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Biomedical subjects

L Zamorano

Publications and source records attributed to L Zamorano.

9 recordsLinked to original sources
PubMed1992

Stereotactic endoscopic interventions in cystic and intraventricular brain lesions.

Image guided stereotaxis is an accurate and safe method of directing therapy to target volumes defined in two-dimensional (2D) multiplanes or three-dimensional (3D) perspectives using computer reconstruction of image data. The major limitations of stereotactic techniques are related to a lack of intraoperative visualization and direct monitoring of the procedures and to changes of intracranial coordinates after decompression of cystic lesions or aspiration of cerebrospinal fluid in the management of intraventricular lesions. Endoscopic laser stereotaxis (ELS) involves integration of rigid-flexible endoscopy and Nd-YAG laser to 3D-2D multiplanar image-guided stereotactic procedures. The major advantages of ELS include: direct intraoperative visualization, hemostasis, evacuation or resection assessment, and wide exploration of intracranial cavities or ventricles. The technique allows safe aspiration, biopsy, and resection or internal decompression of deep and subcortical intracranial lesions. ELS has proved to be safe and effective in the management of 76 clinical cases and appears to be a promising technique in the management of cystic and intraventricular lesions.

Brain Diseases↗
PubMed1992

Computer-assisted neurosurgery: simulation and automation.

Instrumentation has been developed to automate, accurately guide, and integrate microsurgery laser resection equipment that is used in stereotactic brain surgery. The instrument is a computer-controlled laser-guiding system. The improvement in the accuracy comes from relying on a certain well-referenced three-dimensional surgical orientation, and computer-preplanned tumor contours, rather than only the surgeons hand-eye orientation in the operating room.

Automation↗
PubMed1992

Stereotactic management of midline brain lesions.

Eighty-seven patients, aged 10 months to 92 years, with midline brain lesions were treated using stereotactic techniques at our institution between January 1987 and June 1990. A total of 119 stereotactic procedures were performed with no operative mortality. Procedures included 53 biopsies only, 22 endoscopic laser decompressions, 8 stereotactic microsurgical resections, 9 permanent implants of 125I, 12 temporary implants of 125I, 11 cyst aspirations, 2 cystoperitoneal shunts and 2 intracavitary 32P. The morbidity rate was 4.21%. Local anesthesia was used in 106 of the procedures (89%). Accurate diagnosis was achieved in all cases. Image guidance and stereotactic techniques open new frontiers in the diagnostic and therapeutic management of deep-seated midline intraparenchymal lesions.

Biopsy↗
PubMed1992

Permanent iodine-125 implant and external beam radiation therapy for the treatment of malignant brain tumors.

Survival data of 114 patients treated for malignant brain tumors with 125I interstitial radiation therapy at Henry Ford Hospital, Detroit, Mich. (1986-1990), are presented. The first 64 patients were treated with temporary 125I implants with a total prescribed dose of 60 Gy at a dose rate of 40 cGy/h. In order to reduce the risk of injury to the surrounding normal tissue associated with high-dose brachytherapy, a new approach was initiated using permanent implants with a lower dose rate; 50 patients were treated after surgical resection with permanent implantation of 125I seeds at a lower dose rate of 4-7 cGy/h, with a total dose of 10,000-12,000 cGy, and concurrent external radiation therapy of 5,000 cGy. The rationale of this protocol was to increase the effectiveness of the low-dose-rate implant by a concurrent 'daily' boost of external radiation, thus inhibiting the proliferation of tumor cells during the protracted low-dose radiation treatment. Survival was compared between groups with permanent and temporary implants in terms of effectiveness in tumor control as well as impact on clinical condition. Low-dose-rate implant with concurrent external radiation therapy seems to offer the best chance for long-term survival without deterioration in the clinical condition.

Adult↗
PubMed1992

In vivo and in vitro study of the lesions produced with a computerized radiofrequency system.

For many years, radiofrequency-generated lesions have been used for the treatment of pain and abnormal movements. However, the reliability of this method has been questioned because of the variation in the size of lesions produced by the electrode at different times and temperatures. A 500-kHz radiofrequency generator with different electrodes was used to determine the size of lesions, using different time and temperature exposures. A computerized feedback mechanism kept the tip temperature constant during the production of the lesion, regardless of varying tissue impedance. Eight electrodes of different size and tip characteristics were evaluated at different temperatures and time settings, both in vitro and in vivo. Graphic display of the curves in time were obtained at 65, 70, 75, 80, 85 and 90 degrees C. The effects of thermo-coagulation were studied in vitro in fresh egg whites, using time intervals of 20, 40, 60, 80 and 100 s, and in vivo, in the subcortical white matter of 20 adult New Zealand white rabbits. Animals were sacrificed after 7 days. Lesions were photographed and measured under magnification. In all cases, the coagulated masses were ellipsoid, with regular, well-demarcated borders. A two-way statistical analysis of variance was done. The coagulum size increased with higher temperatures and with larger probes. The increase was significant in both diameter and length (p = 0.001). In contrast, the use of different times at the same level of temperature showed no significant increase in most of the electrodes. There were two statistical significant time effects, for both diameter and length, with the monopolar 2-mm electrode. The use of real-time monitoring with graphic display and the feedback information provided for the computerized control of power and current allows high precision of the temperature at the electrode tip during the production of the lesion.

Analysis of Variance↗
PubMed1979

Teratogenetic periods for the principal malformations of the central nervous system.

The teratogenetic periods of the most important CNS malformations are defined and briefly discussed. The results are presented in a synoptic figure. The present study is based on the analysis of normal CNS development and on morphogenetic interpretations of the pertinent anomalies. The data compiled from the literature concerning normal development are presented in an analytical table and are also summarized in a synoptic figure.

Anencephaly↗
PubMed1975

Ultrastructural study of the pineal gland of the chicken (Gallus gallus).

The authors studied the pineal glands of chickens (Gallus gallus) between the ages of 2 and 5 days with the electron microscope. They described two distinct areas in the parenchyma of the organ: the follicles, formed by two cellular categories, the pineal A and B cells, and the parafollicular zone, which surrounds and separates the follicles from the connective walls. This area is formed, fundamentally, by two types of cells and nerve fibers. These cells occasionally delimit cavities. We propound the hypothesis of the possible transformation of the parafollicular zone into follicles.

Age Factors↗