Vestibular Disorders Flashcards
What is the vestibular system?
Somatosensory portion of the nervous system
Provides spatial awareness of the head and body (proprioception) and conscious awareness of active/passive limb movements (kinesthesia)
What are the three components of the vestibular system?
A peripheral sensory apparatus (located in the inner ear)
A central vestibular system (includes structures within the brainstem and cerebellum)
A motor output (connections with various motor nuclei and muscles)
What is the peripheral sensory apparatus also called?
Vestibular labyrinth
What are the two types of motion sensors of the vestibular labyrinth?
Three semicircular canals
Two otolith organs (utricle and saccule)
What type of movement do semicircular canals detect?
Angular or rotational
What type of movement does the utricle and saccule detect?
Linear acceleration with respect to gravity
Utricle - linear movement (sideways, up/down, head tilt)
Saccule - vertical acceleration (when in an elevator)
How is information relayed to the central vestibular system?
The vestibular portion of the VIII N
Are the cochlea and the vestibular labyrinth really close together?
Yes
They share a blood supply, and therefore disorders often affect both
Where does vestibular information go from the vestibular portion of the VIII N?
To parts of the cerebellum and four vestibular nuclei located in the pons
Is input from the vestibular labyrinth is processed in association with visual sensory and somatosensory input?
Yes
Somatosensory system associated with conscious perception of touch, pressure, pain, temp, position, movement, and vibrations
What does output from the vestibular nuclei influence?
Eye movement
Truncal stability
Spatial orientation
What are the three vestibular reflexes?
Vestibulo-ocular reflex - gaze stability reflex
Vestibulo-spinal reflex - stabilizes posture
Vestibulo-collic reflex - stabilizes the head
How does VOR work?
When the head rotates, the eyes are stabilized by rotating the eyes about the same axis, but in the opposite direction
What is it called when you are unable to maintain stability during head movement?
Oscillopsia
What are the VOR and VSR monitored by?
The central vestibular system
Calibrated and recalibrated as necessary by the cerebellum
What are lesions of the cerebellum associated with?
Nystagmus (abnormal involuntary eye movements)
Gait ataxia (abnormal gait)
What are some signs and symptoms of vestibular disorders?
Sense of imbalance
Dizziness/vertigo
Nystagmus
Is dizziness a nonspecific complaint?
Yes, can occur in association with vestibular lesions
Are dizzy spells associated with vestibular disorders abrupt in onset and short in duration?
Yes
Symptom such as nausea and vomiting are commonly associated too
Is vertigo a specific type of dizziness?
Yes
Can either be a sense of motion of self (subjective) or the environment (objective)
Is true vertigo frightening and distressing?
Yes
Associated with an illusory sense of motion or rotation over which the individual has no control
What is episodic vertigo?
Occurs with sudden onset in distinct episodes
What is true vertigo caused by?
Deficits in the peripheral labyrinth or its connections to the central vestibular system
Can vertigo be of peripheral or central origin?
Yes
What question should you ask to distinguish dizziness from vertigo?
Have you ever felt yourself or the room spinning?
What are major conditions that can produce episodic vertigo?
Meniere’s disease (generally lasts the longest)
Recurrent vestibular neuritis
Benign paroxysmal positional vertigo (BPPV) (short duration)
Migraine associated vertigo (longer duration)
Posttraumatic vertigo including labyrinthine fracture and perilymphatic fistula
Superior semicircular canal dehiscence (SSCD)
Vertigo associated with otitis media
What is nystagmus?
Disturbance of ocular movement characterized by nonvoluntary rhythmic oscillations or rapid jerky movements
Can nystagmus be congenital?
Yes, but rare
Either idiopathic or associated with other disorders (albinism, optic nerve hypoplasia, congenital cataracts)
Can nystagmus happen in blind people?
Yes
It is not initiated by visual impulses
Is it always easy to visualize nystagmus?
No
Does nystagmus almost always accompany true vertigo?
Yes
It is not typically seen in other types of dizziness
What is nystagmus evoked by?
Can be spontaneous in response to vestibular upset
May be evoked by head or eye movements
What forms the basis for electronystagmography (ENG)/videonystagmography (VNG) tests?
Detection of nystagmus in response to eye gaze, positional changes, and vestibular stimulation by rotation and temperature variations
Can symptoms associated with a unilateral peripheral vestibular injury subside gradually?
Yes, through compensation
Changes in the central vestibular nuclei that leads to partial restoration of lost neural activity
reduced asymmetry and rebalances vestibular neural activity
Will chronic compensated vestibular deficits still have abnormalities?
Maybe
VOR related
Do bilateral peripheral deficits show vestibular compensation?
No
What is vestibular labyrinthitis?
Inflammation of the inner ear labyrinth
What is vestibular neuritis?
Inflammation of the vestibular nerve
Are both vestibular labyrinthitis and neuritis often preceded by infections?
Yes
Such as cold, flu, OME, measles, meningitis, infectious mononucleosis
How common is vestibular labyrinthitis and neuritis?
About 5% of dizziness cases and about 15% of vertigo cases
What is the most common complication of acute or chronic OME?
Serous labyrinthitis
Do vestibular labyrinthitis and neuritis have similar symptoms?
Yes, but cochlear symptoms present in labyrinthitis
What are the cochlear symptoms in labyrinthitis?
Aural fullness
Tinnitus
High frequency SNHL (resolves in 50% of cases)
What are the vestibular symptoms for both vestibular labyrinthitis and neuritis?
Acute vertigo
Nausea/vomiting
Nystagmus
How long is a labyrinthitis or neuritis attack?
Can last from a few days to a week
What is the treatment for labyrinthitis and neuritis?
Antibiotic/antiviral drugs
Symptomatic treatment with vestibular suppressant drugs for acute symptoms
Steroids also have been used for their anti-inflammatory effects to reverse hearing loss, but the results have been mixed
What are the differential diagnosis for labyrinthitis and neuritis?
Otitis media with effusion
Perilymphatic fistula
Benign paroxysmal positional vertigo (BPPV) – no hearing loss
What is the blood supply to the cochlea?
The labyrinthine artery
What can occlusion of the labyrinthine artery result in?
Sudden and profound SNHL as well as vestibular dysfunction
Vertigo typically subsides but with residual disequilibrium
Vestibular compensation occurs in 4 to 6 months
Is occlusion of the labyrinthine artery more common in older patients?
Yes
With vascular diseases or hyper-coagulation disorders
What do patients complain of prior to the occlusion of the labyrinthine artery?
Episodic vertigo that can herald a transient ischemic attack and even a stroke
What is a migraine?
A severe, episodic, and disabling neurological conditions seen in susceptible individuals
How does a migraine happen?
Migraine involved activation and sensitization of the pain pathways of the trigeminal and cervical nerves as well as the brainstem and thalamic nuclei
Do vascular changes occur during a migraine?
Yes
But they are not the primary cause
Do migraines run in families?
They can
Genetic predisposition
What is the gender ratio for migraines?
3:1 female to male
How many migraine sufferers report episodic vertigo?
1/3 to 1/2
What are migraines characterized by?
Attacks of unilateral, throbbing head pain with sensitivity to movement
Visual, auditory, and other afferent inputs
Fatigue
Nausea/vomiting
What can migraines be triggered by?
Hormonal changes
Diet (e.g., alcohol, caffeine, chocolate, smoked meats, and dairy products)
Stress and anxiety
What are auras?
Premonitions to migraines
Sensory disturbances
Flashes of light and other vision changes
Tingling in hands or face
What is a classic migraine?
Migraine with aura
What is migraine associated vertigo?
The dizziness/vertigo is the aura of the headache
2/3 patients present with true vertigo but may not have a headache
How long does the dizziness/vertigo last with migraine associated vertigo?
From minutes to over 24 hours
Typical for MAV rather than some other vestibular disorder
What are other symptoms of MAV?
Headache, nausea, vomiting, and pallor
Photophobia (insensitivity to light) and loss of peripheral vision
Motion intolerance and noise sensitivity
Ataxia and numbness/weakness of the extremities
How often do MAV patients have migraine symptoms?
At least 50% of the vertigo episodes
How is MAV diagnosed?
No specific test
A physical exam is normal except for nystagmus in some cases
Audiometric and vestibular tests normal
Diagnosis based on case history and subjective symptoms
Is hearing loss uncommon in MAV?
Yes
What is the treatment for MAV?
Medication that is typically prescribed for migraines
Migraine diet – avoid triggers, e.g., smoked meats and cheese
Short duration low dose of vestibular suppressant medicines, i.e., meclizine and diazepam
Vestibular rehabilitation (typically done by PT or OT)
Prophylactic migraine medications for more severe cases
What is the most common cause of vertigo of peripheral origin?
BPPV
What does paroxysmal mean?
Sudden, brief spells
What is the average age of onset for BPPV?
55 years
But can occur at any age
What are possible causes for BPPV?
Idiopathic (most common cause)
Head trauma (including a mild bump on the head)
Vestibular neuritis
Following stapes surgery
Meniere’s disease
Migraine
Diabetes
Osteoporosis
Is BPPV triggered by certain head movements or positions?
Yes
Head positioning, especially when turning in bed and getting in/out of bed
How long do episodes of BPPV last?
One minute
Typically worse in the morning and evening
What canal does BPPV normally involve?
Posterior semicircular canals
Can BPPV involve the horizontal SSC?
Yes, but rare
But generally a result of complication of treatment
More difficult to treat
What are the three forms of BPPV?
Acute - typically resolves over 3 months
Intermittent - active and inactive periods for several years
Chronic - continuous symptoms for long durations
How does BPPV happen?
Otoliths (gravity sensitive organs) become dislodged and migrate into one or more of the fluid-filled SSC
Sends false signals to the brain that the head is moving based on gravity even though its not
Are audiograms and MRIs generally normal for BPPV?
Yes
Issue is in the vestibular system
MRI can be performed if BPPV lasts for 2-3 months post-therapy to rule out other disorders
What is a dix-hallpike test?
Diagnostic head maneuver that moves the head into a position which makes the dislodged otoliths move within a SCC
Erroneous signals cause the eyes to move in a specific pattern (nystagmus) - gives you info on which canal is affected
What is the management for BPPV?
Majority of cases can be corrected mechanically (epley maneuver)
Vestibular suppressants are not typically helpful
Surgery may be required in rare cases
What is menieres?
Idiopathic syndrome
Type of endolymphatic hydrops
Chronic and progressive
What are some of the debated causes of menieres?
Overproduction or under-absorption of endolymph
Alterations in the biochemical gradient within the endolymphatic space
May be an autoimmune disorder
Is menieres multifactorial?
Yes
Patients may have more than one factor simultaneously causing this disorder
Is menieres equally common between genders?
Yes
When is the peak incidence of menieres?
Between 30 to 60 years
Can occur at any age
Rare in childhood
In most cases, is menieres unilateral?
Yes, but it can become bilateral later
Can there be a genetic component to menieres?
Yes
What 4 symptoms is menieres characterized by?
Intermittent episodes of vertigo lasting from minutes to hours
Fluctuating sensorineural hearing loss
Tinnitus (often of low frequency and can be roaring)
Aural fullness/pressure
Are nausea and vomiting common during an acute menieres attack?
Yes
What does a definitive diagnosis of menieres require?
Two or more definitive episodes lasting 20 minutes or longer
At least two of the four characteristic symptoms should be present
What are episodes of acute cases of menieres like?
Fairly stereotypical
Unilateral aural fullness, vertigo, tinnitus, and SNHL
The vertigo lasts from 2 to 4 hours but can last for 12 to 24 hours
The vertigo of long duration with other symptoms is indicative of Ménière’s disease
Nystagmus is always present with the vertigo
Patients can lose balance and fall injuring themselves
Following an acute episode of menieres, does hearing return to normal?
Yes
How long can an acute menieres attack last?
A couple hours to a day
Episodes tend to occur in clusters with the patients remaining symptom-free for months to years
Can remission make menieres difficult to diagnose?
Yes
What happens as menieres progresses?
The attacks become more frequent and severe
The hearing loss does not return to normal following an attack
The vertigo stops but patient may feel dizzy/unsteady frequently and the SNHL may become permanent; the burn-out stage
WRS continue to deteriorate
Diplacusis, tinnitus, and recruitment can become permanent
How does menieres affect the auditory system?
Initial problems with acoustic distortion (affects speech understanding)
Loudness recruitment (low UCL hallmark of menieres)
Initially, fluctuating hearing loss with recovery after a few hours of episodic vertigo
Sudden onset SNHL (rare)
What is considered a significant hearing shift?
Shift of > 15 dB HL for average threshold of 0.5, 1, 2, & 3 kHz
Shift in word recognition scores of 15% to 20% or greater
What is the hearing loss like in the early stages of menieres?
Low freq SNHL
Flat configuration; moderate to moderately severe SNHL
With bilateral dsease, an asymmetry of > 25 dB HL is reported
What is the hearing loss like in the middle stages of menieres?
Hearing sensitivity is reduced at all frequencies, but worse at high and low frequencies – reverse cookie-bite configuration
What is the hearing loss like in the late (burn out) stages of menieres?
Hearing stabilizes with a flat severe sensorineural hearing loss with peaks at 1000 and 2000 Hz, but it may generally be unaidable because of distortion of speech/sound
Rarely does the SNHL progress to profound in Ménière’s
What are the immittance findings for menieres?
Normal tymps
Reflexes usually present and can be obtained at lower SL due to recruitment
What is diplacusis?
Same tone when presented to both ears sounds different and/or distorted in the menieres ear
What is loudness recruitment?
Classic symptom of menieres
Abnormal growth of loudness for signals at suprathreshold intensities
What is an ECochG?
An electrophysiological test that reflect elevation of inner ear pressure, specifically, distension of the BM of the inner ear
Responses are recorded within 2 to 3 ms of auditory stimulus onset
What are the specific components of ECochG?
Summating potential (SP) - from the organ of corti (OHC)
Whole-nerve or compound action potential (AP) - from the auditory nerve (wave I of ABR)
How is menieres diagnosed?
By ECochG
Abnormally large ECochG SP component which increases the SP/AP amplitude ratio
Ratio of >0.42 or >42% is positive for menieres
How many menieres patients show an abnormal SP/AP ratio?
About 60%
When does the frequency of an abnormal ECochG SP/AP ratio increases?
During active episodes of menieres
When the patient is experiencing aural fullness and/or some degree of hearing loss
What is the management for menieres during an acute attack?
Symptomatic treatment to control vertigo and nausea with sedatives and tranquilizers
What is long term management for menieres?
Decreasing the endolymph – low sodium diet & diuretics
Increasing vascular circulation of the inner ear (exercise)
Altering immune activity that maybe causing Ménière’s disease
If the endolymphatic duct is blocked a shunt may be placed to direct excess fluid to the cerebrospinal fluid (CSF)
What is a management method for menieres if the immune system is involved?
Corticosteroid therapy
Recommended patients unresponsive to vestibular suppressants and diuretics, or for patients with sudden SNHL
Are all management methods effective for all cases of menieres?
No
Is amplification successful for menieres?
Not always due to distortion and recruitment
Makes speech perception difficult
Can CIs be beneficial for menieres?
Yes, if candidacy criteria are met
Not be done on those with mild to mod hearing loss
Helps with speech perception
Did the cochlear electrode effect the other symptoms for menieres (aural fullness, tinnitus, and vestibular symptoms)?
No
What are the differential diagnosis for menieres?
Acoustic neuroma (non-episodic symptoms, progressive unilateral SNHL, poor WRS, tinnitus - reflexes are very diff)
Neuritis and labyrinthitis (consistent SNHL, progressive disequilibrium, history of ear surgery or viral infections, no full-on periods of vertigo, symptoms may resolve completely)
Idiopathic vertigo (vertigo of unknown etiology, nausea/vomiting)
Perilymphatic fistula (sudden severe or fluctuating SNHL with disequilibrium, only occasional vertigo)
Cogan’s syndrome (episodic vertigo, SNHL, and eye symptoms)
Is SSCD rare?
Yes
Is SSCD typically unilateral?
Yes
Does the incidence of SSCD increase with age?
Yes, but it can affect all ages
Including children
What is SSCD?
The absence of bone overlying the superior semicircular canal facing toward the dura of the middle cranial fossa
At birth, what is the bone over the top of the inner ear like?
It is very thin or absent (normal)
Thickens over the first 3 years of life (except in about 20% of people)
Most people show no symptoms
Why does SSCD change the way the inner ear functions?
There is a third window added to the inner ear
Alters the normal fluid mechanics
Where can sound energy go with SSCD?
Transmitted outwards through the defect into the cranial vault or from the cranial vault into the endolymph
What is the etiology of SSCD?
Developmental anomaly of the temporal bone – congenital (most common)
Head trauma such as skull fractures or a major pressure-altering event such as scuba diving, air travel, or straining
Idiopathic
What are the signs and symptoms of SSCD?
Vestibular symptoms alone or auditory symptoms alone
Both auditory and vestibular symptoms
No symptoms (no treatment required but patient is observed)
What is one auditory and vestibular disorder that SSCD can mimic?
Patulous ET (aural fullness and hearing internal noises louder than expected - also in SSCD)
How can vestibular symptoms be evoked in SSCD?
By loud sounds and/or by maneuvers that change ME/intracranial pressure (coughing, sneezing, straining, pressure on EAC)
What are the vestibular symptoms of SSCD?
Vertigo/dizziness
Nystagmus
Tullio’s phenomenon (sound-induced vertigo)
Oscillopsia (apparent motion of objects known to be stationary)
What kind of hearing loss can occur with SSCD?
Conductive and/or fluctuating hearing loss (mimicking otosclerosis and menieres)
What is the big reason that people compare SSCD to otosclerosis?
Low freq ABG present (worst at 250 through 1000 Hz)
Why are there low freq ABG in SSCD?
Increased BC sensitivity bc increased perilymph movement with vibrations of the skull
Energy from AC sounds are shunted away from the cochlea and through the dehiscence
What is an important test to differentiate otosclerosis and SSCD?
ART
Patients with otosclerosis show abnormal ARTs but with SSCD ARTs remain normal because its not a ME pathology and it is not a true ABG
How is SSCD diagnosed?
Vestibular assessment
CT scans (MRI useful for differential diagnosis)
ECochG (sensitive to pressure changes in the cochlea)
What are the ECochG results for SSCD?
Abnormal SP/AP ration with high sensitivity/specificity
SP/AP ratio is reduced to normal levels after corrective surgery
What is the treatment for SSCD?
With mild to mod symptoms - conservative treatment, use ear plugs and avoid loud sounds
Debilitating symptoms - surgical repair with bony cement or soft tissue plug
What is mal de debarquement?
Sickness of disembarkment
Originally referred to the illusion of movement felt after long travel on water
Commonly experienced by sailors
What other travel is now included in mal de debarquement?
Airplane, car, and train
Also novel movement
How long does the feeling of mal de debarquement last?
Resolves within 24 hours for most
Others it lasts longer (persistent mal de debarquement)
Possibility of spontaneous resolution decreased after the disorder has persisted for over 12 months
What is the etiology for mal de debarquement?
Unknown why it is persistent in some (especially middle-aged women)
Leading explanation is a problem in the brain due to metabolic/functional changes
Brain is unable to readapt to normal once movement has stopped
What are the symptoms of mal de debarquement?
Rocking, swaying, and disequilibrium after returning to land
Seldom accompanied by true vertigo
Anxiety and depression common
Symptoms worse in an enclosed space or when motionless
Symptoms often improve with continuous movement (driving)
How is mal de debarquement diagnosed?
No specific test
Subjective history
Objective procedures such as vestibular testing and radiologic imaging to rule out other causes (typically normal with mal de debarquement)
What is the treatment for mal de debarquement?
No single treatment
Standard drugs prescribed for motion sickness are usually ineffective
Vestibular rehab (valium and antidepressants)
Avoiding the precipitating event to prevent recurrence
Why are vestibular problems often underdiagnosed in children?
Often compensated if unilateral
Children do not have the vocabulary to express symptoms
Many children with hearing loss and vestibular loss often learn to walk only slightly later than normal peers
What are some things that children with vestibular dysfunction struggle with?
Coordinated and balance related activities
Reading acuity due to abnormal vestibular ocular reflex function
Can cochlear implant failure in children be directly related to vestibular dysfunction?
Yes
Because of the underlying pathology on the VIII nerve
Is vestibular dysfunction in children often accompanied by hearing loss?
Yes
What are some disorders that can affect the pediatric vestibular system?
Genetic conditions with hearing loss (CHARGE, EVA, BOR, usher, waardenburg)
Neurological conditions (motion sensitivity, anxiety/depression, migraine)
Trauma/infection (concussion, labyrinthitis, neuritis, meningitis, CMV, OME)
Other (Ehlers-Danlos syndrome, POTS, perilymphatic fistula, ANSD, SSCD, BBPV)
What percentage of children with acute otitis media will develop chronic otitis media with effusion?
5 to 10%
What has been reported regarding the effects of chronic otitis media on the vestibular system?
Coordination and motor disabilities including delayed walking and balance problems
Reduced vestibular function
What are the ways in which chronic OME can cause vestibular symptoms?
Invasion of bacterial toxins in the inner ear
Cholesteatoma that causes labyrinthitis or perilymphatic fistula resulting in vestibular symptoms
What are some common symptoms for pediatric vestibular disorders?
Dizziness or vertigo
Visual problems
Balance problems
Since children have difficulty describing vestibular symptoms, what should be done?
A good case history
Focus on identifying provoking movements or activities
Use a questionnaire or second opinion for more complex cases
What warrants vestibular evaluation/rehab for children?
Consistent dizziness
Provoking position changes and head movements
If a child has hearing loss >60 dB HL and has not walked by 14.5 months, what should be suspected?
Vestibular dysfunction
