Somatosensory Abnormalities in Primary Focal Dystonia

Can testing somatosensory temporal discrimination — the ability to distinguish two tactile stimuli applied serially to the same body region — reliably detect subclinical sensory impairment in various forms of primary focal dystonia? To find out, researchers tested 82 patients with cranial, cervical, hand, or laryngeal dystonia (or some combination thereof), 82 age-matched healthy adults (controls), and 26 patients with hemifacial spasm, a nondystonic disorder of peripheral origin. Each participant received paired electrical stimuli from surface skin electrodes on the hand, neck, and eye area. As the researchers incrementally increased the time between the two stimuli, participants reported whether they perceived each pair as a single stimul…