ONE-AND-A-HALF SYNDROME, TYPE-II - A CASE WITH ROSTRAL BRAIN-STEM INFARCTION

This article is about a patient who suddenly developed a right hemipar esis and stupor. Her neuro-ophthalmological examination revealed a lef t-sided ptosis and a combined vertical gaze palsy in addition to right esotropia, right conjugate gaze palsy, and abduction paralysis of the left eye on attempted gaze to the left with adduction nystagmus of th e right eye. The horizontal eye movement disorder was similar to that in one-and-a-half syndrome, except for an abduction paralysis and an a dduction nystagmus. MRI showed a rostral brain stem infarction on the left side. Left-sided ptosis and adduction paralysis were attributed t o a left oculomotor fascicular involvement in the presence of a right hemiparesis. Right-sided esotropia and abduction paresis were consiste nt with a 'pseudo-abducens palsy', which has been reported in thalamo- mesencephalic lesions. Combined vertical gaze palsy is a classical fin ding of rostral brain stem infarction. Left-sided abduction paralysis with adduction nystagmus on the right side on attempted gaze to the le ft is thought to be due to involvement of the para-MLF on the left sid e and is called internuclear ophthalmoplegia of abduction (INO-abd). T o our knowledge, this type of horizontal eye movement disorder has nev er been reported before with rostral brain stem infarction.