A scientific and clinical approach to acute vertigo Flashcards
What is meant by conditional probability
Given x, what is the probability of y
In probability theory, conditional probability is a measure of the probability of an event occurring given that another event has (by assumption, presumption, assertion or evidence) occurred. If the event of interest is A and the event B is known or assumed to have occurred, “the conditional probability of A given B”, or “the probability of A under the condition B”, is usually written as P(A | B), or sometimes PB(A) or P(A / B).
Essentially, what is the brain
The brain is a statistical machine- if an object flies past you at 80mph, then your brain will automatically exclude that object being a human being.
This is how we should approach the diagnosis- look for red flags and the commonest causes of those symtpoms.
Outline a generalist’s aim and strategy
AIM • Make the correct diagnosis
• STATEGY • Know the commonest diagnoses very well.
• Know the red flags.
• Know who to call.
What is the key take home message with vertigo
Always look for BPPV - Easy to train to diagnose and treat - Distinguish BPPV vs. central positioning nystagmus- 80% of the time can cure within 2 minutes- simple maneoeveur- no need for drugs
- Expert superior to early MRI in vertigo stroke diagnosis - [MRI (88%) vs. Expert (100%) sensitive (Khattah 2009 HINTS)]- can take four days for sensitivity of MRI to peak to show vertigo stroke- if you think it’s vertigo stroke but the MRI says otherwise- reorder the MRI in 4 days time
- Becoming an expert requires training with an expert! - So use the red flags and ask for help when needed
What is important to remember about the vestibular organ
It is evolutionary conserved- i.e all organisms have it
Summarise the vestibulo-ocular reflex
Angular acceleration – 3 SCCs.
Linear acceleration and tilt – 2 otolith organs- head movement and head acceleration .
What is the purpose of the vestibulo-ocular reflex
It stabilises gaze in space.
Therefore, when you turn your head to the left- your eyes will move to the right as to stabilise whatever you are looking at- 3- neurone pathway
5-10ms latency between head movement and eye movement.
What happens when you lose both peripheral vestibular labyrinths
Lose vestibulo-ocular reflex- so what you are looking at wobbles- because you lose the stabilisation
This is called Oscillopsia
Experimentally, how can you look for oscillopsia
Ask the patient to close one eye.
Then press on your open eye (through the eyelid)
You will see the world wobble
So when they have nil vestibular function- eyes won’t stabilise head movement.
Describe some of the inputs to the vestibular system
Circuits in the brainstem mediating the vestibulo-ocular reflex.
And input from the inner ear.
Vestibular-spinal pathways not too important in humans.
Ascending pathways to cortex- perception- can detect movement even with eyes closed- signal from inner ear to cortex
Will detect if someone moves you passively
If you spin around- with eyes closed- you would feel dizzy- illusionary self motion- vertigo- perceptual component of some problem.
Compare oscillopsia to vertigo
Vestibular-Motion perception
= Sensation of motion: of SELF or ENVIRONMENT- their own words what they are experiencing- their illusionary self motion
• Seeing environmental motion
= oscillopsia (indicates a nystagmus)
Describe the importance of English when speaking to the patient
Dizziness: Old English ‘stupid’
• Vertigo: Latin ‘vertere’ to turn- some patients have conditions which should give them vertigo- but they don’t experience it
Dizziness can mean a variety of different things- need to ask the patient questions to see if their definition matches what you are thinking. Ask if they feel as though they are moving up, down, spinning or on a boar- this indicates illusionary self motion
Clinically, how can we distinguish between dizzinees and vertigo
- Describe the symptoms in words.
- Self or Environmental motion (eyes shut). • Rocking like a boat • Spinning like a merry go round • Floating
- Seeing the room move (which direction?) • Seeing the visual world move = nystagmus
Summarise illusory self-motion
Patient had parietal cortex stimulated with increasing electrical intensity:
Low current: Feeling of gentle rocking of self
High current: A feeling of violent spinning of self & room
Although stimulus for vertigo may come from inner ear= it could also be due to a problem with the brainstem or cortex, as demonstrated in this experiment.
Outline the epidemiology of emergency room vertigo diagnoses
BPPV – 35% - Benign paroxysmal positional vertigo
• Vestibular Neuritis – 15% - bell’s palsy of the 8th CN, self-limiting for around 1 week, vertigo, nystagmus and clumsiness
• Migrainous Vertigo – 15%- not synonymous with headache
• Stroke – 5% - including cerebellar stroke
• Mixed (syncope, anxiety…) – 30%- including postural hypotension and other cardiac causes
• Meniere’s < 1- uncommon
What is Meniere’s disease
a disease of unknown cause affecting the membranous labyrinth of the ear, causing progressive deafness and attacks of tinnitus and vertigo
Before diagnosing acute vertigo, what do we need to rule out
- ?postural blood pressure- to rule out presyncope
- ?arterial saturation - to rule out pulmonary embolism
- ?ECG- to rule out cardiac dysrhythmias
Essentially, we need to rule out any non-neurological causes of dizziness- as neurologists are not specialised to treat or diagnose these.
What percentage of acute admissions to the hospital are neurological
20%
What is meant by nystagmus
rapid involuntary movements of the eyes.
compensatory movement of the eye in the absence of head movement
What is a nystagmus defined by
The direction of the fast phase- i.e right or left
What is a key feature of a visual nystagmus
o Visual suppression of nystagmus – VOR suppression.
Visual fixation can supress peripheral nystagmus but cannot supress central nystagmus.
The nystagmus will increase in intensity when you remove the visual fixation- this tells you that it has a peripheral cause- i.e the ear
What are the main diagnoses of acute vertigo
- BPPV
- Vestibular Neuritis
- Migrainous Vertigo
- Stroke (cerebellar)
- (Meniere’s – rare
History and examination of acute vertigo are aimed at these causes
List the core examinations performed on the eye
- Cover
- Gaze
- VOR
- Hallpike
- Fundoscopy
Describe hallpike
During a Hallpike maneuver, a patient usually sits on a table. A doctor typically lays the patient down very quickly, with the patient situated so that his head hangs over the table’s edge. While the patient lies down, the physician simultaneously turns the patient’s head to the left or the right in most cases. Patients often develop dizziness and nystagmus very quickly from this maneuver if they have an inner ear disorder. Nystagmus is an involuntary eye movement that generally causes fast movement of the eyes in one direction alternating with a smoother eye movement in the other direction.
Describe the gaze test
The gaze test is used to evaluate the ability to generate and hold a steady gaze without drift or gaze-evoked nystagmus- perform with and without fixation- to distinguish between central and peripheral caused
Describe the head impulse test or doll’s eyes
This reflex can be tested by the rapid head impulse test or Halmagyi–Curthoys test, in which the head is rapidly moved to the side with force, and is controlled if the eyes succeed to remain to look in the same direction. When the function of the right balance system is reduced, by a disease or by an accident, a quick head movement to the right cannot be sensed properly anymore. As a consequence, no compensatory eye movement (to the left) is generated, and the patient cannot fixate a point in space during this rapid head movement.
Summarise fundoscopy
Fundoscopy
- Retina – position of disc and macula
- Spontaneous nystagmus?- SPONTANEOUS NYSTAGMUS. Most frequently it is composed of a mixture of slow and fast movements of the eyes. Nystagmus can occur normally, such as when tracking a visual pattern.
- Effect of visual fixation on nystagmus?
Describe otoscopy
- Hearing (if complaint)
- Otoscopy
- Usually informative in acute vertigo (except for looking for VZV vesicles in acute unilateral peripheral vestibular loss or suppurative infection in meningitis- sign of infection penetrating temporal bone- requires neurosurgery
Describe the core examination of the ears and legs
Ears: otoscopy
Legs: gait (+tandem)
Summarise examination of the gait
- Gait • Narrow based?
- Tandem walking • Count how many mistakes out of 10 tandem steps.
- Romberg
- See if eye closure affects balance. • Can they maintain balance for >20s without vision.
Describe a tandem gait
Tandem gait is a gait (method of walking or running) where the toes of the back foot touch the heel of the front foot at each step.
Describe Romberg’s test
Ask the subject to stand erect with feet together and eyes closed. Stand close by as a precaution in order to stop the person from falling over and hurting himself or herself. Watch the movement of the body in relation to a perpendicular object behind the subject (corner of the room, door, window etc.). A positive sign is noted when a swaying, sometimes irregular swaying and even toppling over occurs. The essential feature is that the patient becomes more unsteady with eyes closed.
The essential features of the test are as follows:
the subject stands with feet together, eyes open and hands by the sides.
the subject closes the eyes while the examiner observes for a full minute.
Summarise BPPV
o Intense vertigo when moving the head in certain directions.
o Can be cured/fixed with the Hallpike manoeuvre and Semont treatment – rapidly move the head down to the left and then look for nystagmus then rapidly move the head to the other side to displace the floating otoconia.
There is a latency of the nystagmus to be identified by the clinician.
o Vertical nystagmus is more likely to be CENTRAL vestibular disorder than a peripheral and so you’d most likely see a horizontal nystagmus with BPPV.
What are the key features of BPPV
- Positional – lying back in bed (differentiate postural hypotension) • Brief – seconds [beware prolonged malaise]
- Red flags: • Headache • Atypical nystagmus (vertical nystagmus- indicates CNS cause)
Define vestibular agnosia
The lack of sensation of dizziness despite a peripheral vestibular activation ( as evidenced by the evoked nystagmus) indicates a loss of vestibular sensation
Why should we treat aymptomatic BPPV
Vestibular agnosia patients do not feel vertigo but they still suffer nausea, vomiting and falls.
Theoretically, screening and treating vestibular diagnoses in acute trauma patients would speed recovery and improve clinica outcome.
How many patients with traumatic brain injury will have BPPV
60%
And a third of these will have vestibular agnosia
How can we calculate your vestibular thresholds (both reflex and perceptual)
Sit the patient in a chair in the dark and rotate them a given degrees.
Ask whether they felt the movement or not- and analyse their VOR at the same time.
Find out the threshold for each one- decrease the speed of rotation if they felt dizzy and vice versa
Look at the discrepancy
What is a large discrpenacy between the refex and pereceptual vestibular threshold indicative of
If the perceptual threshold is much larger than that of the reflex- vestibular agnosia
Improves after recovery from traumatic brain injury- so gives us a way of measuring clinical outcomes
Tend to have worser balance than those without vestibular agnosia- and score less on subjective symptom tests- but their scores do not lower as much as those without as recovery continues- which is paradoxically good
How can traumatic brain injury lead to vestibular agnosia
Brain networks for vertigo- which are wipes out by the trauma
Vertigo networks found on studies in ballerinas- who have attenuated vertigo networks- so that they can pirouette easily
What can acute vestibular migraine replicate
Stroke
When the episode is gone- they go back to normal
Summarise vestibular neuritis
Subacute onset (minutes – hours) • Continuous vertigo • Obvious ‘vestibular’ nystagmus • Positive head impulse test • Normal gait • Treatment • Vestibular sedatives for 24-36 hours • Mobilise at day 2 or 3 • Treat any BPPV or migrain
What are the characteristics of vestibular neuritis
ACUTE – Vestibular neuritis characteristics:
o Sudden, unilateral vestibular loss – vertigo, unsteadiness, nausea, nystagmus.
o Hearing spared.
o No CNS symptoms or findings.
o Can last from days to weeks
List some key red flags to be aware of
• Headache – • 40% posterior circulation stroke. • Gait ataxia – • may be only non-vertiginous (non-vertigo related) manifestation of cerebellar stroke. • Hyperacute onset – • suggests vascular origin. • Vertigo + hearing loss – • AICA or urgent ENT problem. • Prolonged symptoms (> 4 days) – • Floor of 4th ventricle problem
Summarise acute vestibular migraine
History of migraine • Can have acute vertigo without prominent headache • Recurrent • Diagnosis of exclusion –
Main differential diagnosis is cerebellar stroke • Red flags: • Headache • Gait problems • Hyperacute onset • Hearing loss • Prolonged symptoms (>4 days
Describe recurrent migraines as a cause of peripheral vestibular disorders
o Usually forms from a history of migraines.
o There are usually migraine symptoms during a vertigo attack.
o Critically, hearing is SPARED – this determines between Meniere’s disease and migraines.
o Migraines usually respond to treatment.
Describe chronic migraines as a cause of peripheral vestibular disorders
o This type of patient is chronically dizzy and there are many aetiologies.
o Anxiety is a cofounding factor as people develop anxiety from having the dizziness.
o Reasons for having chronic dizziness include:
§ A lack of full vestibular compensation.
§ Inadequate testing by physician.
§ Idiosyncratic (odd habits) reactions.
Summarise cerebellar stroke
Thunderclap onset vertigo • Embolic - Valsalva? Atrial fibrillation?
• Dissection – neck pain (stretching, trauma?) • Poor balance - unable to walk or even sit • Headache • Red flags: • Headache • Gait problems • Hyperacute onset • Hearing loss • Prolonged symptoms (>4 days)
What is valsalva
The Valsalva maneuver is performed by moderately forceful attempted exhalation against a closed airway, usually done by closing one’s mouth, pinching one’s nose shut while expelling air out as if blowing up a balloon
