Computed tomography in the planning and evaluation of therapeutic stereotaxic surgical procedures of the brain.

Abstract

Preoperative and serial postoperative computed tomographic (CT) scans were obtained in 38 patients having either stereotaxic thalamotomy, mesencephalotomy, or a cingulumotomy to determine the relevance of the preoperative examination and to evaluate the site and evolution of the surgical lesion. Of the preoperative examinations, 55% were abnormal. The consequences of the stereotaxic procedure were identified in the first 2 postoperative weeks in 26 of the 28 patients having thalamotomy, six of the nine patients having mesencephalotomy, and all three patients having cingulumotomy as a diffuse low-density area (mean attenuation value, 18 Hounsfield units). A central core of increased attenuation due to an intralesional hemorrhage was present on the early postoperative scan in 17% of patients. The late residual lesion studied in seven patients was considerably smaller than the early abnormality. The appearances and temporal sequence of the postsurgical CT changes suggest the early abnormality is due to edema and the late lesion to coagulative necrosis. The findings suggest CT has a role in the preoperative assessment of patients having stereotaxic surgery in defining the target and predicting the stereotaxic coordinates, while postoperatively it documents the site of the lesion and can determine the basis of a complication.