[A case of pontine hemorrhage presenting with abnormal vertical ocular movements]

A 52-year-old woman was admitted to hospital because of sudden loss of consciousness. Neurological examination on admission revealed a comatose consciousness level, horizontal and upward palsies of both eyes and quadriparesis. The diagnosis of pontine hemorrhage was confirmed based on a brain CT scan, which showed a high density area involving the bilateral pontine tegmentum and right midbrain tegmentum at the inferior collicular level. The left eye moved downward below its primary position, and the movements usually comprised rapid downward and slow upward excursions and, on occasion, slow downward and rapid upward excursions, and were arrhythmical with irregular amplitudes. Oculocephalic maneuver did not modify the ocular movements. No horizontal movements were seen with ice-cold water irrigation into the ear canal on either side. Sixty days after hemorrhage onset, her right eye began to assume the same abnormal vertical movements as the left one, and 90 days after their onset, the ocular movements became oscillations. The abnormal vertical ocular movements in our patient were characterized by irregularities of phase, rhythm and amplitude. Accordingly, they were easily differentiated from ocular bobbing and ocular dipping. As these abnormal ocular movements resembled those of a float pulled by a fish, we propose they be termed ocular floating. The paramedian pontine reticular formation (PPRF) is believed to excite the burst neurons of the rosral interstitial nucleus of medial longitudinal fasciculus (riMLF) responsible for upward gaze and inhibit those for downward gaze. This role was suggested by the clinical observation that a pontine tegmental lesion causes upward gaze palsy.(ABSTRACT TRUNCATED AT 250 WORDS)