Overview for the Otologist and Neurotologist
| Evaluation of Pediatric Hearing Loss —Paul R.
Lambert, MD, Professor and Chair, Department of Otolaryngology —Head and
Neck Surgery, Medical University of South Carolina, Charleston
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| Pediatric hearing loss: significant bilateral loss in
1 to 3 per 1000 newborns; number higher if unilateral loss included; 1% to
2% of newborns if mild hearing loss included; losses genetic or acquired;
genetic loss may be congenital (present at birth) or appear later in life;
loss genetic in 50% to 60% of children (number increasing as diagnostic
methods improve and acquired cases decrease due to prevention)
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| Genetic hearing loss: 75% to 80% autosomal recessive,
ó20% autosomal dominant; small percentage syndromic
in both categories; small percentage sex-linked |
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Connexin (CX) mutations: account for
ó50% of genetic hearing loss; CX gene codes
for gap junction proteins important in intercellular communication;
CX proteins found in supporting cells around hair cells and in
stria vascularis; 70 to 100 mutations within gene, most common being
35delG; other genes on which mutations can cause hearing loss
include CX30 and CX26; CX26 gene
mutation—recessive; carrier rate 3% (1 in 4000 births); seems to
disrupt potassium recycling and affect endocochlear potential in stria
vascularis; hearing loss presents at birth but rarely progressive;
bilateral severe-to-profound hearing loss in ó80% of
patients, moderate sensorineural hearing loss (SNHL) in ó20%, unilateral SNHL in small percentage of patients
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| Acquired hearing loss: cytomegalovirus (CMV) most
common cause; infects ó1% of newborns, but majority
asymptomatic; 10% to 15% have some degree of hearing loss; symptomatic
infants present with jaundice, hepatosplenomegaly, and central nervous
system (CNS) complications; ó25% of patients have
severe SNHL; unilateral and bilateral loss almost equal in frequency; loss
not always present at birth (delayed onset) and can be progressive;
determining whether CMV cause of hearing loss problematic; uncertain
whether infection congenital or acquired unless toxoplasmosis, other
infections, rubella, cytomegalovirus, and herpes simplex (TORCH) titer
done soon after birth reveals high CMV levels; risk for hearing loss lower
with acquired infection; study data—one quarter of children ò3 yr of age had positive urine or saliva test for CMV;
child can acquire CMV infection at day care center, bring it back to
pregnant mother, and subsequent child experiences hearing loss
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| Evaluation: work-up begins with clinical and prenatal
history; note perinatal events (eg, prolonged hospital stay) or
fever in early postnatal period (consider aminoglycoside-induced hearing
loss); look for indications of syndromic hearing loss; obtain family
history; determine possible exposure to syphilis or marital consanguinity;
consider Waardenburg syndrome, Pendred’s syndrome, or osteogenesis
imperfecta as cause of hearing loss; look for craniofacial anomalies or
cataracts; laboratory tests in these children usually not diagnostic
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Lambert et al: 17-yr retrospective
study looked at 118 children with bilateral SNHL ô30
decibels (dB) that presented early in life; in 60%, review of history did
not reveal cause of SNHL; in 40%, possible causes present, but association
uncertain; review of laboratory tests not helpful; computed tomography
(CT) performed in 60% of patients, and Mondini malformation or enlarged
vestibular aqueduct found in 15%; another study used CT in 114 patients
and found 37% positive for abnormalities, including dysplasia of
horizontal canal |
| Enlarged vestibular aqueduct: most common abnormality
found on CT; good marker for presence of other inner ear abnormalities;
begins as short, straight, wide structure early in development that
narrows and elongates over time; bilateral enlargement most common but can
be asymmetric; progressive hearing loss found on follow-up; patients also
may have vestibular symptoms, eg, incoordination in children,
unusual types of vertigo in adults; Cincinnati Children’s Hospital
study—prospective; 150 patients, most with bilateral hearing loss,
underwent genetic and other testing; positive CX screen in 12% of
patients overall and in 22% of patients with bilateral severe-to-profound
hearing loss; only one third of patients with positive screen had CX
35delG mutation; full sequencing of gene required to avoid missing
mutations; positive CT found in one third of cases overall; 0% of
laboratory studies diagnostic; algorithm—obtain CT in patients
with unilateral hearing loss; if CT normal, assume CMV infection or some
other viral process; in patients with bilateral hearing loss, begin with
CX screen and if negative, obtain CT; obtain electrocardiography
(ECG) only if evidence of misdiagnosed cardiac conduction abnormality;
obtain fluorescent treponemal antibody (FTA) test only if maternal history
positive for syphilis |
| Cochlear Implantation Update —Lawrence R. Lustig,
MD, Associate Professor and Director of Otology, Neurotology, and Skull
Base Surgery, Department of Otolaryngology—Head and Neck Surgery,
University of California, San Francisco, School of Medicine
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| Bilateral cochlear implantation: binaural
hearing—cells in brainstem receive sound input from both ears and can
detect differences in interaural sound levels and timing; people with
binaural listening have up to 13 dB lower signal-to- noise ratio (SNR)
than those with monaural listening; 5-dB average binaural advantage for
all noise situations (5-dB SNR improvement corresponds to 30% to 40%
increase in hearing-in-noise test [HINT] scores); binaural squelch effect
also improves hearing in noise (brain receives 2 different audible signals
with dichotic phases from each ear and processes both sounds
simultaneously); binaural summation improves hearing of softer sounds
within background of noise; studies show people with 2 hearing aids have
better sound localization, no head shadow effect (30-dB drop of sound
going from one ear to other), improved ability to understand speech in
noise, and improved ease of listening; resistance to bilateral
implantation—reserve one ear for future device upgrades or
advancement in hearing technology; increased costs associated with
procedure, and insurance companies often do not want to pay for second
implant; second implant must be programmed and coordinated with first;
patients with unilateral cochlear implants have difficulty hearing in
noise, difficulty in sound localization, and problems listening to music;
study data—major manufacturers of cochlear implants looking at
efficacy of bilateral implants; studies show 90% of patients have better
HINT scores with bilateral implants; one half to two thirds show benefits
from binaural summation, and one half of patients with bilateral implants
show hearing improvement because of binaural squelch effect; 98% of
patients had better sound localization with bilateral implants; overall,
bilateral implants improved normal listening condition by 25%, compared to
unilateral implants; bilateral implants may aid in survival of neural
elements (eg, spiral ganglion) and optimize hearing conditions to
aid in language development in children; disadvantages—requires
longer programming time (audiologist may not be reimbursed for additional
time); implants inserted asymmetrically require stimulation with different
frequencies (patients may get differential sound input on listening); each
implant costs ó$25,000 (costs associated with
intervention run $45,000 to $60,000); cost-utility analysis shows clear
benefit to society for unilateral implantation but marginal benefit for
bilateral implants |
| Electroacoustic stimulation (EAS): select patients
with low-frequency hearing preservation and high-frequency deafness
>1000 hertz (Hz); technique combines hearing aid that acoustically
stimulates low frequencies with electrode to electrically stimulate high
frequencies in single ear; United States Hybrid study using hybrid implant
with 10-mm array composed of 6 half-banded electrodes inserted ó10 mm into cochlea; patients fitted externally with
hearing aid on ipsilateral side and contralateral behind the ear (BTE)
aid; study looking at pre- and postoperative pure tone hearing thresholds
in patients with Hybrid implant found excellent preservation of
low-frequency hearing; initial results show EAS produces 5-dB improvement
in SNR and superior speech recognition in background of noise; EAS also
improves patients’ ability to hear music; conclusions—EAS
superior to acoustic or electric stimulation alone for word recognition in
quiet; combines electric and acoustic information in same ear as well as
from opposite ear; best performance obtained when hearing aid and cochlear
implant used together; EAS superior for understanding speech in noise and
for music perception |
| The 15-Min Vestibular Examination —Dr. Lustig
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| History: ask patient to define “dizzy” without using
that word (helps determine whether patient has neurologic or
otolaryngologic problem, ie, true spinning vertigo );
determine—timing of spinning episodes (ie, how long
patient actually spinning, eg, minutes, hours, days); associated
symptoms; whether dizziness exacerbated by head movements; whether
dizziness associated with hearing changes, headaches, or dietary triggers;
family history and medication history (eg, ototoxic drugs,
chemotherapy agents); consider—benign paroxysmal positional
vertigo (BPPV) if patient has spinning vertigo lasting for seconds to
minutes; Meniere’s disease if spinning spells continuous for 20 min to 2
hr and associated with hearing loss; atypical Meniere’s disease, migraine
disorder, or recurrent vestibulopathy if patient experiences continuous
spinning but does not have hearing loss; labyrinthitis or vestibular
neuronitis if spinning lasts for days; rare causes of
dizziness—skull base tumors (obtain magnetic resonance imaging
[MRI]), perilymphatic fistulas (trauma-induced and associated with motion
changes and exercise); atypical benign positional vertigo; stroke
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| 15-min examination: ocular smooth pursuit and
saccadic motions—patient follows movement of finger back and forth
(smooth pursuit), and from finger to nose repeatedly in all directions,
and on finger as it is moved toward patient and back (saccadic motions) to
determine functioning of central connections to balance system;
abnormality indicative of central etiology (refer to neurologist and
consider MRI); head thrust sign—vestibulo-ocular reflex (VOR)
response direct arc between horizontal canal and eye muscles; VOR absent
during slow head rotation because cerebellum helps eyes track; VOR
functions during rapid head motion because cerebellum cannot track; rotate
patient’s head rapidly to one direction and alternate to other direction
as patient stares at fixed target; intact VOR indicative of normal
function in balance system (even at rapid rotation, eye able to track
object without moving); delayed catch-up sign (eye “slips”) indicative of
vestibular hypofunction; can perform at bedside if concerned about
ototoxicity or acoustic neuroma with vestibular loss; reveals vestibular
hypofunction without caloric test; obtain MRI if test positive
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Frenzel examination: Frenzel goggles do not
allow patient to fixate on object and suppress nystagmus; perform gaze
stability test and smooth pursuits, looking for for end-point nystagmus
(abnormalities imply central problem); head shake– induced
nystagmus—can determine hypofunctioning ear; performed horizontally
and vertically to check for abnormalities in superior or posterior canals;
hyperventilation-induced nystagmus—in patients with demyelination
(eg, acoustic neuroma) or central process (eg, multiple
sclerosis), test causes hyperactivity of nerve, hyperactivity-induced
nystagmus, and hyperactivity of semicircular canal; valsalva-, sound-,
or pressure-induced nystagmus—to look for evidence of fistula or
superior canal dehiscence (patients with superior canal dehiscence have
hypersensitive hearing, superconductivity, and effort- or sound-induced
dizziness) |
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Dix Hallpike examination: particles float down
into posterior canal, causing fluid drag and inducing 1- to 2-min episode
of delayed-onset nystagmus if head rotated in certain positions; rotate
one ear in down position, see whether nystagmus develops, bring patient
back up, then rotate head in other direction, and put patient down; ear
that induces nystagmus in down position is ear causing BPPV (treat with
Epley maneuver) |
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Dynamic visual acuity testing: for patient who
becomes dizzy only after turning; can determine whether patient with
history of ototoxic medications has bilateral hypofunction (indicated by
bilateral delayed head thrusts; not seen on caloric test); have patients
stand 20 ft from Snellen eye chart and read down to lowest line they can
read; then rotate patient’s head back and forth from behind and have
patient read it again; patient with unilateral hypofunction can read to
same line, but patient with bilateral hypofunction shows at least 2 lines
of degradation; recommend vestibular therapy and balance exercises
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Rhomberg and cerebellar testing: use Rhomberg
test if neurologic issues suspected; patients with central problem perform
abnormally during finger-to-nose testing |
| Venlafaxine for Migraine-associated Dizziness
—Jeffrey P. Staab, MD, Assistant Professor of Psychiatry, Departments of
Psychiatry and Otorhinolaryngology—Head and Neck Surgery, University of
Pennsylvania School of Medicine, Philadelphia |
| Migraine-associated dizziness: 60% to 80% of patients
who present with recurrent or chronic dizziness in absence of other
auditory or major neurologic symptoms meet International Headache Society
(IHS) criteria for migraine; patients experience dizziness before, during,
or after migraine episode and often have some motion hypersensitivity on
daily or frequent basis; studies show one third to one half of patients
with migraines have comorbid anxiety disorders, increasing to 80% in
patients with transformed migraines (chronic daily headaches); migraineurs
have 12-fold increased risk for panic disorder, compared to general
population; study—8-wk trial looked at open-label use of
extended-release venlafaxine (Effexor XR; serotonin-norepinephrine
reuptake inhibitor [SNRI] approved for treatment of generalized anxiety
disorder) in 26 patients with migraine-associated dizziness; daily dose
236 mg; most patients achieved 50% reduction in headache, dizziness, and
associated symptoms; favorable result found in 71% of 21 patients who
completed trial; concluded venlafaxine promising treatment for
migraine-associated dizziness, especially in patients with secondary
anxiety disorders |
Educational Objectives
| The goal of this activity is to provide the listener with a greater
understanding of pediatric hearing loss, cochlear implantation, the
vestibular examination, and the use of venlafaxine for migraine-induced
dizziness. After hearing and assimilating this program, the clinician will
be better able to: |
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1. Evaluate hearing loss in a pediatric
patient. |
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2. Discuss the advantages and disadvantages of
bilateral cochlear implants. |
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3. Describe the use of electroacoustic
stimulation to treat patients with high-frequency hearing loss.
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4. Evaluate a patient complaining of
dizziness. |
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5. Select a therapeutic agent to treat
migraine-associated dizziness. |
Discussed on This Program
Venlafaxine HCl [Effexor, Effexor XR]
Suggested Reading
Angeli
SI et al: Etiologic diagnosis of sensorineural hearing loss in adults.
Otolaryngol Head Neck Surg. 132:890, 2005; Bamiou DE et
al: Temporal bone computed tomography findings in bilateral
sensorineural hearing loss. Arch Dis Child. 82:257, 2000; Das S
et al: Bilateral cochlear implantation: current concepts. Curr Opin
Otolaryngol Head Neck Surg. 13: 290, 2005; Hone SW et al:
Medical evaluation of pediatric hearing loss. Laboratory, radiographic, and
genetic testing. Otolaryngol Clin North Am. 35:751, 2002; Lowe
LH et al: Sensorineural hearing loss in children.
Radiographics.17:1079, 1997; Madden C e al: Enlarged vestibular
aqueduct syndrome in the pediatric population. Otol Neurotol. 24:625,
2003; Offeciers E et al: International consensus on bilateral
cochlear implants and bimodal stimulation. Acta Otolaryngol . 125:918,
2005; Senn P et al: Minimum audible angle, just noticeable
interaural differences and speech intelligibility with bilateral cochlear
implants using clinical speech processors. Audiol Neurootol. 10:342,
2005; Park AH et al: Clinical course of pediatric congenital
inner ear malformations. Laryngoscope. 110:1715, 2000; Ramsden
R et al: Evaluation of bilaterally implanted adult subjects with the
nucleus 24 cochlear implant system. Otol Neurotol. 26:988, 2005;
Staab JP: Chronic dizziness: the interface between psychiatry
and neuro-otology. Curr Opin Neurol. 19:41, 2006; Tyler RS et
al: Update on bilateral cochlear implantation. Curr Opin
Otolaryngol Head Neck Surg. 11:388, 2003; Gantz BJ et al:
Patients utilizing a hearing aid and a cochlear implant: speech perception and
localization. Ear Hear. 23:98, 2002; van Hoesel RJ et
al: Speech perception, localization, and lateralization with bilateral
cochlear implants. J Acoust Soc Am. 113:1617, 2003; Verschuur
CA et al: Auditory localization abilities in bilateral cochlear implant
recipients. Otol Neurotol . 26:965, 2005.
Faculty Disclosure
In adherence
to ACCME guidelines, the Audio-Digest Foundation requests all lecturers to
disclose any significant financial relationship with the manufacturer or
provider of any commercial product or service discussed. For this issue, the
faculty reported nothing to disclose.
Drs. Lambert and Lustig were recorded November 10-12, 2005, at
Otolaryngology Update: 2005, sponsored by the University of California,
San Francisco, School of Medicine. Dr. Staab was recorded May 14-15, 2005, at
the annual Combined Otolaryngological Spring Meetings (COSM) of the American
Neurotology Society. The Audio-Digest Foundation thanks the speakers and the
sponsors for their cooperation in the production of this program.
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