VF - Eye Movements 5 - Central & Peripheral Abnormalities - Week 6

Question 1

What can be a cause of muscular atrophy?

Answer 1

Lack of neural innervation to the muscles. Neural diseases may result in atrophy.

Question 2

Name a consequence of orbital/periorbital fat hypertrophy.

Answer 2

The eyes bulge out, and the cornea is excessively exposed to air, possibly drying it out.

Question 3

Define proptosis.

Answer 3

When the eyes bugle out of their sockets.

Question 4

Name a cause of proptosis.

Answer 4

Thyroid eye disease

Question 5

Describe a problem that occurs if extraocular muscles are excessively hypertrophied.

Answer 5

Too large and therefore have little room to contract. Can cause proptosis.

Question 6

What neurotransmitter is used at the neuromuscular junction?

Answer 6

Acetylcholine

Question 7

Describe myasthenia gravis.

Answer 7

The neuron is fine, but the post-synaptic cleft on the muscle is widened, with fewer ACh receptors.
ACh is removed more quickly as well.

Question 8

What is eaton lambert syndrome, what is it associated with, and what is the cause.

Answer 8

An autoimmune disease, occuring when axon terminals are attacked, and is associated with carcinoma.

Question 9

Consider eaton lambert syndrome and myasthenia gravis. What does repeated stimulation result in each of these?

Answer 9

MG - leads to a fatigued response

ELS - response gets stronger - anti-fatigue effect

Question 10

3rd nerve palsy is a a common secondary complication of what disease?

Answer 10

Diabetes

Question 11

Consider an individual with 3rd nerve palsy. How are their saccades affected, what law is involved, what happens when you patch their good and bad eye, and what adjusts the seeing eye to be on target?

Answer 11

When their bad eye is patched, the good eye is too far of target, driven by Hering’s law. When the patching is reversed, the cerebellum adjusts the seeing eye to be as on-target as possible.

Question 12

What two diseases are common causes for neuropathies?

Answer 12

Diabetes and MS

Question 13

What two regions of the brain are the saccade centres found in?

Answer 13

PPRF and RIMLF

Question 14

Consider a patient with SCA2. What is their smooth pursuit like?

Answer 14

It appears to be smooth, but in reality, they are making a series of small, side to side saccades.

Question 15

What region of the brain is affected in SCA2?

Answer 15

The pons, amongst others.

Question 16

Name three common factors that affect the speed of saccades.

Answer 16

Age, sedating drugs, and lack of sleep.

Question 17

What happens when the saccade pulse is normal, but the step isnt?

Answer 17

The eyes will drift back to the centre.

Question 18

Define gaze-evoked nystagmus.

Answer 18

When a saccade tonic isnt roperly integrated, and the eyes drift back to the centre, the drive to push them out again results in gaze-evoked nystagmus.

Question 19

Name two factors that may cause gaze-evoked nystagmus.

Answer 19

Cerebellar disease, excessive alcohol consumption.

Question 20

Describe dysmetria and its cause.

Answer 20

If the cerebellum is damaged, saccades of the wrong size may be elicited.

Question 21

Describe how omnipause neurons can result in unwanted saccades.

Answer 21

Happens if they inadequately inhibit burst neurons.

Some are normal, but incessant ones are pathological.

Question 22

What effect does anorexia and anxiety have on unwanted saccades?

Answer 22

Two conditions not associated with neuropathology that result in higher rates of unwanted saccades.

Question 23

How do unwanted saccades and cognitive problems relate? Give two examples.

Answer 23

May result in someone being overly distractible, such that they cant maintain gaze on intended targets.
Includes Alzheimers and ADHD

Question 24

What is unilaterally poor tracking an indicator of?

Answer 24

May indicate an ipsilateral disease.

Question 25

Name two conditions in which good pursuit with anticipatory saccades are seen.

Answer 25

Alzheimers and schizophrenia

Question 26

Describe what good pursuit with square wave jerks looks like.

Answer 26

Actual tracking is smooth, but is incessantly interrupted by the saccadic system.