Cerebellar Syndrome Frequently Asked Questions

How may cerebellar signs manifest?
· Disorders of movement:
-Nystagmus: coarse horizontal nystagmus with lateral cerebellar lesions; its direction is towards the side of the lesion.
-Scanning dysarthria: a halting, jerking dysarthria which is usually a feature of bilateral lesions.
-Lack of finger-nose coordination (past-pointing): movement is imprecise in force, direction and distance - dysmetria.
-Rebound phenomenon - inability to arrest strong contraction on sudden removal of resistance. This is known as Holmes' rebound phenomenon.
- Intention tremor.
- Dysdiadochokinesia - impairment of rapid alternating movements (clumsy).
- Dyssynergia - movements involving more than one joint are broken into parts.
· Hypotonia.
· Absent reflexes or pendular reflexes.
· Lack of co-ordination of gait - patient tends to fall towards the side of the lesion.

Note.
1. The classical clinical triad of cerebellar disease is Ataxia, Atonia, Asthenia.
2. The cerebellum is not primarily a motor organ. It is developed phylogenetically from a primary vestibular area and is involved in modulation of motor activity. It receives afferents from the vestibular nuclei, spinal cord and cerebral cortex via the pontine nuclei.

What are the causes of cerebellar syndrome?
· Demyelination (multiple sclerosis).
· Brainstem vascular lesion.
· Phenytoin toxicity.
· Alcoholic cerebellar degeneration (there is atrophy of the anterior vermis of the cerebellum).
· Space-occupying lesion in the posterior fossa including cerebellopontine angle tumour.
· Hypothyroidism (a reversible cause).
· Paraneoplastic manifestation of bronchogenic carcinoma.
· Friedreich's ataxia and other hereditary ataxias.
· Congenital malformations at the level of the foramen magnum.

How are cerebellar signs localized?
· Gait ataxia (inability to do tandem walking): anterior lobe (palaeocerebellum).
· Truncal ataxia (drunken gait, titubation): fiocculonodular or posterior lobe (archicerebellum).
· Limb ataxia, especially upper limbs and hypotonia: lateral lobes (neocerebellum).

What is the difference between sensory ataxia and cerebellar ataxia?
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