The Early Experimental Study Of Percutaneous Laser Disc Decompression In Beagles

Objective: Lumbar disc herniation is a common disease which troubles the daily life of the patients. Percutaneous laser disc decompression(PLDD) is an effective method to treat it. The purpose of our experiment was to find a better method to improve the treatment effect and decrease the complications by operating the PLDD to beagles. The characteristic changes of temperature, pathology and radiology in the discs and the surrounding tissues were observed.Materials and methods: Healthy beagles were used to operate PLDD. The way of operation simulated clinical operation. Beagles were divided into negative pressure suction group and general group. Three discs were chose to operate in each beagle. The beagles' characteristic changes of temperature and complexion were observed in the operations. The changes of vertebral discs and the surrounding tissues were observed by high resolution CT and MRI at different times after the operations. The beagles were sacrificed. The pathological changes of vertebral discs and the surrounding tissues were also observed at different times. The sizes of the boiloff cavity at the gross specimens were observed and the differences of the sizes were compared among different energies, different times and different groups. The results were analyzed and compared with the changes of ultrastructure through microscopic and electronic microscopic.Results: The beagles of the conventional vaporization group occasionally had limb tic and whining in the operations, which occurred with the temperature change of the surrounding tissues of intervertebral discs, and had no direct correspondent relations with total energy. The vital signs of The beagles of the negative pressure suction group were stable, could not be observed transparent limb tic and total body reactions. The mental states of the beagles were poor after the operations, ate a little, and the mental states of the beagles improved at 5th day after operations. Three beagles of the conventional vaporization group occurred limp in right lower extremity. The symptoms of limp beganto take a turn for the better in 6th day after operations. The signs of massive hemorrhage could be viewed by gross observations in the subcutaneous tissues and muscle layer of the operative side. The stratification of soft tissues was unclear and the similar sign could be observed in the intervertebral foramen with diffuse spotty black carbon. The major part of nucleus pulposus of intervertebral disc was vaporized, and became round cavity. The wall of cavities were clear in 2 days after operation, and became turbid and dust color from 4th day to 7th day after operation. The sizes of the vaporization cavity were related with the total energy. The cavity size caused by 500J was significantly larger than that caused by 300J(P<0.01). The cavity size caused by 500J had no significantly difference with that caused by 700J(P>0.05).The range of temperature fluctuation in the general group was 12.1 and greater than that in the negative pressure suction group which was 3.2C. The major part of nucleus pulposus of intervertebral disc was absent immediately after operation by histology observations. The dividing line between remaining nucleus pulposus and cavity was clear, with granular substances at the border. There were many granular substances in the tissues of intervertebral foramen of the paracentetic side, and cellar structure was unclear, while the structure of the other side was clear. The remaining nucleus pulposus of intervertebral disc became unclear at second day. The soft tissues of intervertebral foramen of the paracentetic side had edema manifestation. Mild degeneration and edema could be observed at nerve root.while no abnormal appearance was seen in the tissues of the other side. Hemorrhage could be found in the muscle tissues of the paracentetic side. Anulus fibrosus of intervertebral disc was integrated in 4 days after operations.The structure of the remaining nucleus pulposus was vague. Pieces of necrosis and edema could be observed in the the tissues of inte...