<unk><unk><unk>  usually follows 2–3 weeks after an infection. Onset is abrupt. Vomiting may be present at the onset but fever and nuchal rigidity characteristically are absent. Horizontal nystagmus is present is approximately 50% of cases. * Truncal<unk>  with deterioration of gait * Slurred speech and nystagmus * Afebrile
Acute cerebellar ataxia of childhood
Post viral cerebellar ataxia
Encephalitis lethargica
Alternating hemiplegia of childhood
Bickerstaff brainstem encephalitis
Post-encephalitic parkinsonism
Juvenile primary lateral sclerosis
Chronic paroxysmal hemicrania