A technique for long-term implantation of a microcatheter into the third ventricle of post-pubertal Chinese Meishan pigs based on ventriculography.

The objectives of this study were to implant a microcatheter into the third ventricle of post-pubertal Chinese Meishan pigs, and to maintain the microcatheter for a long time without causing stress. Fourteen pigs (45-60 kg BW) were used. Each pig was anesthetized and the head was orientated on the stereotaxic apparatus. A radiopaque dye was placed into the ventricle via a guide cannula inserted 3.5 mm forward of the bregma. A microcatheter was inserted into the third ventricle using ventriculography, and fixed with dental cement to a metal-mesh protector and screw anchors embedded into the skull. The opposite end of the microcatheter was externalized from the dorsal neck so that corticotropin-releasing hormone (CRH) could be injected easily. Simultaneously, a catheter was fitted in the jugular vein, and the free end of the catheter was externalized from the dorsal neck. Microcatheter-implanted pigs showed a normal progesterone concentration profile, and a constant cortisol level during at least two estrous cycles. Furthermore, intracerebroventricular injections of CRH (25 microg/500 microl) resulted in an increased plasma cortisol concentration (P < 0.05). Thus, the technique developed in this study enables us to approach the third ventricle in post-pubertal freely-moving pigs effectively over a long time, without causing stress.

Air-ventriculography provokes an anterior displacement of the third ventricle during functional stereotactic procedures.

The width of the third ventricle, the length of the anterior commissure-posterior commissure line (AC-PC line), the spatial position of the midplane of the third ventricle, and the co-ordinates of the AC, the PC, and of 17 brain targets in the thalamus, hypothalamus and pallidum, were assessed on a pre-operative stereotactic computed-tomography (CT) study and compared to measurements on intra-operative air-ventriculography, using a non-invasive relocatable stereotactic frame. There were no significant differences in the length of the AC-PC line, in the position of the midsagittal plane of the third ventricle, or in the vertical or lateral co-ordinates of the AC, the PC and the cerebral targets, between measurements on CT and on air-ventriculography. However, the width of the third ventricle was significantly larger, and the spatial positions of both AC and PC were significantly more anterior on air-ventriculography than on the CT study. This anterior dislocation of the commissures was presumably due to the insufflation of air into the ventricles of patients being in the supine position during surgery.

Methodology and clinical experience with computed tomography and a computer-resident stereotactic atlas.

We have developed a computer-resident stereotactic atlas of the human brain that quantitatively defines subcortical structures within anatomical landmarks detected on obliquely reconstructed computed tomography (CT) slices. Horizontal stereotactic atlas sections can be stretched and contracted by polar transformation and labeled by a computer to fit within these CT scan-defined landmarks. The stereotactic coordinates of any substructure on the atlas-labeled CT slice may then be calculated by the computer and expressed in mechanical adjustments on a stereotactic surgical frame located in the operating room. We demonstrate the use of this method in the stereotactic treatment of movement disorders as an augmentation to conventional ventriculography and microelectrode recording.