Teaching neuroimages: reversible paradoxical lithium neurotoxicity.

A 33-year-old man with bipolar affective disorder presented with acute onset of rigidity, tremors, and confusion. He had been taking oral lithium (1,200 mg daily) for the past 2 months. Baseline blood, EEG, and CSF analyses were normal. Serum lithium level was 0.67 mEq/L (0.3–1.3). GadoliniumMRI brain showed multiple bilateral symmetric T2-weighted hyperintensities (figure, A–C). On suspicion of lithium-induced neurotoxicity, lithium was replaced with valproate. At 1-month follow-up, his extrapyramidal symptoms had resolved completely, with significant resolution noted on cranial MRI (figure, D–F). Paradoxical lithium neurotoxicity occurs at therapeutic or low serum levels due to lithium-induced toxic demyelination.