46 Cerebellar syndrome
Salient features
History
• History of falls, wide-based gait, clumsiness and difficulty with fine coordinated movements
• Waxing and waning of symptoms (multiple sclerosis)
• Stroke (brainstem vascular lesion)
• Drug toxicity: phenytoin, alcohol abuse, lead poisoning and solvent abuse
• History of intracranial tumours (posterior fossa including cerebellopontine angle tumour)
• History of hypothyroidism (a reversible cause)
• Lung cancer (paraneoplastic manifestation)
• Family history (Friedreich’s ataxia and other hereditary ataxias)
• Birth defects (congenital malformations at the level of the foramen magnum).
Examination
• Ask the patient a few questions to assess speech
• Ask the patient to keep his arms outstretched; then give them a small push downward and look for rebound phenomenon
• Examine for rapid alternating movements with the hand
• Do the finger–nose test: look for past-pointing and intention tremor
• Examine the gait, in particular tandem walking. If ataxia is not marked, the patient’s gait may be tested with eyes closed; patients will often progresses to the side of the lesion.
• Tell the examiner that you would like to examine the fundus for optic atrophy as demyelination is the commonest cause of cerebellar signs.
Questions
How may cerebellar signs manifest?
• Absent reflexes or pendular reflexes
• Lack of coordination of gait: patient tends to fall towards the side of the lesion.
Notes
• The classical clinical triad of cerebellar disease is ataxia, atonia, asthenia.
• 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)
• 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 bronochogenic carcinoma
• Friedreich’s ataxia (p. 267) and other hereditary ataxias
• Congenital malformations at the level of the foramen magnum.
Advanced-level questions
What is the difference between sensory ataxia and cerebellar ataxia?
| Cerebellar ataxia | Sensory ataxia | |
|---|---|---|
| Site of lesion | Cerebellum | Posterior column or peripheral nerves |
| Deep tendon | Unchanged or pendular | Lost or diminished reflexes |
| Deep sensation | Normal | Decreased or lost |
| Sphincter disturbances | None | Decreased when posterior column involved, causing overflow incontinence |
