What is the recommended history, examination, laboratory, imaging, and management workup for a patient presenting with cerebellar ataxia?

Evaluation of Cerebellar Ataxia

For patients presenting with cerebellar ataxia, MRI brain without contrast is the first-line imaging modality, combined with targeted history focusing on onset timing (acute vs. chronic), associated symptoms, and risk factors to guide the diagnostic workup. 1

History Taking

Critical temporal features to establish:

• Acute onset (within 72 hours): suggests stroke, infection, toxicity, or trauma 1, 2
• Subacute/chronic progressive: indicates degenerative, genetic, or paraneoplastic causes 1
• Episodic/intermittent: points toward migraine, metabolic disorders, or genetic episodic ataxias 3

Essential historical elements:

• Recent infections (postinfectious cerebellar ataxia is most common in acute presentations) 1, 4
• Medication/toxin exposure (metronidazole, chemotherapy agents, alcohol, heavy metals) 1
• Trauma history (vertebral artery dissection, spinal cord injury) 1
• Cancer history (paraneoplastic cerebellar degeneration) 1
• Family history (spinocerebellar ataxias, Friedreich ataxia) 1
• Associated symptoms: headache, altered consciousness, visual changes, hearing loss 1

Physical Examination

Cerebellar signs to document:

• Gait ataxia, limb dysmetria, truncal instability 1, 5
• Dysarthria, ocular dysmetria, nystagmus 1, 6
• Romberg testing (positive suggests sensory ataxia component) 6

Critical extracerebellar findings:

• Deep tendon reflexes (absent in peripheral neuropathy, hyperactive in pyramidal involvement) 5, 6
• Vibratory and proprioceptive sensation (impaired in sensory ataxia) 5, 6
• Cranial nerve deficits (brainstem involvement) 1
• Pyramidal signs (spasticity suggests combined system disease) 5
• Altered consciousness or focal weakness (increases likelihood of urgent pathology by 86%) 4

Laboratory Evaluation

Initial screening tests:

• Complete metabolic panel including glucose, electrolytes, liver and kidney function 4
• Toxicology screen 4
• Lactate and ammonia levels (metabolic disorders) 4
• Vitamin B12, thiamine, vitamin E levels (nutritional deficiencies) 1
• Thyroid function tests 7

Targeted testing based on clinical suspicion:

• Paraneoplastic antibody panel (anti-Yo, anti-Hu, anti-Tr) if subacute onset with cancer risk 1
• Genetic testing for spinocerebellar ataxias or Friedreich ataxia if family history or chronic progressive course 1, 5
• Cerebrospinal fluid analysis if infectious/inflammatory etiology suspected 1

Imaging Approach

Non-Traumatic Ataxia

MRI brain without IV contrast is the primary imaging modality 1, 4

• Superior soft tissue contrast for detecting cerebellar atrophy, demyelination, infarction, and mass lesions 1
• Identifies posterior fossa pathology including tumors, cerebellitis, and structural abnormalities 1
• T2-weighted sequences detect cerebellar hyperintensities in acute cerebellar syndrome from cytarabine or other toxins 1
• Gradient echo/susceptibility-weighted imaging for superficial siderosis (hemosiderin deposition from recurrent subarachnoid hemorrhage) 1

MRA head and neck without contrast should be added if:

• Acute onset with vascular risk factors (posterior circulation stroke) 1
• Vertebrobasilar insufficiency symptoms (dizziness, diplopia, perioral numbness) 1
• Young patient with neck pain (vertebral artery dissection) 1

CT head without contrast is acceptable when:

• MRI unavailable and acute infectious cause suspected 1
• Need to detect calcification in rare genetic ataxias 1
• Rapid screening required, though inferior to MRI for cerebellar pathology 1

Post-Traumatic Ataxia

CT spine without contrast is first-line for acute trauma with stabilization concerns 1

CTA neck is appropriate if vertebral or carotid artery dissection suspected based on mechanism 1

MRI spine follows CT for detailed soft tissue assessment including spinal cord injury and ligamentous integrity 1

Management Framework

Acute Ataxia (<72 hours)

Immediate considerations:

• If stroke suspected, follow acute stroke protocols (imaging within minutes, not hours) 1
• Exclude posterior fossa mass with potential for herniation 1
• Identify and remove toxic exposures (medications, alcohol, drugs) 4, 2

Specific treatments:

• Postinfectious cerebellar ataxia: supportive care, typically self-limiting 4
• Acute cerebellitis: monitor for increased intracranial pressure, hydrocephalus; may require neurosurgical intervention 1
• Cytarabine-induced cerebellar syndrome: discontinue drug immediately; recovery uncertain 1
• Posterior reversible encephalopathy syndrome: strict blood pressure control, discontinue causative agent, antiepileptics if seizures present 1

Chronic Progressive Ataxia

Degenerative causes require:

• Genetic counseling and testing for hereditary ataxias 1
• Intensive physical therapy (appears helpful though disease-modifying treatments limited) 7
• Surveillance for systemic complications (cardiomyopathy in Friedreich ataxia) 5

Treatable causes not to miss:

• Vitamin deficiencies: replacement therapy 1
• Immune-mediated ataxias: immunotherapy trials 7
• Paraneoplastic: treat underlying malignancy 1

Common Pitfalls

Imaging errors:

• Ordering CT when MRI is available and patient stable (misses early cerebellar pathology) 1
• Failing to obtain vascular imaging in acute presentations with stroke risk factors 1
• Not recognizing that normal MRI in acute setting doesn't exclude chronic ischemia without completed infarction 1

Clinical errors:

• Attributing all ataxia to cerebellar dysfunction without examining for sensory ataxia (peripheral neuropathy, posterior column disease) 6
• Missing extracerebellar signs that narrow differential (retained reflexes and spasticity favor late-onset Friedreich ataxia over typical presentation) 5
• Overlooking medication-induced causes in cancer patients (metronidazole, high-dose cytarabine) 1
• Dismissing episodic symptoms as benign without considering metabolic crises or vascular insufficiency 3