Based upon the recent improvement of microsurgical anatomy of the spinal cord, image diagnoses, techniques and materials of intrventional neuroradiology, and microsurgical techniques, there has been remarkable progress in the treatment of spinal arteriovenous marformations. They are classified into three types; namely, intramedullary arteriovenous marformation (AVM), perimedullary arteriovenous fistula (AVF), and spinal dural arteriovenous fistula (DAVF). In this presentation, we are going to present our policy, tactics and techniques of endovascular treatment of three types of spinal arteriovenous marformations. 1) Intramedullary arteriovenous malformation : Complete cure of intramedullary AVM is difficult, because of the participation of perforating arteries. Recommended treatment is the flow directed embolization using polyvinyl alcohol particles. This treatment has been accepted as a measure to put the malformation under control and revert the neurological derangement related to edema. 2) Perimedullary arteriovenous fistula : A subdivision into tree types of perimedullay AVFs was proposed by Merland, et al. Type 1 AVFs are difficult to embolize. Surgical treatment is the primary consideration for this type. Type 2 and 3 AVFs are amenable to embolization. Combined embolization using n-butyl-2-cyanoacrylate (NBCA) and microsurgery is the primary consideration for these types. 3) Spinal dural arteriovenous fistula : Spinal DAVF is the most common type of spinal AVM besides genuine spinal AVM. Embolization using NBCA is preferred to microsurgery to interrupt the shunt in most of the cases with spinal DAVF because of its efficacy, safety and less invasiveness.

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In the present manuscript, the authors described the various kinds of the decompression procedures and fixation methods for the degenerative lumbar disorders. At the evaluation of the patients with the degenerative lumbar disorders, not only the neurological status but also the neuroradiological findings must be meticulously analyzed. According to such findings obtained from these examinations, the operative procedures are decided. Although the wide laminectomy has been used for the standard operation for the lumbar canal stenosis, either the fenestration method or the unilateral approach for the bilateral ligamentectomy can obtain favorable results. The strict indications of the fixation procedures for the degenerative lumbar disorders have not been established. It is necessary to perform the prospective study for the evaluation of the efficacy of the fixation operations. In the present paper, the methods of the in situ fusion and pedicle screw fixation were described.

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Schwann cells (SCs) have been shown to effectively promote axonal regeneration in both peripheral nervous system and central nervous system. We are testing the ability of Scs to enhance regeneration in adult rat spinal cord when they are present in guidiance channels grafted into transected cords. And we performed detailed kinematic analysis of recovery process using a computerized motion analysis system after Schwann cell transplantation into midthoracic area. SCs were purified in culture from adult rat sciatic nerve, suspended in Matrigel : DMEM (30 : 70), and seeded into semipermeable PAN/PVC guidance channels (2.6 mm ID x 8mm long, 50kDa MW cutoff) at a final density of 120 x 10^6 cells/ml. Adult Fischer rat spinal cords were transected at T8 and the T9 segment, the spinal cord was removed to create a 4 mm gap. The rostral and caudal stumps of the cord were each inserted 1 mm into the channel. One month after grafting, a vascularized tissue cable was present within the channel bridging the two ends of the spinal cord. Within the cable, numerous myelinated and unmyelinated axons were observed. Fast Blue retrograde tracing showed that the majority of neurons whose axons regenerated into the channel were located in spinal cord gray matter. The labeling could be traced 9 segments rostrally to C7 and 9 segments caudally to L5. Axons from dorsal root ganglion neurons also regenerated into the channel. Lack of immunostaining for serotonin (5-HT) and dopamine beta hydroxylase (DBH) indicated that supraspinal axons from raphe nuclei (5-HT immunoreactivity) did not grow into the channel. We conclude that SCs in guidance channels serve as a cellular bridge that stimulates axonal regeneration of both ascending and descending spinal cord neurons. And we confirmed restored gait after transplantation with computerized motion analysis system.

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Direct anterior screw fixation of a displaced odontoid fracture (OF) has been indicated for reasonable method of treatment. We have experienced three cases of displaced OF, in which fractured dens were fixed by one cannulated double-threaded compression screw. We present cases, operative techniques and advantages of this type of screw in comparison with the cancellous bone screw used in our early cases. Two cases showed posterior-displaced Anderson Type II OF and one case showed anteriorly displaced shallow Type III OF. The head was retracted to be positioned with fracture-fragment alignment in the best possible reduction. Small part the antero-inferior portion of the dens body was drilled out. Under simultaneous antero-posterior and lateral fluoroscopic control, a guide pin was introduced to penetrate the cortex of distal end of the dens. Following the trajectory of the guide pin, drilling, tapping and then a screw implantation were manipulated. The double-threaded screw with pitch difference between the front and back threads produced compression force across the fracture line and thus rigid internal fixation. All cases showed excellent placement of screws and no nonunion during following period of 12 months. The present surgical method seems to be optimal for displaced OF rather than the anterior fixation method using conventional type of screw or posterior arthrodesis.

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Between January 1987 and December 1996, we have performed anterior decompression and interbody fusion with a "Japanese clog" shaped bone graft in 21 patients with cervical myelopathy and/or radiculopathy caused by adjacent multilevel cervical disc disease. There were 17 men and 4 women, the mean age was 51 years, ranging from 25 to 71 years. Their affected levels consisted of C4/5 and C5/6 levels in 11 patients, C5/6 and C6/7 levels in 9 patients, and C4/5, C5/6 and C6/7 levels in one patient. Surgery : After exposure of affected levels as usual fashion, the anterior half of the vertebral body between the two adjacent affected intervertebral discs is drilled out using a high speed drill. The upper part and lower part of the remaining vertebral body also are drilled out for 3mm of their length. The transverse width of the drilled body is about 15 to 18mm. Then discectomy, osteophytectomy and resection of the posterior longitudinal ligament as well as removal of herniated disc materials are carried out at the level of the adjacent affected disc spaces. After sufficient decompression of the neural tissue, a trough is created in the vertebral bodies above and below to allow the bone graft to be wedged in. In Japan no bone bank is available, so a bone graft from the iliac crest is shaped in the form of a Japanese clog, and the cranial end inserted first. The caudal end is gently tamped into place. In all out one of our 21 patients, marked improvement of spondylotic myelopathy was gained. In conclusion, the benefit of this procedure includes a wide working space, sure and safe manipulation of microinstruments, and safe insertion and complete fusion of the bone graft.

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Selective peripheral denervation for the sternocleidomastoid and the posterior cervical group muscles were performed, according to the method reported by Bertrand, with satisfactory results in two cases with idiopathic spasmodic torticollis. For denervation of the sternocleidomastoid, the skin incision extended from the base of the ear to the junction of the horizontal and the vertical portion of the trapezius muscle. The peripheral accessory nerves were identified at the lower portion of the incision and their proximal parts were exposed until they gave off branches to the sternocleidmastoid. All identified branches innervating the sternocleidomastoid were coagulated and severed and the muscle itself was also sectioned totally. In order to denervate the muscles of the posterior cervical group, the extradural section of the roots of C1 and C2 combined with coagulation and section of the posterior primary divisions (rami) of C3, 4, 5 and 6 was performed with posterior midline skin incision. Bertrand named this procedure ramisectomy to differentiate it from the classical intrathecal rhizotomy (Foerster-Dandy's method). The first case had spasmodic torticollis of rotation to the left side with a retrocollic component which had been intractable to different kinds of treatment for nine years. By peripheral denervation of the right sternocleidmastoid and the bilateral posterior cervical group, the patient became free from any abnormal involuntary movements. The effects continued without restriction of neck movement during the follow up period of one and a half years, though obvious atrophy of the denervated muscles was observed. The second case had rotaional torticollis to the right side. By denervation of the left sternocleidomastoid and the right posterior cervical group, the symptoms improved significantly, but some residual abnormal movements were detected postoperatively. At the second operation, further denervation was sundertaken and satisfactory results were obtained. This method is very effective for spasmodic torticollis which is intractable to other kinds of treatment.

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The pressure dissociation between the ICP and spinal canal pressure caused by the disturbance in CSF flow at the level of foramen magnum region is believed to be responsible for the development and expansion of the syringomyelic cavity that is associated with Chiari type I malfomation. The purpose of this article is to record observations concerning the changes of CSF hydrodynamics in the spinal canal before and after surgery for foramen magnum decompression (FMD), and to evaluate the effect of FMD on syringomyelia from the hydrodynamic point of view. Thirteen syringomyelia patients with the mean age of 42.5, who underwent FMD with dural plasty in our institute from 1994 to 1997, agreed to be measured for the pressure volume index (PVI) and CSF outflow resistance (Ro) by the bolus lumbar intrathecal injection method that was previously descibed by Marmarou in terms of the various neck positions. PVI in neutral, extened and flexed position were improved by 74.8%, 104.4% and 54.3% respectively. Ro in neutral, extended and flexed postion were improved by 34.6%, 27.2% and 40.5% respectively. Mean values of PVI and Ro in any neck positions were improved by 77.8% and 34.1% respectively. The authors concluded that FMD is effective in the correction of the CSF dynamics in syringomyelia associated with Chiari type I malformation. From the hydrodynamic point of view, this is thought to relate with craniospinal CSF pressure dissociation.

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Patients with lumbar canal stenosis have usually been treated by conventional bilateral laminectomy. Using high resolution computed tomographic myelography, in patients with lumbar canal stenosis, it can be shown that the cross sectional areas (CSA) of the stenotic dural sac [0.62±0.22(cm)^2 (mean±SD)] and the hypertrophic ligamentum flava (1.52±0.76(cm)^2) are wider than that of the normal dural sac (1.32±0.28(cm)^2). Based on this result, during the last two years, patients with lumbar canal stenosis due to hypertrophic ligamentum flavum have been treated by unilateral laminectomy and bilateral ligamentectomy. Furthermore, patients with hypertrophic ligamentum flavum combined with lumbar disc herniation or spondylolisthesis have also been treated by this procedure. Decompression of the nerve root in the opposite lateral recess can be more easily achieved than by using the approach side, where the facet joint has to be destroyed to some extent. This approach is undesirable in cases with contralateral nerve root compression peripheral to lateral recess. Because, compared with other techniques, this procedure is less invasive of the paraspinal muscles, the facet joint and the supra-and interspinous ligament, rapid recovery even in elderly patients can be achieved and the incidence of delayed lumbar instability may be decreased. In cases requiring a pedicle screw, this procedure is very useful for saving the grafting area on the opposite side. The early results were good in all cases, but restenosis occurred in two cases. The restenosis was caused by dense scar formation. Meticulous hemostasis especially of contralateral epidural venous bleeding may be important to prevent scar formation and re-stenosis.

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The authors reviewed 103 cases of degenerative lumbar spinal canal stenosis (LSCS) for which interlaminar laminotomies with medial facetectomy (ILMF) were undertaken except for 7 cases of foraminal stenoses. A unilateral total facetectomy was performed for the latter. The surgical indication was for radiculopathy and/or intermittent claudication refractory to the conservative therapy. The patients' ages ranged from 21 to 78 years, with an average of 62. There were 61 males and 42 females. Degenerative LSCS accounted for 72%, while developmental ones accounted for only 7%. The operated intervertebral level was single in 70%, double in 25% and triple in 5%. The most common operated level was L4/5 (64%), followed by L5/S (19%), L3/4 (15%) and L2/3 (3%). Discectomy was carried out in 22 patients with extruded discs and in 2 patients with marked disc bulging. Degenerative spondylolisthesis (one degree) was encountered in 25 patients. Spinal fixation using a pedicle screw was made in 3 patients with unstable spondylolisthesis and only in the initial two patients who underwent total facetectomy. A long-term evaluation which was made by phone interview (ranging from 1 to 9 years, averaging 3.5 years) showed that low back pain and leg pain were absent or negligible in 53%, slight in 26%, moderate in 18% and severe in 3%. As to the performance status, "normal walking" was noted in 63%, "mild difficulty in walking long distances" in 26%, "unable to walk more than 100 meters" in 9% and "unable to walk" in 2%. As a whole, approximately 90% of the patients followed up had enjoyed a useful life. Of the causes that incapacitated about 10% of the patients, half were unrelated to lumbar spinal diseases. None of the 22 patients with stable spondylolisthesis developed significant spinal instability, nor did the patients without prior listhesis. There were no patients who developed spinal restenosis due to the regrowth of bone. Eight patients required reoperation because of lumbar disc hernias in 3, foraminal stenosis in one and scar tissue in another and technical errors in 2. In conclusion, ILMF is a very useful procedure for degenerative central canal stenosis as well as lateral recess stenosis. This procedure carries significantly fewer later complications, such as listhesis and disc hernia. Concurrent instrumental fixation should be limited to the patients with significantly unstable spondylolisthesis.

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Two cases of a solitary plasmacytoma of the spine were reported. Case 1, a 59-year-old male, presented with progressive quadriparesis. MRI and myelogram revealed an osteolytic lesion extending from the 5th to the 7th cervical vertebral bodies with extradural mass. Biopsy was made and histologically the lesion was shown to be a plasmacytoma. A halo vest was put on the patient, who received radiotherapy followed by posterior cervical stabilization with autologous ribs and titanium wires. Physiotherapy was continued for a few months until quadriparesis improved remarkably and he was discharged able to walk by himself. Five years later, he is leading a normal daily life without recurrence. Case 2, a 56-year-old male, became paraplegic within a couple of days following chest pain. CT and MRI revealed the destruction of the 5th thoracic spine with cord compression. Emergency laminectomy was performed to decompress the cord and the lesion was diagnosed pathologically as plasmacytoma. Postoperatively both legs were able to move well. The patient received radiotherapy while still confined to bed. Afterwards, following preoperative embolization, transthoracic anterolateral stabilization with autologous rib and instrumentation (Kaneda's device) was carried out. Postoperative chemotherapy was received during the period of physiotherapy. As a result of those treatments, he was enabled to walk by himself with the help of a cane. After discharge, however, he was readmitted and died of metastatic lung cancer originating from the kidney about a year after the onset. Generally speaking, plasmacytoma is malignant. However, its prognosis might be less poor, if solitary. Also it is radiosensitive as was shown in our cases. On the other hand, it can be said that this tumor is the early stage of multiple myeloma. Therefore, in conclusion, solitary plasmacytoma of the spine should be thoroughly treated with tumor resection and stabilization by the anterior and/or posterior approach, and with adjunctive therapy including pre- or postoperative irradiation and chemotherapy.

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Intramedullary spinal cord metastasis is commonly accompanied with widespread systemic or intracranial metastases. We presented a extremely rare case of solitary intramedullary spinal cord metastasis. A 49-year-old female, who underwent left mastectomy for breast cancer 10 years ago, was admitted with complaints of nausea, vomiting and tetraparesis. Magnetic resonance images clearly demonstrated an intramedullary tumor localized at the C1-C2 level of the spinal cord with a syrinx-like lesion from the medulla to the thoracic cord. After histological diagnosis was made with surgical specimens, the patient received local radiation therapy, resulting in reduction of the size of the tumor and improvement of the neurological symptoms. However, she died of subarachnoid dissemination of the tumor seven months after the onset. In conclusion, it is considered that removal of the tumor together with extensive adjuvant therapy is necessary in the case of metastatic spinal cord tumors.

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