Optimum Target for Tremor Arrest

Abstract

In an attempt to further define the optimum target for abolishing tremor, 25 cases out of a series of 1,000 consecutive thalamotomies for Parkinson''s disease were selected on the basis that mere impact of electrode placement had suddenly arrested tremor. These sites were carefully plotted, and correlated with the available data from physiological exploration. They were grouped in a relatively restricted area, extended from 2 to 8 mm in front of PC, from 8 mm above to 2 mm below the AC-PC line in the sagittal plane, and from 13 to 15 mm laterally, but densely in its posterio-inferior part. There is a soma-totopic arrangement, since tremor is sometimes exclusively arrested in one limb. These sites correspond to the area from where Gillingham and others reported rhythmic bursting activity synchronous with tremor. Stimulation with low frequency produced an increase or activation of tremor, and with higher frequencies, amelioration or suppressive response. In all cases, the radiofrequency lesion at this site produced a long-lasting relief of tremor, with no side effects. This area corresponded to the prelemniscal radiation and lemniscal sector of V.c.p., V.i.m. and posterior-basal part of V.o.p