Acute demyelination with leukoencephalopathy and cerebellar involvement in vitamin B12 deficiency.

A 49-year-old woman presented with progressive ascending quadriparesis associated with paresthesias and recent wide-based gait. Cognitive impairment associated with reduced vibration and proprioception sense was observed. Brain MRI documented the presence of extensive white matter demyelination (Figure 1). Megaloblastic anemia, low B12 level and chronic gastritis were confirmed (Figure 2). Vitamin B12 acts as a coenzyme in the methylmalonylCoA mutase reaction, essential for myelin biosynthesis. This vitamin deficiency may result in a variable neurologic presentation, including spinal cord, brain and cerebellar involvement. Our report supports the importance of performing diffusion and intravenous contrast administration to evaluate MRI evidence of acute demyelination in this setting.