6 Otology Flashcards
1
Q
1 Describe the sensory innervation of the pinna and external auditory canal (EAC).
A
Sensation of the auricle is provided by the greater auricular and lesser occipital nerve (from the cervical plexus), as well as small sensory branches of the facial nerve and auriculotemporal nerve. The EAC is supplied by overlapping contributions from cranial nerves (CN) V, VII, IX, and X.
2
Q
2 What is the foramen of Huschke?
A
The foramen of Huschke is a developmental defect resulting from incomplete fusion of the greater and lesser tympanic spines. When present, it creates a connection between the EAC and the parotid gland, glenoid fossa or infratemporal fossa.
3
Q
3 What are the fissures of Santorini?
A
The fissures of Santorini are anatomical communications that allow lymphatic movement between the anterior cartilaginous EAC and the parotid gland and glenoid fossa.
4
Q
4 What is the notch of Rivinus?
A
The notch of Rivinus is the deficient portion of the tympanic annulus where the pars flaccida attaches to the squamous portion of the temporal bone.
5
Q
5 How are the pars flaccida and pars tensa of the tympanic membrane structurally different?
A
The pars flaccida is, as its name implies, more compliant than the pars tensa. The pars tensa is slightly thicker and contains a middle fibrous layer in addition to an outer skin layer and inner mucosal layer.
6
Q
6 The tympanic membrane is formed by what embryonic layer(s)?
A
The outer epidermal layer from the first branchial cleft (ectodermal origin); middle fibrous layer from neural crest mesenchyme (mesodermal origin); inner mucosal layer from the first pharyngeal pouch (endodermal origin)
7
Q
7 Where does the carotid artery lie in relation to the eustachian tube?
A
The carotid artery courses just medial to the more anterior cartilaginous portion of the eustachian tube.
8
Q
8 In patients with cleft palate, dysfunction of which muscle is most strongly implicated in causing recurrent otitis media?
A
Tensor veli palatini
9
Q
9 What is the most common intratemporal location of facial nerve dehiscence?
A
It occurs most commonly near the oval window, second most commonly at the second genu.
10
Q
10 Describe the origin, insertion, and action of the tensor tympani muscle.
A
The tensor tympani originates from the greater wing of the sphenoid, cartilage of the eustachian tube, and the walls of the semicanal of the tensor tympani. Its tendon then wraps around the cochleariform process to insert onto the medial aspect of the neck and manubrium of the malleus. It functions to medialize the tympanic membrane and increase the impedance of the ossicular chain.
11
Q
11 What landmarks may be used to help identify the facial nerve during middle ear surgery?
A
The Jacobson nerve, located on the cochlear promontory, can be followed superiorly to the cochleariform process. The facial nerve is immediately medial and superior to the cochleariform process and tensor tympani. The facial nerve can also be identified immediately superior to the oval window.
12
Q
12 Aside from the muscles of facial expression, what muscles does the facial nerve innervate?
A
In addition to the muscles of facial expression, the facial nerve innervates all the other muscles of the second branchial arch, specifically, the stapedius muscle, the stylohyoid, and the posterior belly of the digastric.
13
Q
13 What is the cog?
A
The cog is 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.
14
Q
14 When looking at the external surface of the mastoid cortex, what landmark can be used to approximate the level of the middle cranial fossa?
A
The temporal line, which represents the inferior insertion point of the temporalis muscle, can be used as a landmark.
15
Q
15 Describe the boundaries of the Macewen triangle (suprameatal).
A
The suprameatal crest, posterior margin of the external auditory canal, and the tangential line from the posterior ear canal bisecting the suprameatal crest are the bounda ries of the Macewen triangle, which approximates the antrum.
16
Q
16 What is the Körner septum?
A
The Körner septum is a bony plate dividing the mastoid air cells superficial to the antrum. Embryologically, it is the junction between the petrous and squamous portions of the temporal bone and creates a “false bottom” during mastoidectomy.
17
Q
17 Which cells are primarily responsible for trans ducing acoustic energy into neural signals?
A
Inner hair cells are the primary cells onto which afferent auditory neurons (spiral ganglion cells) synapse. The outer hair cells also contribute to transformation of acoustic energy into neural signal; however, they primarily play a role in “tuning” the cochlea to improve frequency selectivity and sensitivity
18
Q
18 What are the boundaries of the scala media? (▶ Fig. 6.1)
A
In the cross-section of the cochlea, the scala media is separated from the scala vestibuli by the Reissner membrane. The basilar membrane and osseous spiral lamina separate the scala media and scala tympani.
The boundaries of the outer periphery of the scala media are the stria vascularis and the spiral ligament.
19
Q
19 What two structures are connected by the peril ymphatic (periotic) duct?
A
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.
20
Q
20 Which structures are innervated by the superior and inferior vestibular nerves, respectively?
A
Superior vestibular nerve innervates the superior and lateral semicircular canals and the utricle. Inferior vestibular nerve innervates the posterior semicircular canal, and the saccule.
21
Q
21 Where is the primary auditory cortex located?
A
Brodmann areas 41 and 42 of the upper temporal lobe
22
Q
22 Describe the geometric anatomy of the semi circular canals and the physiologic significance of this arrangement.
A
The three semicircular canals are located in three mutually perpendicular planes. This orientation provides the vestib ular system with independent resolution of rotational movements in three different axes (pitch, roll, and yaw)
23
Q
23 Describe the course and functions provided by the nervus intermedius.
A
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 (CPA) and internal auditory canal (IAC), but on entering the meatal foramen, these fibers exist within the body of the facial nerve.
24
Q
24 What cell bodies are located in the geniculate ganglion?
A
Cell bodies of the special sensory taste neurons carried by the chorda tympani nerve
25
25 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
26
26 What percentage of temporal bone specimens demonstrate dehiscence of the geniculate gan glion on the floor of the middle fossa?
16%
27
27 What is the prevalence of internal carotid artery dehiscence at the floor of the middle cranial fossa?
Approximately 20%
28
28 Describe the boundaries of the Glasscock triangle (posterolateral).
Greater superficial petrosal nerve, V3, line connecting foramen spinosum and arcuate eminence
29
29 Describe the boundaries of Kawase triangle (posteromedial).
V3, greater superficial petrosal nerve, arcuate eminence, superior petrosal sinus. It marks the boundaries of anterior petrosectomy for gaining access to the posterior fossa.
30
30 What extratemporal branches of the facial nerve arborize proximal to the pes anserinus?
The postauricular nerve, nerve to the stylohyoid, and nerve to the posterior belly of the digastric muscle
31
31 The external ear is formed by what mesodermal structures? (▶ Fig. 6.2)
The six hillocks of His: ● First Arch 1: Tragus 2: Helical crus 3: Helix ● Second Arch 4: Antihelix 5: Antitragus 6: Lobule
32
32 Incomplete fusion or supernumerary development of the hillocks of His may lead to what conditions?
Preauricular cysts, pits, or tags
33
33 Describe the embryologic basis of a persistent stapedial artery.
The stapedial artery is derived from the second branchial arch. This is normally a transient structure, but in rare instances, it can persist into adulthood.
34
34 What skull base abnormality is classically seen with a persistent stapedial artery?
Lack of an ipsilateral foramen spinosum
35
35 Describe the embryologic origin(s) of the ossicles.
The head and neck of the malleus, as well as the incus body and short process, are derived from the first branchial arch (Meckel cartilage). The manubrium of the malleus, long process and lenticular process of the incus, and the stapes superstructure are derived from the second branchial arch (Reichert cartilage). The vestibular half of the stapes footplate and annular ligmanent are thought by many authorities to be derived from the otic capsule
36
36 From which germ cell layers and branchial arch(es) does the otocyst arise?
First seen at the end of the 3rd week of development, the otic placode is a thickening of the ecdodermal surface of the first branchial groove. This invaginates into the under lying mesoderm, which it eventually becomes surrounded by to form the otocyst. This structure goes on to develop into the otic labyrinth.
37
37 List the primary acoustic functions of the external ear.
● 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
38
38 Compared with adults, what anatomical charac teristics of the eustachian tube in young children predisposes toward development of acute otitis media?
The eustachian tube is narrower, shorter, and oriented more in a horizontal plane in children, putting the middle ear at a higher risk for exposure to nasopharyngeal secretions and poor aeration.
39
39 Describe the acoustic transformer mechanism of the middle ear.
The three "levers" provide an average gain of 20 to 30 dB: ● Catenary lever: Elastic properties of stretched tympanic membrane fibers directing sound to the centralized malleus ● Ossicular lever: The length of the manubrium of the malleus divided by the length of the long process of the incus (1:3 ratio) ● Hydraulic lever: A 22:1 ratio of the tympanic membrane to the oval window
40
40 Describe the electrolyte composition of the cochlear fluids.
Perilymph located in scala vestibul and scala tympani is similar to serum and cerebrospinal fluid (CSF) in electrolyte composition (high Na and low K concentration). Endolymph is located within the scala media and is similar to intracellular fluid in electrolyte composition (low Na and high K concentration).
41
41 How are movements of the oval window (stapes footplate) and the round window membrane related?
They are out of phase by 180 degrees. In other words, motion at the oval window into the vestibule leads to an outward movement of the round window membrane into the middle ear. If pressure is exerted on both the round window and oval window simultaneously and equally, phase cancellation occurs resulting in significant hearing loss
42
42 Describe the tonotopic organization of the coch lea.
The cochlea (specifically the basilar membrane) is tono topically "tuned," such that the high frequency sounds are most effectively transduced at the basal cochlea, whereas low-frequency sounds are best transduced in the apical segments.
43
43 What effects do ampullopedal and ampullofugal displacement of the semicircular canal kinocilia have on the firing rates of the vestibular nerves?
Ampullopetal (toward the vestibule) displacement of the kinocilia of the horizontal canal and ampullofugal (away from the vestibule) displacement of the kinocilia of the superior and posterior canals increase vestibular nerve firing rates.
44
44 Define first-degree, second-degree, and third-degree nystagmus.
● FIrst degree: Occurring when gazing in the direction of the fast component ● Second degree: Occurring when gazing in the direction of the fast component or at midline ● Third degree: Occurring when gazing in all directions
45
45 Describe Alexander's law?
The amplitude of the nystagmus will intensify when the patient looks in the direction of the fast phase. Alexander’s law describes the pattern of nystagmus in a patient with a unilateral peripheral vestibular deficit.
46
46 Describe Ewald's three laws?
1. The axis of nystagmus parallels the anatomic axis of the semicircular canal that generated it. 2. In the lateral semicircular canals, ampullopetal endo lymph movement causes greater stimulation than ampul lofugal movement. 3. In the superior and posterior semicircular canals, the reverse is true.
47
47 Describe examination findings that help distin guish 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 often less severe. ● Peripheral deficits are unidirectional; horizontal only (no vertical component), suppresses with visual fixation, often with concurrent hearing loss, otherwise normal neurological examination, positional nystagmus that often has a 2 + second latency, generally more severe.
48
48 Describe the direction of nystagmus with irritative and destructive vestibulopathy?
Irritative vestibulopathy is associated with a fast phase beating toward the affected ear, whereas destructive vestibulopathy is associated with a fast-phase beating away from the affected ear.
49
49 What is the purpose of Frenzel goggles?
● Frenzel goggles assist in evaluating for nystagmus. ● Frenzel goggles magnify and illuminate the patient's eyes and prevent gaze fixation.
50
50 What inner ear structure and nerve do thermal calorics testing interrogate?
Thermal calorics measure the responsiveness of the horizontal semicircular canal (and superior vestibular nerve) to thermal stimuli and is one of the few quantitative evaluations that can test the two ears independently.
51
51 Describe the effects of cold and warm irrigation during caloric testing.
Cold causes the fast phase of nystagmus to beat toward the opposite ear, whereas warm causes the fast phase to beat toward the ipsilateral ear.
52
52 How is electronystagmography (ENG) or video nystagmography (VNG) useful in the evaluation of the dizzy patient?
Nystagmography comes in several forms (ENG or VNG) and serves to quantitatively measure eye movements while performing positional testing or calorics.
53
53 What is computerized dynamic posturography?
This technique, used to quantify postural control in an upright (standing) position in either static or dynamic conditions, requires coordination of sensory input, motor output, and central integration.
54
54 What inner ear structure and cranial nerve does VEMP testing interrogate?
Saccule and inferior vestibular nerve
55
55 How is computerized dynamic posturography performed?
The patient is placed on a platform that is capable of performing various movements and sensing patient sway (oscillations). Additionally, a visual backdrop is placed in front of the patient and can be held stationary or can move. The patient is then subjected to six increasingly difficult tests.
56
56 What pattern of results may be seen in a malingering patient during computerized dynamic posturography?
The patient has poor scores with easier tasks, but as the task difficulty increases, the patient may do disproportion ately better.
57
57 What does the dynamic visual acuity test eval uater?
It tests for impaired ability to preceive objects accurately during head movement. Normally, the vestibular ocular reflex maintains the direction of gaze on a fixed target by moving the eyes in the opposite direction of head move ment.
58
58 Dysdiadochokinesia is a sign of dysfunction in volving what structure?
Dysdiadochokinesia, the difficulty with performing rapid alternating movements, is considered a sign of cerebellar pathology.
59
59 How is the Fukuda test performed, and what does it evaluate?
The patient is asked to march in place with eyes closed for 50 steps. Rotation (\> 30 degrees) may indicate asym metrical labyrinthine function. Rotation generally occurs toward the side of the lesion.
60
60 What is purpose of the vestibulo-ocular reflex?
This reflex generates eye movements in response to head motions perceived by the peripheral vestibular system, permitting visual fixation on an object while the head is moving.
61
61 How do you perform a head-thrust test?
The patient is asked to fixate on the examiner's nose while the head is passively and rapidly rotated in the excitatory direction of a semicircular canal. Normally, the patient will be able to maintain fixation on the examiner.
62
62 What constitutes a positive head-thrust test?
In the case of a left hypoactive labyrinth, the vestibulo ocular-reflex will be impaired, and the head-thrust test toward the patient's left side will be positive; the examiner will note the patient's eyes to rotate with the head, and after a brief delay, a "catch-up saccade" toward the right will bring the gaze back toward the examiner.
63
63 Describe the Hennebert sign?
Induction of nystagmus or vertigo with changes in external auditory canal pressure (tragal pressure, pneumatic otos copy)
64
64 What conditions are associated with a positive Hennebert sign?
Superior semicircular canal dehiscence, perilymphatic fis tula, lateral semicircular canal fistula from chronic ear disease, or otosyphilis
65
65 Describe a positive Tullio phenomenon.
Tullio phenomenon is noise-induced activation of the vestibular system resulting in dizziness and/or nystagmus. Historically, it is associated with syphilis but may occur with inner ear fistula and/or dehiscence syndromes.
66
66 How is a Romberg test performed?
The patient stands with feet close together and arms at the sides. The clinician evaluates the relative amount of body sway with the patient's eyes closed compared with when they are open.
67
67 What is a Romberg test evaluating?
Somatosensation and proprioception carried out by the cerebellum and dorsal column-medial lemniscus
68
68 In what clinical situations would rotary chair testing be useful?
Because rotatory chair testing evaluates bilateral semicircular canal function simultaneously (unlike caloric testing), it may be used for evaluating suspected bilateral vestibular loss (after meningitis, vestibulotoxic medications, etc.).
69
69 What symptom is classically associated with severe bilateral peripheral vestibular hypofunction?
Oscillopsia
70
70 Review the differential diagnosis of Ménière disease.
Perilymphatic fistula, vestibular migraine, Cogan syndrome, autoimmune hearing loss, syphilis, mumps, Mondini mal formation
71
71 What percentage of patients with Ménière disease will develop bilateral involvement?
Approximately 30%
72
72 What medical treatments are most commonly used for symptomatic treatment of active Ménière disease?
● Vestibular suppressants (e.g., benzodiazepines prometh azine) ● Rest ● Potentially corticosteroids
73
73 What are the two most commonly used surgical approaches for vestibular neurectomy?
● Middle fossa or the retrosigmoid approach ● Retrolabyrinthine and transmeatal approaches have also been used.
74
74 How does the efficacy of endolymphatic shunt placement compare with endolymphatic sac de compression for treatment of Ménière disease?
No trials have clearly demonstrated superior results in one treatment over the other.
75
75 Review the clinical presentation of Ménière disease.
Low-frequency sensorineural hearing loss (SNHL, fluctuat ing and progressive), roaring tinnitus, aural fullness, and episodic vertigo generally lasting for hours
76
76 Describe Lermoyez syndrome.
Tinnitus and hearing loss that remit after an attack of vertigo
77
77 Define possible, probable, definite and certain Ménière disease.
● Possible: Episodic vertigo without documented hearing loss or SNHL (fluctuating or fixed) with dysequilibrium but without definitive vertigo episodes; other causes excluded ● Probable: One definitive episode of vertigo, audiometri cally documented hearing loss on at least one occasion, tinnitus or aural fullness in the treated ear; other causes excluded ● Definite: 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, other causes excluded ● Certain: Definite Ménière disease plus histopathologic confirmation
78
78 Describe diet modifications for treatment of Ménière disease.
● Avoidance of alcohol, caffeine, tobacco and monosodium glutamate ● Adherence to a low-sodium diet (less than 1 to 2 g/day)
79
79 How is electrocochleography used in the diagnosis of Ménière 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 of Ménière disease.
80
80 How is electrocochleography performed?
Neural responses to presented sounds are recorded through an electrode in the middle ear (transtympanic needle electrode), on the tympanic membrane, or on a gold foil-wrapped earplug.
81
81 What is the role of intratympanic injections of gentamicin in the treatment of Ménière disease?
● Selectively vestibulotoxic ablative treatment for unilateral Ménière disease, often pursued after failure of more conservative measures such as low-salt diet, caffeine avoidance, diuretic therapy, and intratympanic steroid injection ● Carries a 5 to 20% chance of significant SNHL
82
82 What is the role of intratympanic injections of corticosteroids in the treatment of Ménière dis ease?
These injections are onsidered a nonablative adjunct to medical therapy that carries little risk of inducing hearing loss. Subjects may experience a brief episode of vertigo with injection if the steroid is not body temperature and a low risk for persistent tympanic membrane perforation
83
83 When is a patient considered a candidate for endolymphatic sac surgery?
Frequent vertiginous spells despite conservative treatment in patients who are not candidates for ablative procedures (bilateral disease, good residual hearing, contralateral vestibular hypofunction)
84
84 What is the Donaldson line?
The Donaldson line is an imaginary line running parallel to the plane of the lateral semicircular canal, extending posteriorly and inferiorly through the center of the posterior semicircular canal. The endolymphatic sac lies just inferior to this line on the posterior fossa dura
85
85 What pure tone audiometric findings can be seen in patients with superior semicircular canal dehis cence?
Conductive hyperacusis is sometimes seen, with bone conductive thresholds occasionally less than 0-dB hearing loss. This can lead to an air-bone gap even when air conductive thresholds are within the normal range.
86
86 Describe the third window phenomenon.
The third window refers to a third opening in the inner ear, in addition to the round and oval windows, that permits pathological movement of perilymph within the labyrinth, which may induce vertigo
87
87 Describe the clinical presentation of superior semicircular canal dehiscence syndrome.
Aural fullness, autophony, hearing loss (generally with an air-bone gap and often supranormal bone conduction), and dizziness often associated with loud sounds, exertion or straining
88
88 How can one differentiate otosclerosis from supe rior semicircular canal dehiscence syndrome?
Patients with otosclerosis often have type AS tympano grams, diphasic or absent stapedial reflexes, and elevated to absent cervical vestibular evoked myogenic potentials. Patients with superior semicircular canal dehiscence will usually have normal stapedial reflexes, type A tympano grams, and diminished vestibular evoked myogenic poten tial thresholds (often \< 70 dB).
89
89 How do you perform and interpret the Dix Hallpike test?
With the patient sitting, rotate the patient's head by approximately 45 degrees to the left or the right. The patient then lies flat with the head slightly extended (~ 20 degrees). The eyes are then observed for ~ 45 seconds looking for rotary nystagmus. If rotatory nystagmus occurs, the test is positive. The direction of the fast phase reveals the side that is affected.
90
90 Describe the clinical manifestation of benign paroxysmal positional vertigo?
Short-lived (less than 60 seconds), room-spinning vertigo provoked by head turn
91
91 Which semicircular canal is most commonly involved in benign paroxysmal positional vertigo?
Posterior canal. Five percent involve the horizontal canal and the superior canal is the least common.
92
92 What anatomical structure is the source of otoconia in benign paroxysmal positional vertigo?
The utricle
93
93 What are risk factors for the development of benign paroxysmal positional vertigo?
● Advanced age, head trauma, surgery, migraine ● Most patients do not have an identifiable cause (idio pathic).
94
94 Describe the mechanism of singular neurectomy in the treatment of benign paroxysmal positional vertigo.
The singular nerve innervates the posterior semicircular canal, which is the most commonly affected canal in benign paroxysmal positional vertigo. Division of this nerve may lead to symptom relief in refractory disease.
95
95 What conservative treatment options are available for benign paroxysmal positional vertigo?
● Reassurance and education about the nature of the condition ● No effective pharmacologic therapy is available ● Canalith repositioning maneuvers involve taking a patient through a series of positions that are designed to return dislodged otoconia to the vestibule and are the most ffective nonsurgical treatment
96
96 What test(s) should be ordered when vertebro basilar insufficiency is suspected?
● MRI and magnetic resonance angiography (MRA) provide the best information regarding acute and chronic infarcts, as well as the location and severity of vascular occlusions in the head and neck. ● Patients who cannot undergo MRI should be evaluated with CT and CT angiography (CTA). ● Duplex ultrasound can also provide information regarding proximal vertebral arteries.
97
97 What symptoms may accompany episodic vertigo associated with vertebrobasilar insufficiency?
Diplopia, decrease in visual acuity, ataxia, dysarthria, dysphagia, and other focal neurologic symptoms
98
98 Describe the symptoms of Wallenberg syndrome.
● Loss of pain and temperature sensation on the ipsilateral face and contralateral body, dysphagia, dysarthria, ataxia, vertigo, Horner syndrome, diplopia ● Caused by a lateral medullary infarct supplied by the posterior inferior cerebellar artery
99
99 What are typical initial symptoms of vestibular neuronitis?
● Sudden onset of severe vertigo, nausea, and vomiting lasting days to weeks, often preceded by a viral upper respiratory tract infection ● Unlike labyrinthitis, hearing should remain stable
100
100 What are the mainstays of treatment for vestibular neuronitis?
High-dose corticosteroids, vestibular suppressants in the acute period, antiemetics, and bed rest as needed
101
101 What are the diagnostic criteria for chronic subjective dizziness?
● Subjective unsteadiness or nonvertiginous dizziness that is present for 3 + months and is present most days ● Hypersensitivity to one's own motion and to the move ment of objects in the environment ● Visual dizziness marked by exacerbation of symptoms in settings with complex visual stimuli (grocery stores) or when performing precision visual tasks (reading or working on the computer)
102
102 What are the treatment options for chronic subjective dizziness?
First-line pharmacologic therapy includes selective seroto nin reuptake inhibitors. For patients with concurrent migraine, selective serotonin norepinephrine reuptake inhibitors or tricyclic antidepressants may be used. Behav ioral intervention and psychoeducation serve as comple menting therapies.
103
103 Describe the typical presentation of mal de débarquement syndrome.
The sensation of rocking or swaying back and forth without vertigo, difficulty concentrating, and fatigue. It most commonly occurs in middle-aged women after a week-long cruise. The mean duration of symptoms is 3.5 years.
104
104 What is the mechanism of motion sickness?
Disagreement between vestibular cues and visual and somatosensory input
105
105 Excluding benign paroxysmal positional vertigo, what is the most common cause of vertigo in the general population?
Vestibular migraine, or migraine-associated vertigo, is estimated to have a prevalence of ~ 1% in the general population
106
106 What are the diagnostic criteria for vestibular migraine?
Definite vestibular migraine ● 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 by appropriate investigations Probable vestibular migraine ● Recurrent episodic vestibular symptoms of at least moderate severity ● One of the following: ○ Current or previous history of migraine ○ Migrainous symptoms during ≥ 2 attacks of vertigo ○ Migraine precipitants before vertigo in more than 50% of attacks ○ Response to migraine medications in more than 50% of attacks ○ Other causes are ruled out by appropriate investiga tions.
107
107 Describe the relationship between vestibular mi graine and Ménière disease.
There is substantial overlap between groups. Approximately one-fourth of patients with Ménière disease also fulfill diagnostic criteria for vestibular migraine.
108
108 Describe the clinical features of basilar migraine.
● Similar symptoms to vertebrobasilar insufficiency with headache ● Most patients experience dizziness but may also experi ence ataxia, hearing loss, tinnitus, dysarthria, diplopia, and syncope. ● It most commonly involves young females.
109
109 Describe the common neurotologic examination findings in patients with multiple sclerosis.
Abnormalities of smooth pursuit (96%), saccadic eye movements (76%), optokinetic nystagmus (53%), and defective visual suppression of nystagmus (43%)
110
110 What is the Charcot triad?
Nystagmus, scanning speech, and intention tremor; asso ciated symptoms of multiple sclerosis
111
111 Define balance retraining therapy.
Specialized form of physical therapy focusing on the improvement of static and dynamic balance and gait, and promoting central vestibular compensation by taking advantage of the inherent plasticity of central balance pathways
112
112 What are the two phases of vestibular recovery after an acute vestibular insult?
● Static recovery (initial phase) occurs through a central adaptive process that rebalances tonic neural activity between vestibular nuclei ● Dynamic recovery (second phase) involves recalibrating brain and cerebellar reflex pathways in response to sensory conflicts occurring with head and eye move ments
113
113 Describe the clinical findings during static com pensation and dynamic compensation.
During static compensation, patients will often have marked spontaneous nystagmus and vertigo lasting from days to weeks. During dynamic compensation, patients may experience general imbalance and unsteadiness with quick head turn
114
114 With regard to vestibular rehabilitation, describe the strategy of adaptation.
Exercises aimed at improving vestibule-ocular response (VOR) gain. Initially, the patient is asked to view a stationary object while moving the head back and forth. The same exercise can be repeated but with the object moving in the opposite direction of head turn. This will strengthen gaze stability through improvement of the VOR response.
115
115 With regard to vestibular rehabilitation, describe the strategy of habituation.
Patients may be exposed to repetitive visual, vestibular, or motor exercises that are designed to provoke episodes of imbalance. With repetitive exposure, there is an attenuation or modification of the response.
116
116 With regard to vestibular rehabilitation, describe the strategy of substitution.
Exercises designed to take advantage of alternate intact balance mechanisms (remaining vestibular function, visual input, somatosensory input) to compensate for specific balance system deficits
117
117 Describe the ideal candidate for vestibular reha bilitation.
Patient with stable unilateral vestibular hypofunction who continues to feel general imbalance that is worsened by quick head movements
118
118 What patients are not good candidates for vestibular rehabilitation?
Central compensation requires consistent and predictable peripheral vestibular input; therefore, patients with un stable vestibular deficits (e.g., active Ménière disease, acute viral labyrinthitis) should not enter vestibular rehabilitation until their condition has stabilized.
119
119 Name several conditions that negatively influence the outcome of vestibular rehabilitation.
Coexisting conditions that affect balance may result in less optimal outcomes than in patients with isolated stable vestibular hypofunction. Examples include central nervous system disorders (stroke, multiple sclerosis, Parkinson disease), sensory neuropathy (diabetes, peripheral vascular disease), motor dysfunction, and patients with vestibular migraine, to name a few
120
120 Which medications potentially retard progress during vestibular rehabilitation?
Anticonvulsants and sedating medications may prolong vestibular rehabilitation. Additionally, vestibular suppressive medications hinder initial static compensation.
121
121 To what does presbystasis refer?
Presbystasis refers to the general balance difficulties of elderly patients that is related to cumulative age-related decline in vestibular response, visual acuity, proprioception, and motor control.
122
122 Name the four different subclasses of presbycusis.
● Sensory: Loss of sensory hair cells of the basal turn, resulting in a precipitous high-frequency SNHL and preserved speech discrimination ● Neural: Loss of VIII nerve fibers where speech discrim ination may be disproportionately affected ● Metabolic: Caused by atrophy of the stria vascularis affecting all frequencies (flat audiogram); speech dis crimination is frequently preserved ● Mechanical: Caused by stiffening of the basilar mem brane, resulting in a gradual down sloping SNHL with proportional loss of speech discrimination
123
123 Define mild, moderate, severe, and profound hearing loss.
● Mild = 26 to 40 dB ● Moderate = 41 to 55 dB ● Moderately severe = 56 to 70 dB ● Severe = 71 to 90 dB ● Profound \> 90 dB
124
124 At what air-bone gap range is Rinne testing (512-Hz tuning fork) most reliable at detecting a conductive hearing loss?
Between 17 and 30 dB; any value lower or higher is more likely to produce a false negative result.
125
125 What is the usual air-bone gap seen with a maximal conductive hearing loss?
Roughly 60 dB
126
126 What is the interaural decibel difference required for a Weber examination to lateralize?
Sound should lateralize to the ear with the largest conductive loss or the side with the "better nerve"; a minimum of a 5 dB difference is needed.
127
127 Describe the reliability of bedside hearing screen ing. (▶ Fig. 6.3; ▶ Fig. 6.4)
Finger rub, watch-tick, whispered speech, Rinne test, and Weber test all carry a relatively good specificity (60 to 100%), but they have low sensitivity (\< 50%).
128
128 Define hearing level as it relates to measurement of sound intensity.
Hearing level is a measurement (in decibels) relative to reference data from normal-hearing ears. Normal sensitivi tiy is defined as decibels of hearing level, which varies in absolute intensity at different frequencies because of different frequency sensitivities of the average healthy human ear
129
129 Describe the anticipated test-retest variability seen with pure tone audiometry.
Test-retest variability should be 10 dB or less.
130
130 Define asymmetric hearing loss.
Interaural differences of greater than 15 dB in two or more pure-tone thresholds or a difference of greater than 15% on speech discrimination testing
131
131 What are the advantages of binaural hearing?
Horizontal plane sound localization and improved speech understanding in noise from summation, squelch, and head shadow effect
132
132 Describe two mechanisms that permit sound localization from an "off-center" source in the horizontal plane (left- or right-sided).
● Interaural time difference: Sound will reach the closest ear first (low-frequency dominated). ● 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).
133
133 Why is masking used during audiometric testing?
If sounds presented to the test ear are sufficiently loud, they can cross over to the non-test ear. Interaural attenuation is the loss of intensity that occurs before arriving at the non test ear. If sounds are loud enough to be perceived after interaural attenuation, masking is necessary to obtain an accurate test. Interaural attenuation for air conduction and bone conduction is roughly 40 dB and 0 dB, respectively.
134
134 In audiometric testing, what is meant by the term masking dilemma?
A masking dilemma occurs when the required masking level is loud enough to cross over to the test ear. This most commonly occurs in patients with significant bilateral conductive hearing loss.
135
135 Describe the phenomenon of recruitment.
Recruitment is characterized by minimal difficulty with quiet sounds but having a disproportionately severe noise sensitivity at higher sound levels.
136
136 Describe the phenomenon of rollover.
Rollover is characterized by a paradoxical decrease in speech recognition with increasing sound presentation levels and is associated with retrocochlear lesions
137
137 What are appropriate ages to administer the different methods of behavioral audiometric test ing in children?
● 0 to 5 months: Behavioral observation audiometry ● 5 months to 2 years: Visual reinforcement audiometry ● 2 to 5 years: Conditioned play audiometry ● 5 + years: Conventional audiometry
138
138 Describe how behavioral observation audiometry is performed.
The tester evaluates for changes in patient behavior (e.g., quieting, eye widening, startle) after presentation of unconditioned sound.
139
139 Describe how visual reinforcement audiometry is performed.
The participant is conditioned to provide a specific response when he or she is able to hear a sound. For example, a child turns the head toward the sound source and a toy lights up to reward the behavior
140
140 Describe how conditioned play audiometry is performed.
The participant is conditioned to perform a play activity (e.g., throw a ball, drop a block) when he or she is able to hear a sound. After the child has demonstrated that he or she understands the "game," sound is presented at varying levels to determine frequency specific hearing thresholds and speech reponse threshold.
141
141 What physiologic process generates the auditory brainstem response?
Synchronized responses of specific neuron populations within the auditory pathway, with later waves correspond ing to neuron groups farther down the transmission pathway: ● Wave 1: Distal (lateral) auditory nerve ● Wave 2: Proximal (medial) auditory nerve ● Wave 3: Cochlear nucleus ● Wave 4: Superior olivary complex ● Wave 5: Lateral lemniscus/inferior colliculus
142
142 Why is ABR testing useful in evaluating for retrocochlear pathology?
Abnormally long delays between waves (interpeak latency of Wave 1–5) suggest pathology, such as vestibular schwannoma, that is affecting the conductivity of the neurons that connect structures in the auditory pathway.
143
143 What types of audiometry can be used for evaluation of congenital hearing loss in a 2-month-old infant?
Behavioral observation audiometry, ABR, and otoacoustic emissions
144
144 What are otoacoustic emissions?
Otoacoustic emissions are sound generated by outer hair cells, either spontaneously or evoked by an auditory stimulus, that can be detected by a microphone. They are considered a form of objective audiometry because they do not rely on patient participation. Generally, this type of testing is capable of detecting losses greater than 30 to 40 dB.
145
145 What is the advantage of distortion product otoacoustic emissions over transient evoked otoacoustic emissions?
They are capable of providing frequency specific information.
146
146 What ABR pattern is expected in children with auditory neuropathy?
Severely abnormal or absent ABR with a present cochlear microphonic and otoacoustic emission response
147
147 Describe the following tympanometry patterns (modified Jerger classification) : As, A, Ad, B, and C. (▶ Fig. 6.5)
Tympanometry tests tympanic membrane (TM) compliance (admittance vs middle ear pressure). ● Type A: Normal ● Type As (shallow): Stiffened or hypomobile TM, ossicular fixation (e.g., otosclerosis, tympanosclerosis, malleus fixation), or “glue ear” ● Type Ad (deep): Flaccid or hypermobile TM, ossicular discontinuity, or flaccid TM ● Type B: Flat tracing with no compliance peak. Must combine with canal volume (normal child-adult 0.5 to 1.5 ml) ● Type B (large volume): TM perforation or patent tympanostomy tube ● Type B (normal volume): Middle ear fluid ● Type B (small volume): Cerumen occlusion or probe against side wall of EAC ● Type C: Left shift in peak (negative middle ear pressure) associated with eustachian tube dysfunction
148
148 Describe how stapedial reflex testing is performed.
Tympanometry of the ipsilateral and contralateral tympanic membrane is measured when sound, typically between 80 to 110 dB hearing level, is applied to the ear at different frequencies (500, 1,000, 2,000, and 4,000 Hz). A stapedial reflex is measured as a decrease in compliance, resulting from stapedial muscle contraction
149
149 Describe conditions that may result in an absent or abnormal stapedial reflex.
Conductive hearing loss (e.g., otosclerosis, middle ear disease), severe SNHL, eighth nerve pathology (e.g., vestibular schwannoma), ipsilateral seventh nerve pathol ogy (e.g., Bell palsy)
150
150 Describe the pattern of stapedial reflex testing seen with right-sided retrocochlear pathology.
● The reflexes are always absent when stimulated in the ipsilateral ear. ● Left-sided stimulus: Left response present, right response present ● Right-sided stimulus: Left response absent/elevated, right response absent/elevated
151
151 Describe the stapedial reflex pattern seen with a thick mucoid effusion in the right ear (type B tympanogram) causing a large conductive hearing loss.
● Middle ear effusion can result in dampening of the incoming auditory signal. Also, stapedial reflex detection can be impaired from decreased tympanic membrane compliance. ● Left-sided stimulus: Left response present, right response absent/elevated ● Right-sided stimulus: Left response absent/elevated, right response absent/elevated
152
152 Describe the stapedial reflex pattern seen with bilateral thick middle ear mucoid effusions (type B tympanogram) causing significant conductive hearing loss.
● Left-sided stimulus: Left response absent, right response absent ● Right-sided stimulus: Left response absent, right res ponse absent
153
153 Describe the stapedial reflex pattern seen with proximal right-sided facial nerve pathology.
● The reflexes on the ipsilateral side will be affected. ● Left-sided stimulus: Left response present, right response absent ● Right-sided stimulus: lLft response present, right res ponse absent
154
154 Describe the stapedial reflex pattern seen with a large intra-axial brainstem lesion.
● In practice, the response depends largely on the location of the lesion. However, if the intra-axial lesion is large and affects the bilateral cochlear nuclei and/or the bilateral seventh nerve motor nuclei, then the following pattern may result. ● Left-sided stimulus: Left response absent, right response absent ● Right-sided stimulus: Left response absent, right res ponse absent
155
155 Describe the phenomenon of acoustic decay.
A stimulus is presented in the ear of concern and a contralateral probe is placed. A continuous pure-tone stimulus is presented 10 dB above the stapedial reflex threshold and held for 10 seconds. The test is positive if the magnitude of the reflex drops by more than 50% in 10 seconds.
156
156 What is the difference between the speech awareness (detection) threshold and the speech reception threshold?
● Speech awareness threshold is the minimum volume level (in dB hearing level) at which the subject is able to detect the presence of speech stimuli 50% of the time (although the subject does not need to recognize the word). ● Speech reception threshold is the minimum volume level at which the subject is able to correctly identify a presented word (usually a spondee) 50% of the time.
157
157 If a patient is found to have a PTA of 40-dB hearing level, what can be predicted regarding this patient’s speech detection threshold and speech reception threshold?
Both should correspond with the PTA (average of pure-tone thresholds at 500, 1,000, and 2,000 Hz) within approx imately 5 to 10 dB.
158
158 If there is significant discordance between the pure tone average and the speech detection threshold, what diagnosis should be strongly considered?
Exaggerated hearing loss or pseudohypacusis (factitious hearing loss)
159
159 Described the methods that can be used to evaluate for factitious hearing loss.
● Objective audiometry: OAE and ABR ● Behavioral audiometry: Discrepancy between speech reception test (SRT) and PTA; significant difference in test-retest scores (\> 15 dB) ● Acoustic reflex testing ● Lombard test, Stenger test
160
160 Describe the Stenger test.
Based on the principle that if tones of the same frequency are presented simultaneously to both ears, only the loudest is perceived. Two simultaneous tones with matched fre quency are introduced, but the alleged poor ear receives a tone at a greater intensity (usually \> 20 dB). The truthful patient with normal hearing will report the sound in the ear with the loudest sound level; the truthful patient with asymmetric hearing loss will report the sound in the better hearing ear; and the untruthful subject will deny hearing any sound.
161
161 Describe the Lombard test.
Noise is introduced into the ear with supposed hearing loss while the 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 the loudness of ice, this would support a true hearing l
162
162 Which intrauterine infections are associated with the development of congenital hearing loss?
T Toxoplasmosis O Other, including syphilis, varicella, and parvovirus B19 R Rubella C Cytomegalovirus H Herpes simplex virus
163
163 What factors place a pediatric patient at partic ularly high risk for early SNHL?
● History of intrauterine infection ● Family history of congenital hearing loss ● Low birth weight (\< 1,500 g) ● Hyperbilirubinemia ● Prolonged neonatal intensive care unit stay or prolonged mechanical ventilation ● Concurrent craniofacial anomalies ● Exposure to ototoxic medications ● \< 5 Apgar score at 1 minute, \< 7 Apgar score at 5 minutes ● Bacterial meningitis
164
164 What percentage of congenital hearing loss is genetic?
Approximately 50%
165
165 What percentage of patients with genetic hearing loss will have associated syndromes?
About 70% of genetic hearing loss is nonsyndromic, and 30% is syndromic.
166
166 What percentage of genetic hearing loss is inherited in an autosomal dominant pattern?
80% autosomal recessive, 20% autosomal dominant
167
167 What is the most common form of autosomal dominant hearing loss?
Waardenburg syndrome
168
168 Describe the four subtypes of Waardenburg syndrome.
● WS1: Autosomal dominant, dystopia canthorum, SNHL, iris pigmentary disorder, hair hypopigmentation ● WS2: Autosomal dominant, no dystopia canthorum, SNHL, iris pigmentary disorder, hair hypopigmentation ● WS3: Autosomal dominant, dystopia canthorum, upper limb abnormalities, iris pigmentation disorder, hair hypopigmentation ● WS4: Autosomal recessive, no dystopia canthorum, Hirschprung disease, SNHL, iris pigmentary disorder, hair hypopigmentation
169
169 What are the three most common causes of autosomal recessive syndromic SNHL?
Usher, Pendred, Jervell and Lange-Nielsen
170
170 Describe the three subtypes of Usher syndrome.
● Type 1: Bilateral profound deafness and vestibulopathy at birth; "night blindness," from retinitis pigmentosa, before teens (most severe form) ● Type 2: Moderate to severe hearing loss at birth, worsening vision in young adulthood, and normal vestibular function ● Type 3: Normal hearing at birth with progressive hearing loss and retinopathy by teens, variable vestibular in volvement (mild form)
171
171 What is the most common cause of deaf-blindness in the United States?
Usher syndrome
172
172 Alport syndrome involves faulty synthesis of what protein(s)?
Type IV collagen
173
173 Describe the clinical manifestations of Norrie disease.
X-linked recessive syndrome that results in early rapidly progressive blindness. Progressive SNHL occurs in approx imately a third of patients and usually ensues in the second to third decades of life.
174
174 Describe the classic head and neck manifestations of Pendred syndrome.
SNHL (often associated with enlarged vestibular aqueducts and mondini malformations) and euthyroid goiter
175
175 Describe the thyroid pathology typically seen in Pendred syndrome.
Patients often develop a multinodular goiter in the second decade of life but are usually euthyroid and rarely require intervention.
176
176 What specific precaution should patients diag nosed with enlarged vestibular aqueduct syn drome take to prevent further hearing loss?
Stepwise progression of hearing loss can be seen after minor head trauma. Participation in contact sports or activities associated with "minor head trauma" should generally be avoided.
177
177 Describe the typical presentation of enlarged vestibular aqueduct syndrome.
SNHL generally begins in childhood and often progresses in a stepwise manner. Vestibular symptoms and mixed hearing loss may also develop
178
178 What gene mutation is responsible for approx imately 50% of all cases of genetic hearing loss?
GJB2 encodes connexin 26, located on chromosome 13, autosomal recessive inheritance pattern
179
179 What does the GJB2 gene code for?
Gap junction β-2, responsible for potassium ion exchange of the inner ear
180
180 Describe the clinical manifestations of Jervell and Lange-Nielsen syndrome.
● An autosomal recessive syndrome characterized by congenital profound bilateral SNHL and arrhythmia ● Patients may have syncopal episodes provoked by stress or exercise. ● Sudden cardiac death from arrhythmia may occur if untreated. ● Caused by a defect in potassium channels within the stria vascularis
181
181 Descrie the electrocardiographic findings in Jervell and Lange-Nielsen syndrome.
Long QTc (\> 500 ms) with potential for arrhythmias
182
182 Describe the constellation of findings seen in MELAS syndrome.
ME Mitochondrial encephalopathy LA Lactic acidosis S Stroke Manifestations are variable and include hearing loss, limb weakness, partial paralysis, vision loss and seizures.
183
183 Describe the clinical features of Michel aplasia.
Michel aplasia is characterized by complete failure of inner ear development resulting in congenital anacusis
184
184 Describe the radiographic findings with Mondini malformations.
Mondini malformation accounts for more than 50% of cochlear malformations. The characteristic findings include an incomplete or absent partition and less than 2.5 turns.
185
185 Describe the imaging findings of a common cavity malformation.
The cochlea and vestibule are joined as a single large confluent space. These patients typically have severe to profound SNHL.
186
186 What inner ear abnormalities are seen in Scheibe dysplasia?
Scheibe dysplasia (also called cochlearsaccular dysplasia or pars inferior dysplasia) includes a poorly developed organ of Corti and sacuule, whereas the bony labyrinth, semicircular canals, and utricle are preserved
187
187 What is the most common form of membranous labyrinth dysplasia?
Scheibe dysplasia
188
188 What frequencies are most commonly affected by Alexander dysplasia?
High frequencies resulting from malformation of the cochlear duct and basal turn of the cochlea
189
189 Where is the site of damage in chronic noise induced SNHL?
Outer hair cells are damaged with chronic exposure to loud noise. With brief exposure to extremely loud sound (e.g., explosions), the impulse can lead to trauma of the cochlear membranes
190
190 Describe the characteristic audiogram findings with noise-induced hearing loss.
4-kHZ notch. Hearing loss is almost always bilateral and is greater in the high frequencies compared with lower frequencies.
191
191 Describe the Occupational Safety and Health Administration (OSHA) sound level requirements.
If workplace noise levels are \> 85 dB averaged over an 8- hour period, a hearing-conservation program is required with regular testing. Permissible noise exposure levels are based on duration: 8 hours at 90 dB; 6 hours at 92 dB; 4 hours at 95 dB; 3 hours at 97 dB; 2 hours at 100 dB; 1.5 hours at 102 dB; 1 hour at 105 dB; 0.5 hours at 110 dB; 0.25 hours at 115 dB
192
192 What is the definition of sudden sensorineural hearing loss?
Greater than 30 dB loss over three contiguous pure-tone frequencies occurring within a 3-day period
193
193 What percentage of patients with sudden SNHL can expect to experience some degree of spon taneous recovery?
Approximately two-thirds of patients
194
194 Describe the evaluation of sudden SNHL.
Patients should be evaluated for retrocochlear pathology (MRI with gadolinium), but routine laboratory testing should not be pursued unless there is clinical suspicion for an underlying cause based on history or physical examination
195
195 Review the treatment of idiopathic sudden SNHL.
Options include early oral corticosteroid treatment and hyperbaric oxygen therapy within 3 months of diagnosis. Intratympanic steroid perfusion is offered to patients with incomplete recovery after initial therapy. Routine use of antivirals, thrombolytics, vasodilators, vasoactive substan ces, or antioxidants should be avoided.
196
196 What is the role of CT in evaluating patients with sudden SNHL?
Generally, MRI is preferred over CT. Relative exceptions include patients with focal neurologic findings, recent head trauma, severe claustrophobia, or devices that preclude MRI scanning (e.g., certain pacemakers)
197
197 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
198
198 Describe the diagnostic criteria for primary auto immune inner ear disease.
Characterized by progressive (over weeks to months) bilateral SNHL loss that responds to immunosuppressive treatment (steroids). Other causes of progressive SNHL must be ruled out
199
199 What is the first line of treatment for suspected autoimmune inner ear disease?
High-dose corticosteroids with a prolonged taper
200
200 What is the 68-kD inner ear antigen?
About 20 to 80% of patients with autoimmune inner ear disease will have a positive anti-68 kDa antibody test
201
201 Describe the clinical manifestations of Susac syn drome.
An autoimmune small vessel disease characterized by the triad of encephalopathy, branch retinal artery occlusions and SNHL
202
202 Describe the clinical manifestations of Cogan syndrome.
A syndrome of nonsyphilitic interstitial keratitis and audio vestibular symptoms. Most patients have bilateral sudden progressive SNHL. Dizziness is typically episodic. Although bilateral interstitial keratitis occurs, vision loss is rare. Systemic manifestations commonly include headache and fever.
203
203 What are the potential routes of communication that permit inner ear involvement in patients with meningitis?
Cochlear aqueduct and modiolus
204
204 Which organisms are associated with the highest risk of post-meningitic SNHL?
● Streptococcus pneumoniae ● Neisseria meningitidis ● Haemophilus influenzae
205
205 What percent aggeof patients with bacterial meningitis will develop SNHL?
15 to 20%; 5% have profound loss
206
206 Review the common otologic manifestations of Wegener granulomatosis?
Conductive hearing loss and chronic serous otitis media are most common; however, otalgia, facial palsy, vertigo, SNHL, and external ear involvement can also be seen.
207
207 Describe the differential diagnosis of pulsatile "fluttering" tinnitus that is not synchronous with arterial pulse.
Myoclonus of the tensor tympani, stapedius, or palatal musculature
208
208 Provide a differential diagnosis for pulsatile tinnitus.
● Arterial: Aberrant internal carotid artery, carotid athero sclerosis, persistent stapedial artery, arteriovenous mal formations, aneurysm, carotid artery dissection, vascular compression of cranial nerve eight, vascular tumors (glomus) ● Venous: Jugular bulb abnormalities (high-riding, dehis cence, diverticulum), idiopathic intracranial hypertension, idiopathic pulsatile tinnitus (venous hum) ● Nonvascular: Palatal, stapedial, and tensor tympani myoclonus
209
209 What is the prevalence of carotid artery dehis cence within the middle ear?
Approximately 10%, but rarely does it follow an aberrant course placing it at risk during myringotomy
210
210 What otoscopic findings might make you suspect a dehiscent or high riding jugular bulb?
The most likely area to visualize a dehiscent jugular bulb in the middle ear is behind the posterior inferior quadrant of the tympanic membrane, where a dark blue and possibly pulsatile structure may be seen.
211
211 What is the clinical significance of an empty sella in a patient with pulsatile tinnitus?
Associated with elevated intracranial hypertension (idio thic intracranial hypertension)
212
212 Describe the clinical manifestations of idiopathic intracranial hypertension syndrome.
The most common symptoms are headache (~ 90%) and then pulsatile tinnitus (~ 70%). Other signs and symptoms including extremity paresthesias, generalized weakness, hyposmia, abducens palsy, facial paresis, and incoordination are reported more rarely.
213
213 What constellation of symptoms is commonly associated with patulous eustachian tube?
Tinnitus, aural fullness, autophony, audible respiratory sounds, and vertigo
214
214 List common medications that may cause tinnitus.
Aspirin-containing products (most common), other non steroidal anti-inflammatory drugs (or NSAIDs), aminogly cosides, proton pump inhibitors (omeprazole, esomeprazole), and certain antidepressants
215
215 What device (nonmedicinal) options are available for patients with subjective nonpulsatile idiopathic tinnitus?
Hearing aids, masking devices (deliver constant narrow band white noise to "cover up" ringing), and tinnitus retraining therapy (pitch matched to the patient's tinnitus to theoretically habituate the central auditory system to the noise and eventually neglect it). Cochlear implants improve tinnitus in some patients, but tinnitus itself is not an indication for implantation
216
216 What are assistive listening devices?
Auditory and nonauditory technologies that overcome limitations associated with the physical distance between the sound source and the patient
217
217 Provide examples of auditory and nonauditory assistive listening devices.
● Auditory: Microphone systems that capture the desired sound next to the sound source and transport the signal to the listener using FM, infrared, induction loop, Blue tooth, or hard-wired systems ● Nonauditory: Alarm systems using vibrotactlile or visual signals to alert the patient of an event such as a phone ringing or doorbell activation
218
218 What conservative measures should be discussed with patients who have hearing impairment?
Strategic seating at meetings or events (better ear toward speaker, sitting close to the front), making eye contact with speakers, reducing competing background noise
219
219 Describe the basic components of a hearing aid.
Microphone, amplifier, receiver, power supply
220
220 Define gain as it pertains to conventional hearing aids.
Gain is the difference between the level of input and level of output at any given frequency.
221
221 What advantages do vented hearing aids provide?
Decrease in external auditory canal moisture, decrease in occlusion effect, dissipation of low frequency input (advanta geous in patients with primarily high-frequency hearing loss)
222
222 What factors should be considered in predicting patient satisfaction with traditional hearing aids?
The best candidates are motivated patients who are receptive to the idea of hearing aid use. Those with predominantly high-frequency hearing loss generally do better than those with low-frequency hearing loss. Severe to profound hearing loss is often difficult to aid. Supra threshold speech and speech recognition performance is important; patients with good word recognition when amplification is provided are more likely to report satisfac tion and continued device use.
223
223 Describe the difference between the speech reception threshold and the speech discrimination score.
Speech reception threshold is the quietest volume (in dB) at which presented spondaic words can be identified at least 50% of the time, whereas the speech discrimination score is the percentage of time that a presented word is correctly identified.
224
224 Describe the advantages and disadvantages of the completely-in-canal and the in-the-canal hearing aid.
● Advantages: Discreet size offering enhanced cosmesis; takes advantage of the ear’s innate shape assisting with natural sound amplification and limiting undesirable wind noise ● Disadvantages: Power limitations, cerumen clogging, aural fullness and occlusion effect, difficult fit, fine dexterity requirements, cost, and external ear canal irritation
225
225 Describe the advantages and disadvantages of the in-the-ear hearing aid.
● Advantages: Delivers adequate power to rehabilitate mild to moderately severe losses, more powerful, and easier to manipulate than in-the-canal models ● Disadvantages: Require some manual dexterity for place ment and volume control. Less discreet than in-the-canal models
226
226 Describe the advantages and disadvantages of the behind-the-ear hearing aid.
● Advantages: Most adaptable hearing aid option; delivers enough power to rehabilitate moderately severe to severe hearing loss; generally offers more signal proc essing features; and is easier to handle than smaller devices in patients with poor manual dexterity ● Disadvantages: Larger size, less discreet, pinna irritation
227
227 What is the primary advantage of a body aid?
With severe-to-profound hearing loss, feedback problems occur with ear-level devices because of the close proximity of the microphone to the receiver. The body aid places the microphone at a distant site from the amplifier, typically on a belt or in a pocket
228
228 With regard to hearing aid technologies, what are the primary advantages of digital processing compared with analogue processing?
Beyond affording multiple programs, digital signal pro cessors can selectively amplify specified frequencies, reduce acoustic feedback and background noise, automatically detect changes in listening environments to dynamically optimize signal, and offer enhanced connectivity to external sound sources
229
229 What are directional microphones, and what advantages do they have over standard omnidir ectional technologies?
Directional microphones selectively amplify sounds located in front of the listener, improving the signal-to-noise ratio. Adaptive directional microphones go one step further and are able to vary the direction of maximal amplification.
230
230 Describe the utility of a CROS and BiCROS aid.
The CROS (contralateral routing of signal) aid takes sound from the poorer ear and relays the signal to the better, contralateral ear. The BiCROS (bilateral contralateral routing of signal) aid similarly "throws" sound to the good ear but also amplifies sound in the receiving ear.
231
231 Which patients are candidates for bone-anchored hearing aid placement?
Currently, bone-anchored hearing aids are approved for children 5 years of age or older, patients with conductive or mixed hearing loss who can derive benefit from sound amplification, and patients with single-sided deafness and normal hearing in the contralateral ear.
232
232 What cells are directly stimulated by cochlear implant electrodes?
Spiral ganglion cells, found in the modiolus of the cochlea
233
233 If facial nerve stimulation occurs with cochlear implant use, how should this be managed?
The offending electrodes can be selectively deactivated or removed from the patient's programming strategy.
234
234 What are the Food and Drug Administration (FDA)'s audiometric candidacy criteria for cochlear implantation?
Severe to profound SNHL (\> 70 dB PTA), with \< 50% sen tence testing in the ear to be implanted, and \< 60% in the contralateral ear or best aided condition
235
235 List absolute contraindications to cochlear implantation.
Absent cochlea, congenitally absent cochlear nerve, deaf ness secondary to brainstem lesion, previously resected cochlear nerve
236
236 Describe clinical variables that are associated with good cochlear implant performance.
Age at implantation, prelingual versus postlingual deafness, duration of deafness, preimplant auditory performance, duration of cochlear implant use
237
237 What is the most common indication for revision cochlear implant surgery (reimplantation)?
Documented internal device failure
238
238 What conditions are associated with an unusually high prevalence of nonauditory stimulation (pain, vertigo, facial nerve activation) with cochlear implant use?
● Otosclerosis: Otic capsule bone is replaced with less dense otospongiotic bone, which may permit aberrant stimu lation pathways, resulting in a higher prevalence of facial nerve stimulation. ● Temporal bone fracture: Similarly, previous temporal bone fractures may allow abnormal electrical stimulation, frequently associated with pain.
239
239 Describe the benefits of bilateral cochlear implantation.
Improved speech understanding in noise and directional awareness, as well as the assurance that the "best performing ear" has been implanted
240
240 Theoretically, what is the ideal position of the cochlear implant electrode within the cochlea?
Perimodiolar within the scala tympani
241
241 Describe the potential advantages of implantable middle ear hearing aids.
Enhanced cosmesis, comfort, discrimination, minimized feedback, elimination of occlusion effect, permits amplifi cation during bathing or swimming
242
242 Review the candidacy criteria for implantable middle ear hearing devices.
Candidates should be ≥ 18 years old, have moderate to severe SNHL, and have trialed conventional amplification before implantation. Pediatric patients, those with recur rent or chronic middle ear disease, patients with poor word discrimination, and subjects with fluctuating loss should not undergo implantation.
243
243 What is the 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.
244
244 Review the primary implant criteria for auditory brainstem implantation in the United States.
Bilateral eighth nerve schwannomas (neurofibromatosis type 2, or NF-2), age ≥ 12 years
245
245 What is the typical outcome with auditory brainstem implantation in patients with NF-2?
Most patients receive limited sound perception that aug ments lip reading. Few patients experience open-set speech understanding.
246
246 What are risk factors for development of cerumen impaction?
Use of cotton-tip applicators, narrow canals, hearing aid use, earplug or earphone use, hair in the lateral external auditory canal, developmental delay, advanced age
247
247 Describe the function(s) of cerumen?
● Cleansing, lubrication, and antimicrobial (bacteria and fungus) activity ● Lysozyme, saturated fatty acids, and lower pH of ceru men provide antifungal and antibacterial properties.
248
248 What audiometric findings would you expect to see in a patient with severe cerumen impaction?
● A predominantly high-frequency conductive hearing loss ● Low-volume type B tympanograms
249
249 Describe the clinical presentation of chondroder matitis nodularis chronica helicis.
Intensly painful nodule located on the helix or antihelix that is commonly pale gray or erythematous
250
250 What is the appropriate age for repair in patients with bilateral microtia and congenital aural atresia?
Generally, any repair for microtia or atresia is delayed until the patient is **at least 6 years of age**
251
251 Review the common sequence of repair during microtia surgery.
1. Helix formation with rib cartilage
2. Lobule formation
3. Atresiaplasty
4. Formation of the tragus
5. Postauricular release
252
252 What is the most appropriate initial treatment for an infant with bilateral congenital aural atresia? (▶ Table 6.1)
The most appropriate treatment is application of **bone conduction hearing aids**. Providing amplification is crucial for early hearing and language development, although _surgical procedures (**bone-anchored hearing aid** or **atresia plasty**) are generally delayed until the patient is at least 5 years old._
253
253 What are the indications for surgical treatment of external auditory canal exostoses?
1. Trapping of debris
2. Chronic or recurrent otitis externa
3. Conductive hearing impairment
254
254 How can exostoses be differentiated from osteomas on clinical examination?
**_Exostoses_** are most commonly **multiple, medial, and frequently bilateral,** as opposed to **_osteomas_**, which exist as **single lesions.**
255
255 Where are **osteomas** of the ear canal most likely to develop?
The bony cartilaginous junction
256
256 Review the indications for otomicroscopic removal of an ear canal foreign body (as opposed to blind removal with lavage).
Foreign-body type (e.g., sharp edges, disk battery, vegetable matter), location adjacent to the tympanic membrane, time \> 24 hours in the ear canal, failed previous attempts at removal, in children younger than 4 years
257
257 What is the most appropriate initial treatment for patients with severe frostbite of the auricle?
Rapid rewarming of the ear with warm (38 to 42°C) saline soaked gauze
258
258 Describe the examination findings of keratosis obturans.
Keratosis obturans demonstrates a dense plug of keratin that completely blocks and may widen the EAC. An important distinction between keratosus obturans and canal cholesteatoma is that *keratosis obturans involves the entire circumference of the ear canal while cholesteatoma often has focal erosion.*
259
259 Describe the treatment for psoriasis of the EAC.
This condition is treated in a similar fashion to psoriasis elsewhere. First-line treatments include simple warm-water soaks, application of occlusive ointments (e.g., petrolatum), avoidance of trauma, and use of topical corticosteroids. Other specialized topical or systemic treatments (e.g., methotrexate, cyclcosporin, retinoids) are generally reserved for those with extensive disease.
260
260 What are clinical manifestations of relapsing polychondritis?
Most common initial symptom is **inflammation of the auricle that spares the lobule**. Additional organ systems include the joints, nose (nasal chondritis), eyes (conjunctivitis, scleritis, iritis, keratitis), respiratory tract (laryngeal or tracheal inflammation), inner ear, cardiovascular system, and skin.
261
261 Describe the appearance of seborrheic dermatitis of the auricle.
* Inflammatory condition of the skin, generally limited to oil-rich regions
* It occurs with a wide range of severity, from mild dandruff and flaking to a generalized exfoliating eryth roderma.
* It can be restricted to the ears but more often involves additional areas such as the scalp, face, upper trunk, and axillae.
262
262 Describe the clinical presentation of auricular tophi.
Moderately painful pink nodules most commonly involving the helix that contain chalky white material.
263
263 What is the most commonly cultured organism from the EAC of patients with otitis externa?
Pseudomonas aeruginosa
264
264 Why is water exposure a risk factor for acute otitis externa?
It can lead to **loss of the acidic enviroment** of the EAC. In addition, unclean water may carry a high bacterial load.
265
265 In the presence of a tympanostomy tube or tympanic membrane perforation, how should therapy for acute otitis externa be modified?
Potentially ototoxic medications should be avoided. Specifically, **alcoholic and acidic drops** should not be used, as well as antibiotics with known cochlear toxicity including **aminoglycosides**.
266
266 What is considered first-line therapy for uncomplicated acute otitis externa?
* Pain control, aural toilet, application of ototopical treatments (acidifying/drying agents, antibiotic preparations with or without corticosteroids), and avoidance of risk factors such as water exposure and ear canal trauma
* Systemic antibiotics are not indicated for uncomplicated acute otitis externa in an otherwise healthy patient.
267
267 Describe 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.
268
268 What treatment may be used for patients with chronic hypertrophic otitis externa refractory to maximal medical therapy?
Canaloplasty with split-thickness skin graft resurfacing of the EAC and a generous meatoplasty
269
269 Describe the clinical features of infectious perichondritis and chondritis of the auricle.
**Otalgia** and **pruritus** are the most common symptoms. The auricle is tender, erythematous, and may have flaking/ weeping over the cartilaginous portions of the auricle with sparing of the fatty lobule. Risk factors include trauma and otitis externa.
270
270 What is the most commonly cultured fungus in cases of otomycosis?
Aspergillus spp.
271
271 Define malignant (or necrotizing) otitis externa.
Malignant otitis externa is **progressive osteomyelitis of the temporal bone** that has spread from the external auditory canal. The causative organism is most often Pseudomonas aeruginosa, and this condition ccurs almost exclusively in immunocompromised individuals (commonly elderly diabetics).
272
272 What nuclear medicine study is most helpful in establishing the diagnosis of necrotizing otitis externa?
**Technetium-99m** bone scan detects **_osteoblastic_** activity and is useful for initial diagnosis of osteomyelitis. *However, even after the infection has resolved, the scan remains positive, making it less useful for monitoring response to therapy.*
273
273 What nuclear medicine study is most helpful in evaluating treatment response in patients with necrotizing otitis externa?
**Gallium-67** nuclear medicine scan is useful for detection of inflammation, although its *spatial resolution is poor*. It is a useful adjunct to MRI for the diagnosis of necrotizing otitis externa. It is also useful in following response to treatment.
274
274 Describe the mangement of malignant otitis externa.
Malignant otitis externa is managed primarily with medical therapy, including 6+ weeks of broad-spectrum antibiotics (covering Pseudomas spp.), aggressive aural toilet, and strict glucose control for diabetics. Hyperbaric oxygen therapy is useful for patients with refractory or advanced disease. Surgical intervention is reserved for patients with refractory disease or associated abscess.
275
275 What is the treatment of bullous myringitis?
* Decompression of painful vesicles, oral pain medication, and systemic antibiotics
* Steroids may be used in cases of sensorineural hearing loss
276
276 What antibiotic is considered first-line therapy for an otherwise healthy child with acute otitis media?
Amoxicillin, 90 mg/kg daily, divided into two doses each day for 10 days
277
277 What predisposing factors may put young children at risk for recurrent otitis media?
* Second-hand smoke exposure, group day care, nasal allergy, immunodeficiency, craniofacial abnormalities, adenoid hypertrophy, gastroesophageal reflux, vaccination status, supine bottle feeding, and pacifier use
* Breastfeeding in the first 6 months of life is likely protective against recurrent acute otitis media.
278
278 What factors impact a child's candidacy for surgery to treat otitis media with effusion?
Hearing status, associated symptoms, duration of effusion (\> 4 months), structural damage to the TM or middle ear, developmental delays or risk factors for delay (syndromic children, autism-spectrum disorders, uncorrectable visual impairment, etc.), craniofacial abnormalities/cleft palate
279
279 What condition must be excluded in all adult patients with a unilateral persistent middle ear effusion?
* **Nasopharyngeal carcinoma** should be ruled out by nasopharyngoscopy.
* Examination of the oropharynx, hypopharynx, and larynx should also be performed if otalgia is present.
280
280 Define atticotomy, and describe the typical indications of this approach in the context of chronic ear disease.
**Atticotomy** involves 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 conjuction with tympanoplasty and ossicular chain reconstruction.
281
281 Define congenital cholesteatoma.
Caused by a persistent embryonic rest of epithelial tissue within the middle ear space. Patients should have a normal appearing pars tensa and pars flaccida, no history of prior otorrhea, and no prior otologic surgery
282
282 Differentiate primary acquired and secondary ac quired cholesteatoma.
Primary acquired cholesteatoma arises from a tympanic membrane retraction pocket most commonly involving the pars flaccida; secondary acquired cholesteatoma results from an injury to the tympanic membrane (e.g., tympanostomy tube, surgery, accidental trauma) with implantation of skin into the middle ear space.
283
283 Describe the invagination theory of primary acquired cholesteatoma formation.
Infantile sterile otitis media develops shortly after birth. Before resportion occurs, mucosal fibrosis occurs, resulting in blocakage of the epitymanum and localized negative pressure. This results in poor pneumatization of the mastoid and retraction of the pars flaccida.
284
284 Describe the metaplasia theory of acquired cholesteatoma formation.
Columnar epithelium of the middle ear space undergoes squamous metaplasia, resulting from inflammation asso ciated with recurrent otitis media
285
285 Describe the proposed mechanisms of bony erosion by cholesteatoma.
* **Pressure erosion:** Caused by mechanical pressure from the growing cholesteatoma sac
* **Biochemical erosion:** Bacterial products, inflammation from granulation tissue, and enzyme products of the cholesteatoma itself
* **Cellular-mediated erosion:** Osteoclastic activity
286
286 Define Prussak space.
**Prussak space** is a recess, bordered:
* Laterally by the pars flaccida
* Superiorly by the scutum and lateral malleolar ligament
* Inferiorly by the short process of the malleus
* Medially by the neck of the malleus
287
287 Describe the three most common sites of origin for cholesteatoma.
1. Posterior epitympanum
2. Anerior epitympanum
3. Posterosuperior mesotympanum
288
288 Describe the anatomical limits of the sinus tympani.
* Ponticulus superiorly
* Subiculum inferiorly
* The mastoid segment of the facial nerve laterally
* The posterior semicircular canal medially
289
289 What is the most common site of labyrinthine fistula formation secondary to chronic ear disease?
The horizontal semicircular canal
290
290 Describe the signs and symptoms of labyrinthine fistula secondary to chronic otitis media.
Labyrinthine fistula most commonly involves the **lateral semicircular canal**. Classically, patients show mixed hearing loss, intermittent dizziness, and potentially sound-induced vertigo (Tullio phenomenon), although in practice a large number of patients may lack such findings.
291
291 Describe the likely mechanism of dizziness associated pneumatic otoscopy in a patient with cholesteatoma.
Cholesteatoma eroding into the bony labyrinth has most likely led to an inner ear fistula. With the labyrinth exposed, increased middle ear pressure can be translated to perilymphatic fluid movement and subsequent vertigo.
292
292 How should a lateral semicircular canal fistula associated with chronic ear disease be managed?
In an “only hearing ear” or “better hearing ear,” a canal wall–down procedure is often recommended, with exte riorization of the matrix overlying the erosion. If the other ear has good hearing, same-surgery repair with fascia or a second-look procedure with matrix removal may be considered if an intact canal wall is desired. Large or complex fistulae have a high risk of SNHL and are generally best managed with a canal wall–down procedure.
293
293 What is the difference between a radical and modified radical mastoidectomy?
With a radical mastoidectomy, there is complete removal of the malleus, incus, tympanic membrane, and middle ear mucosa, and the cavity is left open. With a modified radical mastoidectomy, the middle ear space is reconstructed. A Bondy modified radical mastoidectomy implies a canal wall– down procedure where the middle ear space is not entered or reconstructed
294
294 Describe the Wullstein classification system for tympanoplasty.
● Type 1: All ossicles are present and mobile. ● Type 2: The tympanic membrane is grafted to an intact incus and stapes. ● Type 3: The tympanic membrane is grafted to the stapes superstructure. ● Type 4: The tympanic membrane is grafted to the stapes footplate. ● Type 5: Semicircular canal fenestration procedure
295
295 What are common indications for canal wall– down mastoidectomy?
Advanced cholesteatoma with significant canal wall erosion, labyrinthine fistula, cholesteatoma in an only hearing ear
296
296 What are the most common causes of persistent otorrhea after a canal wall–down mastoidectomy?
Inadquate meatoplasty, failure to lower the facial ridge, mucosalization, exposed eustachian tube
297
297 Describe the histologic appearance of cholesteatoma.
A sac of keratinizing squamous epithelium with a central core of keratinaceous debris
298
298 In a healthy patient with cholesteatoma and no history of other otologic procedures, what are the primary indications for surgery?
There is no effective medical therapy for cholesteatoma; surgical removal and exteriorization are the only effective treatments. The primary goal of surgery is to create a safe and dry ear. Surgery is almost universally recommended for healthy patients
299
299 What are the advantages and disadvantages of lateral graft tympanoplasty?
The choice to use a lateral graft technique is based largely on the surgeon's preference. It is commonly used for total, near-total or anterior perforations. The main disadvantages are technical difficulty and the possibility of blunting (loss of the acute anterior canal angle) and lateralization (separation of the graft from the malleus)
300
300 Why is the temporomandibular joint potentially at risk for injury during lateral graft tympanoplasty?
Classically, **lateral graft tympanoplasty involves temporary removal of the anterior canal wall skin with canalplasty**, removing the bony overhang such that the entire drum can be seen through the canal. Overly aggressive drilling risks entry into the glenoid fossa.
301
301 Describe the mechanism of hearing loss in a patient with a tympanic membrane perforation.
There is a decrease in the ratio of the **tympanic membrane** to **stapes footplate surface area** (**_transformer ratio_**). In addition, sound striking the oval window and round window simultaneously (through the perforation) may result in phase cancellation.
302
302 What is the rate of persistent tympanic membrane perforation after tympanostomy tube placement?
Approximately 2 to 5%
303
303 Describe the advantage of cartilage grafts when used in repair of tympanic membrane perforations.
Cartilage is more rigid than other graft materials, making it more **resistant to retraction and resorption**. Long-term studies have demonstrated hearing results to be similar to those obtained with fascia
304
304 Describe the Sade grading system for tympanic membrane retraction.
* Grade I: Simple, shallow, generally self-cleaning and nonadherent
* Grade II: Contacting the incus or stapes
* Grade III: Contacting the promontory without adhesion
* Grade IV: Adhesion to promontory
* Grade V: Grade III or IV with perforation
305
305 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** in this area is also ***incomplete*** and often absent and therefore has less support
306
306 What pathogens are most commonly cultured in chronic otitis media?
**Polymicrobial**, involving Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, Klebsiella spp., and Proteus spp.
307
307 In addition to antibiotics, what adjunctive treatments should be considered for a pediatric patient with **_facial paralysis_ in the setting of acute otitis media**?
* Wide myringotomy or myringotomy with tympanostomy tube insertion is generally recommended.
* Adjunctive use of **systemic corticosteroids** is also advocated by some.
308
308 If appropriately treated, what is the prognosis for facial nerve recovery in children with facial paralysis secondary to acute otitis media?
Generally, outcomes are excellent; greater than 95% of patients will have a full recovery. Treatment consists of systemic antibiotics with a low threshold for ventilation tube placement. Coritcal mastoidectomy should be considered for coalescent mastoiditis; however, facial nerve decompression is not indicated.
309
309 What are the three primary mechanisms of developing intracranial infection from otitis media?
1. Direct extension after bone erosion or through existing congenital of acquired defects
2. Propagating thrombophlebitis of venous channels originating within the mastoid
3. Hematogenous seeding
310
310 What intracranial complication of otitis media is associated with "picket fence" spiking fevers?
1. Lateral sinus thrombophlebitis
2. Septic emboli from the thrombus are believed to cause the spiking fevers associated with this entity
311
311 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 the event of a positive test, compressing on the side ipsilateral to the thrombosis should result in no change, whereas **compression on the contralateral side will cause a rapid rise in pressure**
312
312 What is the most appropriate initial management of **noncoalescent mastoiditis** with an intact tympanic membrane?
Systemic antibiotics with myringotomy and tympanostomy tube placement
313
313 What is the most common complication of pressure equalization tube placement
Post-tympanostomy tube otorrhea (up to ~ 75%)
314
314 What lumbar puncture findings would you expect in a patient with **otitic hydrocephalus**, presumably a result of lateral sinus and possibly concomittant superior saggital sinus thrombosis?
Elevated opening pressure, but otherwise normal CSF composition
315
315 What is Gradenigo syndrome?
Triad of:
1. Otorrhea
2. Retro-orbital pain from trigeminal nerve irritation
3. Abducens nerve palsy from edema within the Dorello canal.
It is a classic presentation of **petrous apicitis.**
316
316 Why is the abducens nerve the most commonly affected cranial nerve in cases of petrous apicitis?
The adbucens nerve travels through the **Dorello canal** at the petrous apex, rendering it susceptible to compression if there is surrounding inflammation.
317
317 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.
318
318 What is the Griesinger sign?
Postauricular edema and tenderness thought to result from septic thrombosis of the mastoid emissary vein
319
319 What is the most common intracranial complication of acute otitis media?
* **Meningitis** is the most common complication, although the incidence has declined significantly with advances in antibiotics.
* **Brain abscess** is the most common lethal intracranial complication of otitis media.
320
320 What is the incidence of malleus fixation?
0.5 to 2%
321
321 In reference to stapes surgery, what is a perilymph gusher?
Excessive flow of perilymph encountered when opening the vestibule during stapes surgery
322
322 What conditions place a patient at high risk for perilymph gusher at the time of stapedotomy or cochlear implantation?
Patients with cochlear and labyrinthine malformations, particularly enlarged vestibular aqueduct and **Mondini malformations**, are at highest risk. A young male patient with mixed hearing loss should raise concern for **X-linked stapes gusher syndrome**.
323
323 Review the differential diagnosis of otosclerosis.
Any disease process that can result in conductive hearing loss, including tympanosclerosis, malleus fixation, congenital stapes footplate fixation, osteogenesis imperfecta, tympanic membrane perforation, cholesteatoma, and superior semicircular canal dehiscence, to name a few
324
324 What genetic disorder of bone development can cause a clinical presentation similar to that of otosclerosis?
Osteogenesis imperfecta
325
325 What findings are typically seen on immittance audiometry for patients with otosclerosis?
It may not impact tympanometry, although a **type A(s)** tympanogram may be seen. **Acoustic reflexes**, however, will most likely be abnormal, with **absent** responses in the affected ear when sound is presented on either side.
326
326 What are the most common otoscopic findings with otosclerosis?
Normal examination. The goal of the examination is to try to exclude other causes, including tympanosclerosis, malleus fixation, cholesteatoma, perforation, and other causes of conductive hearing loss.
327
327 What is a Schwartze sign?
A rosy hue seen through a transparent tympanic membrane resulting from increased blood around the promontory during active otospongiosis
328
328 Describe the pattern of hearing loss with otosclerosis?
Initially, otosclerosis manifests with a **low-frequency conductive hearing loss** and may progress to involve all frequencies. An artificial bone threshold shift is often seen centered at 2 kHz (Carhart notch). Mixed hearing loss is less common and may represent so-called retrofenestral or cochlear otosclerosis
329
329 Describe the management of a prolapsed and dehiscent facial nerve during stapedectomy?
Treatment depends on the experience and comfort level of the performing surgeon. Poststapedectomy hearing results are similar in patients with ~ 50% prolapse compared with those without prolapse, and **there is not a statistically increased risk of facial nerve weakness when performed by an experieneced team**. **The safest option, however, is to discontinue surgery and provide a hearing aid.**
330
330 What is the Carhart notch?
The Carhart notch is an **artificial depression in bone conduction thresholds centered at 2 kHz that is thought to result from disruption of ossicular resonance from stapes ankylosis**. It is not a true measure of cochlear reserve because it usually reverses after stapedectomy. It is **not specific to otosclerosis.**
331
331 With respect to stapedectomy, what is meant by "overclosure" of the air-bone gap?
After stapedectomy with good result, artificially depressed bone conduction will often resolve, potentially resulting in **air conduction that is better than the preoperative bone conduction level.**
332
332 Is the Carhart notch specific to otosclerosis?
No. An identical 2-kHz notch can commonly be seen in other conditions, such as **incudostapedial joint erosion** or **malleus and incus fixation**. It can also be present with **tympanic membrane perforation** and **otitis media**.
333
333 Describe the phenomenon of paracusis of Willis.
In this condition, **subjects 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.
334
334 What preoperative conditions place a patient at high risk for SNHL with stapedectomy?
Obliterative otosclerosis, otitis media, cochlear malformation, endolymphatic hydrops
335
335 What is the primary advantage of **small fenestra stapedotomy** versus **stapedectomy**?
Improved air-bone gap closure at higher frequencies (3 to 8 kHz)
336
336 What is the overall incidence of signficant SNHL after stapedectomy?
0.5 to 1%
337
337 What is the sensitivity of high-resolution CT in diagnosing otosclerosis?
~95%
338
338 What is the most common cause of early stapedectomy failure?
Displacement or slippage of the prosthesis
339
339 How is a depressed footplate (into the vestibule) addressed during stapedectomy?
If the footplate is deeply depressed and/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.
340
340 Describe the timing and symptoms of **reparative granuloma** after stapedectomy.
Most commonly, it occurs 1 to 2 weeks after surgery and manifests with dizziness, SNHL, and tinnitus.
341
341 What is the treatment of otosclerosis in a patient's only hearing ear?
Stapedotomy is generally contraindicated because of the risk of severe SNHL in the patient's dependent ear. Amplification is first-line treatment.
342
342 Why is appropriate sizing of a stapes prosthesis important?
If it is too short, the prosthesis may become **displaced or not resolve the conductive hearing loss**.
An overly long prosthesis may **impinge on the membranous labyrinth**, causing vertigo or SNHL
343
343 If encountered during stapedectomy, how should a persistent stapedial artery be managed?
A very fine persistent stapedial artery may be managed by bipolar or laser coagulation. If the footplate is fixed and the vessel occupies only a portion of the footplate, stapedectomy can proceed if the visualized portion of the footplate is clearly sufficient for fenestration. In cases of a larger-caliber vessel, however, aborting the procedure may be prudent
344
344 What are the guidelines for skydiving and scuba diving after stapedectomy?
There is no obvious risk to inner ear function provided the patient has good eustachian tube function
345
345 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.
346
346 What is the difference between stereotactic radiosurgery and stereotactic radiotherapy?
Stereotactic radiosurgery implies a single fraction treatment (all at once), whereas stereotactic radiotherapy implies delivery of mutliple fractions.
347
347 For what does the NF-2 gene code?
The NF-2 gene is a **tumor suppressor gene** located on **chromosome 22q12.2**, and it codes for the **schwannomin** or **Merlin** protein
348
348 What are the 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
349
349 What percent age of patients with NF-2 have a family history of disease?
**Approximately 50% of cases are inherited**, and 50% develop as a result of a new spontaneous mutation
350
350 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 innumer able intracranial and spinal tumors early in life with rapid progression
351
351 What are current treatment options for patients wtih NF-2?
Observation with serial imaging, stereotactic radiation (focused radiation), microsurgical resection (gross total, near total or subtotal), or bevacizumab (monoclonal anti body targeting vascular endothelial growth factor)
352
352 What are the three surgical approaches commonly used during vestibular schwannoma resection? (▶ Fig. 6.6)
1. Translabyrinthine
2. Middle fossa
3. Retrosigmoid
353
353 What are the common indications for a translabyrinthine approach for resection of a vestibular schwannoma?
Patients with **nonserviceable hearing** (AAOHNS class C or D), or with tumors \> 2 cm where the prospect of hearing preservation is low. The primary advantages include minimal brain retraction, less risk of prolonged headache, and reliable early facial nerve identification at the fundus
354
354 Describe the 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
355
355 What is the initial treatment of a venous air embolism supplied by a large rent in the sigmoid sinus?
Irrigate the wound, and 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.
356
356 Describe the orientation of the seventh to eighth nerve bundle at the fundus of the IAC. (▶ Fig. 6.7)
* Facial nerve (VII): Anterior superior
* Cochlear: Anterior inferior
* Superior vestibular: Posterior superior
* Inferior vestibular: Posterior inferior
357
357 Describe Mike's dot.
The origin of the **superior vestibular nerve** in the medial wall of the vestibule
358
358 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 to 1 cm extension into the CPA. Advantages include ~ 50% chance of hearing preservation; disadvantages include a potentially unfavorable location of the facial nerve with respect to the tumor and temporal lobe retraction.
359
359 In middle cranial fossa surgery, what landmarks are used to locate the IAC?
The IAC is typically oriented parallel to the axis of the EAC, approximated by the line bisecting the angle between the **greater superficial petrosal nerve** and the **arcuate eminence (superior semicircular canal)**.
360
360 To minimize greater superficial petrosal nerve injury during a middle fossa approach, in which direction should dural elevation proceed?
From posterior to anterior
361
361 What are the common indications for a retrosigmoid approach for resection of a vestibular schwannoma?
It may be considered for patients with _serviceable_ hearing and medial-based tumors. Tumors extending to the fundus of the internal auditory canal may be difficult to remove given restricted access around the posterior semicircular canal and vestibule. Larger, medial-base tumors can also be removed, even if hearing preservation is not attempted. Disadvantages include cerebellum retraction, headache, and potentially limited access into to the lateral IAC when hearing preservation is attempted.
362
362 Describe the 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 retrosigmoid craniotomy. **Asterion** is defined by **the junction between the lambdoid, parietomastoid, and occiptomastoid sutures**.
363
363 What percentage of patients with a vestibular schwannoma and "useful" hearing will ultimately lose their hearing after stereotactic radiosurgery?
Less than 25% of patients will retain useful hearing after stereotactic radiosurgery at 10 years after treatment.
364
364 What percentage of vestibular schwannoma are associated with NF-2?
5%
365
365 What percentage of intracanalicular vestibular schwannomas will remain stable in size for the first 5 years after diagnosis?
50 to 80%
366
366 Where along the eighth nerve are vestibular scwhannomas hypothesized to arise from?
**Obersteiner-Redlich zone**, near the porus acousticus, 1 cm from the brainstem
367
367 What is the Hitselberger sign?
Loss of sensation in the posterosuperior part of external auditory meatus and conchal bowl supplied by the sensory division of CN VII
368
368 What is the most common histologic classification for vestibular schwannomas?
**Antoni type A or B. Type A** tissue demonstrates dense cellularity with nuclear palisading and associated Verocay bodies, whereas **type B** has a loose arrangement with a less cellular reticular pattern in a myxoid stroma.
369
369 How are CPA meningiomas radiographically differentiated 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. In contrast, **vestibular schwannomas** have a globular appearance and are centered over the IAC
370
370 From what meningeal layer do meningiomas originate?
The arachnoid cap cells of the outer surface of the arachnoid mater
371
371 What percentage of paragangliomas will prove to be malignant?
Approximately 4%
372
372 From what cells do glomus tympanicum tumors originate?
Cells of neural crest origin arising from the tympanic branch (Jacobson nerve) of the glossopharyngeal nerve
373
373 Describe the Fisch classification system for para gangliomas of the temporal bone.
(▶ Table 6.2; ▶ Table 6.3; ▶ Table 6.4)
374
374 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
375
375 What is the most appropriate management of a growing glomus tympanicum tumor that is limited to the promontory?
Transcanal tumor removal
376
376 What is the most appropriate management of a glomus tympanicum that fills the middle ear and extends into the mastoid air cells?
Tympanomastoidectomy with extended facial recess approach and tumor removal
377
377 How frequently would you expect a patient with a glomus tumor to have elevated catecholamine levels on laboratory workup?
About 1 to 3% of glomus tumors will have a secretory component with elevated catecholamine levels.
378
378 Describe the classic radiographic findings of a glomus jugulare on temporal bone CT.
Homogeneous soft tissue mass centered over an enlarged jugular foramen with "moth-eaten" irregular bony margins.
379
379 What nuclear medicine scans can be used to evaluate for head and neck paragangliomas?
Metaiodobenzylguanidine scan (MIBG), PET scan, and 111 In-pentetreotide scintigraphy
380
380 What is the general approach to treatment of petrous apex cholesterol granulomas?
Rather than excision, cholesterol granulomas are treated by **drainage procedures**. Transcanal (infracochlear), transmastoid (retrolabyrinthine, infralabyrinthine, subarcuate), and transsphenoidal endoscopic approaches are all methods of drainage that spare inner ear function.
381
381 How can a cholesterol granuloma be differentiated from an epidermoid cyst on imaging?
Classically, cholesterol granulomas appear as T1 and T2 hyperintense expansile lesions of the petrous apex that do not enhance with gadolinium. **Epidermoids**, on the other hand, most commonly demonstrate low intensity on T1 and high intensity on T2. Furthermore, diffusion-weighted MRI will reveal diffusion restriction with epidermoids. CT results are often similar.
382
382 What should be considered when determining the best surgical approach for drainage of a petrous apex cholesterol granuloma?
The location of the lesion in relationship to the jugular bulb, sphenoid sinus, eustachian tube, otic capsule, and most importantly the ICA should be considered. The patient's preoperative hearing status is also to be considered. Extended endonasal approaches are now being used with increasing frequency, but lesions in the posterior inferior petrous apex (between the carotid foramen and jugular foramen) are usually best approached by a transcanal infracochlear approach.
383
383 What is the key radiologic feature of a petrous apex epidermoid?
The key distinguishing feature between **epidermoids** and other lesions is the **high-signal intensity of diffusion-weighted images**. Epidermoids exhibit markedly restricted diffusion and therefore are **bright** on diffusion-weighted MRI.
384
384 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-supression techniques.
385
385 Describe the management approach for a CPA/IAC lipoma?
Most CPA/IAC lipomas do not grow, and generally a "watch and-scan" approach is used. Surgical resection is reserved for patients with intractable symptoms that are clearly attributable to mass effect.
386
386 From where do skull-base chondrosarcomas most commonly arise?
Chondrocytes of the **foramen lacerum** at the **petroclival synchondrosis**
387
387 What is the most common location from which a skull base chordoma arises?
Chordomas are tumors that arise from **remnants of the notochord**. These can occur anywhere along the axial skeleton, but at the skull base, they are almost invariably found at the **clivus**.
388
388 What percentage of patients with **Von Hippel Lindau disease** will develop **endolymphatic sac tumors**?
Approximately 10%
389
389 What is the primary management strategy for endolymphatic tumors?
Complete surgical excision
390
390 What are the most common cranial neuropathies seen with neurosarcoidosis?
* Optic nerve, facial nerve, eighth nerve
* Up to 50% of patients will have a least one cranial nerve palsy.
391
391 What are the classic features of **Melkersson Rosenthal syndrome**?
* Recurrent orofacial edema, recurrent facial nerve paralysis, and lingua plicata (fissured tongue)
* The classic triad is seen in only a minority of patients.
392
392 Describe the House-Brackmann grading scale for facial paralysis.
(▶ Table 6.5)
393
393 What is Bell phenomenon?
A reflexive upward and outward movement of the globe during attempts at eye closure. Patients with incomplete eye closure resulting from facial palsy with an absent Bell phenomenon are at higher risk for corneal complications.
394
394 What is the organism responsible for Lyme disease?
Borrelia burgdorferi
395
395 How does treatment for facial paralysis secondary to Lyme disease differ from treatment of idiopathic facial paralysis (Bell palsy)?
Treatment with antibiotics (IV ceftriaxone or IV/PO doxycycline) has been found to improve outcomes in cases of facial paralysis associated with Lyme disease.
396
396 How does the prognosis for facial nerve recovery in Ramsay Hunt syndrome compare with that of Bell palsy?
**The long-term facial nerve outcomes of Ramsay Hunt syndrome are generally worse**, with more severe paralysis and a lower rate of full recovery.
397
397 Which sensory ganglion is believed to harbor latent varicella virus that becomes reactivated in cases of herpes zoster oticus (Ramsay Hunt syn drome)?
The geniculate ganglion
398
398 What is the prognosis for facial nerve recovery in patients with idiopathic facial paralysis (Bell palsy)?
**80 to 90%** of patients who receive no treatment experience full recovery. Among those who do not progress to complete paralysis, the prognosis is even better; 95% or greater of these patients have complete recovery. Evidence suggests that corticosteroids with or without antivirals provide improved outcomes, although the data are not conclusive, particularly for antivirals.
399
399 Where is the narrowest point in the fallopian canal?
At the meatal foramen, which marks the start of the labyrinthine segment
400
400 Describe how electroneuronography is performed.
Electroneuronopgraphy (evoked electromyography) assesses the motor response to supramaximal stimulation of the facial nerve and compares the peak to peak difference between the abnormal side and the normal side. A bipolar stimulating electrode is placed at the stylomastoid forma men and surface electrodes are placed at the nasolabial fold. Increasing stimulation levels are provided until a maximal amplitude in the compound muscle action potential is reached. The difference between the abnormal and normal side provides the "percent drop."
401
401 At what critical electroneurogrphy (ENoG) value is facial nerve decompression considered in patients with Bell palsy?
Greater than 90% reduction compared with the opposite unaffected side
402
402 What is the significance of polyphasic motor unit action potentials during EMG testing?
Neural regeneration
403
403 What is the significance of fibrillation potentials during EMG testing?
Fibrillation potentials are spontaneous action potentials that arise from denervated muscle fibers and are generally not seen until after 21 days beyond denervation.
404
404 Describe how maximal stimulation testing is performed.
Transcutaneous electrical stimulation at the stylomastoid foramen is provided at a level that elicits maximal facial movement in an attempt to interrogate all functioning nerves. The response on the side with facial nerve paralysis is compared with the normal side and graded
405
405 Describe how nerve excitability testing is performed.
Surface electrodes are placed near the stylomastoid foramen. Fixed-current pulses of increasing strength are delivered to the unaffected side until facial twitching is noted. The process is repeated on the affected side, and the difference in current required for stimulation is calculated
406
406 What is the expected rate of neural regeneration following axonal injury?
1 mm/day
407
407 Describe the five levels of neural injury according to the Sunderland classification. (▶ Table 6.6; ▶ Fig. 6.8)
1. Conduction block without axonal degeneration (neuropraxia)
2. Isolated axonal injury that results in wallerian degener ation (axonotmesis)
3. Axonal injury with loss of endoneurium, but the perineurium and epineurium remain intact.
4. Axonal injury with loss of the endoneurium and perinerium, but the epineurium remains intact.
5. Axonal injury with loss of all surrounding structures (transection)
408
408 Describe the three levels of neural injury according to the Seddon classification.
1. Neuropraxia: Axons remain intact but have a temporary conduction block. Full recovery is expected.
2. Axonotmesis: Axons are damaged, but endoneurium remains intact. Wallerian degeneration will occur, but a full recovery without synkinesis is expected.
3. Neurotmesis: Axons and surrounding support (endoneural tubules) are disrupted. Wallerian degeneration will occur, and recovery is variable.
409
409 What are the primary indications 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 who desire dynamic facial rehabilitation may be candidates for muscle transfer techniques (temporalis transfer, masseter transfer, free gracilis, etc.).
410
410 What are the primary indications for rehabilitation of the eye in facial paralysis?
The primary goal is to protect the eye and vision from damage caused by chronic exposure and dryness. Corneal abrasion, ulceration, clouding, and epiphora can occur with facial paralysis and may result in vision loss if not aggressively managed.
411
411 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 to 18 months), facial-hypoglossal transfer is a viable treatment option.
412
412 What medical therapies are indicated for patients with delayed complete facial nerve paralysis after temporal bone trauma?
Eye care (drops, ointment, nocturnal moisture chamber) and corticosteroids
413
413 What is the significance of a completely unresponsive facial nerve after high-level proximal eletrical stimulation at the end of a surgery?
It denotes a 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.
414
414 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
415
415 How can synkinesis after traumatic facial nerve injury be managed?
**Botulinum toxin** injections or **selective myectomy** of affected muscles
416
416 During tympanomastoidectomy, the facial nerve is partially severed, with approximately 75% of its cross section still intact. What is the next step that hould be performed
With most of the nerve still intact, no further intervention should be undertaken. Limited proximal and distal facial nerve decompression could be considered to decrease hemia associated with swell
417
417 What is the best outcome one could expect with **primary tension-free nerve anastomosis** after traumatic facial nerve injury?
**House-Brackmann grade III function.** Patients can achieve symmetric resting tone, good eye closure, and oral sphincter competence.
418
418 When awakening from a tympanomastoidectomy for cholesteatoma, a patient has an unexpected complete facial paralysis. What is the next step in care?
Consider **observing the patient for 4 to 6 hours to allow local anesthetic injection to wear off.**
419
419 What is the most common presentation of an intraparotid facial nerve schwannoma?
Asymptomatic enlarging mass
420
420 What are the common initial symptoms of an intratemporal facial nerve schwannoma?
Approximately 50% have slowly progressive or intermittent facial nerve paresis, and roughly 75% have some degree of hearing loss.
421
421 Describe the histologic appearance of fibrous dysplasia.
Replacement of normal bone with benign fibrous tissue and irregular trabeculae of immature woven bone ("Chinese characters" appearance)
422
422 What are indications for surgical treatment of fibrous dysplasia of the skull base or craniofacial skeleton?
Generally, **only symptomatic patients should undergo surgery (cranial neuropathies, vision loss, disfigurement)**. Some advocate optic canal decompression for asymptomatic patients with radiographic evidence of optic canal impingement, but this is debated.
423
423 What clinical findings are seen in McCune-Albright syndrome?
Polyostotic **fibrous dysplasia**, abnormal skin pigmentation (such as café-au-lait spots), and endocrine dysfunction (such as precocious puberty in girls)
424
424 What is the cause of hearing loss in patients with autosomal recessive osteopetrosis?
Most commonly, hearing loss is conductive, with disordered ossicular chain bony overgrowth, external auditory canal stensosis, stapes fixation, loss of temporal bone pneumatization, and recurrent otitis media resulting from eustachian tube narrowing. SNHL can also occur, likely from narrowing of the bony internal auditory canal.
425
425 What are the cause and the most common treatment for patients with recurrent facial palsy in the setting of osteopetrosis?
Compression of the facial nerve throughout its bony canal secondary to greatly increased bone density seen in osteopetrosis can lead to **episodic, recurrent facial weakness**. Complete facial nerve decompression can be attempted to manage this, because some residual and slowly progressive weakness are often seen after each episode.
426
426 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 the mainstay of therapy. Amplification may also be considered. Generally, hearing loss from bony abnormalities attributable to Paget disease is not correctable by surgical means.
427
427 What is the most common cutaneous malignancy involving the auricle?
**Basal cell carcinoma** is both the most common auricular malignancy as well as the most common skin cancer in general
428
428 What is the most common ceruminous gland malignancy of the external auditory canal?
Adenoid cystic carcinoma
429
429 You suspect a malignancy in a patient with an irregular, pigmented, and ulcerated lesion of the left lobule. Which biopsy techniques are accept able in ascertaining a diagnosis?
A **full-thickness biopsy** is necessary for diagnosis. This should include epidermis, dermis, and some underlying subcutaneous tissue. Shave biopsies or fine needle aspiration of pigmented cutaneous malignancies are inappropriate because they may make tumor staging impossible
430
430 List common risk factors associated with the development of temporal bone malignancy.
Fair complexion, sun exposure, immunocompromised status, recurrent otitis externa, previous radiation
431
431 List the most common types of **temporal bone** malignancy.
Approximately 70% **squamous cell carcinoma**, ~ 11% basal cell carcinoma, 4% adenocarcinoma, 4% adenoid cystic carcinoma
432
432 Describe the clinical presentation of squamous cell carcinoma of the external auditory canal?
Approximately 80% otorrhea and otalgia, ~ 70% hearing loss, 30% facial nerve disturbances
433
433 Describe the T staging of EAC carcinoma?
* T1: Limited to EAC without bony erosion
* T2: Limited to the EAC with limited (not full thickness) bony erosion
* T3: Tumor eroding through the EAC, involvement of the middle ear or mastoid, or facial nerve weakness
* T4: Tumor invading otic capsule, jugular foramen, carotid canal, or dura (Pittsburgh staging system)
434
434 When is radiation indicated for patients with EAC squamous cell carcinoma?
T3–T4 disease, close margins, multiple positive lymph nodes, extracapsular spread, and perineural invasion
435
435 When is lateral temporal bone resection indicated in management of squamous cell carcinoma of the EAC?
Disease that is limited to the external auditory canal without significant extension into the mastoid, middle ear, or beyond (T1 and T2 disease)
436
436 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.
437
437 What is the most common malignant tumor of the **temporal bone in children**?
Rhabdomyosarcoma, embryonal subtype
438
438 What is the appropriate initial management strategy for a carcinoid tumor of the middle ear?
A recent review (Ramsey et al, 2005) identified this rare tumor as a **low-grade malignancy** with the potential for local recurrence and regional metastasis. Complete excision of this tumor with long-term surveillance is recommended.
439
439 In cases of penetrating facial trauma where branches of the facial nerve are suspected to be transected, why should they be explored within 3 days?
The distal branches of the nerve can still be stimulated for approximately **3 days** after they are transected, before wallerian degeneration takes place.
440
440 Describe the two most common classifications for temporal bone fractures. (▶ Fig. 6.9)
Orientation of the fracture line (longitudinal, transverse, or mixed) or by involvement of the otic capsule
441
441 Describe associated sequelae of a longitudinal temporal bone fracture.
CSF otorrhea, tympanic membrane perforation, EAC laceration, conductive hearing loss from hemotympanum or ossicular discontinuity, bloody otorrhea, facial nerve injury uncommon (20%)
442
442 Describe associated sequelae of a transverse temporal bone fracture.
Vertigo, SNHL, facial nerve injury more common and often more severe (30 to 50%)
443
443 What type of head blow is likely to cause a longitudinal temporal bone fracture?
Temporal (lateral) blows are more likely to cause a longitudinal fracture, whereas frontal or occipital blows may cause a transverse fracture
444
444 Describe the initial management of a traumatic CSF leak.
Most traumatic leaks resolve with conservative measures, including bed rest, head of bed elevation, and stool softeners. Generally, surgical repair is pursued if an active leak persists beyond a week from injury.
445
445 Review the role of antibiotics with traumatic temporal bone CSF leaks.
Controversial. A recent Cochrane Database review does not support the use of prophylactic antibiotics to reduce the risk of meningitis after basilar skull fractures.
446
446 Review the role of perioperative antibiotics in otologic and neurotologic surgery.
Available data do not support the use of perioperative antibiotics in routine otologic surgery. In cases with active infection, the role of antibiotics is more controversial. A single dose of perioperative antibiotics is generally recommended in cochlear implantation and skull base procedures, with many surgeons extending this to a 24-hour-long postoperative course.
447
447 What is the initial management of a temporal bone fracture with an intact otic capsule, intact tympanic membrane, and hemotympanum with conductive hearing loss?
**Audiogram in 4 to 8 weeks.** Otic drops can be considered if there is a laceration or blood in the ear canal. Persistent conductive hearing loss may suggest the presence of ossicular chain disruption.
448
448 Where is the most common site of ossicular chain disruption in the setting of temporal bone fracture?
The incudostapedial joint
449
449 What is the most common site of facial nerve injury in temporal bone fractures?
The perigeniculate region (80% +)
450
450 Describe the initial management of a tympanic membrane perforation related to a nonexplosive blast injury, such as a slap to the side of the head?
Conservative management and observation. The vast majority of these perforations will heal spontaneously.
451
451 What is the most common otologic sequelae of lightning strike?
Tympanic membrane perforation
452
452 What needs to be done before burying a traumatically avulsed portion of the pinna in a postauricular subcutaneous pocket?
The skin of the avulsed segment should be dermabraded to remove the surface epithelium while it is buried in the subcutaneous pocket
453
453 What is the mechanism for SNHL resulting from decompression sickness?
Nitrogen, which was made temporarily soluble in blood by increased ambient pressure, comes out of solution in the form of bubbles during rapid depressurization. These "microbubble emboli" can involve the microcirculation of the ear and cause hearing loss, and they may be difficult to distinguish from inner ear barotrauma.
454
454 What are the symptoms of perilymphatic fistula?
Fluctuating hearing loss and intense vertigo that worsens with Valsalva or exertion
455
455 Describe the clinical presentation and radiologic findings of labyrinthine concussion.
Brief loss of consciousness associated with transient (days to weeks) vestibular symptoms, possible hearing loss and tinnitus. Dix-Hallpike maneuver does not elicit symptoms. CT scan does not show acute intracranial complications or otic capsule fracture.
456
456 Describe the most common mechanism of malleus handle fracture.
It is often caused by placing wet finger in ear canal. When the finger is withdrawn under a seal, this creates 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.
457
457 How should bloody otorrhea after temporal bone fracture in a stable and awake patient be managed?
Otomicroscopy to debride the EAC. Irrigation or occlusion (except in cases of massive bleeding) of the EAC should not be performed because of the risk of ascending meningitis.
458
458 Describe the utility of the "halo" or "ring" sign when evaluating for traumatic CSF leak.
Not sensitive or specific. The halo sign may be seen when blood is mixed with CSF, saline, nasal mucus, and tap water. Futhermore, the concentration of CSF and blood must be correct for a halo to be seen.
459
459 In what body fluids can β-2 transferrin can be found?
CSF, perilymph of the inner ear, and vitreous humor of the globe
460
460 What initial screening tests should be performed when a CSF leak is suspected?
β2-transferrin and a fine cut CT of the entire skull base should be obtained with dedicated coronal and axial acquisition.
461
461 How long is CSF (beta-2 transferrin) stable for at room temperature?
Approximately 4 hours at room temperature, and approximately 3 days when refrigerated (not frozen)
462
462 Describe the Dandy maneuver.
The patient leans forward while performing a Valsalva. This maneuver may provoke clear rhinorrhea in a patient with a CSF fistula. The nostril that the drainage comes from generally predicts the laterality of the defect.
463
463 How much CSF is contained within the subarachnoid space at any given time?
Approximately 150 mL, with daily production of approximately 500 mL, which means that the CSF volume is turned over approximately **three times per day**.
464
464 Describe a positive reservoir sign.
Intermittent CSF rhinorrhea associated with change in head position, which results from pouring of CSF collecting in a dependent location of a sinus.
465
465 Describe Hyrtl fissure.
A Hyrtl fissure is 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 for CSF leak, meningitis, or tumor spread (also known as the tympanomeningeal fissure).
466
466 Review possible sources for congenital CSF leaks involving the temporal bone.
* Hyrtl fissure
* Dilated cochlear aqueduct
* Dilated fallopian canal
* Enlarged petromastoid canal (subarcuate canal)
* Abnormal communication between IAC and inner ear (cochlear malformations)
467
467 What is the preferred management strategy for traumatic carotid-cavernous fistula associated with skull base fracture?
Endovascular repair (Ballooning/stenting/coiling)
