Resection Of Brain Lesions Research Articles

Visualization of the eloquent motor system by integration of MEG, functional, and anisotropic diffusion-weighted MRI in functional neuronavigation

Background In this study, we visualized the eloquent motor system including the somatosensory-motor cortex and corticospinal tract on a neuronavigation system, integrating magnetoencephalography (MEG), functional magnetic resonance imaging (fMRI), and anisotropic diffusion-weighted MRI (ADWI). Methods Four patients with brain lesions adjacent to the eloquent motor system were studied. Motor-evoked responses (MER) by finger-tapping paradigm were acquired with a 1.5-Tesla MR scanner, and somatosensory-evoked magnetic fields (SEF) by median nerve stimulation were measured with a 204-channel MEG system. In the same fMRI examination, ADWI and anatomic three-dimensional T1-weighted imaging (3-D MRI) were obtained. Activated areas of MER, estimated SEF dipoles, and the corticospinal tract on ADWI were coregistered to 3-D MRI, and the combined MR data were transferred to a neuronavigation system (functional neuronavigation). Intraoperative recording of cortical somatosensory-evoked potentials was performed for confirmation of the central sulcus. Results Combination of fMRI and MEG enabled firm identification of the central sulcus. Functional neuronavigation facilitated extensive tumor resection, having the advantage of sparing the motor cortex and corticospinal tract in all cases. Conclusions The proposed functional neuronavigation allows neurosurgeons to perform effective and maximal resection of brain lesions, identifying and sparing eloquent cortical components and their subcortical connections. Potential clinical application of this technique is discussed.

CT and MRI findings after stereotactic resection of brain lesions

Objective: To describe postoperative CT and MRI findings and their time course in uncomplicated cases after stereotactic volumetric resections of brain lesions. Materials and methods: One-hundred twenty-eight imaging studies (CT, 86; MRI, 42), performed 6 h to 2 years after 52 stereotactic operations, were retrospectively reviewed and analyzed in relation to time of surgery in cases without complications. Results: The extent of resection bed did not change during the first week after operation; reduction of size then began and continued up to 3–6 months. Mass effect and edema showed no change during the first 4 days, then later regressed gradually. Pneumocephalus was found in 58% of cases in the first 3 weeks, but never later. Benign, surgically-induced enhancement appeared at the margins of encephalotomy and retractor trajectory at the end of the first postoperative week, became more prominent during the following weeks, and lasted up to 3–5 months. In the majority of cases enhancement prevented recognition of the residual tumor. Dural enhancement was observed at the craniotomy site very early after the operation and persisted up to 1 year. Meningeal enhancement over convexities was found in 44% of MRI studies. Conclusion: Extent of the resection bed, mass effect, edema, and pneumocephalus show, in uncomplicated cases, a regular regression during the postoperative period. The time course of enhancement is complex and can be a source of diagnostic misinterpretation.

Stereotactic and computer-assisted neurosurgery at the Cleveland Clinic: review of 501 consecutive cases.

Stereotactic and computer-assisted techniques have revolutionized the diagnosis and treatment of many disorders of the brain by directing surgical instruments, the surgeon's hands, or focused radiation to an imaged target along predefined routes. This report reviews the basic principles and techniques of stereotactic and computer-assisted procedures in 501 consecutive procedures. Procedures performed include biopsy; decompression of cysts, hematomas, ventricles, and abscesses; "point," computer-assisted volumetric, and frameless stereotactic resection of brain lesions; placement of depth electrodes; treatment of movement or pain disorders; implantation of radioactive seeds in malignant tumors; and radiosurgery. Overall, image-directed stereotactic neurosurgery proved safe, accurate, and versatile.