What is a good workup for ataxia?

Comprehensive Workup for Ataxia

MRI brain with and without contrast is the most appropriate initial imaging study for evaluating patients with ataxia, as it provides detailed assessment of the cerebellum, brainstem, and other neurological structures that may contribute to ataxia. 1

Initial Clinical Evaluation

• History focus points:

  • Onset pattern: acute (hours/days), subacute, chronic progressive, or episodic
  • Trauma history
  • Associated symptoms (vertigo, headache, dysarthria, visual disturbances)
  • Family history of neurological disorders
  • Medication use and potential toxin exposure
  • Recent infections or vaccinations

• Neurological examination focus:

  • Cerebellar function tests (finger-to-nose, heel-to-shin, rapid alternating movements)
  • Gait assessment (wide-based, unsteady)
  • Sensory examination (proprioception, vibration)
  • Eye movement abnormalities (nystagmus, ophthalmoplegia)
  • Presence of other neurological signs (weakness, spasticity, extrapyramidal signs)

Diagnostic Algorithm

Step 1: Imaging Studies

• First-line imaging: MRI brain with and without contrast 1

  • Evaluates posterior fossa structures in detail
  • Identifies mass lesions, stroke, demyelination, atrophy
  • Detects cerebellar and brainstem abnormalities

• Additional imaging based on clinical suspicion:

  • MRI spine: If myelopathy or spinal cord involvement suspected 1
  • MRA head/neck: If vascular etiology or dissection suspected 1
  • CT head: If MRI contraindicated or for acute evaluation when stroke intervention is considered 1

Step 2: Laboratory Studies

• Complete blood count
• Comprehensive metabolic panel
• Vitamin B12, vitamin E levels
• Thyroid function tests
• Inflammatory markers (ESR, CRP)
• Autoimmune panel if indicated (ANA, anti-GAD antibodies)
• Paraneoplastic antibodies if subacute presentation or cancer risk
• Heavy metal screening if exposure suspected
• Alcohol and toxicology screen

Step 3: Additional Testing Based on Clinical Context

• Genetic testing: For suspected hereditary ataxias, especially with family history or chronic progressive course
• Lumbar puncture: For suspected inflammatory, infectious, or paraneoplastic causes
• Electrophysiological studies: EMG/NCS if peripheral involvement suspected

Special Considerations by Presentation Pattern

Acute Ataxia

• Priority: Rule out stroke, hemorrhage, acute demyelination, infection
• Key tests: MRI brain (with DWI sequences), CT if MRI unavailable
• Consider toxicology screening and infectious workup

Chronic Progressive Ataxia

• Priority: Evaluate for neurodegenerative disorders, tumors, paraneoplastic syndromes
• Key tests: MRI brain, genetic testing, paraneoplastic antibodies
• Consider whole-body imaging for occult malignancy if paraneoplastic suspected

Episodic Ataxia

• Priority: Consider channelopathies, metabolic disorders, migraine variants
• Key tests: MRI brain, genetic testing for episodic ataxias, metabolic studies

Pitfalls to Avoid

• Premature diagnostic closure: Ataxia has numerous potential etiologies; avoid settling on a diagnosis without thorough evaluation
• Overlooking treatable causes: Always evaluate for vitamin deficiencies, autoimmune conditions, and paraneoplastic syndromes
• Inadequate imaging: Standard CT may miss subtle posterior fossa abnormalities; MRI is superior 1
• Neglecting non-cerebellar causes: Remember that sensory ataxia from peripheral neuropathy or posterior column disease can mimic cerebellar ataxia
• Underutilizing genetic testing: Consider genetic testing even in older patients with late-onset ataxia, as some genetic ataxias can present later in life 2

Pediatric Considerations

In children, the workup should be tailored to age-appropriate etiologies:

• Acute post-infectious cerebellar ataxia is common in children
• Brain tumors account for approximately 11% of acute ataxia cases in children 1
• Consider metabolic disorders, especially in episodic presentations
• MRI brain is the preferred initial imaging modality 1

By following this structured approach to ataxia evaluation, clinicians can efficiently identify the underlying cause and initiate appropriate management to improve patient outcomes.