Neurology
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Presented is a pedigree with infancy-onset benign hereditary chorea (BHC) caused by a novel nonsense mutation in exon 3 (523G-->T, E175X) of the TITF-1 (Nkx2.1) gene. Four confirmed mutation carriers showed the typical movement disorder of BHC and congenital hypothyroidism. Surprisingly, treatment with levodopa improved gait dramatically and reduced chorea in two patients. Dopaminergic drugs should be considered a useful therapeutic option in BHC.
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Deep brain stimulation (DBS) is an effective treatment for several movement disorders. However, its mechanism of action is largely unknown. Both lesioning and DBS of the ventralis intermedius (VIM) nucleus of thalamus improve essential tremor. Although DBS was initially thought to inhibit the target neurons, recent studies suggest that DBS activates neurons. ⋯ Because the ventralis intermedius (VIM) projects directly to the motor cortex, the high motor evoked potential amplitude with deep brain stimulation ON suggests that VIM DBS activates rather than inhibits the target area.