Acquired monocular elevation paresis. An asymmetric upgaze palsy

Five patients with acquired monocular elevation paresis were investigated using direct current electroculography. With recovery, upward saccade velocities significantly increased in both eyes in all patients. The gain of upward-following eye movements significantly increased in the paretic eye of all patients and in the opposite eye of four patients. These findings are interpreted in terms of an asymmetric upgaze palsy which clinically presented as monocular elevation paresis in the more severely affected eye. A brainstem lesion contralateral to monocular elevation paresis was suggested in four patients by contralateral Horner's syndrome and contralateral abduction paresis, each in one patient, and contralateral ptosis in two patients. In only one patient, computerized tomography and magnetic resonance imaging substantiated a contralateral meso-diencephalic lesion.