Takayoshi Shimizu, Shunsuke Fujibayashi, Bungo Otsuki, Koichi Murata and Shuichi Matsuda
The use of indirect decompression surgery for severe canal stenosis remains controversial. The purpose of this study was to investigate the efficacy of lateral interbody fusion (LIF) without posterior decompression in degenerative lumbar spinal spondylosis with severe stenosis on preoperative MRI.
This is a retrospective case series from a single academic institution. The authors included 42 patients (45 surgical levels) who were preoperatively diagnosed with severe degenerative lumbar stenosis on MRI based on the previously published Schizas classification. These patients underwent LIF with supplemental pedicle screw fixation without posterior decompression. Surgical levels were limited to L3–4 and/or L4–5. All patients satisfied the minimum 1-year MRI follow-up. The authors compared the cross-sectional area (CSA) of the thecal sac and the clinical outcome scores (Japanese Orthopaedic Association [JOA] score) preoperatively, immediately postoperatively, and at the 1-year follow-up. Fusion status and disc height were evaluated based on CT scans obtained at the 1-year follow-up.
The CSA improved over time, increasing from 54.5 ± 19.2 mm2 preoperatively to 84.7 ± 31.8 mm2 at 3 weeks postoperatively and to 132.6 ± 37.5 mm2 at the last follow-up (average 28.3 months) (p < 0.001). The JOA score significantly improved over time (preoperatively 16.1 ± 4.1, 3 months postoperatively 24.4 ± 4.0, and 1-year follow-up 25.7 ± 2.9; p < 0.001). The fusion rate at the 1-year follow-up was 88.8%, and disc heights were significantly restored (preoperative, 6.3 mm and postoperative, 9.6 mm; p < 0.001). Patients showing poor CSA expansion (< 200% expansion rate) at the last follow-up had a higher prevalence of pseudarthrosis than patients with significant CSA expansion (> 200% expansion rate) (25.0% vs 3.4%, p < 0.001). No major perioperative complications were observed.
LIF with indirect decompression for degenerative lumbar disease with severe canal stenosis provided successful clinical outcomes, including restoration of disc height and indirect expansion of the thecal sac. Severe canal stenosis diagnosed on preoperative MRI itself is not a contraindication for indirect decompression surgery.
Koichi Murata, Shunsuke Fujibayashi, Bungo Otsuki, Takayoshi Shimizu, Kazutaka Masamoto and Shuichi Matsuda
In this study the authors aimed to evaluate the rate of malposition, including pedicle breach and superior facet violation, after percutaneous insertion of pedicle screws using the coaxial fluoroscopic view of the pedicle, and to assess the risk factors for pedicle breach.
In total, 394 percutaneous screws placed in 85 patients using the coaxial fluoroscopic view of the pedicle between January 2014 and September 2017 were assessed, and 445 pedicle screws inserted in 116 patients using conventional open procedures were used for reference. Pedicle breach and superior facet violation were evaluated by postoperative 0.4-mm slice CT.
Superior facet violation was observed in 0.5% of the percutaneous screws and 1.8% of the conventionally inserted screws. Pedicle breach occurred more frequently with percutaneous screws (28.9%) than with conventionally inserted screws (11.9%). The breaches in percutaneous screws were minor and did not reduce the interbody fusion rate. The angle difference between the percutaneous and conventionally inserted screws was comparable. Insertion at the L3 or L4 level, right-sided insertion, placement around a trefoil canal, smaller pedicle angle, and a small difference between the screw and pedicle diameters were found to be risk factors for pedicle breach by percutaneous pedicle screws.
Percutaneous pedicle screw placement using the coaxial fluoroscopic view of the pedicle carries a low risk of superior facet violation. The screws should be placed carefully considering the level and side of insertion, canal shape, and pedicle angle.
Andrew C. Vivas, Gregory M. Mundis Jr. and Juan S. Uribe
Daiki Murata, Yohei Mineharu, Yoshiki Arakawa, Bin Liu, Masahiro Tanji, Makoto Yamaguchi, Ko-ichi Fujimoto, Nobuyuki Fukui, Yukinori Terada, Ryuta Yokogawa, Maki Yamaguchi, Sachiko Minamiguchi and Susumu Miyamoto
Medulloblastoma is a type of malignant tumor arising in the cerebellum. The clinical importance of programmed cell death 1 ligand–1 (PD-L1) expression in medulloblastoma remains unknown. The aim of the present study was to examine the expression of PD-L1 and tumor-infiltrating T cells, and to evaluate their relationships to the prognosis of patients with medulloblastoma.
The authors immunohistochemically analyzed PD-L1 expression and CD3+ and CD8+ lymphocyte infiltrations in tumor specimens from 16 patients with medulloblastoma.
High expression of PD-L1 was observed in 9 (56.3%) of 16 samples studied. High expression of PD-L1 was associated with low infiltrations of CD3+ or CD8+ lymphocytes. Patients with high expression of PD-L1 had shorter progression-free survival and overall survival times than those with low expression (p = 0.076 and p = 0.099, respectively). In addition, patients with high expression of PD-L1 and with low infiltration of CD8+ lymphocytes had a significantly worse outcome, with a 5-year survival rate of 15%, as compared with the other patients, who had a 5-year survival rate of nearly 90% (p = 0.0048 for progression-free survival and p = 0.010 for overall survival).
These findings indicate that PD-L1 expression was associated with a reduced infiltration of CD8+ T cells and poor prognosis in human medulloblastoma.
Koichi Hayashi, Masayuki Hashimoto, Masao Koda, Atsuhiko T. Naito, Atsushi Murata, Akihiko Okawa, Kazuhisa Takahashi and Masashi Yamazaki
Clinical use of autologous induced pluripotent stem cells (iPSCs) could circumvent immune rejection and bioethical issues associated with embryonic stem cells. Spinal cord injury (SCI) is a devastating trauma with long-lasting disability, and current therapeutic approaches are not satisfactory. In the present study, the authors used the neural stem sphere (NSS) method to differentiate iPSCs into astrocytes, which were evaluated after their transplantation into injured rat spinal cords.
Induced pluripotent stem cell–derived astrocytes were differentiated using the NSS method and injected 3 and 7 days after spinal contusion–based SCI. Control rats were injected with DMEM in the same manner. Locomotor recovery was assessed for 8 weeks, and sensory and locomotion tests were evaluated at 8 weeks. Immunohistological parameters were then assessed.
Transplant recipients lived for 8 weeks without tumor formation. Transplanted cells stretched their processes along the longitudinal axis, but they did not merge with the processes of host GFAP-positive astrocytes. Locomotion was assessed in 3 ways, but none of the tests detected statistically significant improvements compared with DMEM-treated control rats after 8 weeks. Rather, iPSC transplantation caused even greater sensitivity to mechanical stimulus than DMEM treatment.
Astrocytes can be generated by serum treatment of NSS-generated cells derived from iPSCs. However, transplantation of such cells is poorly suited for repairing SCI.