dizziness Flashcards
vertigo
peripheral vs central
Sensation of motion in the absence of actual motion
Exaggerated sense of motion in response to body movement
Peripheral
More common
“Inner ear”
Central
Worse pathology
Brain stem or cerebellar in origin
body orientation
visual:
spacial orientation
vestibular system: Indicates the body orientation relative to the gravity
proprioceptive: Relates body movements
Indicates the position of head relative to the body
vestibular system: otoliths are in the…
otolith organs
is a structure in the saccule of the inner ear
otholith organs: saccule and utricle
Utricle is sensitive to a change in horizontal movement
Saccule provides information about vertical acceleration
*if get stuck–>vertigo
semicircular canals
Sense orientation of movement
Filled with endolymph
Movement of endolymph results in sensory input
Dysfunction results in nystagmus
Abnormalities within the vertical canals (anterior or posterior) result in vertical/torsional nystagmus
Abnormalities within the horizontal canal (lateral) result in horizontal nystagmus
visual + vestibular
vestibulo-occular reflex (VOR) Maintains clear vision with movement Abnormality caused by aberrant stimulation Abnormality caused by lesion Results in vertigo / Nystagmus
nystagmus
Rhythmic movement of eyes
Fast and slow component
Direction is named by the fast component
Slow component is generated from the canals
( resulting in eye movement away from canals )
caloric reflex test
“COWS” ??
Test of the vestibulo-ocular reflex that involves irrigating cold or warm water external auditory canal.
caloric reflex test in pts w. cerebral damage
the fast phase of nystagmus will be absent as this is controlled by the cerebrum. As a result, using cold water irrigation will result in deviation of the eyes toward the ear being irrigated. If both phases are absent, this suggests the patient’s brainstem reflexes are also damaged and carries a very poor prognosis
COWS
Cold Opposite, Warm Same.Cold water = FAST phase of nystagmus to the side Opposite from the cold water filled earWarm water = FAST phase of nystagmus to the Same side as the warm water filled earIn other words: Contralateral when cold is applied and ipsilateral when warm is applied
peripheral vestibular disease
Three common peripheral vestibular disorders
Abrupt onset
Intense sensation of spinning
Worsened by rapid movement
Associated with nausea
Vestibular neuritis
Meniere disease
Benign paroxysmal positional vertigo
Meniere disease
Distention of the endolymphatic compartment Unknown cause ( head trauma, syphilis ) Vertigo ( minutes to hours ) Associated with hearing loss Tinnitus, fullness in ears
tx with diuretics, low salt
(enolymphatic hydrops)
Vestibular neuritis
Unknown cause ( Viral ) Intense vertigo (several days ) Positional nystagmus Very debilitating
tx: Supportive care
Diazepam
Meclizine* (nondrowsy dramamine)
(Vestibular suppressant
BPPV: benign paroxysmal positional vertigo
Inappropriate activation of semicircular canal Vertigo ( minutes ) *Provoked by head movement ( latency after movement ) Central lesions have no latency
central disease
Gradual onset More severe and debilitating Variable nystagmus Vertical / without latency *Worsened by rapid movement (with periph as well)
central causes
Cerebellar infarct
MS
neoplasm
vert. art. dissection
non vestibular dizzines
Imbalance
Syncope
Near syncope