Delayed chorea after recovery from a symmetric parkinsonian syndrome due to striatal myelinolysis

Abstract Extrapontine myelinolysis (EPM) is rare and usually results from osmotic stress due to inappropriate correction of electrolyte disturbances. Parkinsonism is a relatively common manifestation of EPM, seen in 60% of patients. Dopaminergic therapy leads to good recovery in many patients. Delayed extrapyramidal manifestations, including hyperkinetic movement disorders such as chorea or dystonia, are postulated to result from aberrant neuronal regeneration or denervation supersensitivity following the initial osmotic insult. We present a patient with a symmetric parkinsonian syndrome due to EPM involving the striatum who made a good recovery with levodopa therapy, only to develop chorea five months later. The possible mechanisms underlying the genesis of these movement disorders in EPM is discussed.