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Otologic Anatomy/Develop, Hearing loss Flashcards

1
Q

List the TORCH infections

A

Toxoplasmosis
Other: VZV, Syphillis
Rubella
CMV
HSV

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2
Q

What are the complications and features of congenital rubella? 7

A
  1. Blueberry muffin skin rash (anemia, thrombocytopenia)
  2. SNHL
  3. Retinitis/keratitis/cataracts
  4. Hepatosplenomegaly/jaundice/hepatitis
  5. Mental retardation
  6. Microcephaly
  7. Still-birth

“Blueberry for Rubella”

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3
Q

What is the differential diagnosis for pediatric SNHL?

A

UNILATERAL:
1. Structural (absent nerve, EVA, labyrinth/cochlea) - 50% cochlear nerve absent in congenital profound unilateral SNHL
2. Traumatic
3. X-linked gusher
4. Viral (CMV)

BILATERAL:
1. EVA
2. Structural
3. Viral (CMV, Rubella, TORCHES)
4. Meningitis
5. Ototoxicity
6. Jaundice
7. Prematurity
8. Idiopathic
9. Congenital

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4
Q

What is the incidence of congenital hearing loss?

A

2-3/1000

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5
Q

What is the differential diagnosis for congenital hearing loss?

A

ACQUIRED (1/3)
- TORCH infections - CMV 21% most common
- Hypoxia (≤5 APGAR at 5 minutes)
- Meningitis, sepsis
- Ototoxicity
- Hyperbilirubinemia
- Low birth weight

HEREDITARY (2/3)
A. SYNDROMIC (1/4)
Autosomal Dominant “BTOWNS”
- BOR
- Treacher collins
- Otosclerosis
- Waardenburg
- NF2
- Stickler

Autosomal Recessive “UPJ”
- Usher
- Pendred
- Jervell Lange Neilsen

X-linked “WilD (very) ON Alberta”
- Wildervanks
- Deafness Dystonia
- Oculopalatodigital syndrome
- Norrie syndrome
- Alport

Mitochondria:
- A1555G mutation
- MIDD
- MELAS

B. NON-SYNDROMIC (3/4)
- Connexin 26 - GJB2 mutation
- Connexin 30 - GJB6 mutation
- Others (30%)

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6
Q

What are the top two most common CT abnormal findings in SNHL?

A

1) Enlarged vestibular aqueduct
2) Mondini malformation

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7
Q

What is the most common histological cochlear abnormality associated with SNHL

A

Schiebe’s anomaly (cochlear membranous dysplasia)

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8
Q

Describe the embryology of the inner ear

A

ECTODERMAL (Membranous labyrinth)
- Otic placode (ectoderm from hindbrain) invaginates to form otic pit
- Edges of the otic pit then fuse to form the otic vesicle (aka otocyst) which forms into the membrane labyrinth
- Otic vesicle then divides into two parts:
1. Endolymphatic diverticulum (endolymphatic duct and sac)
2. Utriculosaccular chamber (utricular chamber gives rise to utricle and SCCs; saccular chamber gives off saccule and cochlea)

MESODERMAL (Bony labyrinth)
- Mesoderm around otic cyst forms a cartilaginous otic capsule
- This vacuolates to form the scala tympani and scala vestibuli (perilymphatics)
- Week 15 - staples footplate forms
- Week 23 - ossifies to form bony labyrinth

Timing of development:
1. Otic placde at 3 weeks
2. Otic pit at 4 weeks
3. Otic vesicle at 5 weeks
4. Cochlear duct at 8 weeks
5. Saccule at 11 weeks
6. Endolyphatic duct at 11 weeks
7. Utricle at 11 weeks
8. SCC at 19-22 weeks
9. Labyrinthine ossification occurs at 23 weeks
10. Total development at 26 weeks

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9
Q

When do the following otologic structures reach adult size?
1. Pinna
2. EAC
3. TM
4. Ossicles & Petrous Temporal Bone
5. Mastoid Antrum
6. Eustachian Tube

A
  1. Pinna - Near adult size at 4-5 year (95%), full size by 9 years
  2. EAC - Incomplete ossification at birth leads to increased compliance on impedance audiometry until age 6 months
  3. TM - adult sized at birth, horizontal because of incomplete ossification of EAC, vertical position reached by 2 years
  4. Ossicles & Petrous Temporal Bone - adult sized at birth
  5. Mastoid Antrum - present at birth, increase in size during 1st year, pneumatization continues into childhood, fully developed mastoid & styloid by 3 years
  6. Eustachian Tube
    - At birth: 50% adult length, 10angle from the horizontal, enters nasopharynx at hard palate level
    - 5-7 years: lateral portion rises, tube lengthens and widens, reaches a 45deg angle with the horizontal, enters nasopharynx at inferior turbinate level
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10
Q

Describe the anatomy of the eustachian tube:
1. Length in adults/kids and diameter
2. % bony/cartilaginous
3. Angle and location of entry
4. What is the Torus Tubarius
5. What is the Rosenmuller’s fossa?

A
  • Length: 36mm adults, 18mm long infants
  • 1/3 bony (lateral), 2/3 cartilaginous (medial)
  • Wide at both ends, narrow in the midportion at the isthmus (1x2mm)
  • Lateral end 4mm above floor of protympanum, relatively horizontal, meets cartilaginous portion at 160deg angle, cartilaginous portion then descends at a 40-45deg angle, 45deg off sagittal, into the nasopharynx

Torus Tubarius:
- Formed by soft tissue overlying the medial cartilaginous end of the tube

Rosenmuller’s fossa:
- Nasopharyngeal mucosal fold found posterior to torus

Vancouver Pg 514 - Label!

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11
Q

What are the differences between pediatric and adult ET that make them more prone to middle ear disease?

A
    • a. Peds ET are more horizontal (more acute angle against the horizontal), therefore more difficult to drain the middle ear (less gravity dependent than adults)
    • b. Peds ET is narrower than adults (more difficult to drain)
    • c. Peds ET osseous-cartilaginous junction is more inline so the geometry of the TVP muscle attachment to the tube cartilage is altered and therefore less effective
    • d. Peds ET has more dense cartilage with less elastin
    • e. Ostmann’s fat pad, located laterally to the lateral wall of the tube’s cartilage, is relatively more massive in children.
    • f. Mucosa is thicker and more folded in children.
    • g. Children’s tube submucosa is characterized by more developed lymphoid tissue aggregations that form the tubal tonsil.
    • h. Peds ET may be obstructed by larger adenoids in the pediatric population compared to adults, as well as increased URTI/risk of adenoiditis, worsening their symptoms
    • i. Other differences: increased viral infection in children, increased mucous production, allergic rhinitis, Bottle feeding and pacifier usage, especially when breathing from the nose is obstructed, can create a Toynbee phenomenon that leads to negative pressure in the middle ear.

Peds ET tubes are: “FLAT HONDs”
F - fatter (Ostmann’s fat pad is bigger)
L - lymphoid tissue aggregations from tubal tonsil
A - adenoids larger may cause obstruct
T - thicker mucosa
H - horizontal
O - Osseous-cartilaginous junction is more “inline” so TVP muscle attachment is altered and less effective
N - narrower
D - denser cartilage with less elastin

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12
Q

What are four muscles related to the eustachian tube and their innervation? Which one is the main dilator?

A
  1. Tensor veli palatini (V3) - medial head is the main eustachian tube dilator
  2. Levator veli palatini (X)
  3. Tensor tympani (V3)
  4. Salpingopharyngeus (originates off torus tubarius, interdigitates with palatopharyngeus) - (X)
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13
Q

Describe the anatomy of the tensor veli palatini

A

Lateral Head:
- Origin from scaphoid fossa & greater sphenoid wing
- Swings anteriorly, laterally and inferiorly
- Tendon around the hamulus
- Inserts onto posterior hard palate and palatine aponeurosis

Medial Head (main ET dilator):
- Extends from lateral lamina of torus tubarius to hamulus
- Contraction opens eustachian tube, by lateralization of lateral lamina of torus
- Activated by swallowing/yawning

Good image of Hamulus: https://www.earthslab.com/wp-content/uploads/2018/02/plates-of-Pterygoid-process.jpg

Vancouver Pg 514

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14
Q

What are the functions of the Eustachian tube 4

A
  1. Pressure regulation/ventilation
  2. Maintains low O2 and high nitrogen concentrations in the middle ear
  3. Protection from nasopharyngeal reflux
  4. Drainage of middle ear secretions via mucociliary transport mechanism
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15
Q

Discuss the pediatric milestones for receptive and expressive speech

A

1 month:
- Random activity arrested by sound
- Random vocalization (vowel sounds)

6 months:
- Recognize words, “mama”, “bye bye”
- Vocal protest, squeal delight

12 months:
- Recognize Familiar objects by name
- Respond with gestures

18 months:
- Identify and pick out familiar objects when named
- Uses words more than gestures for desires

24 months:
- Understands complex sentences and follows 2-step commands
- Refers to self by name and links 2 words “hi mommy”

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16
Q

What is the etiology of pediatric hearing loss and percentage of cases?

A

A. GENETIC (50%)

  1. Syndromic (30%)
    - AD 20%
    - AR 80%
    - X-linked 1%
  2. Non-Syndromic (70%)
    - AD 20%
    - AR 80%
    - X-linked 1%
    - Mitochondrial 1%

B. ENVIRONMENTAL (25%)

C. IDIOPATHIC (25%)

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17
Q

For normal parents that have a child with SNHL, what is the chances of having further children with SNHL (all comers)?

A

14%

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18
Q

Discuss the history and physical exam for patients with suspected congenital hearing loss

A

HISTORY:
1. Parents, siblings, or cousins with hearing loss (under age 30)
2. Family history of pigment abnormalities
3. Widely spaced eyes
4. Blood or protein in urine or other kidney problems
5. Blindness or night blindness
6. Goiter
7. Childhood fainting, LOC, sudden unexplained death history

PHYSICAL EXAM:
1. Complete head and neck exam
2. Pigmentation abnormalities
3. Eye exam (hypertelorism, coloboma, epibulbar dermoids, etc.)
4. Ears (pinna, EAC atresia, preauricular pits)
5. Oral (cleft palate, teeth)
6. Neck (goiter)

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19
Q

What are high risk factors for congenital hearing loss?

A
  • Prematurity
  • Birth weight < 1500g
  • TORCH infections (Toxoplasmosis, Other (Syphilis), Rubella, CMV, Herpes Simplex)
  • Hyperbilirubinemia
  • Intubation or use of breathing machine > 5 days
  • Low Apgar scores < 4 at 1 min; ≤5 at 5 min
  • Hypoxia
  • ECMO
  • NICU admission
  • Family history
  • Presence of head and neck abnormalities/ craniofacial abnormalities
  • Meningitis
  • Sepsis
  • Ototoxic exposure

“SCHAME LION PFTH”
S - Sepsis
C - Craniofacial abnormalities or other head/neck abnormalities
H - Hypoxia
A - Apgar score < 4 at 1 min, ≤5 at 5 min
M - Meningitis
E - ECMO use

L - Low birth weight < 1500g
I - Intubation or use of breathing machine > 5 days
O - Ototoxic exposure
N - NICU admission

P - Prematurity
F - Family history of hearing loss
T - TORCH infections
H - Hyperbilirubinemia

Kevan Otology Pg 107

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20
Q

Discuss the JCIH 2007 Position Statement for the Universal Hearing Loss Screening guidelines

A

GUIDELINES BY AGE:
1. By 1 month - Hearing screening complete (NICU admission > 5d: ABR; Well-baby: OAE)
2. By 3 months - Audiological and medical evaluation to confirm hearing loss in infants who failed the screening
3. By 6 months: Intervention for hearing loss

  • Definition of “Targeted hearing loss” is expanded to include neural hearing loss (e.g. auditory neuropathy/dyssynchrony)
  • Auditory Brainstem Response screenings (ABR) are recommended for all NICU babies and babies admitted for > 5 days
  • Referrals should be made directly to an audiologist for comprehensive testing to include a diagnostic ABR for all infants who do not pass ABR screening in the NICU
  • Re-screening of all infants should include re-evaluation of both ears, even if the infant only failed one ear in the initial screening
  • Audiologists with expertise in evaluating newborns should conduct diagnostic evaluations
  • All children identified with hearing loss should undergo an evaluation by an Otolaryngologist
  • At least one examination to assess visual acuity with a pediatric Ophthalmologist
  • All children with any degree of bilateral or unilateral hearing loss should be considered eligible for early intervention services
  • Families should be made aware of all communication options and available hearing technologies (presented in an unbiased manner)
  • Early intervention services should be provided by professionals with expertise in hearing loss
  • Children identified with hearing loss should be fit with amplification within 1 month of diagnosis
  • A genetics consultation should be offered to families of infants diagnosed with hearing loss
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21
Q

Regarding OAEs for hearing screening:
1. What is the sensitivity and specificity?
2. What types are used?
3. What hearing does it estimate?
4. When are they absent?

A

Sensitivity = 95%
Specificity = 85%

  • TEOAE (Transient evoked OAEs) used most often
  • DPOAE (Distortion Product OAEs) being used more
  • Estimates hearing in 1-6kHz range, can go higher
  • OAEs are absent in conductive hearing loss
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22
Q

What are two factors affecting impedence tympanography in neonates?

A
  1. Incomplete ossification of the EAC causing greater compliance
  2. Persistence of middle ear fluid or mesenchyme
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23
Q

Regarding ABR for hearing screens, discuss:
1. Sensitivity and sepcificity
2. What range of hearing does it estimate? What does it required?
3. Which waves are seen in a child’s ABR? At what age does it reach adult levels?

A

Sensitivity = 98%
Specificity = 96%

  • Estimates hearing in 1-4kHz range
  • Requires natural sleep or conscious sedation (Chloral hydrate)
  • Newborn ABR composed of waves I, III, V
  • ABR reaches adult levels by 18 months to 3 years
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24
Q

What are four pediatric cochlear implantation criteria for children 12-24 months?

A
  1. Bilateral profound hearing loss (>90dB)
  2. Lack of auditory skills development and minimal hearing aid benefit (documented by parent questionnaire)
  3. No medical contraindications
  4. Enrollment in a thearpy of education program emphasizing auditory development
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25
Q

Four pediatric cochlear implantation criteria for children 25 months to 17 years?

A
  1. Bilateral severe to profound hearing loss (>70dB)
  2. Lack of auditory skills development and minimal hearing aid benefit (word recognition scores < 30% correct)
  3. No medical contraindications
  4. Enrollment in a therapy of education program emphasizing auditory development
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26
Q

Discuss the AAOHNS pediatric Cochlear Implantation criteria

A
  1. Be 9 months to 17 years of age (new 9 months, used to be 12)
  2. Infants age 9-24 months: bilateral, profound hearing loss with thresholds of >90dB at 1000Hz
  3. Children 24mos-17 years: Bilateral severe to profound (>70dB) hearing loss
  4. Infants and older children
    - Appropriate auditory amplification and participation in intensive aural habilitation for 3-6 months; AND
    - Demonstrate lack of progress in simple auditory skills; AND
    - Have < 30% correct on the multi-syllabic lexical neighbourhood test (MLNT) or lexical neighbourhood test (LNT), depending on the child’s cognitive and linguistic abilities (best aided function)

A 3-6 month trial of appropriate hearing aids is required.
- If meningitis is the cause of hearing loss, or if there is radiologic evidence of cochlear ossification, a shorter hearing aid trial and earlier implantation may be reasonable

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27
Q

What are the required immunizations prior to cochlear implantation? 3

A
  1. Hemophilus Influenzae B vaccine
  2. Pneumococcal vaccination series should be completed at least 2 weeks before surgery
    - Age ≤ 24 months - PCV7 or PCV13 (pneumococcal conjugate vaccine)
    - Age 24-59 months (before 5yo) - PCV7 or PCV13, then 2 months later get PPV23 (pneumococcal polysaccharide)
    - Age 5-64 - PPV 23

Note: Prevnar has replaced Prevnar 7, adding six new serotypes to the vaccine

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28
Q

What are the indications for bone conducted hearing aids?

A
  1. Intolerance to traditional hearing aids
    - Draining ear
    - Chronic/recurrent otitis externa
    - Mastoid cavity (Feedback issues)
    - Dermatitis due to hearing aids (topical sensitivity)
  2. Inability to wear hearing aids
    - Microtia/atresia
    - Acquired stenosis
    - Large meatoplasty/CWD mastoids that do not fit a HA
  3. Hearing related:
    - Single sided deafness
    - Conductive hearing loss in an only hearing ear
    - Unilateral SNHL
    - Otosclerosis
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29
Q

What are four indications for imaging in pediatric hearing loss?

A
  1. Evaluation for cochlear implantation (nerve and cochlea)
  2. Recurrent meningitis (look for labyrinthitis ossificans)
  3. Sudden or progressive SNHL (especially with head trauma)
  4. Impact on counselling (e.g. atresia?)
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30
Q

Describe the classification for congenital inner ear malformations?

A

A. Membranous inner ear malformations (80%)
- Complete membranous labyrinthine dysplasia (Bing-Siebenmann)
- Limited membranous labyrinthine dysplasia, such as:
1. Cochleosaccular dysplasia (Sheibe)
2. Cochlear basal turn dysplasia (Alexander)

B. Malformations of the osseous and membranous labyrinth (20%)
- Complete labyrinthine aplasia (Michel)
- Cochlear anomalies:
1. Cochlear aplasia
2. Cochlear hypoplasia
3. Incomplete partition (Mondini)
4. Common cavity

C. Labyrinthine anomalies
- SCC dysplasia
- SCC aplasia

D. Aqueductal anomalies
- Enlarged vestibular aqueduct
- Enlarged cochlear aqueduct

E. IAC anomalies
- Narrow IAC
- Wide IAC

F. 8th nerve anomalies
- Hypoplasia
- Dysplasia

Vancouver Pg 517

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31
Q

Describe the pathology for membranous ear malformations
How do they appear on Radiology
What are their associated syndromes and genetics?

A
  1. Bing-Siebenmann Dysplasia
    - Complete membranous labyrinthine dysplasia
    - Appears normal on radiology
    - Associated syndromes: Jervell & Lange-Nielson syndrome
  2. Scheibe Aplasia
    - Most common histopathologic asplasia
    - Autosomal recessive
    - Limited to the membranous cochleosaccular dysplasia (pars inferioris) - ie. affects only cochlea and saccule (pars inferior), and the SCCs and utricle (pars superior) are fully formed
    - Absent/deficient organ of Corti
    - Normal labyrinth (bony)
    - Associated syndromes: Usher’s, Waardenburg’s, Congenital Rubella
  3. Alexander Aplasia
    - Autosomal recessive
    - Partial aplasia of cochlear duct at basal turn; patients have high frequency HL
    - Able to amplify the low frequencies in these patients
    - Cannot diagnose on CT
32
Q

Describe the pathology for bony & membranous malformations of the ear. For each, also discuss:
1. When does the arrest happen?
2. % incidence?
3. Pathophysiology
4. Symptoms
5. Diagnostic findings (imaging, etc.)

A
  1. Michel’s aplasia (3rd week arrest):
    - Complete labyrinthine aplasia - including cochlear + vestibular aplasia
    - Rare, ~1%
    - Profound SNHL (no hearing), often bilateral, no inner ear structures with one or multiple cystic cavities
    - Arrest at end of 3rd week prior to otic capsule formation
    - Seen with anencephaly and thalidomide exposure
    - CT: Hypoplastic petrous pyramid, absent cochlea and labyrinth, small (hypoplastic) IACs, middle ear cavity is expanded due to missing cochlea (concave medial wall)
  2. Cochlear anomalies:

a. Common cavity (cock deformity, 4th week arrest) - 26%
- Cochlea and vestibule are confluent without internal architecture
- Direct connection between subarachnoid space in IAC and perilymph & endolymph space of cavity
- Risk of meningitis, CSF leak
- Variable SNHL, usually poor

b. Cochlear Aplasia (5th week arrest) - 3%
- Rare, zero hearing
- Arrest in cochlear bud formation
- Still possible to implant these kids into the vestibule if an audiological response is reliably demonstrated before surgery

c. Cochlear Hypoplasia (6th week arrest) - 15%
- Cochlea has single turn or less
- 15% of cochlear deformities
- Variable hearing depending on extent of membranous involvement

  1. Mondini malformation (7th week arrest) - 55%
    - Autosomal dominant - most common cochlear abnormality
    - Incomplete bony and membranous labyrinth
    - Cochlear may be present as a curved tube, organ of corti development/neural development is variable
    - Associated with enlarged vestibular aqueduct, increased risk of perilymphatic gusher and meningitis from dilated cochlear aqueduct (perilymph fistula)
    - Symptoms: Progressive or flucutuating HL, recurrent meningitis
    - CT/MRI findings: Smaller cochlear (5-6mm vs 8-10mm normal), absence of scalar septum, single turn of cochlea
    - Associated syndromes: Pendred, Waardenburg, Treacher Collins
    - Treatment: HA/cochlear implant

Spot Diagnosis Pediatrics PPT

33
Q

Discuss the 3 types of incomplete partition of the cochlea

A
  1. IP-I: Cystic cochleovestibular malformation
    - Lacks entire modiolus and interscalar septa
  2. IP-II: Mondini malformation
    - Normal basal turn, but cystic apex (1.5 turns)
    - Enlarged vestibule AND enlarged vestibular aqueduct
  3. IP-III: X-linked deafness
    - Deficient modiolus
    - Partial interscalar septation at the cochlea’s periphery

CMX

Vancouver Pg 517

34
Q

Syndromes associated with Mondini malformation

A
  • Wildervanck (Klippel Feil)
  • Waardenburg
  • Treacher collins
  • BOR
  • Pendred

“Wild wars teaches brothers patience”

Others:
- Mobius Syndrome
- Fontain
- Kabuki
- Johanson-Blizzard

35
Q

Syndromes associated with Scheibe malformation 6

A
  1. Jervell-Lange Nielsen
  2. Refsum (Retinitis pigmentosa, ataxia, SNHL)
  3. Usher
  4. Waardenburg
  5. Trisomy 18
  6. Congenital Rubella
36
Q

Syndromes associated with Bing-Siebenmann (complete membranous labyrinthine dysplasia) 2

A
  1. Jervell Lange-Nielson
  2. Usher
37
Q

What syndromes are associated with conductive hearing loss?

A
  1. Treacher Collins
  2. Wildervank
  3. Otopalatal Digital
  4. Osteogenesis imperfecta
  5. Apert
  6. Crouzons
  7. Goldenhaar
  8. Marfans

TWO MACs GO
Treacher collins
Wildervank
Otopalataldigital
Marfans
Apert
Crouzons
Goldenhaar
Osteogenesis imperfecta

38
Q

What are autosomal dominant syndromes associated with SNHL?

A

Usually experience progressive hearing loss

  1. Waardenburg syndrome (most common)
  2. Branchiootorenal syndrome (Melnick-Fraser)
  3. Treacher-Collins syndrome
  4. Otosclerosis
  5. Neurofibromatosis 2
  6. Stickler syndrome
  7. Osteogenesis imperfecta (Van der Hoeve syndrome)
  8. CHARGE

the OC BTOWNS
1. Osteogenesis imperfecta (Van der Hoeve syndrome)
2. CHARGE
2. BOR
2. Treacher collins
3. Otosclerosis
4. Waardenburg
5. NF2
6. Stickler’s

39
Q

For non-syndromic hereditary hearing loss, what is the breakdown of inheritance and what is the genetics related to this?

A

70% of HL is Hereditary

  1. Autosomal Dominant 20% - DFNA
  2. Autosomal Recessive 80% - DFNB1 (Connexin 26)
  3. X-linked ~1% - X-linked stapes gusher
  4. Mitochondrial ~1%
40
Q

What gene is associated with non-syndromic autosomal dominant hereditary hearing loss?

A

DFNA gene - high frequency, less severe than autosomal recessive
- 20%

41
Q

What are autosomal recessive syndromes associated with SNHL (in order of frequency)

A

Typically stable HL

  1. Usher Syndrome
  2. Pendred syndrome
  3. Jervell-Lange Niielsen Syndrome

UP J

42
Q

What are X-linked recessive syndromes associated with SNHL?

A

“WilD ON Alberta”

  1. Wildervank syndrome
  2. Deafness Dystonia
  3. Otopalatodigital syndrome
  4. Norrie syndrome
  5. Alport syndrome
43
Q

Regarding Non-Syndromic Autosomal Recessive Hereditary Hearing loss, discuss:
1. What are the most common cause?
2. What is the gene, locus, and protein that is coded?
3. What is the function of the protein?

A

LOCUS:
- Mutations at the DFNB1 locus at 13q is the most common cause of genetic non-syndromic autosomal recessive hearing loss

GENE:
- GJB2 located on DFNB1, 13q (35delG mutation)
- Gene codes for Connexin 26 (CX26)
- Mutation leads to severely shortened non-functional protein, most frequent mutation in Caucasians

PROTEIN: Connexin 26 (CX26)
- Membrane protein with 4 transmembrane domains
- 6 connexin proteins = 1 connexon
- Connexon form the pore for a gap junction between cytoplasm of two adjacent cells, allowing bidirectional flow of ions and signaling molecules
- Connexon is involved in K+ circulation in the inner ear
- Pre-lingual hearing loss - mild to severe progressive hearing loss

44
Q

Regarding Keratitis-Ichthyosis-Deafness syndrome, discuss:
1. Inheritance and Genetics
2. Features

A

Rare, < 100 cases reported

INHERITANCE: Autosomal Dominant
GENE: Mutation in GJB2, chromosome 13
PROTEIN: Connexin 26

FEATURES:
1. Keratitis: Corneal abrasians and abnormalities, Thickening of the skin on the palms of hands and soles (erythrokeratoderma)
2. Red patches on the skin
3. 12% risk of cutaneous SCC
4. Profound SNHL

45
Q

Regarding Refsum’s disease, discuss:
1. Inheritance and Genetics
2. Features

A

INHERITANCE: Autosomal recessive
GENE: PHYH, Chromosome 10p13
PROTEIN: Phytanoyl-CoA hydrozylase enzyme - leads to phytanic acid storage disease, managed with diet restrictions

FEATURES:
1. Retinitis pigmentosa
2. Polyneuropathy
3. Cerebellar ataxia
4. SNHL

46
Q

What are different non-syndromic mitochondrial causes of hearing loss, and their clinical features?

A

Overall < 1% of congenital hearing loss
- Mitochondria = non-nuclear DNA

  1. MERRF: Myoclonic epilepsy with ragged red fibers
    - SNHL
    - Ataxia
    - Epilepsy
    - Optic atrophy
  2. A1555G 12S rRNA mutation
    - Seen more in asians, more susceptible to aminoglycoside ototoxicity (SNHL)
  3. MELAS: Mitochondrial encephalopathy, lactic acidosis, and stroke
    - Progressive HL
    - Stroke like symptoms
    - Begins ~ 40 years old
  4. MIDD: Maternally inherited diabetes and deafness
    - High frequency HL
  5. KEARNS-SAYRE Syndrome
    - SNHL
    - Ataxia
    - Short stature
    - Delayed puberty
    - Ophthalmoplegia
    - Retinopathy
47
Q

What are the different causes of non-syndromic X-linked stapes gusher syndrome? 4

A
  1. DFN3 gene
  2. Congenital progressive mixed hearing loss
  3. Fixed stapes footplate
  4. Perilymph gushing during attempted stapedectomy
48
Q

Order the cochlear osseomembranous malformations disorders, from most to least common

A
  1. Mondini / IP-II (~50-55%)
  2. Common cavity (20-25%) - 4th week
  3. Cochlear Hypoplasia (15%) - 6th week
  4. Cochlear Aplasia (3%) - 5th week
  5. Michel’s Aplasia (1%) - 3rd week

“MC HAMmer”
Mondini malformation
Common Cavity
Hypoplasia of cochlea
Aplasia of cochlea
Michel’s aplasia

49
Q

Describe the pathology of labyrinthine anomalies.
What % of abnormal osseous cochlea abnormalities will also have SCC anomalies?
Which anomaly is more common?
Which canal is most commonly affected and why?

A
  • 40% of radiologically abnormal (osseous) cochlea will have semicircular canal abnormalities
  • SCC dysplasia is 4x as common as SCC aplasia
  • Lateral canal affected most often (it is last to develop)
50
Q

What is the order of the development of the semicircular canals?

A
  1. Superior
  2. Posterior
  3. Lateral

SPL

51
Q

Regarding Enlarged Vestibular Aqueduct, discuss:
1. What is normal VA diameter? What is considered enlarged?
2. Discuss the incidence of VA pathology
3. Pathophysiology of EVA
4. What are the symptoms of VA pathologies?
5. How is EVA diagnosed? What are the signs on imaging?
6. Treatment? What should be avoided?

A

Normal = 0.4-1mm diameter when measured halfway between common crus and external aperture

Enlarged = > 1.5mm (compare to size of the posterior SCC)

Incidence:
- Most common congenital cause for SNHL seen on x-ray
- Usually bilateral

Pathophysiology:
- Progressive cochleovestibular loss
- Increased “fragility” of cochlea - gradually hearing worsens

Symptoms:
- Typically born with normal to mild SNHL, and ~40% eventually develop profound SNHL
- Prone to sudden SNHL with head truama
- ± Vertigo

Imaging:
- Enlarged VA on radiograph
- Associated with Cochlea or SCC malformation
- Intraosseous portion coursing towards the vestibule must be enlarged beyond 1mm; external aperture measures 3-4mm and even beyond 6mm

Treatment:
1. Cochlear implant
2. Avoid endolymphatic surgery/stapedectomy - may be more prone to gusher

52
Q

What is the mechanism of hearing loss in enlarged vestibular aqueduct syndrome?

A

Theory: Hydrostatic forces are transmitted either:
1) From the endolymphatic sac through an enlarged endolymphatic duct; or
2) From the subarachnoid space through cochlear modiolar defects to hair cells within the cochlea, damaging them

Theory 2: Endolymphatic sac contains fluid with abnormal osmolarity and that reflux of this fluid into cochlea by way of a patent endolymphatic duct damages the neuroepithelium

Bilateral progressive SNHL ± vertigo

53
Q

What are the syndromes associated with enlarged vestibular aqueduct?

A
  1. Digeorge
  2. Mobius

Plus the ones that associated with Mondini:
3. Wildervaank
4. Waardenburg
5. Treacher collins
6. Branchiootorenal
7. Pendred

“DM the brothers at war because WILD WARS TEACHERS BROTHERS PATIENCE”

54
Q

Describe the pathology for Internal Auditory canal abnormalities. What is normal and what is abnormal? Narrow and wide

A

Narrow = < 3mm IAC
- If facial function is present, likely suggests CNVIII is absent

Widened is greater than 10mm IAC
- Associated with stapes gusher, potentially via pressure onto the adjacent basal turn of the cochlea

55
Q

Regarding CMV infection and SNHL, discuss:
1. What is the epidemiology?
2. What is the pattern of hearing loss?
3. What is Cytomegalic inclusion disease?
4. Diagnosis
5. Treatment and side effects

A

EPIDEMIOLOGY:
- CMV (Cytomegalovirus) is the most common cause of VIRAL congenital deafness
- Unusual for CMV infection acquired AFTER birth to cause hearing loss
- Present in 1% of all children born
- 90% clinically silent infection –> 10-15% SNHL
- 10% symptomatic infection with CID –> 30-65% SNHL

PATTERN OF HEARING LOSS:
- Flat SNHL common
- Can be unilateral or bilateral
- Can be any pattern

CYTOMEGALIC INCLUSION DISEASE:
- Hemolytic anemia
- Hepatosplenomegaly
- Jaundice
- Purpura
- Intracerebral calcifications & microcephaly
- 30-65% of surviving neonates will have severe, symmetric of unilateral SNHL mostly in high frequencies

ASYMPTOMATIC CMV INFECTION:
- Remainder of CMV infected children
- 8-15% will have mild-moderate SNHL

DIAGNOSIS:
1. Buccal CMV swab
2. CMV salivary/urine PCR in FIRST 3 WEEKS OF LIFE
3. Blood spot (heel prick) PCR after 3 weeks of life if available
4. Maternal CMV IgG

TREATMENT:
1. Valgancyclovir for 6 months has been shown to improve audiologic and neurodevelopmental outcomes
- Risk of nephrotoxicity and neutropenia

56
Q

What are the components of congenital rubella?

A

TRIAD:
1. SNHL - Typically cookiebite configuration, Sheibe malformation
2. Eye - Cataracts, glaucoma, micropthalmia, Retinitis/keratitis/cataracts
3. Heart defects - PDA, pulmonary artery stenosis

Additional Components:
- Encephalitis
- Microcephaly
- Mental retardation
- Hepatosplenomegaly / jaundice / hepatitis
- Thrombocytopenia
- Radiolucency in the long bones
- Interstitial pneumonitis
- Low birth weight
- Blueberry muffin skin rash (anemia, thrombocytopenia)
- Still-birth

NOTE: Degree of symptoms worse if the infection is in the 1st trimester

57
Q

Regarding SNHL associated post-meningitis, discuss:
1. What is the epidemiology?
2. Common bacteriology?
3. When does SNHL typically develop after meningitis?
4. What tests should be arranged if a child has meningitis and concern for HL?
5. What are the options for post-meningitis SNHL?

A

EPIDEMIOLOGY:
- Meningitis responsible for ~33% of all hearing deficits acquired after birth
- 10% experience persistent SNHL
- Incidence of meningitis and HL varies with strain

ETIOLOGY: % meningitis, %HL
- Pneumococcus: 31%, 20%
- Neisseria Meningitides: 11%, 5%
- Haemophilus Influenzae: 6%, 12%

NATURAL COURSE:
1. SNHL develops EARLY (ie. within the first 1-2 weeks of infection)
2. Very unlikely to experience progressive HL months later (think of second pathology instead!)

INVESTIGATIONS:
1. Urgent sedated ABR
2. Urgent behavioural hearing testing (e.g. visual reinforcement audiometry)
3. Urgent tympanometry

Options post-meningitis SNHL:
1. Cochlear implant (bilateral - preferred option)
2. Writing
3. Lip reading
4. SIgn language

58
Q

Describe all the lab tests that can be performed and their association with childhood SNHL

A
  1. CBC – Leukemia/lymphoma; Platelets - Fechner syndrome (Very rare, HF SNHL, Ocular disease, Proteinuria, Macrothrombocytopenia)
  2. BUN, CR, Urinalysis – Alports syndrome (persistent microscopic hematuria)
  3. Glucose – Alstron syndrome (Obesity, Impaired glucose tolerance with insulin resistance, Retinal degeneration, Neurosensory deafness, Acanthosis nigricans, Hepatic dysfunction, and other Endocrine abnormalities)
  4. TORCHS screen – CMV, RPR, VDRL, FTA-ABS – Syphilis
  5. EKG – Jervell and Lange-Nielson syndrome
  6. GJB2 gene – Responsible for 50% of autosomal recessive non-syndromic hearing loss, found to be positive in 35% of moderate to profound SNHL.
  7. CT scan – Michel aplasia, Mondini malformation, Enlarged VA
  8. MRI – Child with NF II, useful if progressive hearing loss, or vestibular symptoms, focal neurological symptoms, ANSD – Not needed in bilateral symmetric SNHL
  9. ANA, ESR, RF – SLE, RA
  10. Thyroid function tests – Cretinism and Pendred syndrome (Pendred may have normal thyroid function tests)
59
Q

Describe some of the workup that can be performed for congenital SNHL and the syndrome associated

A
  1. Urinalysis (Alport)
  2. Renal ultrasound (BOR)
  3. Perchlorate discharge test (Pendred)
  4. Serology - FTA-Abs (syphillis), Rubella and CMV
  5. ECG - JLN, Refsum, Friedrichs ataxia
  6. GJB2 (full genetic screen eventually)
  7. Consider CT/MRI for unilateral HL (generally unilateral HL will have imaging and bilateral HL will have genetics)
  8. Ophthalmology consult
60
Q

Outline a general guideline on how to work up a patient / child that comes in with infant hearing loss. What is the process from start to intervention?

A

A. NEWBORN HEARING SCREENING
- DPOAEs at birth (usually within 3 months, ideally within 1 month)
- Automated ABR if “refer” on DPOAEs (or proceed directly to this if there is risk factors as above)
- Diagnostic ABR if abnormalities on automated ABR

B. HISTORY/EXAMINATION
- Assess for risk factors
- Intrauterine infection, APGAR ≤ 5 at 5 minutes, prolonged intubation, meningitis, sepsis, hyperbilirubinemia, low birth weight, ototoxic exposure
- Assess for craniofacial abnormalities
- Otoscopic examination

C. INVESTIGATIONS
1. First, start with audiometric testing if possible
- Behavioural observation audiometry (0-6 months)
- Visual Response Audiometry (6mos - 2 years)
- Conventional Play audiometry (2-5 years)
- Standard audiometry (> 5 years)

  1. If under 6 months, then do the following:
    - Genetic testing: e.g. for GJB2 and GJB6
    - Urine for CMV PCR (CMV sheds for months; serology may be inaccurate due to maternal antibodies)
    - Can also find the Heel prick/guthrie card for CMV PCR
  2. Special Tests:
    - ECG: Rule out prolonged QT and peaked T waves on JLN (if severe to profound SNHL)
    - Urinalysis: If concern for Alport’s
    - Renal US: If concern for BOR
    - TSH: If concern for pendred’s (typically euthyroid but may be mildly hypothyroid)
    - Ophthalmology referral
  3. Imaging:
    - CT can be done if planning for CI
    - MRI (bundle and sca) if young and unilateral or CI candidate
    - If this will not change clinical management, an MRI can be deferred until later in life to avoid GA
61
Q

What are the early hearing detection and intervention (EHDI) goals?

A

Program of the American Academy of Pediatrics (AAP)

1-3-6 Goals:
- Screening by 1 month
- Assessment by 3 months (e.g. Audiology)
- Intervention by 6 months

62
Q

What are the syndromes that are associated with both deafness and vision loss?

A
  1. Alport - congenital cataracts
  2. Norrie - congenital blindness, pseudotumor of the retina
  3. Usher - retinitis pigmentosa
  4. Stickler - myopia, cataracts, retinal detachment, SNHL
  5. Sturge Weber - Glaucoma
  6. Velocardiofacial - retinal detachment

“the blind and deaf are Not So SUAVe”
Norrie
Stickler
Sturge Weber
Usher
Alport
Velocardiofacial

63
Q

What is the typical ossicle formations in aural atresia?

A
  1. Fused incudomalleal complex
  2. Short manubrium
  3. Small stapes - misshapen crura
  4. Footplate fixation
64
Q

Name 4 different classification systems of aural atresia deformity and severity

A
  1. Ombredanne
  2. Altmann’s
  3. De la cruz classification
  4. Schuknecht
65
Q

What are six syndromes associated with microtia/aural atresia? What are the associated teratogens?

What is the epidemiology of microtia/aural atresia?

A

1 in 4000
M:F 2:1
R>L 2:1
20-30% bilateral
90% non-syndromic

Associated teratogens:
1. Thalidomide
2. Accutane

Associated syndromes:
1. CHARGE
2. Goldenhar’s/hemifacial macrosomia
3. Treacher-collins
4. Crouzon’s disease
5. Pierre robin sequence
6. Branchio-oto-renal

“To unCover Gold, But Charge Pierre”

66
Q

Name 20 syndromes associated with microtia/aural atresia and their genetic abnormalities (at least 6)

A
  1. Bixler (Hypertelorism-microtia-clefting)
  2. Bosley-Salih-Alorainy (HOXA1)
  3. Branchio-oculo-facial BOF (TFAP2A)
  4. Branchio-otic BO (EYA1, SIX1)
  5. **Branchio-oto-renal **BOR (EYA1, SIX5)
  6. CHARGE Syndrome (CHD7, SEMA3E)
  7. Congenital deafness, inner ear agenesis, microtia, microdentis (FGF3)
  8. Craniofacial microsomia CFM
  9. Crouzon Syndrome
  10. Fraser (FRAS1, FREM2)
  11. Kabuki (MLL2)
  12. Klippel-Feil (GDF6)
  13. Goldenhar Syndrome
  14. Lacrimoauriculodentodigital (FGFR2, FGFR3, FGF10)
  15. Mandibulofacial dysotosis (HOXD)
  16. Meier-Gorlin (Ear-patella-short stature) (ORC1 / 4/ 6, CDT1, CDC6)
  17. Microtia, hearing impairement, and cleft palate (HOXA2)
  18. Miller (DHODH)
  19. Nager
  20. Oculo-auricular (HMX1)
  21. Pallister Hall (GLI3)
  22. Townes Brocks (SALL1)
  23. Pierre Robin Sequence
  24. Treacher Collins Syndrome (TCOF1)
  25. Wildervanck (cervico-oculo-acoustic)
67
Q

Describe the general management approach for aural atresia

A

INVESTIGATIONS:
1. Bone conduction ABR: Wave I generated at distal CNVIII, little crossover
2. ECOG: For minor atresia, with transtympanic, TM, or EAC electrode
3. Bone conduction ABR/ECOG: For unilateral, to confirm other ear is normal, for bilateral to evaluate cochlear function
4. High resolution CT of the temporal bone at age 5-6 (rule out cholesteatoma)

TREATMENT:
1. Soft band
2. Bone conduction hearing aids
3. Defer surgery to 6-8 years, allows growth of contralateral ear (template) and rib cage (cartilage graft source)
4. Fix microtia first (preserve vascularity in absence of scar)
5. Unilateral microtia & aural atresia (do not reconstruct canal, as speech and learning will develop normally)
6. Bilateral aural atresia: begin with the BETTER developed ear as child approaches school age, and depending on the results, may proceed with second ear within next few years

68
Q

What are 4 criteria for surgery in aural atresia?

A
  1. Presence of cholesteatoma (emergent indication, and reason every aural atresia requires CT at some point)
  2. Normal sensorineural function (just CHL)
  3. Ossicular mass present
  4. Middle ear space at least 50% normal size
69
Q

What are the contraindications to surgical correction of aural atresia?

A

Absolute:
1. Abnormal inner ear morphology demonstrateed on CT scan
2. Abnormal cochlear function demonstrated by audiologic testing

Relative:
1. Jahrsdoerfer score ≤5/10 (relative)

70
Q

What are two approaches to aural atresia repair?

A
  1. Transmastoid approach
    - Sinodural angle and follow towards facial recess
    - Open Incudostapedial joint
    - Remove EAC atretic bone
  2. Anterior approach (more common approach)
    - Between TMJ and middle cranial fossa –> mastoid air cells (this avoids facial nerve manipulation)
71
Q

What are four facial nerve findings in middle ear atresia?

A
  1. Tympanic segment dehiscence
  2. Inferior/lateral displacement of the tympanic segment
  3. Anterior/lateral displacement of the mastoid segment
  4. More acute angle taken at 2nd genu (60 degrees, vs. 90-120 degrees normally)
72
Q

What are the complications in atresia surgery? 5

A
  1. EAC stenosis
  2. Recurrent / persistent CHL
  3. SNHL (high frequency from drill)
  4. Facial nerve injury
  5. Chronic infection/cholesteatoma

Risks minimizede by near normal CNVII course, middle ear, and mastoid at least 2/3 normal size

73
Q

What are the audiometric results of aural atresia repair?

A

With Jahrsdorfer ≥ 8
- HL < 30 dB in 50-75%
- HL < 20 dB in 15-50%

74
Q

Describe the Brent technique of Microtia repair

A
  1. Stage 1: Auricular framework fabrication with rib cartilage
  2. Stage 2: Lobule transposition
  3. Stage 3: Auricular framework elevation
  4. Stage 4: Tragus reconstruction

Atresia repair could be done between stages 2 + 3

75
Q

Describe the Nagata technique of Microtia repair

A
  1. Stage 1: Fabrication of the auricular framework, tragus reconstruction and lobule transposition
  2. Stage 2: Framework elevation
  • Atresia repair between stages 1+2
  • Same as Brent, but do everything in Stage 1 except framework elevation
76
Q

What is the most common type of congenital syndromic hearing loss?
What is the most common type of non-syndromic hearing loss?

A

Syndromic = Pendred (or Usher?)
Non-syndromic = Connexin 26

Pediatrics (10 decks)

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