[Stereotaxic resection of intracerebral tumors]

Stereotactic computerized technology providing a goal-oriented and low-traumatic access to small intracerebral tumors and their precision microsurgical removal has been developed. A specialized programme implemented on an IBM PC/AT makes a whole set of stereotactic calculations based on computerized tomography (CT). With this, a three-dimensional volumetric tumor reconstruction is conducted by interpolating the tumor outlines which can be seen on consecutive stereotactic CT sections. The system provides laminar visualization of the tumor outlines in the distal aperture plane of an original tubular retractor which makes an access to the tumor and its removal and coincides these sections with the aperture projection. Thus, each discrete unit of tumor volume (minimum 1 cubic mm) proves to be stereotactically oriented against the retractor both in the plane of its aperture and along its trajectory. Examining the images prio and during surgery simulates an operational field, thus computerally supporting the resection of a tumor strictly in the range of CT-defined outlines. A total of 15 patients aged 3 to 52 years who had hemispheric tumors were treated. Five patients presented with cancer metastases (one of them had multiple ones), 7 had gliomas and 1 displayed a radiation necrotic focus at the site of the irradiated glial tumor that was verified by stereotactic biopsy, 2 cases had cavernous angiomas. The use of stereotactic techniques for tumor removal in these patients was determined by their location and small sizes. Eight cases presented with in-depth tumors located in the area of subcortical ganglions, the visual tuber, and the internal bursa. In 7 patients there were a comparatively superficial tumors afflicting the cortex and substantia alba in the projection of central gyri or temporoparietal regions in the predominant hemisphere. The maximum dimensions of tumors varied 10 to 35 mm without exceeding 25 mm in most (14) patients. A small circulatory trephination with a crown cutter, 35 mm in diameter, was employed in the majority of cases (in 13 patients). In 3 cases, there was a slight and transient aggravation of the existing focal symptomatology followed by regression and return to the preoperative values during 5-6 days. Following surgery, 10 had either improved status or no additional iatrogenic defect or they underwent outpatient treatment within 6-7 days after intervention. In 2 cases, a steady-state aggravation of focal symptoms was associated with surgery. Control studies by CT and MRT provided evidence for no residual tumor tissue in all cases except one.