Teaching NeuroImages: 5-FU–induced acute leukoencephalopathy

A 55-year-old man with carcinoma sigmoid colon (fluorouracil [5-FU]: cumulative dose of 6,600 mg/m²; and oxaliplatinum: 245 mg/m²) presented with encephalopathy and pancerebellar involvement 2 weeks after receiving a third cycle of chemotherapy. Brain MRI showed diffusion restriction in bilateral deep white matter, cerebellar peduncles, and splenium of corpus callosum (figures 1 and 2) suggestive of 5-FU–induced leukoencephalopathy. Symptoms improved after discontinuation of chemotherapy as expected in drug-induced encephalopathy.¹ Diagnosis of PRES (posterior reversible encephalopathy syndrome) seemed less likely because it usually involves posterior subcortical white matter. Diffusion-weighted MRI is a useful modality for early detection of this characteristic encephalopathy.^1,2

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Figure 1 Cranial diffusion-weighted MRI showing diffusion restriction in (A) splenium of corpus callosum and (B) deep white matter

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Figure 2 Cranial MRI (A) diffusion restriction involving bilateral middle cerebellar peduncles and (B) T2 hyperintensities in bilateral periventricular and deep white matter and middle cerebellar peduncles

• © 2013 American Academy of Neurology