A scientific and clinical approach to acute vertigo

Question 1

What is meant by conditional probability

Answer 1

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).

Question 2

Essentially, what is the brain

Answer 2

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.

Question 3

Outline a generalist’s aim and strategy

Answer 3

AIM • Make the correct diagnosis
• STATEGY • Know the commonest diagnoses very well.
• Know the red flags.
• Know who to call.

Question 4

What is the key take home message with vertigo

Answer 4

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

2. 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
3. Becoming an expert requires training with an expert! - So use the red flags and ask for help when needed

Question 5

What is important to remember about the vestibular organ

Answer 5

It is evolutionary conserved- i.e all organisms have it

Question 6

Summarise the vestibulo-ocular reflex

Answer 6

 Angular acceleration – 3 SCCs.

 Linear acceleration and tilt – 2 otolith organs- head movement and head acceleration .

Question 7

What is the purpose of the vestibulo-ocular reflex

Answer 7

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.

Question 8

What happens when you lose both peripheral vestibular labyrinths

Answer 8

Lose vestibulo-ocular reflex- so what you are looking at wobbles- because you lose the stabilisation
This is called Oscillopsia

Question 9

Experimentally, how can you look for oscillopsia

Answer 9

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.

Question 10

Describe some of the inputs to the vestibular system

Answer 10

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.

Question 11

Compare oscillopsia to vertigo

Answer 11

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)

Question 12

Describe the importance of English when speaking to the patient

Answer 12

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

Question 13

Clinically, how can we distinguish between dizzinees and vertigo

Answer 13

• 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

Question 14

Summarise illusory self-motion

Answer 14

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.

Question 15

Outline the epidemiology of emergency room vertigo diagnoses

Answer 15

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

Question 16

What is Meniere’s disease

Answer 16

a disease of unknown cause affecting the membranous labyrinth of the ear, causing progressive deafness and attacks of tinnitus and vertigo

Question 17

Before diagnosing acute vertigo, what do we need to rule out

Answer 17

• ?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.

Question 18

What percentage of acute admissions to the hospital are neurological

Answer 18

20%

Question 19

What is meant by nystagmus

Answer 19

rapid involuntary movements of the eyes.

compensatory movement of the eye in the absence of head movement

Question 20

What is a nystagmus defined by

Answer 20

The direction of the fast phase- i.e right or left

Question 21

What is a key feature of a visual nystagmus

Answer 21

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

Question 22

What are the main diagnoses of acute vertigo

Answer 22

• BPPV
• Vestibular Neuritis
• Migrainous Vertigo
• Stroke (cerebellar)
• (Meniere’s – rare

History and examination of acute vertigo are aimed at these causes

Question 23

List the core examinations performed on the eye

Answer 23

• Cover
• Gaze
• VOR
• Hallpike
• Fundoscopy

Question 24

Describe hallpike

Answer 24

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.

Question 25

Describe the gaze test

Answer 25

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

Question 26

Describe the head impulse test or doll’s eyes

Answer 26

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.

Question 27

Summarise fundoscopy

Answer 27

Fundoscopy

1. Retina – position of disc and macula
2. 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.
3. Effect of visual fixation on nystagmus?

Question 28

Describe otoscopy

Answer 28

• 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

Question 29

Describe the core examination of the ears and legs

Answer 29

Ears: otoscopy
Legs: gait (+tandem)

Question 30

Summarise examination of the gait

Answer 30

• 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.

Question 31

Describe a tandem gait

Answer 31

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.

Question 32

Describe Romberg’s test

Answer 32

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.

Question 33

Summarise BPPV

Answer 33

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.

Question 34

What are the key features of BPPV

Answer 34

• Positional – lying back in bed (differentiate postural hypotension) • Brief – seconds [beware prolonged malaise]
• Red flags: • Headache • Atypical nystagmus (vertical nystagmus- indicates CNS cause)

Question 35

Define vestibular agnosia

Answer 35

The lack of sensation of dizziness despite a peripheral vestibular activation ( as evidenced by the evoked nystagmus) indicates a loss of vestibular sensation

Question 36

Why should we treat aymptomatic BPPV

Answer 36

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.

Question 37

How many patients with traumatic brain injury will have BPPV

Answer 37

60%

And a third of these will have vestibular agnosia

Question 38

How can we calculate your vestibular thresholds (both reflex and perceptual)

Answer 38

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

Question 39

What is a large discrpenacy between the refex and pereceptual vestibular threshold indicative of

Answer 39

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

Question 40

How can traumatic brain injury lead to vestibular agnosia

Answer 40

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

Question 41

What can acute vestibular migraine replicate

Answer 41

Stroke

When the episode is gone- they go back to normal

Question 42

Summarise vestibular neuritis

Answer 42

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

Question 43

What are the characteristics of vestibular neuritis

Answer 43

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

Question 44

List some key red flags to be aware of

Answer 44

• 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

Question 45

Summarise acute vestibular migraine

Answer 45

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

Question 46

Describe recurrent migraines as a cause of peripheral vestibular disorders

Answer 46

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.

Question 47

Describe chronic migraines as a cause of peripheral vestibular disorders

Answer 47

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.

Question 48

Summarise cerebellar stroke

Answer 48

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)

Question 49

What is valsalva

Answer 49

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