Ocular motor and imaging abnormalities of midbrain dysfunction in osmotic demyelination syndrome.

After rapid correction of severe hyponatremia, a 36-year-old man developed osmotic demyelination syndrome (ODS), manifested neurologically by impaired cognition, extremity weakness, bilateral third cranial nerve palsies, and gaze-evoked upbeat and rotary nystagmus. Brain MRI showed restricted diffusion in the rostral midbrain and temporal and parietal lobes but not in the pons. Over several weeks, all neurologic and imaging deficits resolved. This is the first report to document ocular motor abnormalities associated with midbrain dysfunction in ODS.