Introduction

Abstract

During the last 25 years, stereotaxic operations have achieved general recognition as one of the most successful treatments for the Parkinson syndrome. Their outcome depends on circumscribed surgical destruction of certain nuclei and tracts in the diencephalon. These areas can be reached by aiming instruments built for this purpose and by a special method of localization (Spiegel et at., 1947; Talairach et at., 1949; Leksell, 1949; Riechert and Wolff, 1950, 1951 a, b; Guiot and Brion, 1952; Narabayshi and Okuma, 1953; Hassler and Riechert, 1954a; Riechert and Mundinger, 1956). During these operations, stimulation produces neurologic and psychological effects that are linked to certain diencephalic structures.Thus far, it has been possible to confirm in only a few cases at autopsy whether the structures aimed at were, in fact, reached by the stimulating electrode and the area of coagulation (Spiegel and Wycis, 1962; Mark et at., 1963; Rayenbuhl et at., 1964; Macchi et at., 1964; Hassler et at., 1965, 1969, 1970; Pagni et at., 1965; Markham et at., 1966; Smith, 1967; Haniek and Maloney, 1969; Hartmann-Von Monakow, 1972).