THE SIGNIFICANCE IN HUMAN STEREOTACTIC BRAIN SURGERY OF INDIVIDUAL VARIATION IN THE DIENCEPHALON AND GLOBUS PALLIDUS

Open Access
Publisher Website
Google Scholar
Abstract
In a study of 40 hemispheres it was found that the thalamic nuclear pattern at the level of the posterior commissure varied considerably. The ventricular length, measured from the interventricular foramen to the posterior commissure, was 20-26 mm; the total thalamic length (T) was 31-38 mm; and the distance from the posterior commissure to the tip of the pulvinar (P) was 26-41% of (T). The anterior-posterior organization in the thalamus was studied in 13 hemispheres and with the other measurements being in the same range, (P) was 23-40% of (T). The differences in both the anterior-posterior and vertical relations of the posterior commissure are explained on the basis of individual variation. This, along with the limits of instrumental accuracy in stereotactic techniques, implies that the posterior commissure is a poor landmark from which to measure the anterior-posterior coordinates of thalamic nuclei for human stereotactic brain surgery of subcortical structures. The total thalamic length is a better measurement because the nuclei appear to occupy relatively constant proportions of it.