99mTc-TRODAT-1 and 123I-IBZM SPECT studies in a patient with extrapontine myelinolysis with parkinsonian features

Osmotic demyelination syndrome can result from the rapid correction of hyponatremia, and is categorized by central pontine myelinolysis and extrapontine myelinolysis (EPM). Magnetic resonance imaging (MRI) is currently the most useful modality for visualizing EPM lesions. However, MRI is unable to delineate the severity of involvement in the nigrostriatal dopaminergic pathway. The authors describe the case of a 48-year-old woman who developed isolated EPM with predominantly right-sided parkinsonian symptoms after rapid correction of hyponatremia. MRI revealed symmetrical demyelinating lesions in the bilateral striatum without central pontine involvement. ^99mTc-TRODAT-1 and ¹²³I-iodobenzamide (¹²³I-IBZM) single-photon emission computed tomography (SPECT) images showed unequally decreased uptake in the bilateral striatum. Treatment with carbidopa/levodopa improved the clinical parkinsonian symptoms. ^99mT_C-TRODAT-1 and ¹²³I-IBZM SPECT images provide presynaptic and postsynaptic molecular information of the nigrostriatal dopaminergic pathway. The lesions demonstrated in the ^99mT_C-TRODAT-1 and ¹²³I-IBZM SPECT images show higher correlation with the severity of clinical features in EPM than MRI, and the modalities may be useful in the evaluation of patients with parkinsonian symptoms.