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