A method for the localization and production of discrete destructive lesions in brain

That the more distressing symptoms of Parkin-sonism and other hyperkinetic disorders may be relieved surgically has now gained general accep-tance. At the present time procedures in which destructive lesions, localized by a stereotactic method and made through a small cranial opening, have gained almost universal preference. It is proposed to describe such a technique. It has been found to work well in practice, disturbance to the patient is minimal, electro-physiological studies are facilitated since general anaesthesia is unnecessary, and the stereotactic instrument used is relatively inexpensive. Stereotaxis In practice, since most workers in the field of human stereotaxy use part of the visualized ventri-cular system as a reference point in localization (Hankinson and Amador, 1956), the problem is reduced to the insertion of a cannula or electrode through the skull in the direction of an identical point plotted on two radiographs taken in planes at right angles to each other. The depth of insertion must also be known. It has been found that a high degree of accuracy is obtainable by the use of a direction indicator so constructed that an adjustment in one plane can be made without altering the position in that at right angles to it. Description of Instrument The instrument (Fig. 1), made of stainless steel, consists of a ball drilled centrally and fitted to an electrode or cannula carrier (a). Into this carrier a directing rod (b) can be inserted. Two lead-containing markers (c) are fitted to the rod in such a way that the distance between.