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