Dizziness and Nystagmus

Question 1

Hair cells in the inner ear are innervated by ?

Answer 1

CNVIII

Question 2

The vestibular nuclei in the dorsolateral part of the pontomedullary junction connect via ___ with cranial nerves ___.

Answer 2

Medial longitudinal fasciculus (MLF)

CN III, IV, VI - form vestibular-ocular reflex.

Question 3

Peripheral vestibular system:

Answer 3

Labyrinth and vestibular nerve of CNVIII.

Question 4

Central vestibular system:

Answer 4

brainstem and cerebellum.

Question 5

All vestibular structures (labyrinth, brainstem, cerebellum) have what blood supply?

Answer 5

Posterior circulation: vertebral and basilar arteries; PICA; less commonly AICA, or SCA.

Question 6

Common causes of dizziness:
30% of dizziness is \_\_\_.
20% is\_\_\_, 
10-15% is \_\_\_, 
10% is \_\_\_
5% is\_\_.

Answer 6

30% of dizziness is vestibular (BPPV, viral labyrinthe infection, meniere...).
20% is cardiovascular, 
10-15% is psychogenic, 
10% idiopathic,
5% is stroke to posterior fossa.

Question 7

Less common causes of dizziness:

Answer 7

acoustic neuromas, bilateral vestibulopathy due to ototoxic drugs, multiple sclerosis, and Chiari malformation

Question 8

Acute vestibular syndrome:
Most common causes?
What % due to strokes?

Answer 8

Patient with dizziness for the first time and it has continued for at least 24hrs.
If peripheral, most common cause is viral.
If central, most common causes is posterior circulation stroke.
25% due to stroke.

Question 9

Recurrent dizziness within days, weeks, months - think about?
Recurrent dizziness for 6 months or more - think about?

Answer 9

1. stroke.

2. benign causes: BPPV or vestibular migraine or meniere

Question 10

Duration of dizziness: 
BPPV lasts \_\_,
TIAs last\_\_, 
Meniere lasts \_\_\_, 
Migraine lasts\_\_\_.

Answer 10

BPPV lasts seconds.
TIAs last minutes.
Meniere last at least 10-20 min and up to a few hrs.
Migraine can last any duration but typically

Question 11

Nystagmus: the direction of the nystagmus is the direction of the ___phase.

Answer 11

Fast phase.

Example: if fast phase is to the left, the nystagmus is left beating.

Question 12

Peripheral nystagmus:

Answer 12

Only one type of peripheral nystagmas (origin is labyrinth):
- Mainly horizontal

• Beats Away from Bad ear
• Unidirectional: same direction whether patient looks up/down/right/left
• Most prominent when gaze in its direction: left beating nystagmus best seen when look left.
• Transient
• Less prominent in light, with fixation. More prominent during funduscopy exam.
• Sick looking patient

Question 13

Central nystagmus:

Answer 13

• Gaze evoked is most common
• Up or down beat
• Pure torsional (very rare)

Question 14

Viral peripheral vestibulopathy:

Answer 14

Any age. 
Patient looks ill. 
Dizziness worsens over minutes to hours and ends up coming into ER or clinic. 
Nausea, blurry vision
Nystagmus - peripheral type.
Admit the patient.

Question 15

Vestibular Migraine:

Answer 15

Female in 30s-40s who has had HA since teens/20s.
Motion sickness as child.
25% of migraine patients get dizziness.

Question 16

BPPV:

Answer 16

Older person with recurrent dizziness spells that last

Question 17

Meniere disease:

Answer 17

Recurrent dizziness lasts minutes-hrs, with fluctuating hearing loss and tinnitus. Can be bilateral. Fullness of ear.
Refer to ENT.

Question 18

Stroke dizziness:

Answer 18

Older patient with new onset isolated dizziness - 1% chance of TIA//stroke. Isolated dizziness = has nausea, blurry vision, sweat, imbalance, but NO weakness, diplopia, dysphagia, dysarthria, incoord, sensory change.
17% of TIA/stroke present with isolated dizziness.

Question 19

Infarct of this __ causes dizziness AND sensory loss, ataxia, and hiccups.

Answer 19

Dorsolateral medullary inract

Question 20

Stroke to __ can mimic peripheral causes since patients present with isolated dizziness and horizontal nystagmus.

Answer 20

PICA.

AICA rarely presents as isolated dizziness due to infarction of labyrinth and will look like peripheral case too.