✓ The authors describe seven cases of cervical spondylosis in which small high-density areas were detected in the spinal cord on delayed computerized tomographic (CT) myelography. These high-density areas are believed to represent cavities or areas of cystic necrosis. In all seven cases the cervical spinal canal was narrow, and the spondylosis was located at multiple levels, causing a so-called “pincer effect.” On the CT scans the high-density areas resembled fried eggs in the gray matter. These areas were localized near the abnormal cervical discs. In two cases in which the Brown-Séquard syndrome was noted, the symptoms could be attributed to the morphology of the high-density area on the affected side of the cord. Following decompressive surgery, most of the symptoms improved except for numbness of the upper extremities and motor weakness of hands.
Yoshinobu Iwasaki, Hiroshi Abe, Toyohiko Isu, and Kazuo Miyasaka
Kazutoshi Hida, Yoshinobu Iwasaki, Katsuya Goto, Kazuo Miyasaka, and Hiroshi Abe
This retrospective study was performed to evaluate the results of surgical treatment and the use of preoperative embolization in managing perimedullary arteriovenous fistulas (AVFs).
The authors studied 20 consecutive patients with perimedullary AVFs who underwent surgical treatment. Arteriovenous shunts were at the level of the cervical spine in five patients, the thoracic spine in 12, and the conus medullaris in three patients. Of the 20 AVFs, three were fed by the anterior spinal artery only, three by the posterior spinal artery, and 14 by both the anterior and posterior spinal arteries. Nine patients had varices that compressed the spinal cord. Eleven patients underwent surgery alone, and 9 patients underwent surgery combined with adjuvant preoperative embolization.
Preoperative embolization remarkably reduced the blood flow through AVFs and facilitated subsequent surgical procedures. Postoperative angiography revealed complete disappearance of the AVF in 16 patients. However, small fistulas persisted in the other four patients whose large lesions were fed by the anterior spinal artery. Neurological status was improved in 11 patients, unchanged in eight, and worse in one patient postsurgery.
Effective interruption of a spinal AV shunt was obtained by surgery in all cases, even when the anterior spinal artery was involved. For large and high-flow AVFs, embolization proved to be a useful adjunct to surgery.
Kazutoshi Hida, Yoshinobu Iwasaki, Katsuya Goto, Kazuo Miyasaka, and Hiroshi Abe
Object. This retrospective study was performed to evaluate the results of surgical treatment and the use of preoperative embolization in managing patients with perimedullary arteriovenous fistulas (AVFs).
Methods. The authors studied 20 consecutive patients with perimedullary AVFs who underwent surgical treatment. Arteriovenous shunts were at the level of the cervical spine in five patients, the thoracic spine in 12, and the conus medullaris in three patients. Of the 20 AVFs, three were fed by the anterior spinal artery only, three by the posterior spinal artery, and 14 by both the anterior and posterior spinal arteries. Nine patients had varices that compressed the spinal cord. Eleven patients underwent surgery, and nine patients underwent surgery combined with adjuvant preoperative embolization.
Preoperative embolization remarkably reduced blood flow through the AVFs and facilitated subsequent surgical procedures. Postoperative angiography revealed complete disappearance of the AVFs in 16 patients. However, small fistulas persisted in the other four patients, whose large lesions were fed by the anterior spinal artery. Postoperatively, neurological status was improved in 11 patients, unchanged in eight, and worse in one patient.
Conclusions. Effective interruption of a spinal arteriovenous shunt was achieved by surgery in all cases, even when the anterior spinal artery was involved. For large and high-flow AVFs, embolization proved to be a useful adjunct to surgery.
Hiroshi Abe, Mitsuo Tsuru, Terufumi Ito, Yoshinobu Iwasaki, and Mitsuyuki Koiwa
✓ Anterior decompression and fusion for treating ossification of the posterior longitudinal ligament of the cervical spine was performed in 12 patients. The central part of the vertebral body and the ossified area of the posterior longitudinal ligament were removed by means of a microrongeur and an air drill. The defect was filled with a long bone graft taken from the ilium. The operative results were excellent. Marked improvement of radicular and spinal cord signs was seen in all 12 cases. Three vertebral bodies were fused in one case, four in nine cases, and five in two cases. The highest level of fusion was C-2 and the lowest was T-1. It is considered that any ossification of the ligament below the C-2 level can be removed via an anterior approach as long as no more than five vertebral bodies are involved. Spinal computerized tomography was valuable in providing more detailed information about the stenotic spinal canal and the shape of the ossified ligament.
Izumi Koyanagi, Yoshinobu Iwasaki, Kazutoshi Hida, Hiroyuki Imamura, and Hiroshi Abe
Object. Because of the lack of magnetic resonance (MR) signal from cortical bones, MR imaging is inadequate for diagnosing ossified lesions in the spinal canal. However, MR imaging provides important information on spinal cord morphology and associated soft-tissue abnormality. The purpose of this study is to determine the role of MR imaging in the diagnosis and treatment of patients with ossification of the posterior longitudinal ligament (OPLL) of the cervical spine.
Methods. The authors reviewed MR imaging findings in 42 patients with cervical OPLL who were examined with a superconducting MR imaging system. The types of OPLL reviewed included eight cases of continuous, 21 cases of segmental, and 13 cases of the mixed type. All patients were treated surgically either by anterior (26 cases) or posterior decompression (16 cases).
Conclusions. The T1-weighted images clearly demonstrated the spinal cord deformity caused by OPLL. Associated disc protrusion was found to be present at the maximum compression level in 60% of the patients in this series. The highest incidence of disc protrusion (81%) was found in patients with segmental OPLL. Intramedullary hyperintensity on T2*-weighted imaging was noted in 18 patients (43%). The neurological deficits observed in these 18 patients were significantly more severe than those observed in the other 24 patients. Postoperative MR imaging revealed improvement in the spinal cord deformity, although the intramedullary hyperintensity was still observed in most cases. The present study demonstrates the importance of associated disc protrusion in the development of myelopathy in patients with cervical OPLL. Magnetic resonance imaging findings may be used to help determine the actual levels of spinal cord compression and to suggest the method of surgical treatment.
Izumi Koyanagi, Yoshinobu Iwasaki, Kazutoshi Hida, Minoru Akino, Hiroyuki Imamura, and Hiroshi Abe
Object. It is known that the spinal cord can sustain traumatic injury without associated injury of the spinal column in some conditions, such as a flexible spinal column or preexisting narrowed spinal canal. The purpose of this study was to characterize the clinical features and to understand the mechanisms in cases of acute cervical cord injury in which fracture or dislocation of the cervical spine has not occurred.
Methods. Eighty-nine patients who sustained an acute cervical cord injury were treated in our hospitals between 1990 and 1998. In 42 patients (47%) no bone injuries of the cervical spine were demonstrated, and this group was retrospectively analyzed. There were 35 men and seven women, aged 19 to 81 years (mean 58.9 years). The initial neurological examination indicated complete injury in five patients, whereas incomplete injury was demonstrated in 37.
In the majority of the patients (90%) the authors found degenerative changes of the cervical spine such as spondylosis (22 cases) or ossification of the posterior longitudinal ligament (16 cases). The mean sagittal diameter of the cervical spinal canal, as measured on computerized tomography scans, was significantly narrower than that obtained in the control patients. Magnetic resonance (MR) imaging revealed spinal cord compression in 93% and paravertebral soft-tissue injuries in 58% of the patients.
Conclusions. Degenerative changes of the cervical spine and developmental narrowing of the spinal canal are important preexisting factors. In the acute stage MR imaging is useful to understand the level and mechanisms of spinal cord injury. The fact that a significant number of the patients were found to have spinal cord compression despite the absence of bone injuries of the spinal column indicates that future investigations into surgical treatment of this type of injury are necessary.
Seiya Kato, Teiji Yamamoto, Yuzo Iwasaki, Hiroshi Niizuma, Tadashi Nakamura, and Jiro Suzuki
✓ Direct destruction of the sensory ganglion or its root, by either surgical transection or injection of phenol, has been employed as preferred treatment for a variety of neuralgic pain syndromes. In this report, the suicide axoplasmic transport of adriamycin is described as a novel approach to sensory ganglionectomy. When injected into a branch of the trigeminal nerve in the cat, adriamycin was swiftly transported by way of retrograde axoplasmic flow to the sensory neurons parental to the injected nerve, where adriamycin-specific autofluorescence was observed. Trigeminal sensory evoked potentials became unobtainable 24 to 48 hours after injection of adriamycin in concentrations of 1% to 10%. The sensory neurons underwent subacute degeneration within a week due to the delayed action of adriamycin, and consequently the primary afferents degenerated in a restricted projection field of the brain-stem trigeminal sensory nuclei. These results indicate that retrograde axoplasmic transport of adriamycin is a unique approach to noninvasive sensory ganglionectomy with strict, albeit simple, safe targeting of sensory neurons and little likelihood of regeneration.
Ki Hong Cho, Yoshinobu Iwasaki, Hiroyuki Imamura, Kazutoshi Hida, and Hiroshi Abe
✓ An experimental model was devised to elucidate the role of spinal blockade in posttraumatic syringomyelia. Thirty-eight Japanese White rabbits, each weighing about 3 kg, were used in this study. The animals were divided into four groups: in Group 1, eight animals received traumatic injury only; in Group 2, 12 animals received traumatic injury following injection of 100 mg kaolin suspended in 1 cc normal saline solution into the subarachnoid space at the site of trauma; in Group 3, nine animals received traumatic injury following injection of 200 mg kaolin in 1 cc normal saline solution into the subarachnoid space at the site of trauma; and in Group 4, nine animals without traumatic injury received an injection of 200 mg kaolin in 1 cc normal saline solution into the subarachnoid space.
The subjective criteria for syrinx formation were the presence of a definite round cyst having a smooth margin and an upper or lower extension of more than 2 cm from the injured site. Syrinx formation was seen in 12.5% (one of eight rabbits) in Group 1, 41.7% (five of 12 animals) in Group 2, 55.5% (five of nine rabbits) in Group 3 and 0% (none of nine animals) in Group 4 (p < 0.05). There was a tendency for the combined trauma/kaolin injection groups to be more prone to develop a syrinx. In the kaolin injection only group (Group 4), no animal showed a definite cyst or an extending cavity during the experimental period. The results suggest that kaolin enhances the extension of multiple small cavities that have already formed at the time of initial injury. The difference between the frequency of syrinx formation and the time of survival was statistically significant well beyond the 0.05% level. The overall difference, relating to the frequency of syrinx development, group, and duration of survival, was also statistically significant. In summary, subarachnoid block secondary to adhesive arachnoiditis is important in initiating the extension of the syringomyelia cavity.
Kazuhiro Chiba, Itsuo Yamamoto, Hisashi Hirabayashi, Motoki Iwasaki, Hiroshi Goto, Kazuo Yonenobu, and Yoshiaki Toyama
Object. Ossification of the posterior longitudinal ligament (OPLL) often progresses after surgery, and this may cause late-onset neurological deterioration. There have been few studies, however, to clarify any correlation between progression and clinical outcome, partly because of the lack of studies involving reliable and reproducible methods by which detection of progression is made possible. The authors conducted a multicenter study to investigate the occurrence of postoperative progression and to elucidate the possible risk factors in a large-scale patient population, and a novel computer-assisted measurement method was used to provide the basis for future clinical studies.
Methods. The authors analyzed lateral plain radiographs obtained immediately and at 1 and 2 years after surgery in 131 patients who underwent posterior decompression at 13 institutions. The x-ray films were transformed via scanner into digital images; the length and thickness of ossifications were measured using a new computer-assisted measurement system, and the incidence of progression was determined. Odds ratios for progression according to age group and types of OPLL were determined and compared to elucidate significant risk factors of progression.
Conclusions. This is the first multicenter study to investigate the incidence of OPLL progression after posterior decompression by using a standardized measurement method. The rate of postoperative progression at 2 years was 56.5%, which was comparable with results reported in other studies. Progression occurred more frequently in younger-age rather than in older-age patient populations at both 1 and 2 years postoperatively. Mixed-type and continuous-type OPLL progressed more frequently than the segmental-type lesion at 2 years. The results of the present study could serve as basis for future studies to assess the efficacy of drug therapy to prevent OPLL progression.
Akihito Minamide, Munehito Yoshida, Hiroshi Yamada, Yukihiro Nakagawa, Masaki Kawai, Kazuhiro Maio, Hiroshi Hashizume, Hiroshi Iwasaki, and Shunji Tsutsui
The authors undertook this study to document the clinical outcomes of microendoscopic laminotomy, a minimally invasive decompressive surgical technique using spinal endoscopy for lumbar decompression, in patients with lumbar spinal stenosis (LSS).
A total of 366 patients were enrolled in the study and underwent microendoscopic laminotomy between 2007 and 2010. Indications for surgery were single- or double-level LSS, persistent neurological symptoms, and failure of conservative treatment. Microendoscopy provided wide visualization through oblique lenses and allowed bilateral decompression via a unilateral approach, through partial resection of the base of the spinous process, thereby preserving the supraspinous and interspinous ligaments and contralateral musculature. Clinical symptoms and signs of low-back pain were evaluated prior to and following surgical intervention by applying the Japanese Orthopaedic Association (JOA) scoring system, Roland-Morris Disability Questionnaire (RMDQ), Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), and 36-Item Short Form Health Survey (SF-36). These items were evaluated preoperatively and 2 years postoperatively.
Effective circumferential decompression was achieved in all patients. The 2-year follow-up evaluation was completed for 310 patients (148 men and 162 women; mean age 68.7 years). The average recovery rate based on the JOA score was 61.3%. The overall results were excellent in 34.9% of the patients, good in 34.9%, fair in 21.7%, and poor in 8.5%. The mean RMDQ score significantly improved from 11.3 to 4.8 (p < 0.001). In all categories of both JOABPEQ and SF-36, scores at 2 years' follow-up were significantly higher than those obtained before surgery (p < 0.001). Twelve surgery-related complications were identified: dural tear (6 cases [1.9%]), wrong-level operation (1 [0.3%]), transient neuralgia (4 [1.3%]), and infection (1 [0.3%]). All patients recovered, and there were no serious postoperative complications.
Microendoscopic laminotomy is a safe and very effective minimally invasive surgical technique for the treatment of degenerative LSS.