Ataxia in Children

I. Enumeration of Causes of Ataxia

Ataxia in children is classified based on the temporal course: Acute, Episodic, or Chronic.

A. Acute Ataxia (Most Common Presentation)

1. Infectious / Post-Infectious (Commonest):
   • Acute Cerebellar Ataxia (ACA): Post-viral (Varicella, Mumps, EBV, Coxsackie).
   • Cerebellitis: Direct viral invasion.
   • Brainstem Encephalitis.
2. Toxic / Accidental Ingestion:
   • Antiepileptics: Phenytoin, Carbamazepine, Phenobarbital (accidental or dosage error).
   • Sedatives: Benzodiazepines.
   • Alcohol / Ethanol.
   • Lead poisoning.
3. Inflammatory / Autoimmune:
   • ADEM (Acute Disseminated Encephalomyelitis).
   • Guillain-Barré Syndrome (GBS): Specifically Miller-Fisher variant (Ataxia, Areflexia, Ophthalmoplegia).
   • Opsoclonus-Myoclonus Syndrome (OMS): Paraneoplastic (Neuroblastoma).
4. Structural / Vascular:
   • Trauma: Concussion, posterior fossa hematoma.
   • Stroke: Cerebellar hemorrhage or infarction (rare in kids; check for dissection).
   • Tumor: Acute presentation of posterior fossa tumor (Medulloblastoma) due to hemorrhage or hydrocephalus.
5. Otogenic: Labyrinthitis, Benign Paroxysmal Vertigo.

B. Acute Recurrent / Episodic Ataxia

1. Migraine: Basilar Migraine, Benign Paroxysmal Vertigo of Childhood.
2. Metabolic:
   • Maple Syrup Urine Disease (MSUD).
   • Urea Cycle Defects (Ornithine Transcarbamylase deficiency).
   • Pyruvate Dehydrogenase Deficiency.
3. Genetic/Channelopathies: Episodic Ataxia Type 1 and 2.
4. Epileptic: Non-convulsive status epilepticus (pseudo-ataxia).

C. Chronic / Progressive Ataxia

1. Congenital Malformations: Dandy-Walker Malformation, Chiari Malformation, Cerebellar Hypoplasia.
2. Hereditary:
   • Friedreich’s Ataxia (FRDA).
   • Ataxia Telangiectasia (AT).
   • Spinocerebellar Ataxias (SCAs).
3. Metabolic/Degenerative: Abetalipoproteinemia, Vitamin E deficiency, Wilson’s Disease.
4. Neoplastic: Slow-growing astrocytoma.

II. Investigations for Acute Onset Ataxia

The goal is to differentiate benign self-limiting causes (ACA, intoxication) from life-threatening ones (Tumor, Stroke, ADEM).

1. First-Line Investigations (Emergency)

• Toxicology Screen: Urine and blood screen for benzodiazepines, alcohol, anticonvulsant levels (if patient is on AEDs).
• Glucose & Electrolytes: Rule out hypoglycemia and hyponatremia.
• Infection Screen: CBC, CRP (Suggestion of viral vs bacterial etiology).

2. Neuroimaging (MRI Brain)

• Indication: Mandatory if there is altered sensorium, focal neurologic deficits, signs of raised ICP, asymmetry of ataxia, or history of trauma.
• Modality: MRI Brain with contrast is superior to CT for posterior fossa visualization.
• Findings to Look For:
  • Demyelination: ADEM (multifocal white matter lesions).
  • Mass Effect: Tumor, Abscess, Hematoma.
  • Stroke: Ischemic/Hemorrhagic changes.
  • Cerebellitis: Swelling/hyperintensity of cerebellar hemispheres.

3. Cerebrospinal Fluid (LP)

• Indication: Suspected meningitis, encephalitis, GBS, or ADEM (after excluding raised ICP).
• Findings:
  • ACA: Mild lymphocytic pleocytosis, slightly elevated protein.
  • GBS: Albuminocytologic dissociation (High protein, normal cells).
  • ADEM: Pleocytosis, Oligoclonal bands (variable).

4. Specific Ancillary Tests (Based on Clinical Suspicion)

• Urine VMA/HVA: Screening for Neuroblastoma in any child with Opsoclonus-Myoclonus (dancing eyes/feet).
• Metabolic Workup: Ammonia, Lactate, ABG (if ataxia is precipitated by fever/high protein load or recurrent).
• EEG: If non-convulsive status is suspected (fluctuating responsiveness).

III. Treatment of Acute Onset Ataxia

Management depends entirely on the underlying etiology.

1. General Supportive Care

• Safety: Gait assistance to prevent falls/injury.
• Hydration: Maintain IV fluids if vomiting is present (common in cerebellar pathology).
• Observation: Monitor GCS and signs of raised ICP.

2. Etiology-Specific Management

• Acute Cerebellar Ataxia (ACA):
  • Course: Benign and self-limiting.
  • Tx: Reassurance. Spontaneous recovery occurs in weeks to months. Steroids are generally not indicated unless swelling causes hydrocephalus.
• Toxic/Ingestion:
  • Stop the offending drug (e.g., hold Phenytoin).
  • Specific antidotes (e.g., Flumazenil for Benzos - use with caution).
  • Enhanced elimination (Charcoal) if acute ingestion.
• ADEM:
  • High-dose IV Methylprednisolone (20–30 mg/kg/day for 3–5 days).
  • IVIG or Plasmapheresis for steroid-resistant cases.
• Guillain-Barré Syndrome (Miller-Fisher):
  • IVIG (2 g/kg over 2–5 days) or Plasmapheresis.
  • Monitor respiratory status.
• Opsoclonus-Myoclonus Syndrome:
  • Resection of Neuroblastoma (if found).
  • Immunotherapy: ACTH/Corticosteroids + IVIG + Rituximab (often required for long-term control).
• Structural (Tumor/Bleed):
  • Neurosurgical referral for decompression or shunting (for hydrocephalus).
• Infectious (Bacterial):
  • Appropriate antibiotics (e.g., Ceftriaxone for meningitis).
  • Acyclovir if HSV encephalitis is suspected.