Sadaaki Nakai

Study Design. Experimental investigation of the dynamics of nerve root circulation. Objectives. To study the dynamics of lumbosacral nerve root circulation by using seriography in dogs. Summary of Background Data. The vascular distribution to the nerve root has been discussed mainly from the morphologic aspects, and no adequate elucidation has been presented concerning the kinetics of the blood supply to the nerve root. Methods. To investigate the direction of blood flow in the nerve roots, a series of photographs of the cauda equina were taken using a motor-driven camera immediately after 3 mL of india ink was injected through the aortic catheter manually. The changes in the blood flow direction caused by compression of the nerve root also were observed. After the dog was killed, the nerve roots were cleared by the Spalteholz technique to identify the vessels observed during the experiment. Results. The blood flow in the radicular arteries was descending in the proximal part and ascending in the distal part of the nerve roots. This observation supports the suggestion that there is a so-called watershed of the blood flow in the radicular arteries themselves. However, when the ascending radicular artery of the nerve root was cramped, the radicular blood flow on the proximal side was downward. The microangiograms also showed that there were abundant anastomoses of intrinsic vessels in the nerve roots. Conclusions. There is no relatively hypovascular region in the nerve root that is vulnerable in the course of degenerative changes in the lumbosacral spine. Therefore, it is unlikely that the watershed represents a weak point of the blood flow in the nerve root.

This study analyzed the results of anterior transvertebral herniotomy for cervical disk herniation to assess the utility of this procedure. Anterior transvertebral herniotomy was performed in 24 patients who had cervical disk herniation without spinal canal stenosis. In most patients, a good result was obtained, but simultaneous or subsequent anterior intervertebral fusion was necessary in four patients. In one (4%) patient, the two adjacent vertebrae had fused spontaneously. The best indication for this treatment judging from the postoperative results is a large disk hernia associated with either myelopathy or radiculopathy, but without spinal canal stenosis.

We carried out sacral en-bloc resection in six patients (three with chordoma one with pheochromocytoma one with malignant schwannoma and one with giant cell tumor) using preoperatively collected autologous blood, to avoid homologous blood transfusion. An average of 3200ml was collected preoperatively, with patients receiving recombinant human erythropoietin (r-HuEPO), at a total dose of 130000 units on average. In four patients, we were able to accomplish the surgery without homologous blood transfusion. Postoperatively, the hemoglobin level in these four patients recovered to the pre-collective level in 4.5 weeks, on average. These clinical results indicate that en-bloc sacrectomy, which requires a large volume of blood transfusion, can be accomplished with preoperatively collected autologous blood alone.

To see whether degenerative changes of the adjacent disks are accelerated by fixation of a lumbar segment, 48 patients who had undergone posterior lumbar interbody fusion (PLIF) more than 5 years previously were investigated radiographically and clinically. Narrowing of disk spaces was observed in 31% of the subjects, but it usually occurred at levels proximal to the fusion. The incidence of adjacent disk narrowing was not significantly higher after PLIF, compared with reports on degenerative changes of lumbar disks with aging. Some subjects showed narrowing of disks that were not adjacent to the fused level, suggesting that individual predisposition played a role in disk narrowing. Instability was not seen in any of the subjects. New development or elongation of the traction spurs at adjacent segments occurred at the disks proximal to the fusion. The clinical results were generally satisfactory, despite progression of degenerative changes on radiographs.