> BILATERAL stapedius muscle contraction
Cogan Syndrome Features
Autoimmune, Interstitial keratitis, vertigo, HL, tinnitus
Rare cause of SNHL
Most common infectious cause of SNHL and % of congenital HL thought to be caused by it?
CMV
20-30% of congenital SNHL attributed to it.
What is the most common radiographically identified inner ear finding for congenital HL?
Enlarged vestibular aqueduct (EVA) (15%)
Inheritence pattern of otosclerosis and main features of the disease?
- AD with incomplete penetrance
- CHL (with 2000 Hz Carhart notch)
- Negative Rinne (so BC better than AC).
- Tinnitus
- ABSENT stapedial reflex (unlike in SSCD or Meniere’s)
Disadvantages of lateral graft or tympanoplasty?
Post op blunting, increased risk of cholesteatoma, greater technical demand, graft lateralization, longer healing
Pros: Useful for large anterior perforations
Positioning: Lateral to TM, MEDIAL to malleus handle
Jackson Glasscock Classification of Middle Ear Tumor (I-IV)
Type I limited to the promontory and the entire tumor is visible through the TM.
Type II confined to the middle ear and hypo-tympanic space.
Type III extends to the mastoid.
Type IV – extends to mastoid, EAC or anterior to ICA.
Keratosis Obturans vs Canal Cholesteatoma (imaging findings)?
Bony remodeling of EAC (+ impacted debris in canal) -→ Keratosis Obturans
Osseous erosion -→ Cholesteatoma
What is a persistent stapedial artery associated with?
Radiographically it is often associated with an absent foramen spinosum.
Usually asymptomatic but may occasionally cause pulsatile tinnitus, hearing loss, vertigo, and vomiting.
What does CI stimulate and where is it placed?
Placement within the scala tympani (ST) optimizes the interaction between the electrode and the spiral ganglion cells, which are being directly stimulated by the implant.
What is Vernet Syndrome?
-→ Vernet syndrome. hoarseness due to vocal cord paralysis (CN10), difficult swallowing (CN9), weakness and atrophy of SCM and trapezius muscles (CN11).
Associated with glomus jugulare tumors, etc.
Histopath of paraganglioma/glomus tumors?
Zellballen → nests of chromafin cells or chief cells and sustentacular cells
What chromosome is NF1 vs NF2 associated with and what are some main differences?
NF1: Chromosome 17.
Lisch nodules and osseous abnormalities are only seen in NF 1
NF2: Chromosome 22
BILATERAL VS
AD!
What procedure is indicated for chronic BPPV (refractory to repositioning + vestibular therapy)?
Posterior canal occlusion
What is the name of the canal that the facial nerve travels through?
Fallopian Canal
What is the nervus intermedius?
Contains PRE ganglionic parasympathetic fibers to salivary and lacrimal glands, carries taste fibers from anterior ⅔ of tongue and sensation fo posterior wall of EAC.
Runs with CN VII and usually merges with it at end of IAC.
Hitselberger test (sensation to conchal bowl) - tests nervus intermedius.
Candidacy criteria for bone conduction device?
-SSD > 65 (CI won’t be covered by medicare)
-Bone conduction thresholds up to 55 dB
-Air bone gap > 30
-Mixed conductive loss (also think microtia, COM, etc where they can’t wear traditional hearing aids)
Translab vs retrosigmoid approach?
Translab:
1) Reduced cerebellar retraction
2) Direct access to the internal auditory canal and cerebellopontine angle
3) Facile identification of the facial nerve both in the mastoid segment and the labyrinthine segment - lowest risk of injury.
4) NO option for hearing preservation
5) Can do CI at the same time (access to cochlea)
*Inferior drilling limit is cochlear aquaduct and jugular bulb
Retrosigmoid approach:
-Medial tumors/good CPA access, but traditionally difficult to get to IAC extension
-No limits on size
-Hearing preservation (unless tumor is growing out towards fundus)
-Cerebellar retraction
-Shorter operating time
-Risks: CSF leak, headache!
Middle fossa:
-Highest chance of FN paralysis for CPA tumor…
-Usually hearing preservation
-Small (< 1 cm) intracanalicular tumors
What is the most common deformity after otoplasty and why does it occur?
Telephone ear (too acute conchal mastoid angle). Due to OVERCORRECTION of MIDDLE third of ear.
What does VNG test (nerve)?
Tests SUPERIOR vestibular nerve/horizontal semicircular canal (so a normal VNG would indicate INFERIOR vestibular nerve abnormality)
Features of HORIZONTAL canal BPPV and maneuver for treatment?
Takes longer to resolve, no side preference, horiztonal nystagmus. TX - BBQ Log Roll
What is the eustachian tube, TM and EAC derived from?
ET: 1st pharyngeal pouch endoderm
TM: 3 layers
Endoderm (1st pharyngeal pouch)
Mesoderm
Ectoderm - stratified sq. epithelium, 1st branchial arch
EAC: Ectoderm of 1st pharyngeal CLEFT
What superior canal does caloric testing test and what is the COWS mnemonic?
Tests lateral SCC
Cold: Opposite fast phase nystagmus
Warm: Same fast phase nystagmus (TOWARDS tested ear)
Jahrsdoerfer criteria?
Score 8 or more/10 predicts better outcomes
Stapes present - 2 points
Oval window patent - 1 point
Round window patent - 1 point
Incus-stapes connection - 1 point
Malleus incus - 1 point
Facial nerve position - 1 point
Middle ear space well aerated - 1 point
Mastoid pneumatized - 1 point
External ear appearance - 1 point
Langerhans Cell Histiocytosis
Proliferation of Langerhans cells
-SX: T bone mass, otorrhea, CHL, post auricular swelling
-CT: Shows punched out lytic lesions
-Path: Birbekc granules
-TX: Surgery + steroids, if many sites need to consider chemo or radiation
Action of Tensor and Levator Veli Palatini?
Tensor: Opens ET, depresses soft palate (CN V)
Levator: Elevates soft palate (CN X)
What do DPOAE test?
Outer hair cell function (and used to measure noise induced damage)
What is an absolute contraindication for repair of canal atresia?
Malformed inner ear with SNHL (can still do repair of microtia for cosmetic purposes)
Diagnostic findings for SSCD (SP/AP ratio on ECOG, CVEMP)?
High SP/AP ratio (above 0.4) on ECOG
LOW thresholds, HIGH amplitude on CVEMP
Primary vs secondary aquired cholesteatoma?
Primary aquired: Due to ET dysfunction –> pars flaccida retraction
Secondary aquired: Due to injury of TM (tubes, perforation, etc.), usually don’t have TM retraction
Relapsing polychondritis - What antibodies would you see and what is TX?
Autoimmune, Ab’s to Type II + IV collagen
Must differentiate from other autoimmune diseases
TX: NSAIDS, Corticosteroids for attacks, DAPSONE
What are the four components of VNG?
- Examination for gaze and spontaneous nystagmus, with and without visual fixation
- Oculo-motor assessment (including saccade, smooth pursuit, and optokinetic tracking)
- Positional testing (Dix Hallpike, usually posterior canal)
- Caloric testing (horizontal canal)
What does the stria vascularis do?
Produces endolymph! (found in scala media)
Trauma to what part of the skull is most likely to result in transverse and longitudinal temporal bone fractures?
Occiput –> transverse fractures
Temporo-parietal –> longitudinal fractures (most common)
What do the following target (and what type of HL):
Aminoglycosides
Quinine
Loop diuretics + macrolides
Streptomycin + Gentamycin
Aminoglycosides: OUTER hair cells starting at basal turn (so HIGH frequency loss first)
Irreversible, dose dependent
Quinine: 4k hearing loss notch, reversible
Loop diuretics + macrolides: stria vascularis (ototoxicity)
Streptomycin + gentamycin specifically (they are aminoglycosides): most vestibulotoxic
HL broken down into % genetic, etc.
50% genetic, 50% environmental/acquired
Within genetic, 30% syndromic, 70% non syndromic
Of non syndromic, 80% are AR, 20% are AD
Most common non syndromic AR –> Connexin 26 (has a subtype which is AD too)
Timeline for newborn hearing screening, etc.
Newborn hearing screening by 1 month (usually done with OAEs)
Definitive testing by 3 months (diagnostic ABR)
Hearing aids (if chosen to pursue) within 1 month of definitive testing/diagnosis
Early intervention by 6 months
What branches innervate the external ear?
CN V, VII, IX and X
What kind of hearing loss does otosyphillis cause and what is the DX?
SNHL, positive FTA-ABS
DX for NEUROsyphilis: CSF CDRL and CSF blood cell count > 20+
Main differences between Brent and Nagata techniques?
Brent Reconstruction:
Starts at age 6
Requires 3 or more stages (usually 4)
The tragus and lobule are elevated in separate procedures
Nagata Reconstruction
Starts at age 10 when there is more available cartilage
Requires 2 stages
The tragus and lobule are elevated in the same stage
