What is ataxia?

Ataxia: Definition, Classification, and Management

Ataxia is a neurological disorder characterized by loss of coordination during voluntary movements affecting walking, vision, and speech, primarily resulting from cerebellar dysfunction or sensory pathway impairment. 1

Types and Classification

Ataxia can be classified based on:

Onset and Duration

• Acute: Develops within 72 hours
• Subacute: Develops within weeks
• Chronic: Duration > 2 months
• Progressive or non-progressive 1

Etiology

1. Genetic/Hereditary Causes:

   • Autosomal dominant spinocerebellar ataxias (SCA)
   • Friedreich's ataxia
   • Ataxia-telangiectasia 1, 2

2. Acquired Causes:

   • Infectious/postinfectious (33.6% of cases)
   • Brain tumors (11.2% of cases)
   • Toxic/nutritional (alcohol, vitamin E deficiency)
   • Immune-mediated (multiple sclerosis, acute disseminated encephalomyelitis)
   • Vascular (infarcts, hemorrhages) 1

Clinical Presentation

Ataxia manifests through different patterns:

1. Cerebellar Ataxia: Loss of coordination due to cerebellar dysfunction 1, 3

   • Unsteady, irregular stepping pattern
   • Wide-based stance
   • Variable step length and timing
   • Lateral veering or swaying

2. Sensory Ataxia: Loss of coordination due to impaired position sense 1, 4

   • Symptoms worsen with eyes closed
   • Difficulty with proprioception

3. Truncal Ataxia: Associated with vermian cerebellar pathology 1

   • Difficulty sitting or standing without support
   • Backward falls due to postural instability
   • Wide-based gait with swaying

Diagnostic Approach

Imaging

• Non-contrast brain MRI: Initial imaging modality of choice 1
• MRI with diffusion-weighted imaging (DWI): For abscesses, cellular tumors, or infections 1
• Susceptibility-weighted imaging: To detect superficial siderosis 1
• Contrast-enhanced MRI: For suspected inflammatory or neoplastic processes 1
• Spinal MRI: When spinal pathology is suspected 1

Laboratory Tests

• Acute-onset ataxia: Toxicology screens, lumbar puncture 1
• Chronic/progressive ataxia:
  • Genetic studies (next-generation sequencing)
  • Anti-GQ1b antibodies for Miller-Fisher syndrome
  • Nutritional deficiency evaluation (vitamin E, B12, copper) 1, 5

Management Strategies

Respiratory Care (Critical for Survival)

• Airway clearance techniques and regular respiratory physiotherapy
• Aggressive treatment of respiratory infections
• Monitoring of pulmonary function 1

Rehabilitation Approaches

• Teach patients to avoid rapid multijoint movements
• Encourage slower movements limited to single joints
• Reduce movement complexity
• Stabilize against inertial effects of limb movement 1, 4

Specific Treatments

• Four autosomal recessive types have specific treatments:
  • Ataxia with vitamin E deficiency
  • Cerebrotendinous xanthomatosis
  • Refsum disease
  • Coenzyme Q10 deficiency 5

Prognosis

For ataxia-telangiectasia:

• Median survival: 19-25 years
• 20-year survival rate: 53.4%
• Primary causes of death: respiratory diseases and cancer 1

Common Pitfalls and Caveats

1. Misdiagnosis: Evaluate for other neurological signs (nystagmus, dysmetria, hypotonia) to avoid incomplete assessment 1

2. Overlooking treatable causes: Always screen for vitamin deficiencies and other reversible causes 1, 5

3. Underestimating respiratory complications: These are the primary cause of mortality in ataxia-telangiectasia 1

4. Dysphagia management: Swallowing difficulties are common but often overlooked. Evidence for specific interventions is limited, highlighting the need for careful monitoring 6

5. Genetic complexity: Despite advances in genetic testing, many individuals with ataxia remain undiagnosed, suggesting more genes remain to be discovered 2