Masahiko Watanabe, Kazuhiro Chiba, Morio Matsumoto, Hirofumi Maruiwa, Yoshikazu Fujimura and Yoshiaki Toyama
Morio Matsumoto, Kazuhiro Chiba, Takashi Tsuji, Hirofumi Maruiwa, Yoshiaki Toyama and Jun Ogawa
✓ The authors placed titanium mesh cages to achieve posterior atlantoaxial fixation in five patients with atlantoaxial instability caused by rheumatoid arthritis or os odontoideum. A mesh cage packed with autologous cancellous bone was placed between the C-1 posterior arch and the C-2 lamina and was tightly connected with titanium wires. Combined with the use of transarticular screws, this procedure provided very rigid fixation. Solid fusion was achieved in all patients without major complications. The advantages of this method include more stable fixation, better control of the atlantoaxial fixation angle, and reduced donor-site morbidity compared with a conventional atlantoaxial arthrodesis in which an autologous iliac crest graft is used.
Morio Matsumoto, Kazuhiro Chiba, Masaya Nakamura, Yuto Ogawa, Yoshiaki Toyama and Jun Ogawa
Object. Structural interlaminar graft materials were used for atlantoaxial transarticular screw fixation (TSF), and its impact on the fusion status was investigated.
Methods. Forty-two patients (10 men, 32 women, mean age 51 years, mean follow-up period 45 months; 30 with rheumatoid arthritis, and 12 with os odontoideum) underwent TSF and modified Brooks posterior wiring involving titanium cables. As interlaminar graft materials, autologous bone from posterior iliac crest alone was used in 20 patients (Group A), and a structural spacer (13 ceramic spacers, nine titanium mesh cages) in 22 (Group B). Lateral radiographs were evaluated to determine bone fusion, alignment of the cervical spine, and wire loosening. Solid osseous fusion was obtained in 95% of Group A and 96% of Group B patients. The mean atlantoaxial angle was 19.1 ± 9.7° and 16.7 ± 10.4° before surgery (p = 0.45), and 27.4± 7.8° and 22.1 ± 5.5° after surgery (p = 0.02) in Groups A and B, respectively. Atlantoaxial hyperlordosis (atlantoaxial angle ≥ 30°) was observed in 32% of Group A and 18% of Group B patients (p = 0.26). Postoperative kyphosis occurred in 40% of Group A and 23% of Group B patients (p = 0.28). Loosening of the cable was demonstrated in 50% of Group A and 36% of Group B patients (p = 0.37). In Group B patients maintenance of cervical lordosis was more likely than in those in Group A, although the differences did not reach statistical significance.
Conclusions. These results indicate that structural interlaminar spacers can maintain proper cervical alignment without a decease in the fusion rate; the authors recommend their use in conjunction with TSF.
Masaya Nakamura, Kazuhiro Chiba, Takashi Nishizawa, Hirofumi Maruiwa, Morio Matsumoto and Yoshiaki Toyama
Object. Pain is one of the major symptoms in patients with syringomyelia; however, its origin is not fully understood, and postoperative improvement of pain is difficult to predict. The objectives of this study were to assess the surgery-related results obtained in patients who underwent treatment for syringomyelia associated with Chiari I malformation, particularly related to pain status, and to identify factors that may influence improvement in postoperative pain by comparing pre- and postoperative magnetic resonance (MR) imaging findings.
Methods. The correlation between pre- and postoperative changes in the size and the location of the syrinx and pain improvement was investigated in 25 patients. The shapes of the syringes were classified into three types: central, enlarged, and deviated. In most cases in which the syrinx deviated toward the posterolateral aspect of the spinal cord at the level corresponding to dermatomal distribution of preoperative pain, the lesion remained at the same position postoperatively, and improvement in pain was poor. On the other hand, enlarged-type syringes were the most frequently observed prior to surgery, exhibited diverse changes postoperatively, and improvement in pain status was difficult to predict. When postoperative MR imaging revealed a transformation to the deviated type, poor pain improvement was noted.
Conclusions. Neurons in the dorsal horn were thought to be involved in the development of pain as a result of the deafferentiation mechanism in cases of syringomyelia.
Masaya Nakamura, Kazuhiro Chiba, Morio Matsumoto, Eiji Ikeda and Yoshiaki Toyama
✓ The authors present clinical, radiological, and pathological features in a patient with a pleomorphic xanthoastrocytoma (PXA) of the spinal cord. To their knowledge, this is only the second report of a spinal cord PXA. In addition they perform a review of the literature on these tumors.
Soya Kawabata, Kota Watanabe, Naobumi Hosogane, Ken Ishii, Masaya Nakamura, Yoshiaki Toyama and Morio Matsumoto
Severe cervical kyphosis requiring surgical treatment is rare in patients with neurofibromatosis Type 1 (NF1). When it occurs, however, dystrophic changes in the vertebrae make surgical correction and fusion of the deformity extremely difficult.
The authors report on 3 cases of severe cervical kyphosis associated with NF1 that were successfully treated with combined anterior and posterior correction and fusion. All patients underwent halo-gravity traction for approximately 1 month prior to surgery to correct the deformity gradually. Posterior correction and fusion were performed with segmental spinal instrumentation consisting of lateral mass screws, lamina screws, pedicle screws, and polyethylene tape for sublaminar wiring. Anterior spinal fusion was performed using a fibula strut to induce solid bone fusion. All patients used a halo vest for postoperative external fixation.
Preoperative CT scans showed dystrophic cervical spine changes, and MR images demonstrated extensive neurofibromas outside the cervical spine in all 3 patients. The preoperative kyphotic angles were as follows: Case 1, 140°; Case 2, 81°; and Case 3, 72°; after halo-gravity traction, the kyphosis angles improved to 50°, 55°, and 51°, respectively; and after surgery, they were 50°, 15°, and 27°, respectively. Solid bone union was observed in all patients at the latest follow-up. All three patients experienced postoperative complications consisting of superficial infection, severe pneumonia, and partial dislocation of the distal fibula graft after removing the halo vest, in one patient each.
Although dystrophic cervical vertebral changes in these patients with NF1 complicated the correction of severe cervical kyphosis, the use of preoperative halo-gravity traction, a combination of spinal instrumentations, an anterior strut bone graft, and postoperative halo-vest fixation made it possible to correct the kyphosis, maintain the correction, and achieve solid bone fusion.
Morio Matsumoto, Kota Watanabe, Takashi Tsuji, Ken Ishii, Masaya Nakamura, Kazuhiro Chiba and Yoshiaki Toyama
The object of this study was to investigate failures after spinal reconstruction following total en bloc spondylectomy (TES), related factors, and sequelae arising from such failures in patients with malignant spinal tumors.
Fifteen patients (12 males and 3 females, with a mean age of 46.5 years) with malignant spinal tumors who underwent TES and survived for more than 1 year were included in this analysis (mean follow-up 41.5 months). Seven patients had primary tumors, including giant cell tumors in 4 patients, chordoma in 2, and Ewing sarcoma in 1. Eight patients had metastatic tumors, including thyroid cancer in 6 and renal cell cancer and malignant fibrous histiocytoma in 1 patient each. Seven patients without prominent paravertebral extension of the tumor were treated using a posterior approach alone, and 8 patients who exhibited prominent anterior or anterolateral extension of the tumors into the thoracic or abdominal cavity were treated using a combined anterior and posterior approach. Spinal reconstruction after tumor resection was performed using a combination of anterior structural support and posterior instrumentation. The relationship between instrumentation failure and clinical and radiographic factors, including age, sex, history of previous surgery, preoperative radiotherapy, tumor histology, tumor level, surgical approach, number of resected vertebrae, rod diameter, number of instrumented vertebrae, and cage subsidence, was investigated.
Six patients (40%) with spinal instrumentation failure were identified: rod breakage occurred in 3 patients, and breakage of both the rod and the cage, combined cage breakage and screw back-out, and endplate fracture arising from cage subsidence occurred in 1 patient each. All of these patients experienced acute or chronic back pain, but only 1 patient with a tumor recurrence experienced neurological deterioration upon instrumentation failure. Cage subsidence (≥ 5 mm), preoperative irradiation, and the number of instrumented vertebrae (≤ 4 vertebrae) were significantly related to late instrumentation failure.
Late instrumentation failure was a frequent complication after TES. Although patients with instrumentation failure experienced back pain, the neurological sequelae were not catastrophic. For prevention, meticulous preparation of the graft site and a longer posterior fixation should be considered.
Masahiko Watanabe, Kazuhiro Chiba, Morio Matsumoto, Hirofumi Maruiwa, Yoshikazu Fujimura and Yoshiaki Toyama
Object. Spinal cord herniation is a rare cause of progressive myelopathy and can be corrected surgically. In most previous reports, closure of the dural defect was the recommended procedure. The object of this paper is to describe a new procedure in which spinal cord constriction is released by enlarging the hiatus; additionally the postoperative results will be discussed.
Methods. In nine patients with spinal cord herniation, enlargement of the dural defect was performed. In eight patients, neurological deficits resolved immediately after surgery. In one patient with a severe preoperative neurological deficit whose spinal cord herniated massively, deterioration occurred postoperatively. To date, no recurrence of herniation has been observed.
Conclusions. The goals of surgery are to reduce the herniation, return the spinal cord to the normal position, and prevent the recurrence of herniation. The use of sutures to close the dural defect has been the method of choice to date. The surgical space in front of the spinal cord, however, is insufficient to accommodate this procedure safely. Because symptoms are caused by the constriction of the spinal cord at the hiatus, surgical expansion of the hiatus allows the goals of surgery to be achieved. This procedure, which is technically easier and less invasive with regard to the vulnerable spinal cord than the closure of the dural defect, could be a viable alternative for the treatment of this rare disease.
Kenya Nojiri, Morio Matsumoto, Kazuhiro Chiba, Hirofumi Maruiwa, Masaya Nakamura, Takashi Nishizawa and Yoshiaki Toyama
The aim of this study was to establish standard values for the normal alignment of the upper cervical spine and to clarify its relationship with the lower cervical spine in terms of alignment.
Three hundred thirteen asymptomatic volunteers (155 men and 158 women) participated in this study. Lateral radiographs were obtained with the neck in neutral position, and the angles formed by the occiput (Oc) and the axis, the atlas and the axis, and C-2 to C-7 were measured. The mean Oc—C2 angle was 14.5 ± 8° in men and 16 ± 8.5° in women; the mean C1–2 angle was 26.5 ± 7° and 28.9 ± 6.7°, respectively; and the mean C2–7 angle was 16.2 ± 12.9° and 10.5 ± 10.3°, respectively. Although weak, statistically significant negative correlation was observed between Oc—C2 and C2–7 angles (r = −0.31 in men and −0.37 in women), and between C1–2 and C2–7 angles (r = −0.22 in men and −0.22 in women). The correlation coefficient between the Oc—C2 and C2–7 angles was greater than that between the C1–2 and C2–7 angles.
Such relationships between alignment of the upper and lower cervical spines should be taken into consideration when performing occipitocervical fusion.