A1.6.5 Alternating hemiplegia of childhood


Infantile attacks of hemiplegia involving each side alternately, associated with a progressive encephalopathy, other paroxysmal phenomena and mental impairment.

Diagnostic criteria:
  1. Recurrent attacks of hemiplegia alternating between the two sides of the body and fulfilling criterion B
  2. Onset before the age of 18 months
  3. At least one other paroxysmal phenomenon1 associated with the bouts of hemiplegia or occurring independently
  4. Evidence of mental and/or neurological deficit(s)
  5. Not attributed to another disorder.

Such as tonic spells, dystonic posturing, choreoathetoid movements, nystagmus or other ocular motor abnormalities and/or autonomic disturbances.


This is a heterogeneous neurodegenerative disorder. A relationship with migraine is suggested on clinical grounds. The possibility that it is an unusual form of epilepsy cannot be ruled out. Mutations in the ATP1A3 gene (encoding the sodium-potassium [Na+/K+] ATPase α3 subunit) are likely to be responsible for at least 70% of cases.