oto pediatric hearing loss Flashcards
Which intrauterine infections are associated with
the development of congenital hearing loss?
T Toxoplasmosis O Other, including syphilis, varicella, and parvovirus B19 R Rubella C Cytomegalovirus H Herpes simplex virus
What factors place a pediatric patient at particularly high risk for early SNHL?
● History of intrauterine infection
● Family history of congenital hearing loss
● Low birth weight (< 1,500 g)
● Hyperbilirubinemia
● Prolonged neonatal intensive care unit stay or prolonged
mechanical ventilation
● Concurrent craniofacial anomalies
● Exposure to ototoxic medications
● < 5 Apgar score at 1 minute, < 7 Apgar score at 5 minutes
● Bacterial meningitis
What percentage of congenital hearing loss is
genetic?
Approximately 50%
What percentage of patients with genetic hearing
loss will have associated syndromes?
About 70% of genetic hearing loss is nonsyndromic, and
30% is syndromic.
What percentage of genetic hearing loss is
inherited in an autosomal dominant pattern?
80% autosomal recessive, 20% autosomal dominant
What is the most common form of autosomal
dominant hearing loss?
Waardenburg syndrome
Describe the four subtypes of Waardenburg
syndrome.
● WS1: Autosomal dominant, dystopia canthorum, SNHL,
iris pigmentary disorder, hair hypopigmentation
● WS2: Autosomal dominant, no dystopia canthorum,
SNHL, iris pigmentary disorder, hair hypopigmentation
● WS3: Autosomal dominant, dystopia canthorum, upper
limb abnormalities, iris pigmentation disorder, hair
hypopigmentation
● WS4: Autosomal recessive, no dystopia canthorum,
Hirschprung disease, SNHL, iris pigmentary disorder, hair
hypopigmentation
What are the three most common causes of
autosomal recessive syndromic SNHL?
Usher, Pendred, Jervell and Lange-Nielsen
Describe the three subtypes of Usher syndrome.
● Type 1: Bilateral profound deafness and vestibulopathy at
birth; “night blindness,” from retinitis pigmentosa, before
teens (most severe form)
● Type 2: Moderate to severe hearing loss at birth,
worsening vision in young adulthood, and normal
vestibular function
● Type 3: Normal hearing at birth with progressive hearing loss and retinopathy by teens, variable vestibular involvement (mild form)
What is the most common cause of deaf-blindness
in the United States?
Usher syndrome
Alport syndrome involves faulty synthesis of what
protein(s)?
Type IV collagen
Describe the clinical manifestations of Norrie disease.
X-linked recessive syndrome that results in early rapidly progressive blindness. Progressive SNHL occurs in approximately a third of patients and usually ensues in the second to third decades of life.
Describe the classic head and neck manifestations
of Pendred syndrome.
SNHL (often associated with enlarged vestibular aqueducts
and mondini malformations) and euthyroid goiter
Describe the thyroid pathology typically seen in
Pendred syndrome.
Patients often develop a multinodular goiter in the second
decade of life but are usually euthyroid and rarely require
intervention.
What specific precaution should patients diag-
nosed with enlarged vestibular aqueduct syndrome take to prevent further hearing loss?
Stepwise progression of hearing loss can be seen after
minor head trauma. Participation in contact sports or
activities associated with “minor head trauma” should
generally be avoided.
Describe the typical presentation of enlarged
vestibular aqueduct syndrome.
SNHL generally begins in childhood and often progresses in a stepwise manner. Vestibular symptoms and mixed hearing loss may also develop.
What gene mutation is responsible for approximately 50% of all cases of genetic hearing loss?
GJB2 encodes connexin 26, located on chromosome 13,
autosomal recessive inheritance pattern
What does the GJB2 gene code for?
Gap junction β-2, responsible for potassium ion exchange of the inner ear
Describe the clinical manifestations of Jervell and
Lange-Nielsen syndrome.
● An autosomal recessive syndrome characterized by
congenital profound bilateral SNHL and arrhythmia
● Patients may have syncopal episodes provoked by stress
or exercise.
● Sudden cardiac death from arrhythmia may occur if
untreated.
● Caused by a defect in potassium channels within the stria
vascularis
Descrie the electrocardiographic findings in Jervell
and Lange-Nielsen syndrome.
Long QTc (> 500 ms) with potential for arrhythmias
Describe the constellation of findings seen in
MELAS syndrome.
ME Mitochondrial encephalopathy
LA Lactic acidosis
S Stroke
Manifestations are variable and include hearing loss, limb
weakness, partial paralysis, vision loss and seizures.
Describe the clinical features of Michel aplasia.
Michel aplasia is characterized by complete failure of inner
ear development resulting in congenital anacusis.
Describe the radiographic findings with Mondini
malformations.
Mondini malformation accounts for more than 50% of
cochlear malformations. The characteristic findings include
an incomplete or absent partition and less than 2.5 turns.
Describe the imaging findings of a common cavity
malformation.
The cochlea and vestibule are joined as a single large
confluent space. These patients typically have severe to
profound SNHL.
What inner ear abnormalities are seen in Scheibe
dysplasia?
Scheibe dysplasia (also called cochlearsaccular dysplasia or
pars inferior dysplasia) includes a poorly developed organ of
Corti and sacuule, whereas the bony labyrinth, semicircular
canals, and utricle are preserved.
What is the most common form of membranous
labyrinth dysplasia?
Scheibe dysplasia
What frequencies are most commonly affected by
Alexander dysplasia?
High frequencies resulting from malformation of the
cochlear duct and basal turn of the cochlea
