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ENT Secrets > Chapter 44 - Neurotology > Flashcards

Chapter 44 - Neurotology Flashcards

1
Q

CPA mass presenting Sx

A

unilateral SNHL, tinnitus, disequilibrium

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2
Q

Hitzelberger sign

A

numbness in medial, posterior or superior EAC

Caused by acoustic neuroma compressing VII

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3
Q

Boundaries of cerebellopontine angle

A 
AL: clivus, petrous T bone
P: ventral brainstem, cerebellum
M: pons, medulla
S: cerebellum, middle cerebellar peduncle
I: cerebellar tonsil
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4
Q

CNs travelling through CPA

A

VII, VIII travel laterally and superiorly from brainstem to IAC
CN V superiorly, travels anteriorly from pons to Meckle’s cave
CN IX, X, XI inferiorly

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5
Q

Relationship between facial, cochlear and vestibular nerves, from perspective of CPA looking lateral at IAC

A

facial anterior/superior
cochlear ant/inf
superior vestibular nerve posterior/superior
inferior vestibular nerve posterior/inferior
Facial n and sup vestibular separated by Bill’s bar
Transverse crest separates sup and inf portions of IAC

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6
Q

Sx from lesion of PICA

A

Wallenberg/Lateral Medullary Syndrome
dysphagia, dysarthria, vocal cord paralysis, vertigo, facial paralysis, ataxia, ipsilateral Horner’s, hemisensory disturbance

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7
Q

Sx from lesion of AICA

A

AICA is close to 7/8 nerve roots
Hemiplegia, CN dysfunction (medial injury)
Ataxia (lateral injury)

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8
Q

Internal auditory artery: branch of, and supplies

A

br of AICA

supplies labyrinth

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9
Q

Differential of CPA mass

A

Acoustic neuroma 60-90%
Meningioma 3-7%
Epidermoid 2-4%
Other CN Schwannoma (5, 7, 9, 10, 11) 1-4%
Arachnoid cyst 1-2%
Rare: mets, hemangioma, lipoma, chordona, chondrosarcoma, dermoid, neuroepithelial tumors, endolymphatic sac tumor, ependymoma, glioma, astrocytoma, medulloblastoma, choroid plexus papilloma, aneurysm, AVM

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10
Q

Acoustic Neuroma: what it is, where its located, incidence

A 
arises from schwann cells
lateral to obersteiner-redlich zone (transition of central to peripheral myelin)
Inferior > Superior vestibular nerve
May extend medially to CPA
1 per 100,000
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11
Q

Syndromes associated with AN

A

NF1 (AD)- intra and extracranial neuroma, <5% develop AN. Chrom 17
NF2 (AD)- bilateral AN >90% pts. Chrom 22q12.2

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12
Q

Natural history of AN

A

Grow 1-2mm/yr, may be as much as 2cm/yr
Possible that they don’t grow after Dx as well
Growth may extend to brainstem, 4th ventricle
May be lethal due to brainstem compression, ICH

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13
Q

Size criteria of AN. How size affects Tx

A

small <1.5cm
medium 1.5-2.5cm
large 2.5-4cm
giant >4cm

Smaller lesion- may be able to follow with IMG esp if elderly. Smaller also makes tx less morbid

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14
Q

Signs/Sx of AN

A

CN VIII dysfunction is how intracanalicular ones present - HL, vertigo, tinnitus
As tumor grows, hearing worse, disequilibrium

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15
Q

Sx of brainstem compression

A

hydrocephalus (HA, N/V, AMS)

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16
Q

Percentage of AN pts with hearing loss. Percentage with tinnitus, disequilibrium

A

95% HL
50-60% tinnitus
40-60% disequilibrium

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17
Q

Tests that indicate AN is likely

A

Unilateral SNHL with disproportionate loss of speech discrimination
88% have absent reflexes or reflex decay
ABR detects 95% (false neg 18-30%)

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18
Q

ABR findings in AN

A

latency of wave V of >0.2msec

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19
Q

Intensity of AN on MRI

A

Isointense T1, mildy hyperintense T2, fairly avid enhancement

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20
Q

How to treat AN

A

Observe- elderly, small
Stereotactic Rads- cannot tolerate surgery, limited life expectancy
Surgery (may have hearing-preservation approach)
If young, tumor will grow and grow most likely, so they should be treated

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21
Q

Recurrence after surgery vs regrowth after Rads

A

Surg: 1-20%
Rads: 5-15%

22
Q

Benefit of Rads over Surgery

A

Earlier return to normal activity

23
Q

Disease free survival and overall tumor control with Rads

A

10 yr 92-98%

overall rate of tumor control: 93-9%

24
Q

Modes of delivering rads to AN

A

SRS (one time) or SRT (fractions)
Gamma Knife (colbalt 60)
CyberKnife (linear accelerator)

25
Q

Complications after Rads for AN

A

trigeminal neuropathy (0-27% SRS)
facial nerve palsy/paresis (0-23%)
HL that worsens over time
Second cancer

26
Q

Translab approach: Indications, Adv/Disadv

A

Ind: >2cm, small w/o serviceable hearing, facial nerve decomp/vestibular neurectomy and poor hear

ADV: exposure, less HA, highest rate CN VII fxn 99% anatomic 75% HB I-IV, ID VII laterally at fundus, may repair nerve, no cerebellar retraction, low recurrence

DISADV: hearing loss, short-term vvertigo if poor preop compensation, CSF leak 4-14%, fat graft needed

27
Q

Size of AN where hearing preservation is unlikely

A

> 2cm

28
Q

Retrosigmoid approach: Ind, ADV, DISADV

A

Ind: AN servicable hearing, doesn’t extend to lateral IAC, Meningioma with limited IAC involve

ADV: exposure, hearing preserve, CN VII preserve

DIS: fundus not visualized, more cerebellar retraction, 65% postop HA, limited ventral brainstem view, higher CSF leak than translab

29
Q

Middle Fossa approach AN: Ind, Adv, Dis

A

Ind: <1cm AN with CPA extension, superior based meningioma of IAC/petrous bone

Adv: hearing preservation 65%, CN VII preserve 91-95%

Dis: Not for >65 since dura fragile/adherent, must work around VII, CSF leak equal to translab

30
Q

Retrolab approach: Ind

A

Vestibular neurectomy

Posterior craniotomy between sigmoid sinus and otic capsule, exposes posterior fossa

31
Q

Transcochlear approach: Ind

A

Anterosigmoid posterior fossa craniotomy
View anterior CPA
Extends translab craniotomy
For meningioma medial to IAC, chordoma, chondrosarcoma, residual AN

32
Q

Infratemporal fossa approach

A

for T bone tumors extending inferior to jugular foramen near petrous ICA
ALso fro deep lobe parotid tumors with temporal bone involve

33
Q

Meningioma: what it is, syndromes, malignant potential

A

Arise form arachnoidal cap cells associated with arachnoid villi
Sporadic, but more often in NF2
5% become malignant

34
Q

Sx of meningioma of CPA

A

HL, tinnitus, imbalance

35
Q

Classic imaging for meningioma

A

enhance postcontrast MRI, dural tail, hyperostosis on CT

36
Q

Tx of meningioma

A

Surgery if growing or Sx

SRS or SRT for <3cm or residual post-surg dz may control growth

37
Q

Postop complications CPA surgery

A

CSF leak 10-15% - fluid collections near ear (Tx with pressure dress/bed rest, lumbar drain, fat obliteration mastoid)
Meningitis
VII dysfunction
Stroke, edema, air embolus, cerebellar ataxia, death (<1%)

38
Q

DDx petrous apex lesion

A

Inflam: cholesterol granuloma, cholesteatoma, mucocele
Infectious: apicitis, osteomyelitis
Neo: schwannoma, meningioma, paraganglioma, chordoma, sarcoma, nasopharyngeal carcinoma, metastatic lesions (renal cell, lung, breast, prostate)
Vascular: carotid artery aneurysm
Anatomic: asymmetric pneumatization (up to 35%)

39
Q

Cholesterol granuloma

A

Occurs after hemorrhage into petrous apex air cells
Punched out bony lesion CT, isodense mass, rim enhancement
Drain lesion to other portions of skull if Sx via transsphenoid or infralabyrinthine or infracochlear approach

40
Q

How to tell cholesterol granuloma vs cholesteatoma/mucocele on imaging

A

Chol Gloma: hyperintense T1-2

Cholestea: hypointense T1, hyper T2

41
Q

Jugular foramen (Vernet) syndrome and tumors that cause it

A

Paresis of IX, X, XI

Paraganglioma, schwannoma, meningioma, metastatic lesions, jugular vein thrombosis

42
Q

Sx of glomus tumors in jugular bulb/promontory

A

pulsatile tinnitus, CHL, aural fullness, CN deficits

Purplish-red mass

43
Q

Brown’s Sign

A

Paraganglioma blanches when positive pressure is applied

44
Q

Blood supply to jugular/tympanic paragangliomas

A

Jug: ascending pharyngeal artery
Tymp: inferior tympanic artery (br of ascending pharyngeal)

45
Q

Names of two staging system for paragangliomas

A

Fisch

46
Q

vessel traveling with IX, X, XI in pars nervosa compartment of jugular foramen

A

inferior petrosal sinus

47
Q

Relationship between CN IX, X and XI in jugular foramen

A

IX most anterior, ant to ICA
XI most posterior, anterior to IJ
X is medial, between ICA, IJ

48
Q

Most common tumors of EAC

A

SCCa

basal cell, adenoid cystic

49
Q

Staging of SCCa EAC

A

Pitt System
T1 limited to EAC
T2- limited bony erosion
T3- eroding bony EAC full thickness, or involves middle ear/mastoid
T4- Eroding cochlea, petrous apex, medial wall carotid, jug

50
Q

2-year survival rates of T stages of SCCa EAC

A

T1- 100%
T2- 80%
T3- 50%
T4- 15%

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