What is cerebral ataxia?

Cerebellar Ataxia

Cerebellar ataxia is a neurological disorder characterized by impaired coordination of voluntary movements resulting from damage to the cerebellum and/or its connections, causing unsteadiness that persists regardless of visual feedback. 1

Pathophysiology

• Cerebellar ataxia results from damage to the cerebellum and its connections, disrupting the coordination of voluntary movements 1
• Unlike proprioceptive ataxia, cerebellar ataxia shows unsteadiness that does not significantly worsen with eye closure 1, 2
• The underlying mechanism involves an inability to coordinate the relative activity of multiple muscles and adjust movements at joints for the effects of other moving joints 3

Clinical Characteristics

• Key features include incoordination of voluntary movements affecting stance, gait, eye movements, muscle tone, skilled movements, and speech 4
• Truncal ataxia (difficulty maintaining posture) is particularly common with cerebellar vermian pathology 1
• Cerebellar ataxia typically presents with nystagmus, dysmetria, and intention tremor, which are not seen in proprioceptive ataxia 2
• The Romberg test cannot be properly performed in cerebellar ataxia as unsteadiness is present regardless of visual input 1

Differential Diagnosis

• Cerebellar ataxia must be distinguished from proprioceptive ataxia, which:

  • Results from dysfunction in sensory pathways (dorsal columns, dorsal root ganglia, peripheral sensory nerves) 2
  • Worsens significantly when visual input is removed (positive Romberg test) 2
  • Often presents with sensory loss and hyporeflexia 2

• Pure cerebellar symptoms are rarely observed; clinical presentations are often complicated by extracerebellar neurological or multisystem pathology 4

Etiologies

• Cerebellar ataxia can be caused by various conditions including:
  • Inherited disorders (autosomal dominant, autosomal recessive, X-linked) 5
  • Acquired conditions (stroke, infections, toxic exposures, immune-mediated disorders) 6
  • Metabolic disorders, vitamin deficiencies, and structural lesions 6
  • Paraneoplastic syndromes 6

Diagnostic Approach

• MRI of the head without IV contrast is the preferred initial imaging modality for evaluating cerebellar ataxia 1
• If inflammatory or neoplastic causes are suspected, contrast-enhanced MRI should be included 1
• Advanced MRI techniques such as diffusion-weighted imaging and spectroscopy may help detect early changes and distinguish between ataxia subtypes 1
• Brain MRI is important to rule out cerebellar or brainstem involvement 2

Management

• Balance training programs can improve stability in patients with cerebellar ataxia 1
• Postural training can improve trunk control 1
• Task-oriented upper limb training can improve reaching and fine motor control 1
• Prescription of appropriate assistive devices and orthoses can improve balance and mobility 1
• Treatment approaches should focus on reducing movement complexity by minimizing the number of moving joints or stabilizing against inertial effects of limb movement 3

Clinical Pitfalls to Avoid

• Failing to distinguish cerebellar from proprioceptive ataxia (cerebellar ataxia does not worsen significantly with eye closure) 1, 2
• Overlooking associated brainstem involvement, which should be checked for in many forms of cerebellar ataxia 1
• Missing potentially treatable causes of acute cerebellar ataxia, which requires prompt and thorough investigation 6
• Neglecting to consider that cerebellar disorders can affect functions beyond motor coordination 7