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Ryo Taiji, Masanari Takami, Yasutsugu Yukawa, Hiroshi Hashizume, Akihito Minamide, Yukihiro Nakagawa, Hideto Nishi, Hiroshi Iwasaki, Shunji Tsutsui, Motohiro Okada, Sae Okada, Masatoshi Teraguchi, Shizumasa Murata, Takuhei Kozaki and Hiroshi Yamada

OBJECTIVE

Various surgical treatments have been reported for vertebral pseudarthrosis after osteoporotic vertebral fracture (OVF). However, the outcomes are not always good. The authors now have some experience with combined anterior-posterior short-segment spinal fusion (1 level above and 1 level below the fracture) using a wide-foot-plate expandable cage. Here, they report their surgical outcomes with this procedure.

METHODS

Between June 2016 and August 2018, 16 consecutive patients (4 male and 12 female; mean age 75.1 years) underwent short-segment spinal fusion for vertebral pseudarthrosis or delayed collapse after OVF. The mean observation period was 20.1 months. The level of the fractured vertebra was T12 in 4 patients, L1 in 3, L2 in 4, L3 in 3, and L4 in 2. Clinical outcomes were assessed using the lumbar Japanese Orthopaedic Association (JOA) scale and 100-mm visual analog scale for low-back pain. Local kyphotic angle, intervertebral height, bone union rate, and instrumentation-related adverse events were investigated as imaging outcomes. The data were analyzed using the Wilcoxon signed-rank test.

RESULTS

The mean operating time was 334.3 minutes (range 256–517 minutes), and the mean blood loss was 424.9 ml (range 30–1320 ml). The only perioperative complication was a superficial infection of the posterior wound that was cured by irrigation. The lumbar JOA score and visual analog scale value improved from 11.2 and 58.8 mm preoperatively to 20.6 and 18.6 mm postoperatively, respectively. The mean local kyphotic angle and mean intervertebral height were 22.6° and 28.0 mm, respectively, before surgery, −1.5° and 40.5 mm immediately after surgery, and 7.0° and 37.1 mm at the final observation. Significant improvement was observed in both parameters immediately after surgery and at the final observation when compared with the preoperative values. Intraoperative endplate injury occurred in 8 cases, and progression of cage subsidence of 5 mm or more was observed in 2 of these cases. Proximal junctional kyphosis was observed in 2 cases. There were no cases of screw loosening. No cases required reoperation due to instrument-related adverse events. Bone union was observed in all 14 cases that had CT evaluation.

CONCLUSIONS

This short-segment fusion procedure is relatively minimally invasive, and local reconstruction and bone fusion have been achieved. This procedure is considered to be attempted for the surgical treatment of osteoporotic vertebral pseudarthrosis after OVF.

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Noriko Tamura, Motohiro Hayashi, Mikhail Chernov, Manabu Tamura, Ayako Horiba, Yoshiyuki Konishi, Yoshihiro Muragaki, Hiroshi Iseki and Yoshikazu Okada

Object

The focus of the present study was the evaluation of outcomes after unstaged and staged-volume Gamma Knife surgery (GKS) in children harboring intracranial arteriovenous malformations (AVMs).

Methods

Twenty-two children (median age 9.5 years) underwent GKS for AVMs and were followed up for at least 2 years thereafter. The disease manifested with intracranial hemorrhage in 77% of cases. In 68% of patients the lesion affected eloquent brain structures. The volume of the nidus ranged from 0.1 to 6.7 cm3. Gamma Knife surgery was guided mainly by data from dynamic contrast-enhanced CT scans, with preferential targeting of the junction between the nidus and draining vein. The total prescribed isodose volume was kept below 4.0 cm3, and the median margin dose was 22 Gy (range 20–25 Gy). If the volume of the nidus was larger than 4.0 cm3, a second radiosurgical session was planned for 3–4 years after the first one. Nine patients in the present series underwent unstaged radiosurgery, whereas staged-volume treatment was scheduled in 13 patients.

Results

Complete obliteration of the AVM was noted in 17 (77%) of 22 patients within a median period of 47 months after the last radiosurgical session. Complete obliteration of the lesion occurred in 89% of patients after unstaged treatment and in 62.5% after staged GKS. Four (67%) of 6 high-grade AVMs were completely obliterated. Complications included 3 bleeding episodes, the appearance of a region of hyperintensity on T2-weighted MR images in 2 patients who had no symptoms, and reappearance of the nidus in the vicinity of the completely obliterated AVM in 1 patient.

Conclusions

Radiosurgery is a highly effective management option for intracranial AVMs in children. For larger lesions, staged GKS may be applied successfully. Initial targeting of the nidus adjacent to the draining vein and application of a sufficient radiation dose to a relatively small volume (≤ 4 cm3) provides a good balance between a high probability of obliteration and a low risk of treatment-related complications.

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Akihito Minamide, Munehito Yoshida, Andrew K. Simpson, Hiroshi Yamada, Hiroshi Hashizume, Yukihiro Nakagawa, Hiroshi Iwasaki, Shunji Tsutsui, Motohiro Okada, Masanari Takami and Shin-ichi Nakao

OBJECTIVE

The goal of this study was to characterize the long-term clinical and radiological results of articular segmental decompression surgery using endoscopy (cervical microendoscopic laminotomy [CMEL]) for cervical spondylotic myelopathy (CSM) and to compare outcomes to conventional expansive laminoplasty (ELAP).

METHODS

Consecutive patients with CSM who required surgical treatment were enrolled. All enrolled patients (n = 78) underwent CMEL or ELAP. All patients were followed postoperatively for more than 5 years. The preoperative and 5-year follow-up evaluations included neurological assessment (Japanese Orthopaedic Association [JOA] score), JOA recovery rates, axial neck pain (using a visual analog scale), the SF-36, and cervical sagittal alignment (C2–7 subaxial cervical angle).

RESULTS

Sixty-one patients were included for analysis, 31 in the CMEL group and 30 in the ELAP group. The mean preoperative JOA score was 10.1 points in the CMEL group and 10.9 points in the ELAP group (p > 0.05). The JOA recovery rates were similar, 57.6% in the CMEL group and 55.4% in the ELAP group (p > 0.05). The axial neck pain in the CMEL group was significantly lower than that in the ELAP group (p < 0.01). At the 5-year follow-up, cervical alignment was more favorable in the CMEL group, with an average 2.6° gain in lordosis (versus 1.2° loss of lordosis in the ELAP group [p < 0.05]) and lower incidence of postoperative kyphosis.

CONCLUSIONS

CMEL is a novel, less invasive technique that allows for multilevel posterior cervical decompression for the treatment of CSM. This 5-year follow-up data demonstrates that after undergoing CMEL, patients have similar neurological outcomes to conventional laminoplasty, with significantly less postoperative axial pain and improved subaxial cervical lordosis when compared with their traditional ELAP counterparts.

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Masayuki Nitta, Yoshihiro Muragaki, Takashi Maruyama, Soko Ikuta, Takashi Komori, Katsuya Maebayashi, Hiroshi Iseki, Manabu Tamura, Taiichi Saito, Saori Okamoto, Mikhail Chernov, Motohiro Hayashi and Yoshikazu Okada

OBJECT

There is no standard therapeutic strategy for low-grade glioma (LGG). The authors hypothesized that adjuvant therapy might not be necessary for LGG cases in which total radiological resection was achieved. Accordingly, they established a treatment strategy based on the extent of resection (EOR) and the MIB-1 index: patients with a high EOR and low MIB-1 index were observed without postoperative treatment, whereas those with a low EOR and/or high MIB-1 index received radiotherapy (RT) and/or chemotherapy. In the present retrospective study, the authors reviewed clinical data on patients with primarily diagnosed LGGs who had been treated according to the above-mentioned strategy, and they validated the treatment policy. Given their results, they will establish a new treatment strategy for LGGs stratified by EOR, histological subtype, and molecular status.

METHODS

One hundred fifty-three patients with diagnosed LGG who had undergone resection or biopsy at Tokyo Women's Medical University between January 2000 and August 2010 were analyzed. The patients consisted of 84 men and 69 women, all with ages ≥ 15 years. A total of 146 patients underwent surgical removal of the tumor, and 7 patients underwent biopsy.

RESULTS

Postoperative RT and nitrosourea-based chemotherapy were administered in 48 and 35 patients, respectively. Extent of resection was significantly associated with both overall survival (OS; p = 0.0096) and progression-free survival (PFS; p = 0.0007) in patients with diffuse astrocytoma but not in those with oligodendroglial subtypes. Chemotherapy significantly prolonged PFS, especially in patients with oligodendroglial subtypes (p = 0.0009). Patients with a mutant IDH1 gene had significantly longer OS (p = 0.034). Multivariate analysis did not identify MIB-1 index or RT as prognostic factors, but it did identify chemotherapy as a prognostic factor for PFS and EOR as a prognostic factor for OS and PFS.

CONCLUSIONS

The findings demonstrated that EOR was significantly correlated with patient survival; thus, one should aim for maximum tumor resection. In addition, patients with a higher EOR can be safely observed without adjuvant therapy. For patients with partial resection, postoperative chemotherapy should be administered for those with oligodendroglial subtypes, and repeat resection should be considered for those with astrocytic tumors. More aggressive treatment with RT and chemotherapy may be required for patients with a poor prognosis, such as those with diffuse astrocytoma, 1p/19q nondeleted tumors, or IDH1 wild-type oligodendroglial tumors with partial resection.

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Shizumasa Murata, Akihito Minamide, Hiroshi Iwasaki, Yukihiro Nakagawa, Hiroshi Hashizume, Yasutsugu Yukawa, Shunji Tsutsui, Masanari Takami, Motohiro Okada, Keiji Nagata, Munehito Yoshida, Andrew J. Schoenfeld, Andrew K. Simpson and Hiroshi Yamada

OBJECTIVE

Persistent lumbar foraminal stenosis (LFS) is one of the most common reasons for poor postoperative outcomes and is a major contributor to “failed back surgery syndrome.” The authors describe a new surgical strategy for LFS based on anatomical considerations using 3D image fusion with MRI/CT analysis.

METHODS

A retrospective review was conducted on 78 consecutive patients surgically treated for LFS at the lumbosacral junction (2013–2017). The location and extent of stenosis, including the narrowest site and associated pathology (bone or soft tissue), were measured using 3D image fusion with MRI/CT. Stenosis was defined as medial intervertebral foraminal (MF; inner edge to pedicle center), lateral intervertebral foraminal (LF; pedicle center to outer edge), or extraforaminal (EF; outside the pedicle). Lumbar (low-back pain, leg pain) and patient satisfaction visual analog scale (VAS) scores and Japanese Orthopaedic Association (JOA) scores were evaluated. Surgical outcome was evaluated 2 years postoperatively.

RESULTS

Most instances of stenosis existed outside the pedicle’s center (94%), including LF (58%), EF (36%), and MF (6%). In all MF cases, stenosis resulted from soft-tissue structures. The narrowest stenosis sites were localized around the pedicle’s outer border. The areas for sufficient nerve decompression were extended in MF+LF (10%), MF+LF+EF (14%), LF+EF (39%), LF (11%), and EF (26%). No iatrogenic pars interarticularis damage occurred. The JOA score was 14.9 ± 2.6 points preoperatively and 22.4 ± 3.5 points at 2 years postoperatively. The JOA recovery rate was 56.0% ± 18.6%. The VAS score (low-back and leg pain) was significantly improved 2 years postoperatively (p < 0.01). According to patients’ self-assessment of the minimally invasive surgery, 62 (79.5%) chose “surgery met my expectations” at follow-up. Nine patients (11.5%) selected “I did not improve as much as I had hoped but I would undergo the same surgery for the same outcome.”

CONCLUSIONS

Most LFS existed outside the pedicle’s center and was rarely noted in the pars region. The main regions of stenosis were localized to the pedicle’s outer edge. Considering this anatomical distribution of LFS, the authors recommend that lateral fenestration should be the first priority for foraminal decompression. Other surgical options including foraminotomy, total facetectomy, and hemilaminectomy likely require more bone resections than LFS treatment. The microendoscopic surgery results were very good, indicating that this minimally invasive surgery was suitable for treating this disease.

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Motohiro Hayashi, Mikhail Chernov, Noriko Tamura, Shoji Yomo, Taku Ochiai, Mariko Nagai, Manabu Tamura, Masahiro Izawa, Yoshihiro Muragaki, Hiroshi Iseki, Yoshikazu Okada and Kintomo Takakura

Abducent nerve schwannomas are extremely rare. The authors recently performed Gamma Knife surgery (GKS) in 4 patients with such tumors and describe their experiences with these cases.

The patients consisted of 3 women and 1 man whose ages varied from 31 to 60 years (mean 46 years). Two patients had no symptoms, 1 complained of slight visual disturbances, and the other 1 had abducent nerve palsy. Neurofibromatosis was not diagnosed in any case. All 4 tumors were located in the cavernous sinus: 2 of these tumors within the borders of the sinus, 1 tumor extending into the orbit, and 1 tumor extending into the prepontine cistern. The volume of the neoplasms varied from 1.7 to 4.9 cm3 (mean 3.0 cm3). No patient underwent tumor resection. Treatment was delivered with the aid of a Leksell Gamma Knife model C unit and the automatic positioning system. The dose directed to the tumor margin was 12 Gy in all cases. The dose directed to the anterior visual pathways was kept below 10 Gy and that to the brainstem below 14 Gy. The length of follow-up varied between 7 and 43 months (mean 27 months).

There were no acute complications or side effects. Imaging studies showed temporary enlargement of all tumors during the 1st posttreatment year, but thereafter, there was a trend toward reduction in volume. None of the neoplasms displayed regrowth. In the 3 patients who did not have abducent nerve palsy before GKS, it appeared, at least temporarily, after the procedure. Purely intracavernous neoplasms in general followed uneventful posttreatment courses, but dumbbell-shaped tumors were associated with significant morbidity. The cisternocavernous schwannoma underwent cystic degeneration 2 years after GKS, and the patient developed diplopia. After GKS, the patient treated for an orbitocavernous schwannoma experienced a significant deterioration in vision, temporary blindness in 1 eye, and late development of permanent abducent nerve palsy, which were seemingly caused by compression of neurovascular structures within the anulus of Zinn during a temporary increase in the lesion's volume after irradiation.

Gamma Knife surgery controls the growth of abducent nerve schwannomas and may be effectively used to manage intracavernous neoplasms. Caution, however, should be used in cases of dumbbell-shaped tumors, particularly those extending through the superior orbital fissure.