Applied neurophysiology最新文献

Installation of the first United States 201-source 60Co gamma unit for stereotactic radiosurgery was completed at the University of Pittsburgh in May, 1987. Despite a very favorable 19-year experience in Stockholm, introduction of this technology into the US proved to be a formidable task. Extensive internal and government regulatory review by the Health Systems Agency, the Food and Drug Administration and the Nuclear Regulatory Commission ultimately resulted in approval of marketing and use of the gamma unit. Clinical use and radiobiological research has begun.

Stereotactic tumor biopsy and brachytherapy catheter implantation can be accomplished with targets derived from computed axial tomography and magnetic resonance scans. Computer manipulation of image data allows both diagnostic and therapeutic procedures to be carried out from a single set of scan slices. This eliminates the need for repeat scanning as part of the surgical procedure. Microcomputer technology is sufficiently advanced to handle the images and graphics necessary for stereotactic neurosurgery. A system based on the IBM PC/AT designed for this purpose uses readily available graphics software and custom-designed imaging programs. Direct loading of computed axial or magnetic resonance scan images from magnetic tape can be accomplished. Determination of points, contours and volumes in three-dimensional space allows intraoperative alignment of image data and patient landmarks within the stereotactic head frame using pattern recognition overlays. Three-axis scaling for magnification correction along with rotational and linear data transformations provide the basis for single-scan stereotaxis. Interactive computer graphics integrate image, patient and frame coordinates for target determination. This method eliminates the need to design and fabricate nonmagnetic or radiolucent scanner-compatible devices.

A method using Multiplanar CT-guided stereotactic biopsy and high-dose 125I interstitial radiotherapy in patients with malignant nonresectable or recurrent brain tumors is presented. Optimal interstitial radiotherapy requires careful preoperative planning, computer-assisted dosimetry, CT-guided stereotactic biopsy and implantation of catheters that will be loaded with 125I seeds. A method is presented by which the isodose curve distribution is adjusted to the tumor size, volume and axis, allowing treatment of the imaged and histologically determined border of the tumor with 60 Gy at a dose rate of 40 rad/h.

Dorsal root entry zone (DREZ) lesions were made in the cervical dorsal horn in cat and monkey. Terminal degeneration was observed in the lateral cervical nucleus in cat and contralateral VPL in monkey by Fink-Heimer stain. WGA-HRP was injected in the cervical dorsal horn of cat and retrograde labelled cells were observed mainly in the raphe nucleus, parabrachial nucleus, locus coeruleus, Kölliker-Fuse nucleus, Eddinger-Westphal nucleus, and hypothalamic area, indicating that these descending fiber systems are involved by the DREZ lesion. The functional role of these fibers in regard to deafferentation pain relief seems now to be open to discussion.

The authors propose a hypothesis about the mathematical relationship between the position and intensity of epileptogenic discharge and the potential recorded from an electrocorticographic electrode. A computer program is used to solve the equation and to determine a small area of maximal probability for the focus to be found.

A technique to apply reconstructed X-ray computed tomography (CT) and magnetic resonance imaging (MRI) for target determination in stereotactic Bragg peak proton beam therapy of intracranial lesions was developed. Twenty-one benign intracranial tumors and vascular abnormalities were managed using this technique. Clinical features of these lesions, as well as targeting problems associated with the MRI and CT image interpretation, are presented.

The lateral geniculate nucleus (LGN) of fetal Wistar rats was transplanted to the visual cortex (VC) of 33 neonatal Wistar rats. Histological examination showed transplanted cells in all the host brains. Intensively labeled cells were demonstrated in the transplant by labeling with true blue. Electrophysiological studies with brain slice preparations demonstrated that the transplanted LGN sent axons and made excitatory monosynaptic connections mainly in layer IV of the VC area 17. Corticogeniculate projections were also demonstrated in the transplanted LGN.

While target localization for human stereotactic surgery has been refined by computed tomographic (CT) and magnetic resonance imaging (MRI), stereotaxis in experimental animals has remained dependent upon external cranial landmarks and standardized atlas coordinates. To overcome the limitations and inaccuracies of animal devices using the original Horsley-Clarke method, we modified a standard animal stereotactic instrument in order to make target localization and coordinate determination possible with CT imaging. Although the device can be adapted to any medium-sized animal species, we demonstrate its use with dogs here.