Cerebellum and Ataxia

Question 1

Describe the Archicerebellar syndrome

Answer 1

disturbance of equilibrium of the body manifested by unsteadiness during:
1) Standing: swaying (trunkal ataxia).
2) Walking or standing: Impaired tandem gait → wide-base or “drunken” gait (Feet placed widely apart and difficulty standing with feet together).

Question 2

Describe Neocerebellar syndrome

Answer 2

incoordination of voluntary motor activities in the
form of:
1) Nystagmus in the eye (fixation nystagmus having rapid and slow components; the rapid component is towards the fixation point while the slow component is towards the resting point).
2) Dysarthria (ataxic speech)in the form of staccato speech (explosive and interrupted).
3) Dysmetria: movements that fall short of or go past the intended target.
4) Dysdiadochokinesia: a disturbance in rapid alternating movements.
5) Tremor: Intention kinetic tremor (worsens as the target is approached) in the extremities.
6) Deviation of the body towards the affected side in unilateral lesions or zigzag gait in bilateral lesions.
7) Hypotonia and Hyporeflexia.

Question 3

Ataxia definition

Answer 3

Incoordination of voluntary motor activity with or without disequilibrium in the absence of motor weakness.

Question 4

Clinical picture of Cerebellar ataxia

Answer 4

1) Incoordination of movements of different muscles in the form of:
a) Nystagmus in the eyes.
b) Staccato speech.
c) Nodding of the head.
d) Titubation of the trunk.
e) Kinetic tremors of the limbs.
2) Hypotonia and hyporeflexia of the affected muscles.
3) Gait disturbance: Wide-based “drunken” gait in archicerebellar lesions.
4) Positive tests ofcerebellar ataxia: (see neurology sheet).

Question 5

Causes of cerebellar Ataxia

Answer 5

1) Developmental:
❖ Arnold-Chiari malformation
❖ Dandy-Walker malfomation.
❖ Cerebellar hypoplasia.
2) Infective:
❖ Encephalitis
❖ Cerebellar abscess or acute viral cerebellitis.
3) Vascular:
❖ Cerebellar stroke (ischemia or hemorrhage).
❖ AVM.
4) Toxic:
❖ Alcohol.
❖ Metals (lead, thallium, mercury).
❖ Solvents.
5) Drug-induced:
❖ Anticonvulsants (phenytoin, carbamazepine).
❖ Cytotoxic drugs (methotrexate).
6) Neoplastic:
❖ Medulloblastoma (tumor of the vermis).
❖ Cerebellar hemangioblastoma.
❖ Metastatic tumors.
7) Immune-associated:
❖ MS.
❖ Postinfectious cerebellitis.
8) Metabolic or nutritional:
❖ Hypothyroidism hypoglycemia.
❖ Deficiency in vitamins B1, B12, or E.
9) Hereditary:
❖ Autosomal-dominant spinocerebellar ataxia.
❖ Autosomal-recessive
spinocerebellar ataxias e.g. Friedreich’s ataxia.

Question 6

Tests of cerebellar ataxia

Answer 6

1) Finger-to-nose test.
2) Finger-to-finger test.
3) Finger-to-doctor’s finger test.
4) Adiadokokinesis or Dysdindokokinesis.
5) Rebound phenomenon.
6) Buttoning and unbuttoning test.
7) Heel-to-knee test.
8) Walking along a straight line foot close to foot: i.e. tandem gait.

Question 7

What does Friedreich’s ataxia present with?

Answer 7

▪ Progressive cerebellar ataxia of the archicerebellar type i.e. disturbance of equilibrium in the form of gait disturbance and trunkal ataxia.
▪ Diminished or lost deep reflexes with positive Babinski sign. The loss of reflexes is due to the degeneration of the peripheral nerves, posterior columns and cerebellum. Positive Babinski is due to pyramidal lesion.
▪ Impaired deep sensations (movement, position and vibration), i.e.sensory ataxia due to degeneration of the posterior columns.
▪ Stock and glove hyposthesia with lost ankle reflex and preserved knee reflex due to degeneration of the peripheral nerves.
- Skeletal deformities in the form of pescavus or kyphoscoliosis (50%) are frequent.
- Heart disease: cardiomyopathy and ECG changes are common leading to death.
- DM in 25% of cases.

Question 8

Definition of Sensory ataxia

Answer 8

It is ataxia due to loss of the proprioceptive (deep) sensations, at any point in their pathway

Question 9

Causes of sensory ataxia

Answer 9

1) Peripheral nerve: peripheral neuropathy (DM, CIDP, sarcoidosis, alcoholic & nutritional).
2) Posterior root:
▪ Infective (syphilis i.e.tabes dorsalis, Lyme disease).
▪ Toxic (e.g. pyridoxine).
3) Posterior column:
● Compression of the cervical or thoracic spinal cord (e.g. meningioma)
● Friedreich’s ataxia
● MS
● Syphilis
● Vitamin B12 deficiency (SCD).
4) Medial lemniscus: brain stem lesions (infarction, MS, tumor).
5) Thalamus: thalamic syndrome.
6) Cortical sensory area: parietal lobe lesions.

Question 10

Clinical picture of Sensory ataxia

Answer 10

1) There is gross ataxia with a tendency to fall to either side. The patient focuses on the floor since the absence of visual cues will aggravate the ataxia.
2) Kinetic tremors as tested by finger-to-nose or finger-to-finger tests appear only on closure of the eyes.
3) Rhomberg’s test: when the patient stands with his feet close together and his eyes closed.The patient’s body sways and may fall if not supported.
4) Heel/shin testing deteriorates with eye closure.
5) Stamping gait: slower associated with a wide-based heavy strike of the ground on walking due to lost deep sensation.
6) Deep sensory loss.
7) Hypotonia and hyporeflexia.
8) Patient complains of swaying and may be fall during activity needs eye closure (e.g wash his face [water basin sign] or take off his T-shirt).

Question 11

Vestibular Ataxia Definition

Answer 11

It is ataxia due to lesions of the vestibular division of the 8thCN

Question 12

Causes of Vestibular ataxia

Answer 12

1) Meniere’s disease.
2) Labyrinthitis.
3) Acoustic neuroma.

Question 13

Clinical presentation of Vestibular ataxia

Answer 13

1. Vertigo, tinnitus, and deafness.
2. Impaired tests for vestibular function.
3. Vestibular nystagmus.