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PEDIATRIC LABYRINTHITIS OSSIFICANS
Unilateral Profound Sensorineural Hearing Loss with a
Non-Meningogenic Etiology: Case Report:
Laura Kirk, MSPAS, PA-C†, Christine M. Glastonbury, MBBS††, Kristina Rosbe, MD†
†Department
of Otolaryngology, Head and Neck Surgery, University of California at San Francisco
††Department of Radiology, University of California at San Francisco
ABSTRACT
Objectives: Profound sensorineural
hearing loss (SNHL) is a potentially
serious and irreversible complication
of viral labyrinthitis. We present our
case report to highlight the challenges
in early diagnosis of unilateral
deafness in a young child. We would
advocate for early, comprehensive
audiologic testing and subsequent
temporal bone imaging in children
presenting with vestibular symptoms
in the setting of an upper respiratory
infection (URI).
Study Design: Case report with
review of medical records and current
literature
Results: A 5yo female presented with
unilateral profound hearing loss 3
years following a URI associated with
disequilibrium. Documented ear
examination and head computed
tomography (CT) were normal and
the differential diagnosis was postviral cerebellitis versus labyrinthitis.
After the patient presented to us with
subjectively worsening hearing, an
audiogram demonstrated profound,
unilateral SNHL and a temporal bone
CT demonstrated extensive, unilateral
labyrinthitis ossificans. She
underwent ipsilateral bone anchored
hearing aid placement for single-sided
deafness.
Conclusion: We propose that in
children presenting with vestibular
symptoms in the setting of a URI,
serial audiograms and imaging studies
should be added to the diagnostic
algorithm.
CASE PRESENTATION
A 5 year old female presented to our practice for
evaluation of a newly diagnosed, profound, unilateral
hearing loss. The child was healthy at birth, passed her
newborn ALGO hearing screening, and had no known
risk factors for hearing loss. Her speech and language
development had been normal.
Figure 1 Pure tone audiogram demonstrates
normal hearing AS and profound SNHL AD.
INTRODUCTION
Labyrinthitis ossificans (LO) is pathologic
heterotopic bone formation within the otic capsule.
Ossification occurs in response to inflammatory or
destructive changes in the inner ear from the
following: infection, most commonly bacterial
meningitis; temporal bone trauma; autoimmune
disease; otosclerosis; leukemia; other malignancy; or
vascular occlusion. (1,2) Presenting symptoms of
LO may include vertigo, hearing loss, aural fullness,
tinnitus, otorrhea, otalgia, visual disturbances,
nausea and vomiting, fever, neck pain or stiffness,
and current or recent URI.
Labyrinthitis ossificans is most commonly
caused by bacterial invasion, which occurs via one of
3 routes: hematogenic spread from cochlear
vasculature, otitis media pathogens passing through
the round window membrane, or, most commonly,
meningogenic spread from the subarachnoid space.
Hearing loss may be seen as early as 48 hours after
infection in meningitis, with ossification visualized
intraoperatively as early as 21 days post-infection
and demonstrated on hi-resolution CT (HRCT)
within one year. (3)
Her parents recalled a febrile URI with nausea and
vomiting 3 years prior. One week into the viral illness,
the child, then 2 years old, was improving and had
defervesced, then became irritable and severely ataxic.
She was afebrile upon presentation to a local
Emergency Department (ED) with evaluations
documenting ataxia with otherwise normal exam. The
patient reportedly could not maintain her balance for
more than 3 seconds without becoming unstable. A
head CT was marred by motion artifact but interpreted
as normal. Neurologist’s diagnosis was postviral
cerebellitis versus labyrinthitis. After observation for 2
days, she was discharged to home. No treatment,
follow-up testing, or imaging was recommended and
the ataxia gradually resolved.
The parents began to suspect unilateral hearing loss
in the patient’s 5th year of life and a hearing screening
was abnormal unilaterally. A pure tone audiogram
(see Figure 1) confirmed profound SNHL across all
frequencies on the right, so referral to Pediatric
Otolaryngology was made. An HRCT of the temporal
bone (see Figure 2) demonstrated a normal left inner
ear and hyperdense basal and middle turns of the right
cochlea with a hyperdense vestibular apparatus.
Diagnosis of LO was reviewed with the family and they
were counseled regarding the permanent nature of the
hearing loss. Discussion ensued about amplification
and the family ultimately chose to proceed with an
osseointegrated temporal implant.
CONTACT
Laura Kirk, PA-C
UCSF Otolaryngology,
Head and Neck Surgery
[email protected]
415-353-2952
In the case of our patient, imaging at the time of
disequilibrium was normal and there was no obvious
source of suppurative labyrinthitis. Therefore, viral
labyrinthitis was the most reasonable cause of her
LO. We suspect this was from a hematologic
source, given the normal ear exam and lack of
systemic symptoms. Literature review indicates
that labyrinthitis ossificans from a tympanic source
is outnumbered by meningeal causes. (5,6) It is not
entirely clear why, in our patient, unilateral disease
resulted from a presumably systemic illness.
Most causes of acquired sensorineural hearing
loss in childhood can be associated with vestibular
complaints. Bacterial labyrinthitis of any type
accounts for one in three cases of all acquired
hearing loss. (7) Viral labyrinthitis carries fewer
morbidities and mortalities than bacterial, but is
much more common. We believe that a hearing
evaluation for any child presenting with vestibular
complaints is warranted, though there is no data on
this in the literature.
Unilateral sensorineural hearing loss of
childhood is often investigated with high resolution
computed tomography (HRCT) of the temporal
bone. The risks of CT have recently been
highlighted in several papers, with greater life-time
cancer risk in the pediatric population. HRCT of
the temporal bone can be performed with a lowered
dose protocol and preferential angle to minimize the
radiation to the child, and specifically away from the
ocular lenses. Careful patient selection and preimaging conversation with parents regarding the
risks of CT should be a part of the decision making
process in the work-up of pediatric hearing loss.
CONCLUSIONS
Profound sensorineural hearing loss is a
potentially serious and irreversible complication of
viral labyrinthitis. We present our case report to
highlight the challenges in early diagnosis of
unilateral deafness in a young child. We would
advocate for early, comprehensive audiologic testing
and, when indicated, temporal imaging in children
presenting with vestibular symptoms.
symptoms
Children presenting with acute disequilibrium
provide a diagnostic dilemma, largely due to the
patient’s inability to provide a precise description of
symptoms. A detailed history from caregivers
including onset; recent infection, history, injury or
potential toxin exposure; progression; and associated
symptoms such as vomiting or headache should be
investigated. Comprehensive ophthalmologic,
otologic, neurologic, and vestibular examinations are
warranted prior to proceeding with imaging. (4)
The differential diagnosis for pediatric
disequilibrium encompasses a diversity of conditions
including: infectious and autoimmune disorders of
the cerebellum, meninges, and labyrinth; alcohol,
drug, or toxin exposure; head trauma; intracranial
masses or lesions; atypical seizure disorder; migraine
phenomena; psychogenic disequilibrium; and genetic
ataxia disorders.
DISCUSSION
REFERENCES
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Figure 2 Axial non-enhanced 0.625mm CT through right
temporal bone at level of internal auditory canal shows patent
cochlear canal, but almost complete ossification of the cochlea
(red arrow) and of the horizontal semicircular canal. The
vestibule (black arrow) is partly ossified, resulting in an unusual
dysmorphic contour.
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Boston ME, Strasnick B, Steinberg AR. Inner ear, labyrinthitis [eMedicine
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http://emedicine.medscape.com/article/856215-overview. Accessed June 2010.