Posterior reversible encephalopathy syndrome associated with methotrexate neurotoxicity: conventional magnetic resonance and diffusion-weighted imaging findings.

The addition of intrathecal methotrexate to treatment protocols has increased survival rates in children with acute lymphoblastic leukemia but is also associated with varying degrees of neurotoxicity. We describe a 15-year-old female patient diagnosed with acute lymphoblastic leukemia presenting with status epilepticus after receiving intrathecal methotrexate. Magnetic resonance imaging showed reversible cortical and subcortical changes consisting of high-intensity lesions on T2-weighted and fluid-attenuated inversion recovery sequences with postgadolinium enhancement, low signal intensity on diffusion-weighted imaging and increased apparent diffusion coefficient. These findings were consistent with the posterior reversible encephalopathy syndrome. We report our conventional magnetic resonance and diffusion-weighted imaging findings and briefly discuss the pathophysiology of the syndrome.