Microelectrode findings and topographic reorganisation of kinaesthetic cells after gamma knife thalamotomy.

A 64-year-old woman with Parkinson is disease had a severe resting tremor that was not completely relieved by right-sided gamma knife thalamotomy (GKT). We performed bilateral staged thalamic deep brain stimulation (DBS) and compared the right and left ventral intermediate nucleus (Vim) of the thalamus including the frequency of single units recorded with microelectrodes, and also the somatotopical distribution of kinaesthetic cells (Ki). The average frequency of units for the presumed left Vim exceeded that of the right (22.6 +/- 19.2 Hz vs. 14.3 +/- 8.8 Hz). Regarding the somatotopic distribution of Ki, the receptive field for the leg, which is usually situated in the dorsolateral Vim, was more widely scattered in the right Vim than the non-lesioned left side. Our findings raise the possibility that the specific properties of the neurons changed due to partial coagulation by GKT within both the coagulated and the surrounding thalamic lesions.