Ataxia

Question 1

Ataxia definition:

Answer 1

• An inability to generate a normal or expected voluntary movement trajectory that cannot be attributed to weakness or involuntary muscle activity (chorea, dystonia, myoclonus, tremor) about the affected joints. In simple terms, ataxia is the inability to make smooth, accurate and coordinated movements, not due to weakness or movement disorders.

Question 2

Ataxia results from:

Answer 2

impairment of spatial pattern of muscle activity or from impairment of the timing of that activity, or both.

Question 3

Ataxia affects:

Answer 3

motor control of eyes, speech, trunk and limbs.

Question 4

Nystagmus =

Answer 4

oscillatory rhythmic eye movements

Question 5

Saccadic intrusions =

Answer 5

involuntary conjugate fast eye movements that interrupt fixation

Question 6

Undershooting of saccades =

Overshooting of saccades=

Answer 6

hypometria.

hypermetria.

Question 7

Imprecise production of sounds

Answer 7

Dysarthria

Question 8

Poor regulation of prosody

Answer 8

Scanning speech = explosive speech.

Question 9

Bobbing of the head and trunk

Answer 9

Titubation

Question 10

Imprecise targeting of distal limb movements

Answer 10

Dysmetria

Question 11

Errors in relative timing of components of complex movements resulting in uncoordinated, abrupt movement. May split up a complex movement into smaller movements.

Answer 11

Dyssynergia

Question 12

Dysdiadochokinesia

Answer 12

Errors in rate and regularity of rapid alternating movements. Impaired ability to perform rapid, alternating movements

Question 13

Intention tremor

Answer 13

Tremor at the end of movement, seen on finger-to-nose, heel-to-shin testing

Question 14

Another name for the Flocculonodular lobe ___.

Lesion of this part of the cerebellum causes ___.

Answer 14

Vestibulocerebellum.
Causes:
1. Nystagmus and other eye movement abnormalities.
2. Balance problems (sitting/standing, gait) due to equilibrium dysfunction - cant tell body position.

Question 15

Which part of the body does the vermis of the cerebellum control__. Lesions of the vermis cause__.

Answer 15

Midline, axial trunk, proximal muscles.
Lesions cause:
1. Trunk movements: unsteadiness while standing or sitting. Titubations.
2. Gait ataxia.

Question 16

Which part of the body do the hemispheres of the cerebellum control __. Lesions of the cerebellar hemispheres cause__.

Answer 16

Lateral, distal limb muscles. 
Lesions cause:
1. Limb ataxia: Dysmetria, Dysdiadochokinesis, Intention tremor. 
2. Dysarthria
3. Hypotonia.

Question 17

Problems with the vestibular system cause__.

Answer 17

Vertigo, nausea, nystagmus, abnormal vestibulo ocular reflex.

Question 18

A positive Romberg sign is __ and it indicates an impairment in ___.

Answer 18

Loss of proprioception input leads to reliance on visual input to maintain posture. (Fall over when close eyes).
Impairment in Posterior columns in spinal cord. Causes Sensory Ataxia.

Question 19

Damage of peripheral nerves of the sensory pathway can result in ___.

Answer 19

1. Impairment of proprioception and vibration.
2. Pain, temperature symptoms.
3. Decreased or absent deep tendon reflex.

Question 20

Acute ataxia could be from:

Answer 20

1. Intoxication 
Examples: alcohol, antiepileptic drugs, antihistamines, lots of other drugs.
2. Post infectious. 
3. Demyelinating: 
•	Acute disseminated encephalomyelitis (ADEM)
•	Multiple sclerosis (MS)
4. Migraine: Basilar migraine, or BPV
5. Vascular: infract, hemmorhage.

Question 21

Chronic ataxia

Answer 21

1. Tumors

2. Hereditary - there are a lot.

Question 22

1/3 of all acute ataxia in kids: ___

Answer 22

Drug ingestion - 1/3 of all acute ataxia in kids. (young - accident; adolescent - substance abuse). EtOH, antiepileptics, benzos, antihistamines. Often accompanied by confusion, dysarthria. Urine tox screen in ER.

Question 23

Most common cause of childhood ataxia ___.

Answer 23

Acute (Postinfectious) Cerebellar Ataxia (APCA). An autoimmune phenomenon incited by infection (cross reaction of antibodies against cerebellar epitopes). • Often has antecedent viral febrile illness (varicella, mumps, EBV, etc). Mostly affects preschool-age children (2 ~ 4yo).
NO extracerebellar neurologic signs (mental status changes, seizure, etc). Ataxia improves over a few weeks to a few months. Prognosis for complete recovery is excellent.

Question 24

Where do 60% of all childhood brain tumors arise?

Answer 24

Brainstem or cerebellum

Question 25

What is the most common brain tumor of childhood?

What grade is it?

Answer 25

Cerebellar pilocystic astrocytoma.
Low grade (WHO grade I)

Question 26

What are the radiologic features of the cerebellar pilocystic astrocytoma?
Pathology features?

Answer 26

Radiologic: Cyst with an enhancing mural nodule.
Pathology: Rosenthal fibers (eosinophilic and corkscrew shape)

Question 27

Treatment of cerebellar pilocytic astrocytoma? Prognosis?

Answer 27

Surgery +- radiation&/or chemo.

Excellent prognosis.

Question 28

What is the most common Malignant brain tumor in children?

Answer 28

Medulloblastoma.

A form of primitive neuroectodermal tumor (PNET)

Question 29

Where does the medulloblastoma arise?

Answer 29

Midline (vermis and 4th ventricle roof). It can compress the 4th ventricle causing hydrocephalus (increasing ICP).

Question 30

Symptoms of medulloblastoma?

Answer 30

Truncal ataxia, gait disturbances, increased ICP.

Question 31

Pathology of medulloblastoma?

Answer 31

Rosettes or perivascular pseudorosettes.

Question 32

Treatment of medulloblastoma? Prognosis?

Answer 32

Surgery+radiation+chemo.

Prognosis: 50-85% 5year survival.

Question 33

The most common inherited ataxia? It’s genetic inheritance pattern and gene?

Answer 33

Friedreich’s Ataxia.
Autosomal recessive. Expanded GAA triplet repeat in FRDA gene that encodes frataxin.
Mechanism: suppressed gene expression, decreased frataxin levels, iron accumulation, oxidative stress, degeneration of PNS, CNS, and cardiomyopathy.

Question 34

Age of onset of Freidrich’s ataxia?

Answer 34

Puberty - before 25.

Question 35

Clinical features of Freidrich’s ataxia? Prognosis?

Answer 35

Progressive sensory ataxia.
Progressive leg weakness. 
Impaired vibration, proprioception. 
Areflexia of lower extremities.
Occulomotor abnormalitiesa and vision problems. 
Dysarthria. 
Sensorineural hearing loss. 
DM, Hypertrophic cardiomyopathy, scoliosis. 
Whealchair bound in 10yrs.

Question 36

Chronic ataxia disease that presents in early childhood (2yrs)? Inheritance pattern?

Answer 36

Ataxia-Telangiectasia (AT).

Autosomal Recessive: Mutated ATM gene. ATM protein is involved in cell cycle control and DNA repair.

Question 37

Clinical features of ataxia-telangiectasia?

Answer 37

Occulomotor apraxia: Inability to initiate saccades - child uses thrusts of the head in order to position eyes on target.
Occulocutaneous telangiectasias.
Recurrent sinopulmonary infections: decreased immune function.
Increased risk of malignancy: lymphoma, leukemia, brain tumor…Do NOT irradiate them.

Question 38

Labs changes in ataxia-telangiectasia? Prognosis?

Answer 38

Increased alpha-fetoprotein.
IgA deficiency.
Live into early adulthood.