ataxia (SM 409 module)

1. Ataxia
Dr mohamed rizk khodair
Lecturer of neurology
Mohamedrizk.med@o6u.edu.eg

2. • Developed from the metencephalon
• Located in the posterior cranial fossa

3. Lobes of the cerebellum
Primary fissure
Posterolateral fissure
Anterior lobe
Posterior lobe
Flocculonodular lobe

5. The cerebellum consists of
three functional subdivisions:
1- Vestibulocerebellum
2- Spinocerebellum
3- Cerebrocerebellum

6. Phylogenetically Formed of Primary afferent
connections
Concerned with
Vestibulocerebellum Archicerebellum
(the oldest part)
Flocculonodular
lobe
Vestibular nuclei Eye movements,
gross balance,
equilibrium,
orientation of the
body in space
Spinocerebellum Paleocerebellum Midline vermis
and adjacent
paravermal cortex
Spinocerebellar
tracts
Posture, muscle
tone, axial muscle
control
Cerebrocerebellum Neocerebellum
(the most recent
part)
The cerebellar
hemispheres (the
largest part)
Pontine nuclei,
which receives
corticopontine
fibers from the
cerebral cortex
Coordination of
movement and
providing fine
motor control for
the precise
movements of the
extremities

7. The cerebellum is connected to the brainstem by
3 cerebellar peduncles:
• ICP: connects cerebellum with the medulla
• MCP: connects cerebellum with the pons
• SCP: connects cerebellum with the midbrain

8. SCA (from basilar artery)  superior surface
AICA (from basilar artery) anterior part of
the inferior surface
PICA (from 4th part of vertebral artery) 
posterior part of the inferior surface + lateral
part of the medulla

9. The cerebellum is made up of a white
matter core, covered with a thin layer of
grey matter, the cerebellar cortex
The cortex is made up of 3 layers:
• Outer molecular layer
• Purkinje cell layer
• Inner granular layer

10. Incoordination of voluntary motor activity in absence of motor weakness
Cerebellar ataxia
Sensory ataxia
Vestibular ataxia
Mixed
HYSTERICAL ATAXIA

11. Causes of cerebellar ataxia
 Hereditary : Friedrich's ataxia , Marie's ataxia
 Idiopathic : delayed cortical cerebellar degeneration in old age
 Toxic: alcohol.
 Drugs: phenytoin; lithium.
 Vascular: ischemic stroke; hemorrhage.
 Inflammatory: demyelination (MS, ADEM).
 Neoplastic: metastases (breast, bronchus); primary brain tumors (in children, pilocytic astrocytoma and medulloblastoma);
Paraneoplastic syndrome, associated with small cell lung cancer; ovarian cancer, breast cancer, testicular cancer , Hodgkin’s
lymphoma , neuroblastoma , and thymoma.
 Infectious/post-infectious: viral cerebellitis (measles); SSPE; HIV; Miller Fisher syndrome (ataxia, areflexia, ophthalmoplegia
+ GQ1b antibody).
 Structural: Arnold–Chiari malformation; AVM;
 Degenerative: Friedrich ataxia, adult-onset cerebellar ataxia
 Nutritional: vitamin E deficiency, thiamine (B1deficiency), e.g., in Wernicke’s encephalopathy;
 Endocrine: thyroid.

12. History/ clinical examination
• Type of ataxia (cerebellar, sensory, vestibular)
• Affected parts of the body  zone of the cerebellum affected
• Associated manifestations
• Severity of symptoms
• Cause of ataxia
Investigations

13. Personal history
• Age at onset, gender
• Occupation history, possible toxic exposure to chemicals
• Sexual history (HIV, syphilis)
• Drug abuse, and excessive alcohol intake
Past history
• Regular drug use and a possible temporal association with ataxia onset
• HTN, DM, other chronic medical illness
Family history and pedigree analysis
Present history
• Mode of onset (acute, subacute, chronic)
• Natural history (progressive, regressive, stationary, episodic/intermittent)
• Associated symptoms/signs that provide localizing information and
determine the underlying etiology
• Other systemic features e.g. cardiac, hepatic
 Functional ataxia should be a diagnosis of exclusion

14. Laboratory testing Condition
Routine labs (CBC, serum electrolytes) Metabolic abnormalities
ESR, ANA, ds-DNA Abs, RF Inflammatory conditions, vasculitis
Vitamin B12, B6 levels Nutritional deficiency
Vitamin E levels Vitamin E deficiency, AVED
TSH Thyroid disease
Virology, RPR/FTA Infections e.g. HIV, syphilis
Therapeutic drug levels Drug-induced ataxia
Urinary heavy metal levels , blood alcohol levels Toxicity
Serum/ urine protein electrophoresis Lymphoproliferative disorders
Paraneoplastic panel Paraneoplastic
Autoantibodies:
• anti- GAD65 antibody
• anti-GQ1b
• antigliadin antibody
Glutamic acid decarboxylase (GAD) ataxia
Miller Fisher syndrome
Gluten ataxia
CSF analysis CJD, encephalitis, MS, neoplasm,
paraneoplastic, mitochondrial disease, ..
 Laboratory tests for evaluation of acquired ataxia:

15. Testing Condition
Copper, ceruloplasmin, 24-hour urinary copper Wilson’s disease
Vitamin E levels AVED
Serum lipoprotein, acanthocytes in blood film Abetalipoprotinemia
Serum cholesterol levels and urinary bile alcohol levels Cerebrotendinous xanthomatosis
Serum phytanic acid levels Refsum’s disaese
Alpha- fetoprotein and immunoglobulin Ataxia telangiectasia
Serum cholesterol and albumin Ataxia with oculomotor apraxia type 1
Alpha-fetoprotein Ataxia with oculomotor apraxia type 2
Erythrocyte glucose uptake assay - CSF glucose level Glucose transporter type 1 deficiency
CoQ10 in skeletal muscle by high performance liquid
chromatography
Ataxia associated with coenzyme Q10
deficiency
Lactate, pyruvate Mitochondrial disorder
EMG/NC Evaluation for polyneuropathy (axonal
vs. demyelinating)
Muscle biopsy Mitochondrial disorder
Consider genetic testing
 Certain tests if hereditary ataxia is suspected:

16. • Detect the cause
• Assess for brainstem and cerebellar atrophy
• Some MRI signs are diagnostically useful, as hot cross bun sign
(MSA), MCP sign (FXTAS), panda sign (Wilson's disease),..
 Neuroimaging:

17. Clinical Significance
1-Hypotonia, the muscles lose resistance to palpation due to diminished influence of the cerebellum
on gamma motor neurons.
2- The patient walks with a wide or broad-based gait and leans toward the affected side.
3- Disturbances of voluntary movements, called ataxia, involve tremors with fine movements, such as
writing or buttoning the clothes.
4- Finger to nose test is performed to examine the coordination of the muscle movements. When a
patient is asked to touch the tip of the nose with the index finger, the movements are not properly
coordinated, and tremor is observed at the end of the movement, called intention tremor.
5- A similar test can be performed on the lower limbs by asking the patient to place the heel of one
foot against the shin of the opposite leg (foot to heel to leg).

18. 6- Ataxia of ocular muscles results in nystagmus, a rhythmical oscillation of the eyes. To provoke
nystagmus, the patient should rotate eyes horizontally.
7- Similarly, ataxia of the larynx muscles results in dysarthria in form of staccato speech .
8- Dysdiadochokinesia is the lack of ability to perform rapidly alternating movements. One can ask
the patient to quickly supinate and pronate both forearms simultaneously. Movements will be slow
and incomplete on the side of the cerebellar lesion.
9- Dysmetria—an inability to perform acute finger-to-nose movements accurately with past pointing
or a similar inability on heel/shin testing.

19. Coordination System
examination
A. Upper limb (With opened and closed eyes)
1. Finger to nose ,
2. Finger to finger test ,
3. Finger to nose to doctor’s finger test
4. Dysdiadokokinesia : inability to perform rapid alternating movement (pronation and supination
)
5. Rebound phenomenon : with sudden release of flexed elbow
6. Buttoning or unbuttoning test : earliest sign

20. Finger to nose to doctor’s finger test
Finger to nose test Finger to finger test
Dysdiadokokinesia
Rebound phenomenon

21. B. Lower limb : (With opened and closed eye )
1.Heel to knee test.
2. Standing : swaying ----- truncal ataxia
3. Walking along straight line
4. Romberg sign

22. Friedreich’s ataxia
• It occurs in First decade of life
• More common in Female > male
• Postive Family history (Autosomal recessive)
• Pathologically there is degeneration of Four :
1-cerebellum espcialley archicerebellum and spinocerebellum tracts
2- pyramidal tract
3-posterior column
4- peripheral nerve
• Sketeltal deformities pes cavus and kyphioscoliosis
• Congential heart disease and ECG changes are common

23. Sensory ataxia
Clinical features : any marked loss of proprioception will result in sensory ataxia.
• Signs of a neuropathy with loss of joint position sense.
• Pseudo athetosis of fingers when arms outstretched, and eyes closed.
• Upper limb position sense loss is tested by attempting to bring both horizontally
outstretched index fingers together in the midline with eyes closed.
• Heel/shin testing deteriorates with eye closure.
• Positive Romberg’s sign.

24. Differential diagnoses of sensory ataxia
• CIDP.
• Refsum’s disease (due to defect in phytanic acid metabolism. Other features include
deafness, retinitis pigmentosa).
• Spinal cord disorders (affecting posterior columns):
• demyelination (MS).
• B12 deficiency.

25. Vestibular ataxia
• Vestibular ataxia has prominent vertigo (directional spinning sensations) and may cause
past pointing of limb movements, but spares speech.

26. Thank you
Mohamedrizk.med@o6u.edu.eg