TBL Neuro Flashcards
This accounts for an estimated 5 percent of primary care clinic visits
dizziness
What are the four categories of dizziness?
vertigo
disequilibrium
presyncope
lightheadedness
4 main causes of vertigo?
benign paroxysmal positional vertigo Meniere disease (increased endolymph in inner ear) vestibular neuritis (viral infection of vestibular nerve) labyrinthitis
What can cause presyncope?
many medications
**medication regimens should be assessed in pts with this type of dizziness
What are two major causes of disequilibrium?
diabetic neuropathy
Parkinson disease
What kinds of things can cause vague lightheadedness?
depression
anxiety
hyperventilation syndrome
What tests can be done to hone in on a diagnosis for dizziness?
nystagmus
Dix-hallpike maneuver
orthostatic blood pressure testing
What is used to treat benign paroxysmal positional vertigo?
Epley maneuver
vestibular rehabilitation
What is used to treat Meniere disease?
intratympanic dexamethasone
gentamicin
What is used to treat vestibular neuritis?
steroids
What is used to treat orthostatic hypotension?
alpha agonists
mineralocorticoids
lifestyle changes
How to treat disequilibrium and lightheadedness?
treat the underlying cause
What should you ask patients about when they present with dizziness?
drugs caffeine nicotine alcohol head trauma and whiplash injuries
False sense of motion, possibly spinning sensation
vertigo
What two things usually cause vertigo with hearing loss?
Maniere disease
labyrinthitis
What two things usually cause vertigo without hearing loss?
BPPV
vestibular neuritis
What usually causes episodic vertigo?
BPPV
Maniere disease
What usually causes persistent vertigo?
vestibular neuritis
labyrinthitis
This diagnosis should be considered after other causes of vertigo have been ruled out, and the vertigo presents with current migraine or history of migraine and one of the following symptoms during last two episodes of vertigo: migraine headache, photophobia, aura
migrainous vertigo
What are some cardiovascular causes of dizziness?
arrhythmias
MI
carotid artery stenosis
orthostatic hypotension
What are some cardiovascular meds that increase the risk of orthostatic hypotension in older people?
alpha blockers ACE inhibitors beta blockers clonidine reserpine doxazosin diuretics etc etc etc
**used to treat HTN
Loose otolith in semicircular canals causing a false sense of motion
benign paroxysmal positional vertigo
What are some diagnostic criteria for benign paroxysmal positional vertigo?
episodic vertigo
no hearing loss
positive findings on Dix-Hallpike maneuver
What is hyperventilation syndrome? How can you diagnose it?
hyperventilation causing respiratory alkalosis; may be provoked by anxiety; symptoms are reproduced by voluntary hyperventilation
What is Meniere disease? How can you diagnose it?
a type of vertigo; increased endolymph in the inner ear; episodic vertigo with hearing loss
What is orthostatic hypotension? How much must blood pressure drop?
a type of presyncope, in which blood pressure drops in response to position change and causes decreased blood flow to the brain; BP drops 20mmHg systolically or 10mg diastolically or pulse increases 30bpm
What does this make you think of?
shuffling gait with reduced arm swing and possible hesitation
Parkinson disease
If dizziness lasts minutes, this needs to be ruled out; other associated symptoms usually present
stroke or TIA
These two drugs increase the risk of ataxia and falls in older persons
benzos
TCAs
What questions should you ask when a patient complains of lightheadedness?
anxiety?
depression?
panic disorder?
hyperventilation syndrome?
How should you measure BP for a dizzy patient?
measure it while they are supine, and then again 1 minute after the patient stands
**look for 20mmHg drop in systole, 10mmHg drop in diastole or 30 bpm increase in pulse
What does the Dix-Hallpike maneuver test for? If it is positive, what does it rule in?
benign paroxysmal positional vertigo
How do you perform the Dix-Hallpike maneuver?
while the patient is seated, turn their head 45 degrees to one side, then lie them down with their head partially off of the table; observe the patient’s eyes for 30 sec; if there is nystagmus, it is diagnostic for debris in the ear that is facing down
**repeat maneuver to other side
How can you confirm hyperventilation syndrome?
have the pt breathe in and out 20 times to see if you can replicate symptoms of dizziness
T/F: A full neurological and cardiovascular exam should be performed on all patients with complaints of dizziness
True
3 treatment modalities for benign paroxysmal positional vertigo?
meclizine (25-50mg every 4-6hrs)
Epley maneuver
vestibular rehabilitation (series of head and neck exercises)
How do you treat Meniere disease?
salt restriction and/or diuretics
intratmypanic dexamethasone or gentamicin
How do you treat vestibular neuritis?
methylprednisolone
How to treat orthostatic hypotension?
review medication regimen midodrine fludrocortisone pseudoephedrine paroxetine desmopressin
How to treat hyperventilation?
breathing control exercises
beta blockers
antianxiety agents
Vertigo implies (blank) of vestibular inputs from the two labyrinths or in their central pathways
asymmetry
If dizziness lasts for seconds, what should you consider?
BPPV
orthostatic hypotension
If dizziness lasts hours, what should you consider?
migrainous vertigo
Meniere’s disease
If dizziness lasts an intermediate duration (minutes), what should you consider?
TIA or stroke
Unilateral hearing loss and other aural symptoms typically point to a (blank) cause
peripheral
**central lesions are unlikely to cause unilateral hearing loss, because auditory pathways become bilateral right away
Symptoms such as double vision, numbness, and limb ataxia suggest a (blank) lesion
brainstem or cerebellar lesion
Answer the following in regards to perpiheral vertigo:
Direction of associated nystagmus?
Purely horizontal nystagmus w/o torsional component?
Purely vertical or purely torsional nystagmus?
Visual fixation?
Tinnutus and/or deafness?
CNS abnormalities?
Common causes?
unidirection (fast phase opposite the lesion)
uncommon
never
inhibits nystagmus
often present
none
BPPV, infection, vestibular neuritis, Meniere’s disease, trauma, toxin
Answer the following in regards to central vertigo?
Direction of associated nystagmus?
Purely horizontal nystagmus w/o torsional component?
Purely vertical or purely torsional nystagmus?
Visual fixation?
Tinnutus and/or deafness?
CNS abnormalities?
Common causes?
bidirectional may be present may be present no inhibition usually absent extremely common (dplopia, hiccups, cranial neuropathies, dysarthria) vascular, demyelinating, neoplasm
What does the head impulse test assess? How do you perform it?
tests the VOR to look for unilateral or bilateral vestibular hypofunction; begin w patient’s head rotated to the left or right while the patient looks at the examiner’s face. If the VOR is deficient, a catch up saccade is seen at the end of the rotation
All patients with episodic dizziness, especially if it is provoked by positional change, should be tested with this
Dix-Hallpike maneuver
What is the dynamic visual acuity test?
first visual acuity is measured with the head still and then the head is rotated back and forth; and visual acuity is measured again and if they can’t read w/i one line of what they read previously, the test is abnormal
Predominantly low frequency hearing loss is characteristic of this disease
Meniere’s disease
When a patient presents with an acute vestibular syndrome, what is the most important question?
whether the lesion is central or peripheral
**give attention to any symptoms that suggest central dysfunction (diplopia, weakness, numbness, dysarthria)
Episodes of brief vertigo (<1min); usu provoked by changes in head position relative to gravity; attacks caused by free-floating otoconia that have dislodged and are free floating
benign paroxysmal positional vertigo
Should patients with bilateral loss of vestibular function get vertigo? What are some symptoms of bilateral loss of vestibular function?
no, because there is no asymmetry of vestibular input; loss of balance particularly in the dark and oscillopsia during head movements or riding in a car
Examination findings for bilateral vestibular hypofunction?
diminished dynamic visual acuity (due to loss of stable vision when head is moving)
abnormal head impulse responses in both directions
Romberg sign
When should medications be used to vertigo?
for short-term control, such as during the first few days of acute vestibular neuritis or for attacks of Meniere’s disease
Antihistamines used for vertigo?
meclizine
dimenhydrinate
promethazine
Benzodiazepines used for vertigo?
diazepam
clonazepam
Anticholingergic used for vertigo?
scopolamine transdermal
Physical therapy used for vertigo?
repositioning maneuvers
vestibular rehabilitation
Other drugs used for vertigo?
diuretics low sodium antimigrainous drugs methylprednisolone SSRIs
What comprises the membranous labyrinth?
cochlea (hearing)
semicircular canals (equilibrium)
utricle (equilibrium)
saccule (equilibrium)
Sensory organs of the utricle and saccule used to detect orientation of the head with respect to gravity
maculae
- *macula of the utricle is horizontal (determines orientation of the head when you’re upright)
- *macula of the saccule is vertical (determines orientation of head when lying down)
Explain the directional sensitivity of hair cells
small cilia plus one large cilium, the KINOCILIUM - when the stereocilia bend in the direction of the kinocilium, this causes fluid channels to open and depolarization occurs; when the cilia bend in the opposite direction, hyperpolarization occurs and decreases the impulse traffic or turns if OFF
When a person’s head begins to rotate in any direction, the inertia of the fluid in one or more of the semicircular ducts causes the fluid to remain stationary but the duct rotates with the head. So, the fluid flows from the duct through the ampulla and bends the (blank) to one side. This causes the hair cells to bend toward or away and cause (blank) or (blank). This signal is transmitted via the vestibular nerve to the CNS to tell you that your head is rotated.
cupula; hyperpolarizes; depolarizes
The utricle and saccule can detect (blank) acceleration, but not linear velocity
linear
T/F: The semicircular duct transmits a signal of one polarity when the head begins to rotate and of opposite polarity when the head stops rotating
true
What is the semicircular ducts’ function in the maintenance of equilibrium?
they only detect when a person is beginning or stopping to rotate in one direction or another; they don’t maintain equilibrium during steady directional or rotational movements
**loss of function of semicircular ducts causes a person to have poor equilibrium when performing rapid intricate changing body movements
The semicircular duct mechanism (blank) that dysequilibrium is going to occur and causes the equilibrium centers to make appropriate adjustments
predicts
Where are proprioreceptors located that tell about the orientation of the head relative to the body?
in the neck
**when the head is leaned in one direction by bending the neck, neck proprioreceptors keep the person from feeling dysequilibrium
This part of the brain is especially concerned with the dynamic equilibrium signals from the semicircular ducts
flocculonodular lobes
**if damaged, this messes with equilibrium during rapid changes in direction of motion
