Acquired "double elevator" palsy and polycythemia vera.

A 67-year-old woman had the acute onset of vertical diplopia. Examination revealed that she had a "double elevator" palsy of the fixing left eye which resulted in a right hypertropia. During the medical evaluation of the patient it was established that she had polycythemia vera. It is suggested that the ocular movement disorder seen in this patient resulted from a small lesion adjacent to and including the right superior rectus subnucleus. The increased blood viscosity resulting from the patient's polycythemic state may have been a significant predisposition in the development of an occlusive vascular episode involving this area of the midbrain.