[in Japanese]

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objective : We report on the utility and necessity of myelography and CT myelography in diagnosing spinal disease. methods : The study population consisted of 150 patients who had undergone spinal surgery in our institution within the past one year ; cervical disease was involved in 42 cases, thoracic in 4 cases and lumbar in 104 cases. The utility of these procedures was evaluated according to 3 stages : 1.) necessity, 2.) usefulness and 3.) non-necessity. Moreover, to enable evaluation according to disease distribution, the disease was further classified into four (4) types based on location : lateral disease (group A), medial- (group B), stenotic- (group C) and others (group D). results : The myelography and CTM necessity cases comprised 18 (42.9%) cases of cervical disease and 30 (28.8%) cases of lumbar disease. The: non-necessity cases 14 (33.3%) cases of cervical disease, all thoracic and 65 (62.5%) cases of lumbar disease, and the other cases were categorized by their usefulness. In lateral disease (group A), the necessity cases were mede up of 15 (75.0%) cases of cervical disease and 13 (56.5%) cases of lumbar disease. In medial cases and stenotic cases, the non-necessity cases accounted for 3 (25.0%) and none 0% of cervical disease, and 1 (16.7%) and 16 (25.8%) of lumbar cases. At any rate, all reoperation cases were classified as CTM necessity and usefulness cases. conclusions : Myelography and CTM are necessary in those cases where MRI is unusable and post operation. They are useful procedures in cases which have instability and/or lateral disease, and which are not definable from the responsibility point of view from several neurological studies. On the other hand, these procedures lack the necessity in cases involving thoracic region, clear disc herniation and cases with severe stenosis.

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Factors affecting titanium cage subsidence after anterior cervical fixation were evaluated in 31 patients who were radiologically followed-up for at least 1 year. Cage subsidence was defined as significant when the cage sank into the vertebral endplate to a depth of 2 mm or more. Subsidence occurred at 16 of 47 intervertebral spaces, and was invariably prominent at the antero-inferior side of the cages. Box-type cages (Syncage-C, Synthes) were more preventive against subsidence than cylindrical cages (Amslu, Eurosurgical) requiring reaming of the endplate. Box-type cage subsidence occurred exclusively at malaligned intervertebral spaces with a flexibility of 10 degrees or more, however, the contents (local bone fragment vs. hydroxyapatite plate) or position (between the anterior vertebral cortex vs. behind the cortical surface) of the box-type cage had no influence on the subsidence. The results imply that mechanical load is an essential factor causing cage subsidence. Prediction of subsidence seems to be possible by measuring segmental flexibility and an optimal operative procedure can thus be chosen to improve the architectural outcome after anterior fixation of the cervical spine.

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We report a unique case of bleeding lumbar myxopapillary ependymoma, causing superficial siderosis (SS), which is characterized by the deposition of hemosiderin in the leptomeninges on the surface of the brain, cranial nerves, and spinal cord. A 67-year-old man, presenting with progressive hearing disturbance and ataxia, was diagnosed with SS by brain MRI. The source of hemorrhage was a cauda equina ependymoma, which was surgically removed. Early identification of the hemorrhage source is important in the treatment of SS, and neurosurgical intervention to the causal lesion can prevent neurological deterioration.

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We report a case of idiopathic thoracic spinal cord herniation treated with a combination technique including a widening of the dural defect and applying a graft patch. A 64-year-old female presented with progressive spastic paresis of the right lower limb and sensory disturbance below the level of the bilateral T5 dermatome. Magnetic resonance imaging (MRI) showed ventral deviation of the spinal cord from the T2 to T4 level. Laminectomy of T2, 3 and 4 was performed, the widening of the ventral dural defect was carried out first and the soft herniated spinal cord was carefully reduced. Finally, the dural defect was covered with a Gore-Tex patch graft. Postoperative MRI revealed a normal positioning of the spinal cord. The patient's spastic paresis also improved after the operation. The authors conclude that a widening and patch grafting procedure is a safe and promising surgical method for treating idiopathic spinal cord herniation.

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Hemangiopericytoma of the spinal cord is rare, and its neuroradiological characteristics of and surgical findings are still unknown. A 62-year-old male presented with gradual paraparesis, bilateral leg paresthesia and urinary dysfunction. Magnetic resonance imaging (MRI) of the lumbar spine demonstrated an intramedullary tumor at the L1 spinal level. The tumor markedly progressed during a 4-month follow-up, and demonstrated an intramedullary and extramedullary compartment with a dural attachment. The tumor was fed by the lumbar artery and demonstrated fair and persistent enhancement without apparent venous drainage on spinal angiography. The patient underwent surgery for total excision of the spinal tumor. The tumor had a septal wall between the intramedullary and extramedullary portion, which facilitated easy detachment of the extramedullary portion from the intramedullary portion. The margin between the intramedullary tumor and the normal spinal cord was obvious, and the tumor was completely resected without major bleeding. Pathological findings were compatible with hemangiopericytoma. Hemangiopericytoma should be considered as part of the differential diagnosis of a highly vascular tumor showing rapid growth. Careful radiological follow-up after initial treatment might be required due to the aggressive nature of this rare tumor.

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We report a rare case of obstruction of the cerebrospinal fluid (CSF) pathway caused by a dilated anterior longitudinal epidural venous plexus in a 32-year-old man. The patient had a history of multiple cyst-peritoneal shunting procedures for a large posterior fossa arachnoid cyst and had been troubled by gait disturbance and clumsiness of the fingers. MR revealed T2 prolongation and swelling of the upper cervical cord and stenosis of the spinal canal due to a well-developed anterior longitudinal epidural venous plexus. Cerebral angiography revealed anomalous venous drainage of the posterior fossa and cranio-cervical junction. Internal jugular veins were not seen, but a well-developed anterior longitudinal epidural venous plexus was apparent. The cervical canal was narrowed by the dilated venous plexus and a myelopathic change of the upper cervical cord was noticed. The patient underwent C2 laminoplasty and fenestration of the cyst. In addition to describing this patient's specific case, we discuss the pathophysiology of this disease in general.

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C1-2 rod/cantilever constructs using C2 pedicle screws and C1-2 transarticular screws have been widely applied in posterior atlantoaxial fixation. However, both of these constructs have the potential risk of causing vertebral artery (VA) injury because of the variable location of the transverse foramen. Recently, C2 crossing laminar screws were described as a method for rigid fixation of the axis. The authors report the successful results of atlantoaxial fixation in five cases with high riding VAs using bilateral crossing C2 laminar screws. The possible advantage of this technique in high riding VA cases is discussed.

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