Clinical Analysis of the Automated Percutaneous Discectomy

A retrospective study was performed in order to evaluate the efficacy of automated percutaneous discectomy in lumbar disc herniations that were treated in our institute between May, 1992 and December, 1994. Of the 68 patients that were followed up for 12 weeks, the success rate was 82% according to Onik classification. No serious complications, vascular or nerve damage and discitis, were noted except transient postoperative muscular spasms. The results of this study indicates that automated percutaneous discectomy can be used successfully to treat lumbar disc herniations with minimal morbidity and also emphasized the need for proper patient selection prior to performing the automated percutaneous discectomy.

Experimental Studies of Hydroxyl Radical Generation in Reperfusion Injury after Cerebral Ischemia

The time course of hydroxyl radical generation in the brain and the intensity of brain hydroxyl radical(OH) generation were examined in rat during the first four hours after postischemia reperfusion. Hydroxyl radical production was measured using the salicylate trapping method in which the production of 2, 3-dihydroxybenzoic acid(DHBA) in hippocampus(CA1) 5 minutes after salicylate administration was used as an index of OH formation. The interstitial concentration changes of salicylate and 2, 3-DHBA were detected by intracerebral microdialysis following the intraperitoneal administration of salicylate(150mg/kg) using high pressure liquid chromatography-electrochemical(HPLC-EC) and -ultraviolet(-UV). Adult Sprague-Dawley rats were subjected to 20 minutes of bilateral carotid artery occlusion(BCAO) in either normotensive or hypotensive state. Serial changes of cerebral blood flow(CBF) were monitored by H2 clearance method. CBF of normotensive BCAO group(n=6) was found to be decreased only to 52% of baseline value, and OH production after reperfusion did not develop in this group. Rats in the BCAO hypotensive group(n=10) showed remarkable reduction of CBF to 27% of baseline(p<0.05) and 2~4 folds increase of 2, 3-DHBA/salicylate during the first 40 minutes of recirculation . Hydroxyl radical production in rats died(n=5) after the insult was significantly higher and lasted longer than that in rats survived(n=5)(p<0.05). Concentration of salicylate in perfusate increased during 100 minutes after the peritoneal injection and before reaching to a plateau, which lasted for 3 hours. The changes of cerebral tissue concentration of 2, 3-DHBA differed from those of salicylate. In 2, 3-DHBA, the plateau was reached rather slowly than that of salicylate and lasted for 2 hours. These data indicate that lobal cerebral ischemia could be induced by temporary BCAO only if the systemic hypotenion is accompanied, it can not be induced in normotensive group. The hydroxyl radical produced brain damage is prone to develop early in the reperfusion period and is correlated with the severity of ischemic insult.

Studies on Experimental Vasospasm: Effect of Reserpine on Experimental Vasospasm

Preliminary in vitro experiments were performed to define the contraction effects of the serotonin and prostaglandin F2 alpha in cat's internal carotid artery. Subsquently 12 cats were used to study changes in contractility resulting from pretreatment with reserpine. The arteries, which were exposed to serotonin and prostaglandin F2 alpha contracted significantly just after exposure time. And by addition of higher concentrated serotonin and prostaglandin F2 alpha more contractions were noted. Arteries isolated from reserpine-pretreated cats responded to the serotonin and prostaglandin F2 alpha with similar pattern to those seen in control groups, but the contractility showed some what more decreased slope compared to those with high concentration of serotonin only. These results suggested that reserpine might have yet unknown effects which were different from known mechnism of serotonin to cerebral arteries.

Studies of Vascular Ultrastructure in Experimental Subarachnoid hemorrhage

Cerebral Vasospasm was produced experimentally by injecting normal cat's blood into the cisterna magna of the cat. Ultrastructural changes were observed sequentially from 24 hours to 15 days following subarachnoid hemorrhage(SAH). Twenty-four hours after SAH, endothelial cells in the intima were round shaped and their cellulrar surface was corrugated, these changes remained to 72 hours after SAH with intimal thickening and loss of tight intercellular junction. But since 7 days after SAH, the endothelial cells assumed a more normal spindle-shaped configuration with tight intercelluar junction and an increase in cytoplasmic filaments and vacuoles. The internal elastic laminae was thickened and somewhat more electron dense than normal. In the media, the smooth muscle cells were most consistently and severely affected showing degeneration of mitochondria, vacuoles containing fine particles and loss of complex internal structure, surrounded by increased amounts of intercellular collagen. These findings concluded that the ultrastructural changes in the cat's basilar arterisl wall observed after induction of subarachnoid hemorrhage with fresh autogenous blood occurred as a consequence of vasospasm.