NCIt definition : A rare syndrome affecting conjugate vertical eye movement. It is often caused by a
dorsal midbrain neoplasm, commonly a pinealoma, but may also be attributable to demyelinating
diseases or stroke. Clinical signs include limitation of upward gaze, light-near dissociation
of the pupillary response, eyelid retraction (Collier's sign) and convergence-retraction
nystagmus. Clinical course is dependent on effective treatment of underlying cause.;