Background: Alternating hemiplegia of childhood is a syndrome which begins in the first year of life. It is characterized by repeated attacks of uni-or bilateral hemiplegia or hemiparesia. In most cases paroxysmal manifestations are observed: movements or dystonia++ attacks, episodic nystagmus, abnormal eye movements and disturbance of the neurovegetative system, predominantly in the first year of life.
Analysis: In half of the cases, neurological anomalies begin during the neonatal period with a non characteristic aspect. Typical attacks take place after one year of life, sometimes associated with partial epilepsy. In a quarter of cases, the oculomotor anomalies have been known since early life. The diagnosis is made prior to one year on the basis of associated oculomotor anomalies and other symptoms without EEG arguments for epilepsy. Paroxysmal nystagmus is always found. One eye is affect in most cases, generally with horizontal and seldom with vertical movements of large variable pendular amplitude. One eye with nystagmus and the other with mydriasis is sometimes reported. Most attacks last from 30 sec to 3 min. Paroxysmal strabismus described in half of the cases seems to be generally unilateral internuclear transitory ophthalmoplegia. Finally, ocular deviations on the hemiparetic side are described. They are generally unique or sometimes associated with head deviation. Spontaneous blinking is reduced.
Conclusion: Alternating hemiplegia of childhood is a non-epileptic sporadic, paroxysmal manifestation of unknown pathogenesis. Prognosis is poor. The presence of oculomotor signs suggests the diagnosis.