|Budget Amount *help
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2000: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1999: ¥2,300,000 (Direct Cost: ¥2,300,000)
The aim of this study was to study the nerve vasculature using a specially designedoperationmicroscope supplied with video camera in the area of the caudaeuina just cranial and caudal to the compression-zone in a controlled experimental set-up. Atotal of 10 dogs, bodyweight 7-12 Kg, were anaesthetized. The dogswere placed prone and a laminectomy of the 6th lumbar vertebra and the sac-rum was performed. A specially designedinflatable plastic balloon was gently placed under the lamina of the 7th lumbar vertebra. The balloon was connectedto a ATS-1000 compressed-air system. When the pressure in the balloon was increased, the balloon compressed the cauda equina in the segment of the spinal canal covered by the lamina of the 7th lumbar vertebra. In 5 of the dogs, compression at 100mm Hgwas maintained for 120 minutes and then the nerve roots were allowed to recover for 90 minutes. The blood flow and the distribution of vascular networks was studied by the operation microscope. In the remaini
ng 5 dogs, compressionat 10 mmHg was maintained for one week. In this series, the balloon was connected to a ATS-1000 compressed-air system that now was used to infuse a substancecalled konnyakuinto the balloon at a slow rate at 10 mmHg infusion pressure. This substanceis first liquid but gradually beoomes viscous in 10-20 minutes. When there was no more flow of konnyakuinto the balloon, the infusion pressure was maintajned for 30 minutes to compensatefor pressure loss resulting from displacement of the tissues in the spinal canal. The inflated balloon was ligated, still under infusion, at the cranial and caudal border of the lamina, respectively, and the parts of the balloon locatedcranial and caudal to the ligatures were cut and removed. Seven days after the initial procedure, the dogs in both were reanesthetized. Similar to the acute series, the nerve root vasculature was studied in the cranial and the caudal segments of the cauda equina.
Results : In the acuteseries, venousstasis, narrowing of capillaries, and a reduction of the blood flow were observed during the 120 minutes of compression in the cranial part of the caudaeuina. These changes gradually recovered after release of the compression. In the caudal part of the cauda equina, there were vessels running parallel to the nerve roots. The upper vessel is an arteriole and the lower vessel is a venule in this slide. Duing the 120 minutes of compression, venous stasis, narrowing of capillaries, and a reduction of the blood flow were also observed in the caudal part of the caudaequina. Similar to the acuteseries, there was venous stasis, narrowing of capillaries, and a reduction of blood flow bothcranial and caudal to the compression zone. However, a clearly more pronouncedvascular network was seen in all of these chronically compressed nerve roots, which contrasted significantly to the acuteseries. Both acute and chronic compressioninducedevident vascular changes. However, in the chronically compressednerve roots there was a more developedvascular network that might indicate that chronically compressed nerve roots mayrecover functionally due to neovascularisation of the intrinsic vasculature of the nerve roots. Less