Download mri and ct evaluation of acquired sensorineural

MRI AND CT EVALUATION OF ACQUIRED SENSORINEURAL HEARING LOSS
MARK B JOHNSON MD, JOHN VARVARIKOS MD, HEATHER BURBANK MD, JOSHUA NICKERSON MD.
DEPARTMENT OF RADIOLOGY, UNIVERSITY OF VERMONT MEDICAL CENTER, BURLINGTON, VT
Educational Objective:
Vestibular Schwannoma
1. Review the pertinent inner ear and auditory
pathway anatomy.
2. Review the pathology of different forms of acquired
sensorineural hearing loss as well as their signs
and symptoms.
3. Review the MRI and CT characteristics of the
various forms of acquired sensorineural hearing
loss.
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Benign primary tumor arising from myelin
forming Schwann cells surrounding the
vestibulocochlear nerve.
Imaging: Avidly enhancing on C+ T1W.
Microhemorrhage often present on T2 GRE.
CP angle mass with an “Ice cream cone”
appearance extending from the IAC.
Symptoms: Hearing loss, tinnitus, balance
disorders, headache.
Ramsay Hunt Syndrome
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Infection due to reactivation of Varicella Zoster
in the geniculate ganglia of the facial nerve.
Imaging modality: Contrast enhanced T1 MRI.
Finding may include enhancement of the
external ear, CN7, membranous labyrinth, and
facial nucleus within the brainstem.
Symptoms: Facial nerve palsy, pain and
vesicles of the ear canal, hearing loss, vertigo.
Arteriovenous Fistula
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A congenital malformations which typically presents
later in life.
Although most are asymptomatic, some may become
symptomatic due to turbulent vascular flow or venous
infarction with compromised venous outflow.
Imaging: MR/CTA or angiography.
Patient presented with pulsatile tinnitus.
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Introduction
Acquired sensorineural hearing loss (SNHL) is a
common problem among both pediatric and adult
populations with varied pathologies. Although the
majority of acquired SNHL is age related with no
relevant imaging findings, numerous other forms of
SNHL have unique characteristics on both MRI and
CT. SNHL abnormalities may involve the bony
labyrinth, membranous labyrinth, vestibulocochlear
nerve, extra-axial space, or intra-axial space. Early
recognition is paramount, and radiology plays a key
role in evaluation and diagnosis, potentially limiting
permanent disability.
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C+ T1W images reveal an enhancing left
cerebellopontine angle mass exiting from the left
IAC.
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Invasive papillary epithelial tumor arising from
the endolymphatic sac.
Imaging: Permeative destructive lesion on CT.
Often increased signal on T1, increased T2
signal of the cystic components, and
heterogeneous enhancement.
Strong association with von Hippel-Lindau
disease.
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1. Internal Auditory
Canal
2. Cochlea
3. Vestibule
4. Vestibular Aqueduct
5. Incus
6. Malleus
7. Facial Nerve Canal
8. Lateral Semicircular
Canal
9. CNVII/CNVIII Nerve
Complex
10. Cerebellopontine
Angle
11. Medial Geniculate
Ganglia
12. Heschl’s Gyrus
• Autosomal dominant osteodystrophy of the otic
capsule with variable penetrance.
• Replacement of “ivory-like” endochondral bone
with spongy vascular bone.
• Types: Fenstral and retrofenstral/cochlear.
• Imaging: Temporal bone CT. Lucency at the oval
window which spreads to the bony labyrinth.
• Signs/symptoms: Progressive disease
presenting in the 2-4th decades with SNHL,
conductive hearing loss, or tinnitus.
A) Prominent vascular malformation extending into the left
temporal lobe on post contrast T1W images. B) Signal loss
on susceptibility weighted images highlights the
pronounced vascularity.
Contrast enhanced T1W images reveal subtle
enhancement of the labyrinthine segment of the left
facial nerve (red arrow).
Endolymphatic Sac Tumor
Normal Anatomy from the Inner Ear,
Internal Acoustic Canal, Vestibulocochlear
Nerve, and Neuronal Pathways.
Otosclerosis/Otospongiosis
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Retrofenstral/cochlear otosclerosis: Lucency
surrounding the bony labyrinth has a molted
appearance on CT.
CPA Epidermoid Cyst
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Congenital benign lesion arising from displaced
ectodermal rests during neural tube closure.
Slow growing cyst which accumulate keratin
and cholesterol from epithelial desquamation.
Imaging: “Light bulb bright” on DWI, T2
isointense to CSF.
Symptoms: SNHL, vertigo, headache,
trigeminal neuralgia (with CNV involvement).
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Angiography reveals an AV fistula draining to the left transverse
and sigmoid sinuses, with the major inflow artery arising from left
ICA. The severely stenotic left sigmoid sinus drains via the
contralateral right transverse and sigmoid sinuses.
Otic Capsule-Violating Temporal
Bone Fracture
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Longitudinal fracture: Parallel to the petrous
ridge. Typically do not involve the otic capsule.
Transverse fracture: Perpendicular to the
petrous ridge and may involve the otic capsule.
Otic capsule-violating signs/symptoms: CNVII
injury, SNHL, CSF leak.
Labyrinthine Ossificans
• Ossification of the membranous labyrinth as a
response to a inflammatory or traumatic insult.
• Most commonly occurs as bilateral SNHL in
infants after acute meningitis.
• Less common causes include prior surgery,
trauma, middle ear infection, autoimmune
disease.
• Temporal bone CT: Findings range form
increased density within the membranous
labyrinth to complete obliteration.
• May impede successful cochlear implantation.
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A) Destructive lesion centered over the
endolymphatic sac with partial dehiscence of the
semicircular canal. B) Increased signal of cystic
components on T2W.
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A) CSF isointense lesion on T2WI within the right CPA
cistern, contacting CNVII/VIII. The cyst displaced the
CNV nerve at its cisternal segment (not shown). B)
The mass restricts diffusion on DWI.
CT images reveal a transverse
fracture extending through the
otic capsule, involving the
vestibular aqueduct, vestibule,
and facial nerve canal at the
geniculate ganglion.
Labyrinthine ossificans secondary to prior surgery.
CT images show a focus of increased density within
the fluid filled spaces of the cochlea.