Otology Flashcards
1
Q
Portions of the temporal bone
A
- Squamous
- Petrous
- Mastoid
- Tympanic
2
Q
The geniculate ganglion is dehiscent without bony covering about what percentage of temporal bones?
A
10-20%
3
Q
Fissures of santorini
A
natural fissures in anterior cartilaginous ear canal that allow spread of disease to superficial parotid
4
Q
Bony and cartilaginous makeup of EAC
A
- Lateral one third is cartilaginous with cerumen glands and hair follicles.
- Medial two thirds are boney with no cerumen glands or hair follicles
5
Q
Foramen of Huschke
A
Anterioinferior bony defect that typically obliterates during development (failure of fusion of greater and lesser tympanic spines). Patency allows spread of disease to the deep parotid lobe/TMJ/ glenoid fossa or infratemporal fossa
6
Q
Prussack’s space
A
Space medial to pars flaccida and lateral to malleus neck
7
Q
Cochleariform process
A
Where the tensor tympani tendon takes a 90 degree turn from the medial wall of the middle ear and inserts onto the malleus
8
Q
Why is the long process of the incus predisoposed to erosion?
A
Because it only has a single blood supply without collaterals
9
Q
What innervates the stapedial tendon?
A
Facial nerve
10
Q
What innervates tensor tympani?
A
V3
11
Q
Course of the facial nerve
A
- Exits the brainstem (cisternal or CPA portion 14-17mm)
- Enters the porus of the IAC and courses to the fundus (meatal portion 8-10mm)
- Labryinthine segment (3-5mm): narrowest portion and completely enclosed by bone, most susceptible to compression from edema and trauma
- Geniculate ganglion at the first genu of the facial nerve
- Tympanic segment: facial nerve enters just posterior and superior to the cochleariform process, courses over the superior border of the oval window (10-12mm), dehiscent in up to 25-55% of temporal bones
- Second genu
- Mastoid segment (12-15mm)
- Exits as stylomastoid foramen
12
Q
Air cell tracts of mastoid bone
A
- Sinodural
- Retrofacial and retrolabryinthine
- Subarcuate
- Perilabryinthine
- Peritubal
13
Q
Central auditory pathway
A
Auditory nerve -> cochlear nuclei (dorsal cochlear nucleus, anterior ventral and posterior ventral cochlear nucleus) -> superior olivary complex -> lateral lemniscus -> inferior colliculus -> medial genicular body -> auditory cortex
- majority of auditory fibers in posterior ventral cochlear nucleus cross midline
14
Q
Stapedius reflex
A
Auditory nerve -> cochlear nucleus -> bilateral superior olivary nucleus -> bilateral facial motor nuclei -> bilateral stapedius tendon
15
Q
Semicircular canals and firing rates
A
Excitatory signal with angular acceleration in the direction of the leading canal and inhibitory in the coplanar, lagging canal
Ampulopetal flow (toward the vestibule) of the endolymph in the lateral canals is excitatory. Ampulofugal flow (away from vestibule) of the endolymph in the superior and posterior canals is excitatory
16
Q
Otolithic organs (linear accelerometers)
A
Saccule: vertical acceleration
Utricle: horizontal acceleration, head tilt
17
Q
Innervation of SCC and otolithic organs
A
- Superior vestibular nerve: utricle, superior SCC, lateral SCC
- Inferior vestibular nerve: saccule, posterior SCC
18
Q
Eustachian tube make up
A
- Two thirds cartilaginous, one third bony
- Tensor veli palatini is the primary dilator
19
Q
Ostmann fat pad
A
Metabolically sensitive adipose in the lateral wall of the Eustachian tube distally (rapid weight loss can atrophy the fat pad and results in patulous Eustachian tube syndrome)
20
Q
Five waves of ABR
A
- Distal (lateral) eighth nerve
- Proximal (medial) eighth nerve
- Cochlear nucleus
- Superior olivary complex
- Lateral lemniscus/ inferior colliculus
21
Q
what would use see on objective auditory measures in auditory neuropathy
A
No ABR but present OAEs and cochlear microphonic
22
Q
Pathway of cVEMP
A
acoustic energy -> saccule -> inferior vestibular nerve -> vestibular nuclei -> ipsilateral spinal accessory nucleus -> relaxation of SCM
23
Q
Acute otitis externa bugs
A
- 90% bacteria: pseudomonas, s. epidermidis, staph aureus
- 2-10% fungus/other: aspergillus, candida
24
Q
Imaging characteristics of cholesterol granuloma
A
CT: air cell trabecular breakdown, expansile
T1: hypertinense
T2: hyperintense, unchanged with fat saturation
T1+contrast: no enhancement
25
Imaging characteristics of mucocele
CT: air cell trabecular breakdown, expansile
T1: hypointense
T2: hyperintense
T1 + contrast: rim enhancement
26
Imaging characteristics of cholesteatoma
CT: air cell trabecular breakdown, expansile
T1: hypointesne
T2: hyperintense
T1+ contrast: may have rim enhancement if granulation tissue present
DWI restriction, bright signal
27
Imaging characteristics of vestibular schwannoma
T1: isointense to brain
T2: slightly hyperintense
T1+ contrast: enhances
28
Imaging characteristics of meningioma
T1: isointense to brain
T2: hypointense/hyperintense - signal depends on calcium content
T1+ contrast: enhances
29
Imaging characteristics of arachnoid cyst
T1: hypointense
T2: hyperintense
T1+ contrast: no enhancement
Signal characteristics mimic those of CSF
30
Imaging characteristics of epidermoid
T1: hypointense
T2: hyperintense, slightly more dense than CSF is
T1 + contrast: no enhancement
DWI shows resitriction (bright signal)
31
Imaging characteristics of lipoma
T1: hyperintense, signal disappears with fat suppression
T2: hyperintense
T1 + contrast: no enhancement
32
Scans in following malignant OE
Technetium scan: can diagnose bony activity and will show long term change, even after resolution
Gallium scan: used to follow patients
33
Development theories of acquired cholesteatom
1. Invagination (retraction pocket)
2. Basal cell hyperplasia (defect in the basal membrane allows ingrowth of epithelial cells
3. Migration theory (through a perforation without contact inhibition into the middle ear)
4. Squamous metaplasia of middle ear mucosa
34
Gradenigo Syndrome
- Petrous Apicitis presents with the following:
1. Draining ear (otorhea)
2. Retro-orbital pain (from trigeminal irritation)
3. Ipsilateral abducens palsy (from edema of Dorello canal)
35
Complications of acute and chornic otitis media
- Extracranial: acute mastoiditis, coalescent mastoiditis (erosion of mastoid air cell separations), chronic mastoiditis, subperiosteal abscess, petrous apicitis, labyrinthine fistula, facial paralysis, encephalocele, CSF leak
- Intracranial: meningitis, epidural abscess, subdural empyema, brain abscess, lateral/sigmoid sinus thrombosis, otitic hydrocephalus
36
Types of superiosteal abscess from otitis media
1. Postauricular (through the cribiform area, with direct extension through bone and or thrombophlebitic)
2. Bezold (medial wall of mastoid tip medial to SCM muscle into the neck
3. Luc's (zygomatic root)
37
Findings to look for with T bone trauma
1. facial nerve exam
2. CSF leak
3. potential carotid canal injury
4. Dizziness
38
Sunderland classification of facial nerve trauma
First degree: neuropraxia (conduction block without axonal injury)
Second degree: axonotmesis (axons cut, but endoneurium stay intact, no synkinesis)
Third degree: neurotmesis (endoneurium disrupted, synkinesis possible on regeneration)
Fourth degree: neurotmesis transects entire trunk (endoneurium and perineurium), epineurium intact
Fifth degree: neurotmesis (all three layers cut, endoneurium, perineurium, epineurium)
39
OSHA noise limits
90dB exposure: 8 hr limit
95dB exposure: 4 hr limit
100dB exposure: 2hr limit
105dB exposure: 1hr limit
110dB exposure: 0.5hr limit
noise intensity doubles every 3 dB OSHA rounded to 5dB
40
Aminoglycoside toxicity
Vestibulotoxicity > cochleotoxicity : streptomycin, gentamicin (both medications cause damage to sensory cells in the crista ampullaris of the semicircular canals)
Cochleotoxicity> vestibulotoxicity: kanamycin, tobramycin, amikacin, neomycin, dihydropstreptomycin
- Effect outer hair cells and result in an irreversible high frequency SNHL
- Aminoglycoside sensitivity is caused by a mutation of the A1555G gene which is inherited through the mitochondrial DNA
41
Ototoxic and vestibulotoxic medications
- Aminoglycosides (likely from reactive oxygen species injuring outer hair cells)
- Cisplatin (ROS injuring stria vascularis and outer hair cells)
- Carboplatin (less otoxic compared to cisplatin)
- Loop diuretics (affects stria vascularis)
- Macrolides (erythromycin possibly reversible, azithromycin likley reversible HL, affect stria vascularis)
- Hydrocodone (from mostly abuse/recreational use, presents as rapidly progressive bilateral loss not responsive to corticosteroids, tx with CI)
- Methadone (possibly reversible)
- Vancomycin (questionable otoxicity)
- Quinines (possibly permanent with reversible component)
- Acetylsalicylic acid (typically reversible, affects motor protein prestin in OHCs)
42
Basic components of hearing aids
- Microphone
- Transducer (convert one form of energy into electrical energy)
- Amplifier
- Speaker (or receiver)
43
Gain
The amount of energy added to the input signal. Can be linear (ex any input signal gets 20dB added to it) or compressed nonlinear (the amount of gain changes as a function of input level)
44
Dynamic range
An individual's threshold of sound perception to discomfort.
- Compression (type of gain) allows a hearing aid to amplify into a smaller dynamic range
45
Alexander's law of nystagmus
Nystagmus from a peripheral vestibular lesion is worsened with gaze in the direction of the fast phase.
46
Which canal do calorics test
Lateral semi circular canal and superior vestibular nerve
47
Pathway of oVEMP
acoustic sound or bone oscillation -> utriclar stimulation -> superior vestibular nerve -> contralateral oculomotor nucleus -> contralateral inferior oblique stimulation
48
Most common canal affected in BPPV
Posterior SCC (85-90%) then lateral canal, superior canal very rare
49
Tullio phenomenon
Sound induced vertigo
50
Hennebert's sign
Pressure induced vertigo
51
Signs of superior canal dehiscence
Low frequency mild conductive hearing loss, increase amplitude and decreased VEMP thresholds (because of lower amount of energy required to stimulate vestibular system), intact acoustic reflexes, CT temporal bone demonstrating dehiscence. Often have pressure and sound induced vertigo. May have supranormal bone conduction thresholds.
52
Time frame to complete electroneurography
3-21 days after injury. Cannot be done until 3+ days after injury because that's how long it takes for Wallergian degeneration (degeneration of axon distal to site of injury) to occur. The stimulation for ENG is at the stylomastoid foramen which is distal to the site of injury in the temporal bone. Testing shouldn't be done after 21 days because after that time dyssynchrony (potentials from two axons that occur out of phase) may occur and degeneration may be overestimated.
53
Electroneurography (evoked electromyography)
Uses surface electrodes maximally to stimulate both sides and measure resulting EMG bilaterally. Response as a percentage (affected/unaffected). Best prognosis if done 10-14 days after injury
54
ENG testing results
Fibrillation potentials: indicates degeneration
Polyphasic potentials: indicates nerve regrowth
> 95% degeneration one should consider decompression
55
When might you use a middle fossa craniotomy approach?
IAC tumors with minimal CPA extension, age <65 and serviceable hearing (PTA <50 and SDS > 50%)
56
When might you use a translabryinthine craniotomy?
When no serviceable hearing or large CPA tumors where hearing preservation is less likely
57
When might you use a suboccipital/retrosigmoid craniotomy?
When there is serviceable hearing and the tumor is primarily in the CPA with minimal IAC extension
58
Staging system for tumors of the EAC (Pittsburgh system)
T1: tumor limited to EAC without bony erosion or soft tissue extension
T2: tumor limited to EAC w partial thickness bony erosion or limited soft tissue involvement (<0.5cm radiographically)
T3: tumor erodes osseous EAC (full thickness) with limited (<0.5cm) soft tissue involvement or tumor involves middle ear or mastoid
T4: tumor erodes cochlea, petrous apex, medial wall of middle ear, carotid canal, jugular foramen or dura or shows extensive (>0.5cm) soft tissue involvement or facial paralysis
Any involvement of lymph nodes is a poor prognostic indicator and places patient in advanced stage (III or IV)
59
Findings of ENOG
Polyphasic potentials - Good findings early on, indicates new axons are innervating the muscle fibers
Fibrilation - individual muscle fibers not innervated, given off random activity. Not present until 10-14 days
Normal motor unit response - later finding, good finding
No response - poor finding, later finding
60
Describe sensory innervation of pinna and EAC
Sensation of auricle is provided by greater auricular and lesser occipital nerve (from cervical plexus), small branches of facial nerve and auriculotemporal nerve.
EAC supplied by overlapping contribution from CN V, VII, IX and X
61
What is the notch of Rivinus?
The deficient portion of tympanic annulus where the pars flaccida attaches to the squamous portion of the temporal bone
62
How are the pars flaccida and pars tensa of the TM structurally different?
Pars flaccida is more compliant. Pars tensa is thicker and contains a middle fibrous layer in addition to an outer skin layer and inner mucosal layer
63
The tympanic membrane is formed by what embryonic layers?
The outer epidermal layer from the first branchial cleft (ectoderm); middle fibrous layer from neuro crest mesenchyme (mesoderm) and inner mucosal layer from first pharyngeal pouch (endoderm)
64
Where does the carotid lie in relation to the Eustachian tube
Carotid artery courses medial to the more anterior cartilagenous portion of the ET
65
In cleft palate patients dysfunction of which muscle is the most strongly implicated in causing recurrent otitis media?
Tensor veli palatini
66
Most common intratemporal location of facial nerve dehiscence?
Most commonly near oval window, second most commonly at the second genu
67
What landmarks may be used to help identify the facial nerve during middle ear surgery?
Jacobson's nerve, located on cochlear promontory, can be followed superiorly to the cochleariform process. Facial nerve is immediately medial and superior to the cochleariform process and tensor tympani. Facial nerve can also be identified immediately superior to the oval window.
68
Aside from muscles of facial expression what other muscles does facial nerve innervate?
Stapedius, posterior belly of digastric, stylohyoid (all muscles of the second branchial arch)
69
Cog
A coronally oriented bony septum located just anterior to the head of the malleus that seperates the anterior epitympanic recess (supratubal recess) from the attic
70
When looking at the external surface of the mastoid cortex, what landmark can be used to approximate the level of the middle cranial fossa?
The temporal line (represents the insertion point of the temporalis muscle)
71
Boundaries of Macewen triangle
The suprameatal crest, posterior margin of the EAC, the tangential line from the posterior ear canal bisecting the suprameatal crest are the boundaries of the Macewen triangle, which approximates the antrum.
72
Korner septum
Bony plate dividing mastoid air cells superficial to antrum. Embryologically it is the junction between the petrous and squamous portions of the temporal bone.
73
Which cells are primarily responsible for transducing acoustic energy into neural signals?
Inner hair cells are the cells which afferent auditory neurons (spiral ganglion cells) synapse.
Outer hair cells contribute to transformation of acoustic energy into neural signal bur primarily play a role in tuning the cochlea to improve frequency selectivity and sensitivity.
74
Boundaries of the scala media
Scala media is separates from scala vestibuli by the Reissner membrane. The basilar membrane and osseus spiral lamina separate the scala medial and scala tympani. The boundaries of the outer periphery of the scala media are the stria vascularis and spiral ligament.
75
What two structures are connected by the perilymphatic (periotic) duct?
The perilymphatic duct which runs in the bony canal of the cochlear aqueduct connects the scala tympani of the cochlea and the subarachnoid space of the posterior cranial fossa
76
Where is the primary auditory cortex located?
Brodmann areas 41 and 42 of the upper temporal lobe
77
Describe the course and function provided by the nervus intermedius
The taste, secretory and sensory fibers of the facial nerve are carried by the nervus intermedius. It exists as a distinct nerve in the cerebellopontine angle and the IAC, but on entering the meatal foramen these fibers exist within the body of the facial nerve.
78
What cell bodies are located in the geniculate ganglion?
Cell bodies of the special sensory taste neurons carried by the chorda tympani nerve
79
What nerve fibers are carried by the greater superficial petrosal nerve?
Preganglionic parasympathetic fibers that synapse in the pterygopalatine ganglion as well as afferent special sensory taste fibers that supply the soft palate
80
What is prevalence of internal carotid artery dehiscence at the floor of the middle cranial fossa?
~20%
81
Describe boundaries of Glasscock triangle (posteriolateral)
GSPN, V3, line connect foramen spinosum and arcuate eminence
82
Describe boundaries of Kawase triangle (posteriormedial)
V3, GSPN, arcuate eminence, superior petrosal sinus. It marks the boundares of the anterior petrosectomy for gaining access to the posterior fossa
83
What extratemporal branches of the facial nerve arborize proximal to the pes anserinus?
Postauricular nerve, nerve to the stylohyoid and nerve to posterior belly of digastric
84
The external ear is formed by what mesodermal structures?
The six hillocks of His
- First arch: tragus, helical crus, helix
- Second arch: antihelix, antitragus, lobule
85
Incomplete fusion or supernumerary development of the hillocks of His may lead to what conditions?
Preauricular cysts, pits or tags
86
Describe embryologic basis of a persistent stapedial artery
The stapedial artery is derived from second branchial arch. This is normally a transient structure, but in rare instances it can persist into adulthood
87
Skull base abnormality classically seen with persistent stapedial artery?
Lack of ipsilateral foramen spinosum
88
Embryologicl origin of ossicles
First branchial arch (Meckel cartilage) - Head and neck of malleus, inus body and short process
Second branchial arch (Reichert cartilate) - Manubrium of malleus, long process and lenticular process of inus, stapes superstructure
Otic capsule - Stapes footplate and annular ligament
89
From which germ cell layers and branchial arches does the otocyst arise?
Fist seen at the end of the 3rd week of development, the otic placode is a thickening of the ectodermal surface of the first branchial groove. This invaginates into the underlying mesoderm, which it eventually becomes surrounded by to form the otocyst. This structure goes on to develop into the otic labyrinth.
90
Primary acoustic functions of the EAC
- Filter to reduce low frequency background noise
- Resonator to amplify mid frequency sounds (up to 20 dB)
- Direction dependent filter to augment spatial perception at high frequencies
91
Describe the acoustic transformer mechanism of the middle ear
Three levers provide an average gain of 20-30dB
- Catenary lever: elastic properties of stretched TM fibers directed sound to the centralized malleus
- Ossicular level: the length of the manubrium of the malleus divided by the length of the long process of the incus (1:3)
- Hydraulic lever: A 22:1 ratio of the TM to the oval window
92
Describe the electrolyte composition of the cochlear fluids
- Perilymph located in scala vestibuli and tympani is similar to serum and CSF - high Na and low K
- Endolymph is located within the scala media and is similar to intracellular fluid - low Na and high K
93
Define 1st degree, 2nd degree and 3rd degree nystagmus
1 - occuring when gazing in the direction of the fast component
2 - occuring when gazing in the direction of the fast component or at midline
3 - occuring when gazing in all direction
94
Describe Ewald's three laws
- The axis of nystagmus parallels the anatomic axis of the semicurcular canal that generated it
- In the lateral SCC ampulopetal endolymph movement causes greater stimulation that ampulofugal
- In the superior and posterior SCC the reverse is true
95
Describe examination findings that help distinguish between central and peripheral vestibular deficits
- Central deficits may occur in any direction (vertical, horizontal or torsional), may alternate direction, do not suppress with visual fixation, do not fatigue, rarely are associated with hearing loss, often have other abnormal neurologic examination findings, have minimal latency with positional change and are often less severe
- Peripheral deficits: unidirectional; horizontal only (no vertical component), suppress with visual fixation, often with concurrent hearing loss, otherwise normal neuro exam, postional nystagmus that often has 2+ second latency, generally more severe
96
Frenzel goggles
Assist in evaluating nystagmus, magnify and illuminate the patient's eyes and prevent gaze fixation
97
Describe the effects of cold and warm irrigation during caloric testing
Cold causes the fast phase of the nystagmus to beat toward the opposite ear, whereas warm causes the fast phase to beat toward the ipsilateral ear
98
What inner ear structure and cranial nerve does VEMP testing interrogate?
Saccule and inferior vestibular nerve
99
What pattern of results may be seen in a malingering patient during computerized dynamic posturography?
Poor scores with easier tasks but as task difficulty increases patient may do disproportionately better
100
Fakuda stepping test
Patient is asked to march in place with eyes closed for 50 steps. Rotation (> 30 degrees) may indicate asymmetric labyrinthine function. Rotation generally occurs toward the side of the lesion.
101
Vestibulo ocular reflex
Reflex generates eye movements in response to head motions perceived by peripheral vestibular system, permitting visual fixation on an object while head is moving
102
What constitutes a postive head thrust test
In the case of left hypoactive labyrinth, the VOR will be impaired and the head thrust test toward patient's left will be positive; examiner will note the patient's eyes rotate with the head and after a brief delay, a "catch up saccade" toward the right will bring gaze back toward the examiner.
103
What conditions are associated with a positive Hennebert sign?
Superior SCC dehiscence, perilymphatic fistula, lateral SCC fistula or otosphyilis
104
In what clinical situations would rotary chair testing be useful?
Testing evaluates bilateral SCC function simultaneously (unlike calorics). It may be used for evaluating suspected bilateral vestibular loss
105
What % of patients with Meniere disease will develop bilateral involvement?
~30%
106
Clinical presentation of Meniere disease
Low frequency SNHL (fluctuating and progressive), roaring tinnitus, aural fullness, episodic vertigo generally lasting hours
107
Lermoyez syndrome
Tinnitus and hearing loss that remit after an attack of vertigo
108
Diagnosis of definite Meniere disease
Two or more definitive spontaneous episodes of vertigo lasting 20 minutes or longer, audiometrically documented hearing loss on at least one occasion, tinnitus or aural fullness in the treated ear and other causes excluded
109
Diet modifications for Meniere disease
Avoidance of alcohol, caffeine, tobacco and monosodium glutamate. Adherence to a low sodium diet (less than 1-2g/day)
110
How is electrocochleography used in diagnosis of Meniere disease?
If the ratio of the summating potential, generated by the organ of Corti, and the action potential, generated by the auditory nerve is elevated, diagnosis is indicated. A value of 0.5 or greater is considered suggestive.
111
Donaldson's Line
An imaginary line running parallel to plane of the lateral SCC extending posteriorly and inferiorly through the center of the posterior SCC. Endolymphatic sac lies just inferior to this line on the posterior fossa dura
112
What pure tone findings can be seen in patients with superior SCC dehiscence
Conductive hyperacusis sometimes with bone conduction thresholds occasionally less than 0dB. Can lead to an air bone gap even when air conductive thresholds are within normal range
113
Clinical presentation of superior SCC dehiscence
Aural fullness, autophony, hearing loss (air bone gap), dizziness associated with loud sounds, exertion or straining
114
How to differentiate otosclerosis from superior SCC dehiscence
Patients with otosclerosis often have type A2 tymps, absent stapedial reflexes and elevated to absent cVEMPs. Patients with SSCCD usually have normal refelxes, type A tymps and diminished VEMPS (<70dB)
115
Which canal is most commonly involved in BPPV
Posterior SCC
- 5% involve lateral canal and superior canal is least common
116
What anatomical structure is the source of the otoconia in BPPV?
The utricle
117
Describe mechanisms of sinuglar neurectomy in treatment of BPPV
The singular nerve innervates the posterior SCC which is most commonly affected. Division of this nerve may lead to symptom relief in refractory disease
118
What symptoms may accompany episodic vertigo associated with vertebrobasilar insufficiency?
Diplopia, decrease in visual acuity, ataxia, dysarthira, dysphagia, other focal neurologic symptoms
119
Describe symptoms of wallenberg syndrome
-Loss of pain and temp sensation on ipsilateral face and contralateral body, dysphagia, dysarthira, ataxia, vertigo, Horner syndrome, diplopia
-Caused by lateral meduallry infarct supplied by posterior inferior cerebellar artery
120
Typical initial symptoms of vestibular neuronitis
- Sudden onset severe vertigo, nausea, vomiting, lasting days to weeks often preceded by a viral URI
- Hearing should remain stable (unlike labryinthitis)
121
Treatment for vestibular neuronitis
High dose steroids, vestibular suppressants in acute period, antiemetics, bed rest
122
Typical presentation of mal de debarquement syndrome
The sensation of rocking or swaying back and forth without vertigo, difficulty concentrating and fatigue. Most commonly occurs in middle aged women after a week long cruise. Mean duration of symptoms is 3.5 years
123
What is the mechanism of motion sickness
Disagreement between vestibular cues and visual and somatosensory input.
124
Excluding BPPV what is the most common cause of vertigo in the general population?
Vestibular migraine or migraine associated vertigo (prevalence of 1% in general population)
125
Diagnostic criteria for vestibular migraine
Definite
- Recurrent episodic vestibular symptoms of at least moderate severity
- Current or previous history of migraine
-Migrainous symptoms during >2 vertiginous attacks
-Other causes ruled out
126
Describe relationship between vestibular migraine and Meniere disease
Substantial overlap between two groups. 1/4 of patients with Meniere disease will diagnostic criteria for vestibular migraine.
127
Clinical features of basilar migraine
-Similar symptoms to vertebrobasillar insufficiency with headache
- Most patients dizziness but may also have ataxia, hearing loss, tinnitus, dysarthria, diplopia and syncope
- Commonly involves young females
128
Common neurotologic exam findings in patients with MS
Abnormalitis in smooth pursuit (96%), saccadic eye movements (76%), optokinetic nystagmus (53%), defective visual suppresion of nystagmus (43%)
129
Charcot triad
Nystagmus, scanning speech, intention tremor - associated with symptoms of multiple sclerosis
130
Presbystasis
General balance difficulties of elderly patients related to cumulative age related decline in vestibular response, visual acuity and proprioception and motor control
131
Four different subclasses of presbycusis
Sensory: loss of sensory hair cells of basal turn resulting in precipitous high frequency SNHL and preserved speech discrimination
Neural: loss of VIII nerve fibers where speech discrimination may be disproportionately affected
Metabolic: caused by atrophy of the stria vascularis affecting all frequencies (flat audiogram); speech discrimination frequently preserved
Mechanical: stiffening of basilar membrane resulting in gradual down sloping of SNHL with proportional loss of speech discrimination
132
At what air bone gap is Rinne testing with a 512 Hz tuning fork most reliable at detecting conductive hearing loss?
17-30 dB; any value lower or higher is likely to produce a false negative
133
Usual air bone gap with maximal conductive loss
60dB
134
What is the ineraural dB difference required for a Weber exam to lateralize?
Sound should lateralize to the ear with largest conductive loss of the side with the better nerve; a minimum of 5dB difference is needed
135
Anticipated test retest variability seen with pure tone audiometry
Test retest variability should be 10dB or less
136
Asymmetric hearing loss
Interaural dlifferences of greater than 15dB in two or more pure town thresholds or a difference of greater than 15% on speech discrimination testing
137
Interaural time difference
Sound will reach the closest ear first (low frequency dominated)
138
Interaural intensity difference
The intensity of sound in the ear farthest from the source will be attenuated by the head shadow effect (high frequency dominated)
139
Interaural attenuation
The loss of intensity that occurs before arriving at the non test ear. The reason masking is used. Roughly 40dB for air conduction with circumaural headphones/70dB for insert headphones and 0 dB for bone conduction
140
Recruitment
Minimal difficulty with quiet sounds but having a disproportionately severe noise sensitivity at higher sound levels
141
Masking dilemma
Occurs when required masking level is loud enough to cross over to the test ear. Most commonly occurs in patients with significant bilateral conductive hearing loss
142
Rollover
Characterized by a paradoxical decrease in speech recognition with increasing sound presentation levels and is associated with retrocholear lesions
143
Appropriate ages to administer behavioral audiometric testing in children?
0-5months: behavioral observation audiometry
5months-2years: visual reinforcement audiometry
2-5 years: conditioned play audiometry
5+ years: conventional audiometry
144
What might you see on ABR with retrocochlear pathology?
Abnormally long delays between waves (interpeak latency of wave 1-5) indicating lesion affecting conductivity of neurons that connect structures in auditory pathway
145
Otoacoustic emissions
Sound generated by outer hair cells spontaneously or by an auditory stimulus. Considered a form of objective audiometry as they don't rely on patient participation. Testing capable of detecting losses greater than 30-40 dB.
146
Advantage of distortion product OAEs over transient evoked OAEs
Provide frequency specific information
147
Describe different tympanometry patterns
A: normal
As: shallow, stiffened or hypomobile TM (ossicular fixation or glue ear)
Ad: deep, flaccid or hypermobile TM (ossicular discontinuity, flaccid TM)
B: flat - must combine with canal volume to interpret. If large canal volume consider perforation or PET, small volume indicates middle ear fluid, cerumen or probe against wall of EAC
C: left shift in peak, negative middle ear pressure (associated with retraction or ETD)
148
How is stapedial reflex testing performed
Tympanometry of the ipsilateral and contralateral TM is measured when sound (80-110dB) is applied to the ear at different frequencies. A stapedial reflex is measured as a decrease in compliance resulting from stapedial muscle contraction.
149
Conditions that may results in absent or abnormal stapedial reflexes?
Otosclerosis, middle ear disease, severe SNHL, eight nerve pathology, ipsilateral seventh nerve palsy (Bell's palsy)
150
Pattern of stapedial reflex testing with right sided retrocochlear pathology
- Reflexes absent when stimulated in the ipsilateral (right) ear
- Left sided stimulus will have a left sided and right sided reflex
- Right sided stimulus will result in absent/elevated response on both left and right
151
Stapedial reflex pattern seen with thick mucoid effusion in right ear (type B tymp) causing large CHL
- Can result in dampening of the incoming auditory signal
- Left sided stimulus: left response present, right response absent/elevated
- Right sided stimulus: absent/elevated responses bilaterally
152
Stapedial reflex pattern seen with bilateral thick middle ear mucoid effusions
- Absent responses bilaterally regardless of which side stimulated
153
Stapedial reflex pattern with right sided facial nerve pathology
- Left sided stimulus: present reflex on left, absent on right
- Right sided stimulus: absent on right, present on left
154
Acoustic decay
A stimulus is presented in the ear of concern and a contralateral probe is placed. A continuous pure tone stimulus is presented 10dB above stapedial reflex threshold and held for 10 seconds. Test is positive if magnitude of reflex drops by more than 50% in 10 seconds
155
Methods that can be used to evaluate for factitious hearing loss
- Objective audiometry: OAE, ABR
- Behavioral audiometry: discrepancy between speech reception test and pure tone audiometry, significant difference (>15dB) in test retest scores
- Acoustic reflex testing
- Lombard test
- Stenger test
156
Stenger test
Based on the principle that if the tones of the same frequency are presented simultaneously to both ears only the loudest is perceived. Two simultaneous tones with matched frequency are played but the alleged poor ear receives a tone at a greater intensity (usually > 20dB). Truthful patient with normal hearing will report sound in the ear with loudest sound level. Truthful patient with asymmetric hearing loss will report the sound in the better hearing ear. Untruthful subject will deny hearing any sound.
157
Lombard test
Noise is introduced into ear with supposed hearing loss while patient is asked to read. The noise level is gradually increased until the patient raises his or her voice or stops reading. If there is no change in loudness of voice this would support a true hearing loss.
158
Factors that place pediatric patient at high risk for early SNHL
- history of intrauterine infection (TORCH)
- family history of congenital hearing loss
- low birth weight (<1500g)
- hyperbilirubineia
- prolonged NICU stay or mechanical ventilation
- concurrent craniofacial abnormalities
- exposure to ototoxic medications
- < 5 Apgar score at 1 min, < 7 Apgar at 5 min
- bacterial meningitis
159
What % of congenital hearing loss is genetic?
50%
160
What % of patients with genetic hearing loss will have associated syndromes?
30%
161
What % of genetic hearing loss is inherited in an autosomal dominant pattern?
20%
162
Most common form of autosomal dominant hearing loss?
Waardenburg syndrome
163
4 subtypes of Waardenburg syndrome
WS1: autosomal dominant, dystopia canthorum, SNHL, iris pigmentary disorder, hair hypopigmentation
WS2: same as WS1 with no dystopica canthorum
WS3: same as WS1 plus limb abnormalities
WS4: autosomal recessive, no dystopia canthorum, Hirschprung disease, SNHL, iris pigmentary disorder, hair hypopigmentation
164
Three most common causes of autosomal recessive SNHL
Usher, Pendred, Jervel and Lange-Nielsen
165
Three subtypes of Usher syndrome
Type 1: profound bilateral deafness, vestibulopathy at birth, night blidness from retinitis pigmentosa before teenage years, most severe form
Type 2: moderate to severe hearing loss at birth with worsening vision in young adulthood and normal vestibular function
Type 3: normal hearing at birth with progressive hearing loss and retinopathy by teens, variable vestibuar involvement
166
Most common cause of deaf-blindness in US
Usher syndrome
167
Alport syndrome involves faulty synthesis of what proteins?
Type IV collagen
168
Norrie disease
- X linked recessive syndrome
- Results in early rapidly progressive blindness
- Progressive SNHL in ~1/3 of patients which usually ensues in 2-3rd decade of life
169
Head and neck manifestions of Pendred syndrome
- SNHL often associated with enlarged vestibular aqueducts and mondini malformations
- Euthyroid goiter
170
Thyroid pathology typically seen in Pendred syndrome
Multinodular goiter in 2nd decade of life. usually euthyroid and rarely require intervention
171
What gene mutation is responsible for ~50% of all cases of genetic hearing loss
GJB2 encodes connexin 26 located on chromosome 13, autosomal recessive inheritance pattern
- gene codes for a gap junction protein responsible for potassium ion exchange of inner ear
172
Jervell and Lange Nielson syndrome
- Autosomal recessive
- Congenital profound bilateral SNHL
- Arrhythmia
- Patients may have syncopal episodes provoked by stress or exercise
- Sudden cardiac death from arrhythmia if untreated
- Long QTc
- Caused by defect in potassium channel within stria vascularis
173
MELAS syndrome
- Mitochondrial encephalopathy
- Lactic acidosis
- Stroke
- Manifestations are variable and include hearing loss, limb weakness, partial paralysis, vision loss and seizures
174
Clinical features of Michel aplasia
Complete failure of inner ear development resulting in congenital anacusis
175
Mondini malformation
Incomplete or absent partition and less than 2.5 turns of cochlea
176
Imaging findings of a common cavity malformation
Cochlea and vestibule are joined as a single large confluent space usually results in severe to profound SNHL
177
Most common form of membranous labyrinth dysplasia?
Scheibe dysplasia
178
What frequencies are most commonly affected by Alexander dysplasia?
high frequencies resulting malformation of cochlear duct and basal turn of cochlea
179
Where is the site of damage in chronic noise induced SNHL
outer hair cells
180
Characteristic audiogram finding with noise induced hearing loss
4kHz notch
181
Sudden sensorineural hearing loss
Greater than 30dB loss over three contiguous pure tone frequencies within a 3 day period
182
What % of patients with sudden SNHL can expect some degree of spontaneous recovery?
~2/3
183
Evaluation for sudden SNHL
Audiogram and then patients should get MRI for retrocochlear pathology rule out. Routine labs only not needed unless high suspicion based on physical exam and history
184
What clinical variables are associated with a more favorable prognosis after sudden SNHL
Young age, less severe hearing loss, absence of dizziness, low frequency pattern of hearing loss, early treatment
185
Diagnostic criteria for primary audoimmune inner ear disease
Progressive (over weeks to months) bilateral SNHL that responds to steroid. Other progressive SNHL causes must be ruled out
186
What is 68kD inner ear antigen?
About 20-80% of patients with autoimmune inner ear disease will have a positive anti 68kD antibody test
187
Susac syndrome
An autoimmune small vessel disease characterized by the triad of encephelopathy, branch retinal artery occlusions and SNHL
188
Cogan syndrome
A syndrome of nonsyphilitic intersitial keratitis and audiovestibular symptoms. Most patients have bilateral fluctuating progressive SNHL, episodic dizziness. Systemic manifestations commonly include headache and fever. Tends to present in 20-30s and is autoimmune in nature. Treat with steroids and immunosuppressants.
189
Potential routes of communication that permit inner ear involvement in patients with meningitis
Cochlear aqueduct and modiolus
190
Which organisms are associated with highest risk of post meningitic SNHL?
- strep pneumonia
- neisseria meningitidis
- Haemophilus influenzae
191
What percentage of patients with bacterial meningitis will develop SNHL?
15-20%, 5% with profound loss
192
Common otologic manifestations of GPA
Conductive hearing loss, chronic serous otitis media are most common. Can have otalgia, facial palsy, vertigo, SNHL and external ear involvement
193
Differential diagnosis of pulsatile fluttering tinnitus that is not synchronous with arterial pulse
Myoclonus of the tensor tympani, stapedius or palatal musculature
194
Differential diagnosis for pulsatile tinnitus
Arterial: aberrant IAC, carotid atherosclerosis, persistent stapedial artery, AV malformation, carotid artery dissection, vascular compression of cranial nerve eight, glomus tumor
Venous: jugular bulb abnormalities, idopathic intracrnail hypertension, idiopathic pulsatile tinnitus (venous hum)
Non vascular: palatal, stapedial and tensor tympani myoclonus
195
What otoscopic findings might make you suspect a dehiscent or high riding jugular bulb?
Dark blue area behind posterior inferior TM qudarant, possible pulsatile structure may be seen
196
Clinical manifestations of idiopathic intracranial hypertension syndrome
- Headache (90%)
- Pulsatile tinnitus (70%)
- Extremity paresthesias, generalized weakness, hyposmia, abducens palsy, facial paresis, incoordination, CSF leak
197
Symptoms associated with patulous Eustachian tube
tinnitus, aural fullness, autophony, audible respiratory sounds, vertigo
198
Some medications that can cause tinnitus
Apirin containing products, NSAIDs, aminoglycosides, PPIs, certain antidepressants
199
What advantages do vented hearing airs provide?
Decrease in EAC moisture, decrease in occlusion effect, dissipation of low frequency input (advantageous in patients with primarily high frequency hearing loss)
200
What factors should be considered in predicting patient satisfaction with traditional hearing aids?
- Best candidates are those who are motivated
- High frequency losses do better than low frequency
- Severe to profound loss is difficult to aid
- Good word recognition scores will do better
201
Speech reception threshold
the quietest volume at which presented spondaic words can be identified at least 50% of the time
202
Speech discrimination score
The percentage of time that a presented word is correctly identified
203
Which patients are candidates for bone anchored hearing aid placement?
BAHAs are approved for children 5 years an older or patients with conductive or mixed hearing loss and patients with single sided deaness and normal hearing in the contralateral ear.
204
What cells are directly stimulated by CI electrodes?
Spiral ganglion cells found in the modiolus of the cochlea
205
If facial nerve stimulation occurs with CI use how should this be managed?
The offending electrodes can be selectively deactivated or removed from the patient's programming strategy
206
What are the FDAs audiometric candidacy criteria for CIs?
Severe to profound SNHL (>70dB) with <50% sentence testing in the ear to be implanted and < 60% in the contralateral ear or best aided condition
207
Absolute contraindications to CI
Absent cochlea, congenitally absent cochlear nerve, deafness secondary to brainstem lesion, previously resected cochlear nerve
208
Most common indication for revision CI surgery
Documented internal device failure
209
What conditions are associated with an unusually high prevalence of nonauditory stimulation (pain, vertigo, facial nerve activation)
with CI use?
- Otosclerosis: less dense otospongiosis bone may permit aberrant stimulation pathways resulting in higher prevalence of facial nerve stimulation
- T bone fractures: may allow abnormal electrical stimulation and frequently associated with pain
210
Ideal position of CI electrode within the cochlea
Perimodiolar within scala tympani
211
Potential advances of implantable middle ear hearing aids
Enhanced cosmesis, comfort, discrimination, minimized feedback, elimination of occlusion effect, permits amplification during bathing or swimming
212
Candidact critera of implantable middle ear hearing devices
> than 18 years of age with moderate to severe SNHL and have tried conventional amplification before implantation
213
Mechanism behind implantable middle ear hearing aids
They use either piezoelectric or electromagnetic platforms that transform sound signal into mechanical energy that is directly coupled to the ossicular chain
214
Primary implant criteria for auditory brainstem implantation in the US
Bilateral eighth nerve schwannomas (NF type 2) age > 12 years
215
Typical outcome with auditory brainstem implantation in patients with NF2
Receive limited sound perception that augments lip reading. Few patients experience open set speech understanding
216
Functions of cerumen
- Cleansing, lubricating, antimicrobial
- Lysozyme, saturated fatty acids, lower pH of cerumen provide antifungal and antibacterial properties
217
What audiometric findings would you expect in a patient with severe cerumen impaction?
- High frequency conductive hearing loss
- Type B tympanogram, low volume
218
Clinical presentation of chondrodermatitis nodularis chronica helicis
Intensly painful nodule located on the helix or antihelix that is commonly pale gray or erythematous
219
Common sequence of repair during microtia surgery
1. Helix formation with rib cartilage (patient must be at least 6 years of age)
2. Lobule formation
3. Atresiplasty
4. Formation of tragus
5. Postauricular release
220
Jahrsdoerfer grading scale score for congenital aural atresia
Stapes bone - 2
Oval window open - 1
Middle ear space - 1
Facial nerve - 1
Malleus incus complex - 1
Mastoid pneumatization - 1
Incus stapes connection - 1
Round window - 1
External ear - 1
Total possible score: 10
221
Indications for surgical treatment of EAC exostoses?
Patients with chronic or recurrent otitis externa, trapping of debris, or if conductive HL develops
222
How can exostoses be differentiated from osteomas on clinical exam?
Exostoses are commonly multiple, medial and frequently bilateral as opposed to osteomas which exist as single lesions
223
Where are osteomas of the ear canal most likely to develop?
The bony cartilaginous junction
224
Describe exam findings of keratosis obturans
Demonstartes a dense plug of keratin that completely blocks and may wident the EAC. It involves the entire circumference of the ear canal while cholesteatoma often has focal erosion
225
Clinical manifestations of relapsing polychondritis
Inflammation of the auricle that spares the lobule. May also affect joints, nose, eyes, respiratory trach, inner ear, CVS and skin
226
Describe the appearance of seborrheic dermatitis of the auricle
- Inflammatory condition of the skin, generally limited to the oil rich regions
- Wide range of severity
- Can be restricted to ear but often involves scalp, face, upper trunk and axillae
227
Clinical presentation of auricular tophi
Moderately painful pink nodules most commonly involving the helix that contain chalky white material
228
Common initial treatments for fungal otitis externa
- Acidifying (aluminum sulfate calcium acetate) or drying agents (boric acid)
- Antifungal creams such as clotrimazole may also be used
229
What is the most commonly cultured fungus in cases of otomycosis?
Aspergillus spp.
230
Define atticotomy and describe the typical indications of this approach in the context of chronic ear disease
Atticotomy involves the removal of a portion of the scutum (lateral epitympanic wall) to visualize and access the epitympanum. This technique is often used in patients with limited cholesteatoma or retraction pockets and small contracted mastoids and can be performed in conjunction with tympanoplasty and OCR
231
Define Prussak space
A recess bordered laterally by the pars flaccida, superiorly by the scutum and lateral malleolar ligament, inferiorly by the short process of the malleus and medially by the neck of the malleus
232
Three most common sites of origin for cholesteatoma
Posterior and anterior epitympanum and posteriosuperior mesotympanum
233
Anatomical limits of the sinus tympani
Superiorly- ponticulus
Inferiorly - Subiculum
Laterally - mastoid segment of facial nerve
Medially - Posterior semicircular canal
234
Signs and symptoms of labyrinthine fistula secondary to chronic otitis media
Most commonly involves lateral canal. Patient show mixed hearing loss, intermitten dizziness, sound induced vertigo
235
What is the difference between a radical and modified radical mastoidectomy?
Radical mastoidectomy: complete removal of malleus, incus, TM and middle ear mucosa, cavity is left open
Modified radical mastoidectomy the middle ear space is reconstructed
236
Wullstein classification system for tympanoplasty
Type 1: all ossicles are present and mobile
Type 2: The TM is grafted to an intact incus and stapes
Type 3: The TM is grafted onto stapes superstructure
Type 4: The TM is grafted onto stapes footplate
Type 5: Semiciruclar canal fenestration
237
What are the most common causes of persistent otorrhea after a canal wall down mastoidectomy?
Inadequate meatoplasty, failure to lower the facial ridge, mucosalization, exposed eustachian tube
238
Advantages and disadvantages of lateral graft tympanoplasty
Advantages: commonly used for total, near total or anterior perforations
Disadvantages: technically difficult, blunting (loss of acute anterior canal angle), lateralization (separation of graft from malleus)
239
Rate of persistent TM perforation after tympanostomy tube placement?
2-5%
240
Sade grading system for TM retraction
Grade 1: simple, shallow, generally self cleaning and nonadherent
Grade II: contacting incus or stapes
Grade III: contacting the promontory without adhesion
Grade IV: adhesion to promontory
Grade V: grade III or IV with perforation
241
Why is the posterior superior quadrant of the pars tensa particularly susceptible to retraction?
This area is highly vascular which may lead to increased inflammation with infection resulting in thinning. The middle fibrous layer is this area is also incomplete and often absent and therefore has less support
242
If appropriately treated what is the prognosis for facial nerve paralysis in children with facial paralysis secondary to acute otitis media?
Greater than 95% will have full recovery
243
Three primary mechanisms of developing intracranial infection from otitis media
- Direct extension after bone erosion or through existing congenital or acquired defects
- Propagating thrombophlebitis of venous channels originating within the mastoid
- Hematogenous seeding
244
What intracranial complication of otitis media is associated with "picket fence" spiking fevers?
- Lateral sinus thrombosis
- Septic emboli from the thrombus are believed to cause the spiking fevers
245
What is the Tobey-Ayer or Queckenstedt's test?
To evaluate for lateral sinus thrombosis, the internal jugular vein is compressed on one side while intracranial pressure is being monitored. In a positive test compressing on the side ipsilateral to the thrombosis should result in no change while compression on the contralateral side will cause rapid rise in pressure
246
Why is the abducens nerve the most commonly affected cranial nerve in cases of petrous apicitis?
The abducens nerve travels through the Dorello canal at the petrous apex, rendering it susceptible to compression if surrounding inflammation
247
How does a subperiosteal abscess of the mastoid develop?
Acute coalescent mastoiditis leads to erosion of the mastoid cortex and pus can track into the subperiosteal plane, presenting as an area of fluctuance
248
Griesinger sign
Postauricular edema and tenderness thought to result from septic thrombosis of the mastoid emissary vein
249
Most common intracranial complication of acute otitis media
- Meningitis is most common and brain abscess is most lethal
250
Incidence of malleus fixation
0.5-2%
251
In reference to stapes surgery what is a perilymph gusher?
Excessive flow of perilymph encountered when opening the vestibule during stapes surgery
252
What conditions place a patient at high risk for perilymph gusher at the time of stapedotomy or cochlear implantation?
Patients with cochlear and labryinthine malformations, particularly enlarged vestibular aqueduct and Mondini malformations are at highest risk.
A young male with mixed hearing loss should raise concern for X linked stapes gusher syndrome
253
What genetic disorder of bone development can cause a clinical presentation similar to that of otosclerosis?
Osteogenesis imperfecta
254
Schwartze sign
A rosy hue seen through a transparent TM resulting from increased blood around the promontory during active otospongiosis
255
Carhart notch
An artificial depression in bone conduction thresholds centered at 2kHz that is thought to result from disruption of ossicular resonance from stapes ankylosis. It is not specific to otosclerosis
256
Describe the phenomenon of paracusis of Willis
Pts with conductive hearing loss hear better in noise. It is thought to result from the dampening of background noise by a conductive hearing deficit and the fact that people tend to speak louder and more directly when competing with background noise
257
What is overall incidence of significant SNHL after stapedectomy?
0.5-1%
258
What is the most common cause of early stapedectomy failure?
Displacement or slippage of prosthesis
259
How is a depressed footplate addressed during stapedectomy?
If the footplate is deeply depressed or no longer visible removal should not be attempted. If the footplate is readily visible and accessible a small hook may be used to deliver the footplate from the stapedectomy. A vein or fascia graft can then be used to seal the oval window and a prosthesis can be placed.
260
What is the treatment of otosclerosis in a patient's only hearing ear?
Stapedotomy usually contraindicated due to risk of SNHL. Amplification is first line if it is the patient's only hearing ear
261
If encountered during stapedectomy how should a persistent stapedial artery be managed?
- Bipolar or laser coagulation
- If the footplate is able to be visualized and the vessel occupies only a small portion of the footplate can continue with fenestration
- In cases of larger caliber vessel may need to abort procedure
262
What is the natural history of dysgeusia after chorda tympani nerve injury resulting from otologic surgery?
More than 90% of patients will have complete symptomatic recovery by 1 year
263
For what does the NF2 gene code?
The NF2 gene is a tumor suppressor gene located on chromosome 22q12.2 and it codes for the schwannomin or Merlin protein
264
Diagnostic criteria for NF-2
- Bilateral vestibular schwannomas
- First degree relative with NF-2 and the occurrence of a unilateral vestibular schwannoma or any two of the following: meningioma, neurofibroma, schwannoma, glioma or posterior subcapsular lenticular opacities
- Unilateral vestibular schwannoma and any two of the following: meningioma, neurofibroma, schwannoma, glioma or posterior subcapsular lenticular opacities
- Multiple meningiomas and a unilateral vestibular schwannoma or any two of the following: schwannoma, glioma, neurofibroma, cataract
265
What % of NF-2 patients have a family history of disease
Approximately 50% of cases are inherited, 50% develop from spontaneous mutation
266
What are the two subtypes of NF-2
- Gardner (mild) phenotype: development of a limited number of intracranial tumors at a later age with slow progression
- Wishart (severe) phenotype: development of innumerable intracranial and spinal tumors early in life with rapid progression
267
Common indications for a translabryinthine approach for resection of vestibular schwannoma
Patients with non-serviceable hearing or with tumors >2cm where the prospect of hearing preservation is low
Advantages: minimal brain retraction, less risk of prolonged headache, and reliable early facial nerve identification at the fundus
268
Trautmann triangle
The dura of the posterior fossa located between the bony labyrinth anteriorly, the sigmoid sinus posteriorly, the superior petrosal sinus superiorly, and the jugular bulb inferiorly
269
What is the initial treatment of a venous air embolism supplied by a large rent in the sigmoid sinus?
Irrigate the wound, place wet Gelfoam over the opening to block "air sucking." Place the patient in the left lateral decubitus (Durant maneuver) and Trendelenburg position to trap the air pocket in the right heart. Administer 100% oxygen. Perform cardiopulmonary resuscitation if cardiorespiratory collapse ensues.
270
Describe the orientation of the seventh to eighth nerve bundle at the fundus of the IAC
- Facial nerve (VII): anterior superior
- Superior vestibular: posterior superior
- Cochlear: anterior inferior
- Inferior vestibular: posterior inferior
271
Describe Mike's dot
The origin of the superior vestibular nerve in the medial wall of the vestibule
272
What are the common indications for a middle fossa approach for resection of a vestibular schwannoma?
Patients with serviceable hearing who have intracanalicular tumors or no more than 0.5-1cm extension into the CPA.
Advantages: ~50% change of hearing preservation
Disadvantages: temporal lobe retraction
273
To minimize greater superficial petrosal nerve injury during a middle fossa approach, in which direction should dural elevation proceed
From posterior to anterior
274
Common indications for retrosigmoid approach for resection of vestibular schwannoma?
- May be considered for patients with serviceable hearing and medial based tumors.
Disadvantages: cerebellum retraction, headache and potentially limited access to the lateral IAC when hearing preservation is attempted
275
Superficial landmarks for approximating the transverse and sigmoid sinus
The asterion approximates the location of the junction of the transverse sinus and sigmoid sinus and is often used during retrosig. Asterion is defined by the junction between the lambdoid, parietomastoid and occiptomastoid sutures.
276
What % of patients with a vestibular schwannoma and "useful" hearing who undergo sterotactic radiosurgery will lose their hearing
Less than 25% of patients will retain useful hearing after sterotactic radiosurgery at 10 years after treatment
277
What % of vestibular schwannomas are associated with NF-2
5%
278
What % of intracanalicular vestibular schannomas will remain stable in size for the first 5 years after diagnosis
50-80%
279
Where along the eighth nerve are vestibular schannomas hypothesized to arize from?
Obersteiner-Redlich zone, near the porus acousticus, 1cm from the brainstem
280
Hitselberger sign
Loss of sensation in the posteriorsuperior part of the EAC and conchal bowl supplied by the sensory division of CN VII
281
Most common histologic classification for vestibular schwannomas
Antoni type A and B
Type A: tissue demonstrates dense cellularity with nuclear palisading and associated Verocay bodies
Type B: loose arrangement with a less cellular reticular pattern in a myxoid stroma
282
How are CPA meningiomas radiographically different from vestibular schwannomas?
Meningiomas are sessile, demonstrating a broad base along the petrous ridge and they have dural "tails." They often cause hyperostosis of the adjacent underlying bone and may have intratumoral calcifications. Vestibular schwannomas have a globular appearance and are centered over the IAC.
283
From what meningeal layer do meningiomas originate?
The arachnoid cap cells of the outer surface of the arachnoid mater
284
What % of paragangliomas will prove to be malignant?
~4%
285
From what cells do glomus tympanicum tumors originate?
Cells of neural crest origin arising from the tympanic branch (Jacobson's nerve) of the glossopharyngeal nerve
286
Describe a positive Brown's sign
- Blanching of a middle ear mass when performing pneumatic otoscopy
- May be seen with glomus tympanicum or glomus jugulare tumors
287
What is the most appropriate management of glomus tympanicum tumor limited to the promontory?
Transcanal tumor removal
288
What is the most appropraite management of glomus tympanicum tumor that fills the midle ear and extends into the mastoid air cells?
Tympanomastoidectomy with extended facial recess approach and tumor removal
289
What % of glomus tumors will have a secretory component
1-3% will have elevated catecholamine levels
290
Classic radiographic findings of glomus jugulare on temporal bone CT
Homogenous soft tissue mass centered over an enlarged jugular foramen with "moth eaten" irregular bony margins
291
General approach to treatment of petrous apex cholesterol granuloma
Rather than excision treated with drainage procedures via transcanal, transmastoid or transsphenoidal approach
292
How can cholesterol granuloma be differentiated from an epidermoid cyst on imaging?
Classically, cholesterol granulomas appear on T1 and T2 as hyperintense expansile lesions of the petrous apex that do not enhance with gadolinium.
Epidermoids commonly demonstrate low intensity on T1 and high intensity on T2. Diffusion weighted MRI will reveal diffusion restriction and epidermoids will appear bright
293
How can you radiographically differentiate an IAC/CPA lipoma from a vestibular schwannoma or meningioma
A lipoma is hyperintense on precontrast T1 weighted MRI and will subtract with fat suppression techniques
294
Management of IAC/CPA lipomas
Usually watchful waiting. Surgical resection reserved for patients with intractable symptoms related to mass effect
295
From where do skull base condrosarcomas most commonly arise?
Chondrocytes of the foramen lacerum at the petroclival synchondrosis
296
Most common location from which a skull base chordoma arises?
Chordomas are tumors that arise from remnants of the notochord. There can occur anywhere along the axial skeleton but at the skull base are almost invariably found at the clivus.
297
What % of patients with von Hippel Lindau will develop endolymphatic sac tumors?
~10%
298
What is the primary management strategy for endolymphatic tumors?
Complete surgical resection
299
Most common cranial neuropathies see with neurosarcoidosis
- Optic nerve, facial nerve, eighth nerve
- Up to 50% of patients will have at least one cranial nerve palsy
300
Classic features of Melkersson Rosenthal syndrome
- Recurrent orofacial edema, recurrent facial nerve paralysis, and lingua plicata (fissured tongue)
- Classic triad is seen only in a minority of patients
301
Which sensory ganglion is believed to harbor latent varicella virus that becomes reactivated in cases of herpes zoster oticus
The geniculate ganglion
302
Where is the narrowest part in the fallopian canal?
At the meatal foramen which marks the start of the labyrinthine segment
303
Primary indication for rehabilitation of facial paralysis using dynamic muscle procedures such as temporalis tendon transfer
Long standing facial paralysis (>2 years) is not amenable to primary reanastamosis, cable grafting or jump grafts because facial motor endplates are no longer viable. Patients in these groups may be candidates for muscle transfer techniques (temporalis, masseter free gracilis transfer)
304
What subset of patients with facial nerve paralysis are candidates for rehabilitation with facial-hypoglossal transfer?
Direct reinnervation (either primary anastomosis or cable grafting) is preferable, but when the proximal nerve stump is not available and the target facial motor endplates are still viable (within 12-18 months), facial-hypoglossal transfer is an option
305
What is the significance of a completely unresponsive facial nerve after high level proximal electrical stimulation at the end of surgery?
It denotes complete conduction block, but without a subsequent examination to determine whether wallerian degeneration has occurred, a single test at the time of injury cannot differentiate between a simple neuropraxia and a transected nerve.
306
What is the mechanism of gustatory lacrimation after facial nerve injury?
Caused by a lesion proximal to the geniculate ganglion where fibers destined for the submandibular/sublingual glands reinnervate the lacrimal gland.
307
Describe the histologic appearance of fibrous dysplasia
Replacement of normal bone with benign fibrous tissue and irregular trabeculae of immature woven bone ("Chinese character appearance")
308
What are indications for surgical treatment of fibrous dysplasia of the skull base or craniofacial skeleton?
Only symptomatic patients should undergo surgery (cranial neuropathies, vision loss, disfigurement)
309
What clinical findings are seen in McCune Albright syndrome?
Polyostotic fibrous dysplasia, abnormal skin pigmentation (cafe au lait spots), endocrine dysfunction (precocious puberty in girls)
310
What is the treatment for hearing loss secondary to Paget disease of bone involving the temporal bone?
Medical therapy consisting of bisphosphonates and calcitonin is mainstay of therapy. Amplification may be considered. Generally hearing loss from bony abnormalities attributable to Paget disease is not correctable by surgical intervention
311
Most common cutaneous malignancy involving the auricle
Basal cell carcinoma
312
What is the most common ceruminous gland malignancy of the external auditory canal
Adenoid cystic carcinoma
313
Common risk factors associated with development of temporal bone malignancy
Fair skin, immunocompromised, sun exposure, recurrent otitis externa, previous radiation
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Most common types of temporal bone malignancy
~70% SCC, ~11% BCC, ~4% adenoid cystic carcinoma, ~4% adenocarcinoma
315
When is radiation indicated for patients with EAC SCC
T3-T4 disease, close margins, multiple positive lymph nodes, extracapsular spread, preineural invasion
316
When is lateral temporal bone resection indicated in management of SCC of the EAC?
Disease that is limited to the EAC, without significant extension into the mastoid, middle ear or beyond (T1 or T2 disease)
317
What is the most common malignancy of the petrous apex?
Metastasis (breast). The low-flow marrow of the petrous apex is particularly susceptible to hematogenous metastasis.
318
What is the most common malignant tumor of the temporal bone in children?
Rhabdomyosarcoma, embryonal subtype
319
What is the appropriate initial management strategy for a carcinoid tumor of the middle ear?
Complete excision. This is a low grade malignancy with the potential for local recurrence and regional metastasis.
320
Where is the most common site of ossicular chain disruption in the setting of temporal bone fracture?
The incudostapedial joint
321
What is the most common site of facial nerve injury in t bone fractures
The perigeniculate region (80+%)
322
Symptoms of perilymphatic fistula
Fluctuating hearing loss, intense vertigo that worsens with valsalva or exertion
323
Describe the most common mechanism of malleus handle fracture
Often caused by placing a wet finger int he ear canal. When the finger is withdrawn under a seal this creates a negative pressure in the ear canal that can result in fracture of the malleus. Patients often report a "pop" with sharp pain and immediate hearing decline.
324
In what fluids can beta 2 transferin be found?
CSF, perilymph of the inner ear, vitreous humor of the globe
325
How long is CSF (beta-2-transferin) stable for at room temp?
~4hr at room temp and ~3days when refrigerated (not frozen)
326
How much CSf is contained within the arachnoid space at any given time?
~150mL with daily production of approximately 500mL, which means that CSF volume is turned over approximately three times a day
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Positive reservoir sign
Intermittent CSF rhinorrhea associated with change in head position, which results from pouring of CSF collecting in dependent location of a sinus
328
Hyrtl fissure
An embryonic anomaly that leaves a connection between the middle ear and posterior fossa (between the jugular bulb and otic capsule). It may be a conduit of CSF leak, meningitis, or tumor spread (also known as tympanomeningeal fissure)
329
Possible sources for congenital CSF leaks involving the temporal bone
- Hyrtl fissure
- Dilated cochlear aqueduct
- Dilated fallopian canal
- Enlarged petromastoid canal (subarcuate canal)
- Abnormal connection between IAC and inner ear (cochlear malformations)
330
Cochlear afferent nerves
There are two types of nerve cells. Type I (95%) and Type II (5%). Type I are bipolar neurons which synapse directly on a single inner hair cell. Each inner hair cell has about 20 type I fibers synapsing at it's terminal. Type II are pseudounipolar and synapse on multiple outer hair cells.
331
Fisch infratemporal fossa approaches
All methods involve mastoidectomy and facial nerve dissection and transposition. All approaches are used to resect jugular foramen paragangliomas
Type A: involves anterior facial nerve transposition for access to jugular bulb and foramen, vertical ICA and infralabyrinthine regions
Type B: includes removing zygomatic arch, temporalis muscle, retraction of the condyle, dissection of the horizontal ICA. Exposes sigmoid sinus, petrous apex, clivus and foramen ovale
Type C: requires removing pterygoid plates to expose parasellar region, foramen rotundum and cavernous sinus. Also allows access to the nasopharynx.
332
Which arteries supply the saccule and utricle
Saccule: Posterior vestibular artery (as well as posterior semicircular canal)
Utricle: Anterior vestibular artery (as well as superior and lateral semicircular canal)
333
Most common site of spontaneous perilymphatic fistula
Anterior to the anterior crus
334
What nerves make up the tympanic plexus
the tympanic plexus is formed on the tympanic promontory by branches of Jacobson's nerve (tympanic branch of the glossopharyngeal nerve) and caroticotympanic nerves originating from the internal carotid artery plexus.
335
When to mask
When 40dB difference between test ear air conduction threshold and non test ear bone conduction threshold with circumaural (or a 70dB difference with insert headphones)
Traditionally stated than when there is a >10dB air bone gap in the test ear because there is no interaural attenuation with bone conduction and bone conduction threshold greater than 10dB can cross over to the non test ear.
336
Relationship of schwannoma to the nerve vs neurofibroma
Nerve fibers pass over/around the tumor in a schwannoma and through the tumor in a neurofibroma
