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Jangbo Lee, Kazutoshi Hida, Toshitaka Seki and Yoshinobu Iwasaki

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Shuji Hamauchi, Toshitaka Seki, Toru Sasamori and Kiyohiro Houkin

Intermediate incisions are considered necessary to pass a catheter tube from the head to the abdomen in ventriculo-peritoneal (VP) shunting via a frontal bur hole. However, an intermediate incision can sometimes become dehiscent, resulting in CSF leakage or infection of the shunt system in the early period after shunt implantation, particularly in infant patients. In this article, the authors describe a novel method of VP shunt insertion that does not require an intermediate incision. This nonintermediate-incision VP shunt procedure was performed in 3 infant patients with hydrocephalus and was not associated with any complications. This method can eliminate the intermediate incision, which is a disadvantage of VP shunt insertion via a frontal bur hole.

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Toshitaka Seki and Michael G. Fehlings

Object

Although posttraumatic syringomyelia (PTS) develops in up to 30% of patients after spinal cord injury (SCI), the pathophysiology of this debilitating complication is incompletely understood. To provide greater insight into the mechanisms of this degenerative sequela of SCI, the authors developed and characterized a novel model of PTS.

Methods

The spinal cords of 64 female Wistar rats were injured by 35-g modified aneurysm clip compression at the level of T6–7. Kaolin (5 μl of 500 mg/ml solution) was then injected into the subarachnoid space rostral to the site of the injury to induce inflammatory arachnoiditis in 22 rats. Control groups received SCI alone (in 21 rats), kaolin injection alone (in 15 rats), or laminectomy and durotomy alone without injury (sham surgery in 6 rats).

Results

The combination of SCI and subarachnoid kaolin injection resulted in a significantly greater syrinx formation and perilesional myelomalacia than SCI alone; SCI and kaolin injection significantly attenuated locomotor recovery and exacerbated neuropathic pain (mechanical allodynia) compared with SCI alone. We observed that combined SCI and kaolin injection significantly increased the number of terminal deoxytransferase-mediated deoxyuridine triphosphate nick-end labeled–positive cells at 7 days after injury (p < 0.05 compared with SCI alone) and resulted in a significantly greater extent of astrogliosis and macrophage/microglial-associated inflammation at the lesion (p < 0.05).

Conclusions

The combination of compressive/contusive SCI with induced arachnoiditis results in severe PTS and perilesional myelomalacia, which is associated with enhanced inflammation, astrogliosis, and apoptotic cell death. The development of delayed neurobehavioral deficits and neuropathic pain in this model accurately reflects the key pathological and clinical conditions of PTS in humans.

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Jangbo Lee, Izumi Koyanagi, Kazutoshi Hida, Toshitaka Seki, Yoshinobu Iwasaki and Kenji Mitsumori

Object

Spinal cord edema is a rare radiological finding in chronic degenerative disorders of the spine. Between 1997 and 2001, the authors treated six patients with cervical spondylotic myelopathy in whom postoperative spinal cord edema was demonstrated. The authors describe the radiological and clinical features of this unusual condition.

Methods

The six patients were all men, and ranged in age from 44 to 72 years. All patients presented with mild quadriparesis and underwent laminoplasty or anterior fusion. Preoperative magnetic resonance (MR) imaging revealed marked spinal cord compression with intramedullary hyperintensity on T2-weighted sequences and spinal cord enhancement at the compression level after administration of Gd.

After surgery, spinal cord edema was observed in all patients; the spinal cord appeared swollen on the postoperative MR images. Preoperative and postoperative Gd-enhanced MR imaging demonstrated clear enhancement of the white matter at the compressed segment. Neurologically, five of six patients experienced good improvement of symptoms; however, the spinal cord edema as documented on follow-up MR imaging persisted for several months after surgery.

Conclusions

The radiological characterization of spinal cord edema was based on the reversible white matter lesion most likely caused by disturbed local venous circulation induced by chronic spinal cord compression. Such unusual MR findings in cervical spondylotic myelopathy should be differentiated from intramedullary spinal cord tumors, demyelinating disorders, or inflammatory processes.

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Kazutoshi Hida, Yoshinobu Iwasaki, Satoshi Ushikoshi, Shin Fujimoto, Toshitaka Seki and Kazuo Miyasaka

Object. In this report, the authors describe five consecutive patients with cervical perimedullary arteriovenous fistulas (AVFs) that were successfully treated using a corpectomy performed via an anterior approach.

Methods. Five patients with cervical perimedullary AVF underwent corpectomy via an anterior approach. There were four women and one man who ranged in age from 34 to 62 years (median 55 years). Four patients presented with subarachnoid hemorrhage and one with intramedullary hemorrhage. All five AVFs were located on the anterior surface of the cervical spinal cord and fed by the anterior spinal artery. All patients underwent an anterior approach with 1.5- or two-level corpectomy, opening of the dura mater, and coagulation of the fistula. After dural closure, an iliac bone graft was inserted.

Four patients were treated by surgery alone and one patient by embolization and surgery. Postoperative angiography revealed complete disappearance of the AVF in all patients. Neurological status improved in two cases and stabilized in the other three. There were no surgery-related complications.

Conclusions. Safe and effective interruption of cervical AVFs can be accomplished by an anterior-approach corpectomy.

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Kazutoshi Hida, Hiroki Shirato, Toyohiko Isu, Toshitaka Seki, Rikiya Onimaru, Hidefumi Aoyama, Satoshi Ushikoshi, Kazuo Miyasaka and Yoshinobu Iwasaki

Object

Radiosurgical treatment of spinal arteriovenous malformations (AVMs) is becoming a practical therapeutic option as methodology improves, but no comparative study has yet been published on focal fractionated radiotherapy. The authors report their experience with conventional and hypofractionated radiotherapy for spinal AVM.

Methods

Candidates for this study were patients who experienced symptoms due to an intramedullary AVM but were ineligible for embolization or surgery. Of 21 patients with spinal AVMs, 10 cases in a 10-year period met this criterion. Angiography and contrast-enhanced computerized tomography scanning were used for treatment planning in all cases. Fractionated radiotherapy was performed using a linear accelerator, extracranial immobilization system, and frequent orthogonal linacographic verification. The starting radiation dose was 32 Gy in two, 36 Gy in three, and 40 Gy in two patients, in a regimen involving 1.8 to 2—Gy daily fractions; this was recently changed to a hypofractionation schedule of 30 Gy (in eight sessions) in one and 20 Gy (in four sessions) in two patients.

Results

The follow-up period ranged from 26 to 124 months (median of 49 months). There were no hemorrhages nor any adverse reactions attributable to irradiation. Of the seven patients who consented to undergo follow-up angiography, the nidus size decreased in five, but complete obliteration did not occur in any patient.

Conclusions

Because no patient experienced adverse effects, the maximum tolerable radiation dose for the spinal cord associated with an AVM could not be identified, although it presumably is higher than those administered. The lack of rebleeding in patients in whom complete angiographic occlusion was absent suggests that the natural history of spinal AVMs may be less aggressive than previously reported.

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Shuji Hamauchi, Toshiya Osanai, Toshitaka Seki, Masahito Kawabori, Michinari Okamoto, Kazutoshi Hida and Kiyohiro Houkin

The authors describe a novel method of observing blood flow in abnormal vessels with slow-motion video during surgical treatment of spinal arteriovenous shunts. The method is based on the use of superselective angiography with saline for visualizing abnormal vessels in bright field and commercially available high frame rate digital camera for recording slow-motion video.