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102 Cards in this Set

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What is the purpose of vestibular system?
To perceive relative motion between self & objects in space and to maintain equilibrium
What are the 5 vestibular organs?
1. Saccule
2. Utricle
3, 4, & 5. Cristae of 3 semicircular canals
Which of the vestibular organs sense angular and which sense linear acceleration?
1. Macules of the saccule and utricle sense linear acceleration
2. Cristae sense angular acceleration
What is an otolith composed of?
Calcaneous material embedded in a gelatinous matrix
What is the cupula?
A bulbous gelatinous mass covering the epithelium of the cristae of the SCC
What is the 1st of Ewald's 3 laws?
Eye & head movements always occur in plane of canal being stimulated & in direction of endolymph fluid
What is the 2nd of Ewald's 3 laws?
Ampullopetal endolymph flow in H-SCC caused a greater response than did ampullofugal endolymph flow
What is the 3rd of Ewald's 3 laws?
Ampullofugal endolymph in vertical canals caused greater response than did ampullopetal endolymph flow
What is the purpose of the vestibular nuclei?
Receive signals originating in the vestibular end-organs
What are the 4 main vestibular nuclei?
1. Superior
2. Lateral
3. Medial
4. Descending
relate to anatomical planes
What is the function of the superior vestibular nucleus?
Major relay center for ocular reflexes mediated by SCCs
relay
What is function of lateral vestibular nucleus?
Controls vestibulospinal reflexes, particularly those involving the forelimbs
control
What is the function of the medial vestibular nucleus?
Center for coordinating eye, head, and neck movements
coordinate
What is function of descending vestibular nucleus?
Integrates vestibular signals from the 2 sides with signals from cerebellum and reticular formation
integration
What is the function of the interstitial nucleus of vestibular nerve?
Efferent projections from these nuclei enter ascending medial longitudinal fasciculus and may be important in mediating vestibulo-ocular reflex
What is the VOR?
Vestibulo-ocular reflex sends info about head movement through central pathways; allows for gaze stabilization during active head movements
What are the 2 pathways of VOR?
1. Direct
2. Indirect
What 3 neurons make up VOR direct pathway?
1. CNVIII
2. An interneuron from vestibular nucleus to CNVI
3. Motorneuron to lateral rectus muscle
What tests VOR indirect pathway and what does abnormal result indicate?
High-frequency head shake with vision denied.
Nystagmus results when abnormal because velocity storage is "off"
HFHS
What are the 2 vestibulo-ocular reflexes?
1. Semicircular canal-ocular reflexes
2. Otolith-ocular reflexes
What are the 3 VOR planes?
1. Yaw=horizontal movement
2. Pitch = vertical movement
3 = roll = ear to shoulder movement (not as efficient)
What are the 3 cranial nerves associated with innervation of eye muscles?
1. Oculomotor (III)
2. Trochlear (IV)
3. Abducens (VI)
What are the 5 muscles innervated by the oculomotor nerve (CNIII)?
1. medial rectus
2. superior rectus
3. inferior rectus
4. inferior oblique
5. levator palpebrae superior
Which muscle does the trochlear nerve (IV) innervate?
Superior oblique
Which muscle does the abducens (IV) innervate?
lateral rectus
Which 3 vestibular systems assess visual-vestibular interaction?
1. Saccade system
2. Smooth pursuit system
3. Optokinetic system
How is the saccade system used to assess visual-vestibular interaction?
Responds to error in direction of gaze with respect to position of an object of interest by initiating rapid eye movement (a saccade)
How is smooth pursuit system used to assess visual-vestibular interaction?
Test compares eye velocity with that of target velocity; smooth pursuit is responsible for maintaining gaze on moving target; sinusoidal pattern
How is optokinetic system used to assess visual-vestibular interaction?
A primitive form of smooth pursuit involving whole retina instead of just the fovea
What is vestibular neuritis and describe the characteristics?
Acute dysfunction of vestibular system accompanied by nausea, vomiting, and usually vertigo
Where is site of lesion of vestibular neuritis?
Superior vestibular nerve & vestibualr ganglion
What is vestibular profile of vestibular neuritis?
Reduced caloric response during acute phase, possible spontaneous nystagmus, may fall towards affected side
What are differential diagnosis for vestibular neuritis?
Cerebellar bleeds, infarcts & tumors, brainstem lesions, CPA tumors, MS
What is treatment for vestibular neuritis?
self-limiting; medical treatment controls symptoms; vestibular rehab if compensation does not occur
What is autoimmune inner ear disease (AIED)?
rapidly progressive bilateral SNHL that responds to administration of immunosuppressants
What are characteristics of AIED?
Unexplained fluctuating SNHL, sudden onset, most common in 20-50 y/o, more prevalent in females, 50% have dizziness
What is audiometric profile for AIED?
WRS often poorer than suggested by thresholds, any configuration of SNHL possible, mostly bilateral
What is vestibular profile for AIED?
Dizziness, unsteadinesses, rarely vertigo; may see deterioration in balance/decrease in caloric function
What is differential diagnosis for AIED?
Meniere's, otosyphilis, vestibular neuroma, meninigitis, MS
What is treatment for AIED?
corticosteroid therapy
What is labyrinthitis?
Inflammatory process of labyrinth
What are characteristics of labyrinthitis?
SNHL in involved ear, acute vertigo, tinnitus, fever, HA, nausea & vomiting
What is audiometric profile of labyrinthitis?
Sudden profound SNHL in involved ear
What is vestibular profile of labyrinthitis?
Caloric weakness in involved ear, spontaneous nystagmus beating away from involved ear
What is criteria for diagnosis of labyrinthitis?
SNHL in involved ear and increased white cell count from CSF
What is treatment for labyrinthitis?
antibiotics, steroids, antiemetics, vestibular suppressants treated by MD; SNHL permanent
What are characteristics of Meniere's syndrome/disease?
Fluctuating SNHL, episodes of vertigo, roaring tinnitus, and aural fullness believed to be due to increased pressure involving endolymph
What audiometric profile occurs with Meniere's disease?
Rising pure-tone SNHL, WRS consistent with degree of HL, abnormal ECochG
What is vestibular profile seen with Meniere's?
unilateral weakness of affected ear or directional preponderance, spontaneous nystagmus
What is differential diagnosis for Meniere's?
vestibular schwannoma, autoimmune disease, HSV, migraine, food allergy, perilymphatic fistula
What is treatment for Meniere's?
low salt, low caffeine diet, vestibular suppressants, antiemetics; rarely surgery
What is a perilymphatic fistula (PLF)?
Results when there is break in bony labyrinth or oval or round windows, allowing perilymph to leak out
What are characteristics of perilymphatic fistula?
vertigo, tinnitus, hearing loss, complaint of sudden audible pop in the ear
What is audiometric profile of PLF?
conductive or SNHL, WRS consistent with degree of hearing loss
What is vestibular profile of PLF?
unilateral caloric weakness may be present, but calorics may be unremarkable
What is differential diagnosis of PLF and how is diagnosis confirmed?
Meniere disease, superior canal dehiscence, vestibular schwannoma; diagnosis confirmed only by surgery
What is treatment for PLF?
bed rest, reduced activity; surgical exploration of middle ear and patching of fistula
What is superior canal dehiscence (SCD)?
Opening in bone overlying superior SCC may cause vertigo or imbalance triggered by loud noise or pressure in the ear; may be congenital, infectious, or traumatic origin
What are characteritics of SCD?
vertigo caused by noise or pressure in ear, disequilibrium and unsteadiness
What is audiometric profile seen with SCD?
Low frequency air-bone gap, but may have little to no conductive component; normal tymps and reflexes
What is vestibular profile of SCD?
VEMP thresholds lower than normal
What is differential diagnosis associated with SCD?
PLF, Meniere's
What is treatment for SCD?
Surgical repair of dehiscence
What is labyrinthine concussion?
Post-traumatic vertigo; vestibular dysfunction after blunt head trauma
What are characteristics of labyrinthine concussion?
history of trauma, acute vertigo or dysequilibrium, hearing loss, tinnitus in affected ear, may be delayed symptoms
What is audiometric profile of labyrinthine concussion?
high-fequency SNHL in affected ear
What is vestibular profile of labyrinthine concussion?
caloric weakness in affected ear, spontaneous nystagmus beating away from affected ear
What is the treatment for labyrinthine concussion?
Corticosteorids (acute treatment), rule out PLF with ME surgery, vestibular suppressant, vestibular rehab if compensation does not occur
What is vestibulotoxicity?
bilateral vestibular dysfunction mostly due to antibiotic treatment, solvents, or cisplatinin in high doses
What are the characteritics of vestibulotoxicity?
dysequilibrium (especially walking in dark), oscillopsia
What is vestibular profile of vestibulotoxicity?
No static positional nystagmus, absent responses during all calorics, even to ice water
What is treatment for vestibulotoxicity?
Encourage use of alternative sensory inputs
What is vestibular schwannoma?
Benign, slow-growing tumor arising from Schwann cells of vestibular portion of CNVIII
What are characteristics of vestibular schwannoma?
One or more of following: hearing loss, tinnitus, dysequilibrium, aural fullness/pressure, facial sensory dysfunction
What is audiometric profile of vestibular schwannoma?
Asymmetric hearing loss, may be sudden HL, decreased WRS, abnormal reflexes 80%, ABR may be abnormal or WNL
What is vestibular profile for vestibular schwannoma?
VNG may be normal or may show gaze, spontaneous, or positional nystagmus; abnormal OKNs & pursuit, caloric weakness (depending on site of lesion)
What is differential diagnosis and criteria for diagnosis of vestibular schwannoma?
Differentials include Meniere's or NIHL, but MRI of IACs with and without contrast is gold standard criterion for diagnosis
What is treatment for vestibular schwannoma?
Observation, surgery, or gamma knife radiation
What is cervicogenic vertigo?
Injury to cervical region resulting in disturbance of afferent discharge from mechanoreceptors & precipitate vertigo and nystagmus
What are characteristics of cervicogenic vertigo?
positional unsteadiness, postural instability when turning, imbalance with sudden head movements, neck pain, stiffness, HAs
What is vestibular profile of cervicogenic vertigo?
complaint of dizziness during cervical ROM, positive cervical vertigo test
What is treatment for cervicogenic vertigo?
muscle relaxant, physical therapy
What is mal de debarquement (MDD)?
Persistent rocking or dysequilibrium after prolonged exposure to motion
What are characteristics of mal de debarquement?
imbalance not alleviated by motion-sickness drugs, symptoms pronounced when sitting still and minimized by motion
What is vestibular profile of mal de debarquement?
Usually unremarkable, may see unusually strong or prolonged OKN or vestibular responses, may see positional nystagmus
What is treatment for mal de debarquement?
self-limiting condition, Valium may alleviate severe symptoms, vestibular rehab
Describe multiple sclerosis (MS)
Believed to be an autoimmune disease affecting CNS in which myelin is lost in multiple areas around nerve fibers and leaving scar tissue (sclerosis, plaques)
What are characteristics of MS?
Muscle weakness, possible ataxia, imbalance, lightheadedness, occasional memory loss & facial pain
What is vestibular profile of MS?
spontaneous nystagmus that enhances with vision denied, rebound nystagmus, VEMPs reveal bilateral asymmetrically prolonged latencies
What is vertebrobasilar insufficiency (VBI)?
Poor circulation of blood in vertebral & basilar arteries
What are characteristics of VBI?
difficulty walking, imbalance, diplopia, dizziness, nausea, drop attacks, brief LOC
What is vestibular profile of VBI?
May have caloric weakness, positive VBI screen
What is benign paroxysmal positional vertigo (BPPV)?
Common mechanical disorder of inner ear when otoconia become loss and float into one of 3 SCC
What are signs & symptoms of BPPV?
Nystagmus occurring in plane of affected canal, vertigo, nausea & vomiting
What is primary BPPV?
Patients have no prior history of otologic pathology; may be due to trauma, age, migraines, strokes, vascular disease, diabetes, etc
What is secondary BPPV?
Patients have history of prior pathology such as vestibular neuritis, labyrinthitis, prior BPPV, stapes surgery, Meniere's chronic ear infections
How is BPPV evaluated?
Vertebral artery screen, modified Hallpike, modified supine Hallpike, side-lying maneuver, or roll test
What responses are observed with posterior canal BPPV?
Latency of 1-40 sec & lasts less than 30 sec, rotary with upbeating nystagmus, fatigable, occurs 90%; provoking maneuver is DixHallpike
What responses are observed with horizontal canal BPPV?
Very short latency lasting up to 1 min, purely horizontal nystagmus, not fatigable, occurs in 6% of patients, provoking maneuver is roll test
What are treatments for BPPV?
Repositioning maneuvers and surgical procedures
What are necessary questions to answer when evaluating and before treatment of BPPV?
Which is involved ear? bilateral? which canal is involved? which maneuver is appropriate? does patient have anxiety?
What are options for repositioning maneuvers for BPPV?
Epley maneuver/canalith repositioning, Semont Liberatory, Appiani, Casani