The nystagmus compensation (blockage) syndrome.

The nystagmus compensation syndrome identified in 12 to 247 consecutive patients with congenital esotropia had these characteristic features: onset of esotropia in early infancy, pseudoparalysis of both abducens nerves, head turn toward the side of the fixating eye, absence fo nystagmus with the fixating eye in adduction, and appearance of a manifest jerky nystagmus as the fixating eye moved into primary position and abduction. The nystagmus may be actively neutralized by convergence innervation, the esotropia being caused by sustained convergence and secondary changes in the medial rectus muscles. The differential diagnosis includes crossed fixation and bilateral sixth nerve paralysis.