Ocular Motility #14: Ataxia and Apraxia

What is the difference between oculomotor ataxia and apraxia?

Ataxia = clumsiness

Apraxia = long latency

Which of the AD types of SCA causes pigmentary retinopathy?

SCA 7

What are the 7 autosomal dominant types of SCA?

SCA 1, 2, 3, 6, 7, 8, 20

What are the 3 recessive types of SCA?

1) Friedreich Ataxia

2) SCA with Saccadic Intrusions

Name the 3 stress-induced ataxias and how to treat them?

1) Episodic Ataxia Type I

-Diamox

2) Episodic Ataxia Type II

3) Benign Recurrent Vertigo

Episodic Ataxia Type 1

Typically in 2-20 year olds with AD inheritance

-short episodes (sec to min)

-eyelid myokymia of the levator or orbicularis

What can trigger a Type 1 Episodic Ataxia?

exercise or the startle reflex

****Treatment of choice for Type 1 Episodic Ataxia

Diamox

Second choice medication for Type 1 Episodic Ataxia

Ampyra

Type 2 Episodic Ataxia

Also AD inheritance, but happens in adults up to 30 yo at the time of diagnosis (instead of 2-20 for Type 1)

-episodes last HOURS instead of sec/min

Type 1 vs. Type 2 Episodic Ataxia: inheritance

Both AD

Type 1 vs. Type 2 Episodic Ataxia: duration of episodes

Type 1: seconds to minutes

Type 2: hours

Type 1 vs. Type 2 Episodic Ataxia: age of diagnosis

Type 1: 2-20

Type 2: adulthood through 30's

Type 1 vs. Type 2 Episodic Ataxia: triggers

Type 1: exercise or startle reflex

Type 2: 50% migraines! The rest is from exercise, caffeine, fight or flight stress

Type 1 vs. Type 2 Episodic Ataxia: ocular signs

Type 1: myokymia of the levator or orbicularis

Type 2: nystagmus, irregular VOR, irregular OKN, irregular pursuits / saccades, migraine pain

Type 1 vs. Type 2 Episodic Ataxia: treatment

Type 1: Diamox (ampyra is a second best option too)

Type 2: Diamox (90% success)

Benign Recurrent Vertigo

dizziness episodes that are often associated with trigeminal neuralgia

Benign Recurrent Vertigo: demographic

up to 50 year olds, x2 females > males

Benign Recurrent Vertigo: duration

minutes to hours

Benign Recurrent Vertigo: triggers

Headaches (75%)

Also sleep deprivation, hormonal changes, stress

Benign Recurrent Vertigo: treatment

Diamox (70% success)

What foods are possible triggers for pain when someone with Benign Recurrent Vertigo is experiencing hyperactive trigeminal neuralgia?

Spicy foods like salsa, chili, hot sauce OR foods that are very cold like ice cream

***Review the colorful figure 10-12 in Wong on page 173, it's super organized for comparing the 3 stress induced ataxias

Spinocerebellar Ataxia / atrophy (SCA)

a category genetic diseases that result in slow loss of coordination of all muscle movements, including gait and eye movements

Spinocerebellar Ataxia / atrophy (SCA): treatment

No known cure :(

SCA 1 has the greatest number of cases in what 2 countries?

Italy and South Africa

SCA 1 was the first discovered SCA, usually having onset around age _____, but can start as early as ___

40,10

Describe SCA 1 saccades and nystagmus

hypermetric and slow saccades

gaze evoked and rebound nystagmus

SCA 1 progresses for _____ years before causing death :(

15 years

*****SCA 1 causes what unique pupil finding?

SCA 1 causes near-light dissociation due to optic nerve pallor!!!!!!

SCA 2 is also known as

olivopontocerebellar atrophy

SCA 2 has highest rates in what countries?

Cuba is the most prevalent

Also: Italy, India, Singapore, USA

SCA 2 demographics

usually starts in 30's-40's

SCA 2 progresses for _____ years before causing death :(

10

Describe SCA 2 saccades

slow but accurate saccades

Other signs of SCA 2

areflexia (loss of reflexes) and dysarthria (trouble talking)

SCA 3 is also called

Machado-Joseph Disease

SCA 3 has the same avg age of onset and lifespan as the previous two, but SCA 3 can occur as late as age ____

70

SCA 3 saccades and nystagmus

hypometric VOR, gaze evoked nystagmus, slow saccades

What part of the world is SCA 3 most prevalent?

#1 Portugal

also Brazil, China, and USA

****What unique ocular finding is associated with SCA 3 Machado Joseph disease?

Chorioretinal atrophy

SCA 6 is also called

Holmes Type

SCA 6 onset and lifespan

as late as 60's, but lifespan is 25 years!

SCA 6: demographic

Most common in Germany and Japan

-also seen in USA

SCA 6 nystagmus and vertigo

positional vertigo with downbeat nystagmus

****Unique finding for SCA 6 on MRI?

Cross sign on the pons, and cerebellum has atrophy

********WHICH SCA HAS THE CROSS SIGN

6

SCA 7 is also called

ADCA2 of Harding

SCA 7 can be seen as early as age _____ and can last up to ______ years, but an earlier onset correlates with a shorter lifespan

1, 45

****Unique ocular characteristic of SCA 7

Pigmentary Maculopathy

SCA 7 demographics

Most common in South America, Netherlands, and USA, also China

Ocular appearance of SCA 7

bilateral oculomotor III palsy with pigmentary maculopathy

SCA 8 is also called

Saccadic dysmetria

SCA 8 demographics

avg age is 40, but these patients have normal lifespans!!!!!!!!

Main ocular symptom of SCA 8

horizontal nystagmus

****SCA 8 saccades

very Hypermetric overshooting

Haw River Syndrome

ataxia and dementia are universal, children will have myoclonus epilepsy and intellectual disabilities, while adults will have choreoathetosis and dementia

The most common of the recessive ataxias

Friedreich Ataxia

Friedreich Ataxia

poor fixations, saccadic dysmetria, ocular flutter, and square wave jerks

***What conditions are correlated with having Friedreich Ataxia

Gluten sensitivity

Diabetes

Scoliosis

SCA with Saccadic Intrusions (SCASI)

poor fixations due to MACROsaccadic oscillations that cause decreased foveation time

-major jiggling of the eyes when doing saccades

Define apraxia

inability to initiate otherwise voluntary skeletal muscle movements, like saccades, in a timely manner. Unlike ataxia, eye movements ARE ACCURATE once they initiate, it just takes a long time to do them

True or false: Reflexive eye movements are NOT affected by apraxia

True, because they are not voluntary! ie reflexive saccades are initiated by superior colliculus

****Apraxia can be compared to what condition, and what drug can be used for both?

Parkinson Disease

L-Dopa or Levodopa!!! it can help ocular motor apraxia too!!!

What are the 3 forms of congenital oculomotor apraxia?

1) Cogan OM Apraxia

2) Ataxia Telangiectasia

3) Joubert Syndrome

How do babies with apraxia react to compensate?

They do huge head thrusts to shove their eyes involuntarily in the opposite direction using VOR to look around

****What are the neurological causes of cogan oculomotor apraxia?

1) agenesis of corpus callosum (it never formed)

2) aqueductal stenosis of the 4th ventricle and multiple arachnoid cysts causing hydrocephalus

3) cerebellar atrophy esp. vermis

True or false: head-eye coordination is often normal for kids with congenital oculomotor apraxia of Cogan

True

Cogan OM apraxia: saccadic amplitude and latency

hypometric small amplitude, longer latency "intermittent saccadic initiation failure"

***True or false: Cogan apraxia is not progressive and does not affect lifespan

True

Ataxia Telangiectasia (Louis Bar Syndrome)

recessive SCA that is accompanied by injection of the conj (telangiectasia), difficulty speaking, PAN nystagmus

*****Ataxia Telangiectasia patients are _____ sensitive, including things like CT scans. These can cause permanent damage!

Radio (associate the radio demon Alastor with Ataxia Telangiectasia- he can seriously harm those with the blood shot eyes!)

***Cogan apraxia and Ataxia Telangiectasia patients have head direction pointing towards

the direction of the spinning

Ataxia Telangiectasia has OKN aftereffects that last a long time. Which direction is the OKN saccading?

Opposite of the spin (not normal)

Joubert Syndrome

rare brain malformation characterized by absence or underdevelopment of the cerebellar VERMIS (which controls balance and coordination)

*******Joubert Syndrome Sign on MRI

MOLAR TOOTH SIGN due to elongation of superior cerebellar peduncles

Unlike the other oculomotor apraxias, what ocular signs will you see in Joubert Syndrome?

retinal dystrophy from chromosome 6