Inner Ear - Balance

Question 1

Describe the physiology of balance of the inner ear

Answer 1

Vestibule is the balance part of the ear
Has utricle and saccule
3 semi circular canals which connect with the utricle
Vestibular nerve picks up signals which go to internal auricular meatus

Question 2

What are the 2 otolith organs in the inner ear?

Answer 2

Utricle and saccule

Question 3

Explain the structure of the Utricle and Saccule

Answer 3

Have sensory epithelium called macula - horizontal in utricle and vertical in saccule
Cilia of hair cells embedded in gelatinous otolithic membrane
Have calcium crystals called otoliths - add momentum to movement

Question 4

Describe the ampulla of semi-circular canals

Answer 4

Ampullae are the expanded areas at each end of semi-circular canals
They contain the sensory organ - the crista
Kinocilium push on the ampulla

Question 5

What is the movement of the crista a stimulus of?

Answer 5

Vestibulo-ocular reflex

Question 6

What is the function of the vestibulo-ocular reflex (VOR)?

Answer 6

Stabilises gaze by moving eyes in order to compensate for head and body movement
This fixes image on retina for clear sight

Question 7

Describe the vestibulo-ocular reflex

Answer 7

If head turns to right
Signals on right increase and left decrease
Difference tells brain which direction head has gone
Goes to vestibular nuclei then the nuclei of eye movement

Question 8

What are the 3 systems regulating body balance?

Answer 8

Input
CNS
Output

Question 9

What inputs regulate body balance?

Answer 9

Visual
Vestibular - rotation and gravity
Pressure

Question 10

What in the CNS regulates body balance?

Answer 10

Cerebral cortex
Brainstem
Cerebellum
Dizziness can cause nausea

Question 11

What outputs help regulate body balance?

Answer 11

Ocular reflex - keeping clear image on retina
Postural control

Question 12

What clinical conditions of the inner ear can effect balance?

Answer 12

Benign Paroxysmal Positional Vertigo - most common
Vestibular Neuritis
Meniere’s Disease

Question 13

Describe Benign Paroxysmal positional vertigo (BBPV)

Answer 13

Loose otoconia move out of utricle into semi-circular canals - most common is posterior canal as happens when lying down
Provokes vertigo and nystagmus

Question 14

What is the test for posterior canal BPPV?

Answer 14

Dix-Hallpike manoeuvre

Question 15

What is the treatment for posterior BPPV?

Answer 15

Epley manoeuvre - crystals go back into utricle

Question 16

Describe vestibular neuritis

Answer 16

Inflammation of the vestibular nerve
Acute onset of vertigo, nausea and vomiting
Rarely hearing loss - usually due to labyrinthitis
Nystagmus

Question 17

What are the causes of vestibular neuritis?

Answer 17

Aetiology is rarely proven
Points towards viral damage of vestibular nerve rather than sensory cells of labyrinth
If hearing loss - mumps, measles and infectious mononucleosis

Question 18

What is the classical triad for Meniere’s Disease?

Answer 18

Vertigo
Hearing loss - unilateral
Tinnitus
Often also sensation of fullness in ear

Question 19

Describe the pathophysiology of Meniere’s Disease

Answer 19

Endolymph produced by stria viscularis - increase endolymph
Hydrops due to malabsorption of endolymph in endolymphatic duct and sac

Question 20

Describe hearing loss and vertigo in Meniere’s Disease

Answer 20

Vertigo is unpredictable and severe - can last 30 mins to days
May burn out - episodic
Hearing loss is unilateral and sensorineural in nature

Question 21

Describe migraine affecting balance

Answer 21

Commo cause of episodic vertigo
Lifestyle management is key
Prophylactic meds can be helpful