What is the approach to a case of acute ataxia in a 4-year-old child?

Diagnostic Approach to Acute Ataxia in a 4-Year-Old Child

MRI of the brain is the first-line diagnostic imaging modality for evaluating acute ataxia in children, as it provides superior detection of cerebellar and posterior fossa pathology compared to CT. 1

Common Etiologies of Acute Ataxia in Children

• Infectious and postinfectious disorders account for approximately 33.6% of cases, making them the most common cause of acute ataxia in children 2, 1
• Brain tumors represent approximately 11.2% of cases and require prompt identification 2, 1
• Toxic ingestions/exposures account for about 25.6% of cases, particularly in boys under 6 years of age 3
• Trauma-related ataxia occurs in approximately 5% of cases 2, 1
• Other causes include migraine-related ataxia, peripheral neuropathies, encephalitis, and vestibular dysfunction 2

Initial Diagnostic Approach

History and Physical Examination Focus

• Determine onset and progression of ataxia (acute = within 72 hours) 1
• Assess for recent infections, particularly varicella, nonspecific viral infections, mycoplasma, enterovirus, and Epstein-Barr virus 3
• Evaluate for recent trauma history 2
• Screen for possible toxic ingestions 4
• Look for associated neurological symptoms (presence of extracerebellar symptoms increases likelihood of significant pathology) 2

Imaging Studies

• Brain MRI: First-line imaging for all children with acute ataxia 1

  • Higher sensitivity for detecting posterior fossa abnormalities, small intracranial hemorrhages, and cerebellar infarcts 2
  • Particularly important in children >3 years with symptoms lasting >3 days and those with extracerebellar symptoms 2

• Head CT: Consider when:

  • MRI is not immediately available and there is concern for acute pathology requiring urgent intervention 1
  • Recent trauma with concern for intracranial hemorrhage, mass effect, or herniation 2
  • Note: IV contrast may obscure small hemorrhages in trauma settings 2

Additional Imaging Based on Clinical Suspicion

• MRA of head and neck: When posterior circulation stroke, hemorrhage, or vascular malformation is suspected 2, 1
• CTA of head and neck: In cases of recent trauma with suspicion for vertebral artery dissection 2
• MRI of spine: When conditions with spinal cord involvement are suspected 1
• MRI/CT of chest, abdomen, and pelvis: In cases of opsoclonus-myoclonus-ataxia syndrome to evaluate for neuroblastoma 2, 1

Laboratory Studies

• Toxicology screening (urine and serum) for all patients 4
• Lumbar puncture if infectious etiology is suspected (may be deferred until after admission in most cases) 4
• Basic metabolic profile and screening labs for metabolic disorders (lactate and ammonia) based on clinical judgment 4

Management Approach

• Postinfectious cerebellar ataxia: Supportive care (most cases are self-limiting with full recovery within approximately 18 days) 1, 3
• Brain tumors: Neurosurgical consultation for potential resection 1
• Toxic ingestions: Removal of offending agent and supportive care 1
• Traumatic causes: Management based on type and severity of intracranial injury 1

Important Considerations and Pitfalls

• While most causes of acute ataxia in children are benign and self-limiting, it is crucial to identify potentially life-threatening etiologies requiring urgent intervention 5, 6
• Yield of clinically significant findings on imaging is highest in children >3 years with symptoms lasting >3 days and those with extracerebellar symptoms 2
• Consider "watchful waiting" in young children with recent viral illness, no extracerebellar signs, and negative toxicology screen, with imaging reserved for clinical deterioration 2
• Hemicerebellitis is a rare complication that can present with asymmetric cerebellar signs 3