Distribution and response evoked by microstimulation of thalamus nuclei in patients with dystonia and tremor.

The effect of 806 microstimulations were observed in 16 patients with movement disorders, dystonia (DA, n = 6) and tremor (TR, n = 10). Among the 347 sites in DA patients motor response was seen at 29 sites, the response with increased dystonia was seen at 28 sites. The effect could be seen at 14 sites (50%) in ventrointermedialis (Vim), five sites (18%) in ventrocaudalis (Vc) and five sites (18%) in white matter (Wm). As for the other four sites, one site was in ventraloralis anterior (Voa), two sites in ventraloralis posterior (Vop), and one site in dorsal thalamus (dth), but reduction of dystonia drive was only seen at one site in dth. On the other hand, among the 459 sites in TR patients, motor response leading to reduction of tremor drive was seen at 38 sites, of which 30 sites (79%) were noted in Vim nuclei, and five sites (13.2%) in vc nuclei; of the remaining sites, two were seen in Vop nuclei, one in dth, and no increasing tremor drive was observed in all area. In general, paresthesia was the most common response, which was found at 159 sites (45.8%) with DA and 216 sites (47.1%) with TR. Pain was only seen at one site in Wm of DA; warm/cold and vertigo could be seen in Vop, Vim, and vc nucleus respectively. No responses were shown at 156 sites (45%) in DA, and 201 sites (43.8%) in TR.