Forty patients with previously untreated intracranial glial neoplasms underwent stereotaxic serial biopsies assisted by computerized tomography (CT) and magnetic resonance imaging (MRI). Tumor volumes defined by computer reconstruction of contrast enhancement and low-attenuation boundaries on CT and T1 and T2 prolongation on MRI revealed that tumor volumes defined by T2-weighted MRI scans were larger than those defined by low-attenuation or contrast enhancement on CT scans. Histological analysis of 195 biopsy specimens obtained from various locations within the volumes defined by CT and MRI revealed that: contrast enhancement most often corresponded to tumor tissue without intervening parenchyma; hypodensity corresponded to parenchyma infiltrated by isolated tumor cells or in some instances to tumor tissue in low-grade gliomas or to simple edema; and isolated tumor cell infiltration extended at least as far as T2 prolongation on magnetic resonance images. This information may be useful in planning surgical procedures and radiation therapy in patients with intracranial glial neoplasms.

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Gadolinium-labeled diethylenetriaminepentaacetic acid was used as a contrast agent for stereotactic magnetic resonance (MR) imaging in six selected patients with brain tumors who underwent stereotactic biopsy. Regions of contrast enhancement demonstrated by computed tomography (CT) and MR imaging in four of the six patients correlated with areas of malignant neovascularity and endothelial proliferation within solid tumor. Radiation necrosis produced contrast enhancement indistinguishable from that of recurrent neoplasm. Isolated tumor cells within intact white matter were identified in biopsy specimens obtained outside of regions that were depicted as abnormal by contrast material-enhanced CT, as well as by precontrast and postcontrast T1- and T2-weighted MR images.

We studied the effects of medial pallidotomy in the first 20 consecutive patients with Parkinson's disease (PD) undergoing this MRI/electrophysiologically guided procedure at our institution. The mean age of patients was 65.5 years (median 66.5) and none suffered any serious complications. Pallidotomy significantly improved motor function in both "on" and "off" states as measured by Unified Parkinson's Disease Rating Scale (UPDRS) motor scores and timed tests (Purdue pegboard and counter tapping) in the arm contralateral to surgery 3 months postoperatively. Patients also improved in terms of activities of daily living, reflected by improved UPDRS activity of daily living and complications of therapy scoring and reduced levodopa-induced dyskinesias; six of 11 patients who could not walk in an "off" state prior to surgery could do so postoperatively. The total UPDRS score improved by 22% from preoperative values. The aforementioned improvements occurred similarly in patients greater than (n = 11) or less than 65 years (n = 9) at surgery. Neuropsychological measures indicated that although the majority of cognitive function remains unchanged in right-handed PD patients following dominant (left) hemisphere pallidotomy, mild specific declines in word generation are present. The findings of this study suggest that unilateral pallidotomy is safe and associated with improved motor functioning in elderly as well as younger PD patients experiencing significant disability despite optimal medical therapy.

Computer interpolation of stereotaxic computerized tomography (CT) scanning data allows the transposition of a tumor volume in stereotaxic space. A stereotaxically directed and computer-monitored CO2 laser is then utilized to vaporize that volume as the surgeon monitors the position of a cursor representing the laser beam against planar contours of the tumor displayed on an operating room computer monitor. Computer-assisted stereotaxic laser microsurgery provides precise three-dimensional control for aggressive resection of deep-seated tumors from neurologically important areas with acceptable postoperative results. Thus, a significant cytoreduction can be achieved in addition to providing a tissue diagnosis and internal decompression. The authors report 83 computer-assisted stereotaxic laser procedures for tumor excision in 78 patients. The tumors were located in the thalamus/basal ganglia in 15 patients, ventricular system in five, corpus callosum in four, brain stem in three, and deep and centrally in the hemispheres in 51. Histologically, there were 26 glioblastomas, seven grade III astrocytomas, 14 grade II astrocytomas, 14 metastatic tumors, nine vascular lesions, and eight miscellaneous lesions. Resection of these subcortical lesions was confirmed by postoperative contrast-enhanced CT scanning. Neurological examinations performed 1 week after the 83 procedures revealed that 48 patients had improved from their preoperative level and 23 were unchanged (12 were neurologically normal preoperatively). Twelve patients had an increase in a preoperative neurological deficit, three of whom died in the postoperative period: one from infection, one from pulmonary emboli, and one from brain-stem edema. The average survival period (37.6 weeks) of patients having glioblastomas treated by this technique and irradiation was no different from that of patients having glioblastomas in more favorable locations treated by conventional surgery and irradiation. Patients with circumscribed lower-grade astrocytomas did better in terms of morbidity and completeness of resection than those with infiltrative neoplasms. Other circumscribed lesions, such as metastatic tumors, vascular lesions, and intraventricular tumors, were easily resected by the technique described.