A 30-year-old woman suffering from an eating disorder and alcoholism presented with a progressively worsening gait disturbance lasting 2 weeks. Her neurological findings included impaired ocular motility and trunk ataxia. Fluid-attenuated inversion recovery imaging of the brain showed hyperintensity in the dorsal brainstem, aqueduct, thalamus, and cerebral cortex. A long hyperintense segment on T2-weighted imaging was visible in the central gray matter of the cervical spinal cord. No restricted diffusion was observed; thus, T2 elongation in the spine was suggested to be due to vasogenic edema. We diagnosed the patient with Wernicke's encephalopathy and initiated vitamin supplementation. Thereafter, her symptoms rapidly improved; magnetic resonance imaging on the 11th day of hospitalization showed normalization of the signals in her brain and spinal cord. As our case demonstrates, Wernicke's encephalopathy can induce vasogenic edema of the spinal cord, which can rapidly improve with early therapeutic intervention.