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Ataxia in Children

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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.

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