Vision loss, gaze palsy, and nystagmus in a patient with leukemia.

A 22-year old male with a history of B-cell acute lymphoblastic leukemia with recent bone marrow transplantation and on immunosuppressive therapy presented with painless, subacute vision loss of two weeks duration. He exhibited a horizontal gaze palsy, nystagmus, and mildly swollen and hyperemic optic discs with peripapillary flame hemorrhage on retinal exam. He had bilateral cecocentral scotomas on visual field exam, and MRI of his brain/orbits demonstrated hyperintensities in the hypothalamus, periaqueductal gray, and dorsal rostral medullary regions. After continued progression of symptoms despite discontinuation of the patient's tacrolimus, an empiric trial of IV thiamine treatment was started before the patient's lab vitamin levels were available, given strong clinical suspicion for a nutritional etiology. The patient's clinical presentation improved dramatically, and he achieved a final visual acuity of 20/20, full visual fields bilaterally, and resolution of nystagmus. A final diagnosis of Wernicke's encephalopathy was supported by his clinical course, imaging findings, and further confirmation with blood thiamine levels. This case presents unique ocular manifestations of Wernicke's encephalopathy and highlights the importance of early diagnosis in this potentially reversible condition.