This disorder of unknown etiology is characterized by rhythmic jerking movements of head in the form of intermittent head nodding, usually in the lateral or horizontal direction, together with intermittent rapid pendular nystagmus.
The movements disappear when the child concentrates or sleeps.
The manifestations are noticed from the age of 4 to 12 months, always disappearing spontaneously by the age of 3 or 4 years.
Inadequate lighting and absence of visual stimuli have been incrimated as the etiologic factors
but without sufficient evidence.