C7 Fracture as a Complication of C7 Dome-Like Laminectomy : Impact on Clinical and Radiological Outcomes and Evaluation of the Risk Factors

Objective@#: Cervical expansive laminoplasty is an effective surgical method to address multilevel cervical spinal stenosis. During surgery, the spinous processes of C2 and C7 are usually preserved to keep the insertion points of the cervical musculature and nuchal ligament intact. In this regard, dome-like laminectomy (undercutting of C7 lamina) instead of laminoplasty is performed on C7 in selected cases. However, resection of the lamina can weaken the C7 lamina, and stress fractures may occur, but this complication has not been characterized in the literature. The objective of the present study was to investigate the incidence and risk factors for C7 laminar fracture after C7 dome-like laminectomy and its impact on clinical and radiological outcomes. @*Methods@#: Patients who underwent cervical open-door laminoplasty combined with C7 dome-like laminectomy (n=123) were classified according to the presence of C7 laminar fracture. Clinical parameters (neck/arm pain score and neck disability index) and radiologic parameters (C2–7 angle, C2–7 sagittal vertical axis, and C7–T1 angle) were compared between the groups preoperatively and at postoperatively at 3, 6, 12, and 24 months. Risk factors for complications were evaluated, and a formula estimating C7 fracture risk was suggested. @*Results@#: C7 lamina fracture occurred in 32/123 (26%) patients and occurred at the bilateral isthmus in 29 patients and at the spinolaminar junction in three patients. All fractures appeared on X-ray within 3 months postoperatively, but patients did not present any neurological deterioration. The fracture spontaneously healed in 27/32 (84%) patients at 1 year and in 29/32 (91%) at 2 years. During follow-up, clinical outcomes were not significantly different between the groups. However, patients with C7 fractures showed a more lordotic C2–7 angle and kyphotic C7–T1 angle than patients without C7 fractures. C7 fracture was significantly associated with the extent of bone removal. By incorporating significant factors, the probability of C7 laminar fracture could be assessed with the formula 'Risk score = 1.08 × depth (%) + 1.03 × length (%, of the posterior height of C7 vertebral body)', and a cut-off value of 167.9% demonstrated a sensitivity of 90.3% and a specificity of 65.1% (area under the curve, 0.81). @*Conclusion@#: C7 laminar fracture can occur after C7 dome-like laminectomy when a substantial amount of lamina is resected. Although C7 fractures may not cause deleterious clinical outcomes, they can lead to an unharmonized cervical curvature. The chance of C7 fracture should be discussed in the shared decision-making process.

C7 Fracture as a Complication of C7 Dome-Like Laminectomy : Impact on Clinical and Radiological Outcomes and Evaluation of the Risk Factors

Objective@#: Cervical expansive laminoplasty is an effective surgical method to address multilevel cervical spinal stenosis. During surgery, the spinous processes of C2 and C7 are usually preserved to keep the insertion points of the cervical musculature and nuchal ligament intact. In this regard, dome-like laminectomy (undercutting of C7 lamina) instead of laminoplasty is performed on C7 in selected cases. However, resection of the lamina can weaken the C7 lamina, and stress fractures may occur, but this complication has not been characterized in the literature. The objective of the present study was to investigate the incidence and risk factors for C7 laminar fracture after C7 dome-like laminectomy and its impact on clinical and radiological outcomes. @*Methods@#: Patients who underwent cervical open-door laminoplasty combined with C7 dome-like laminectomy (n=123) were classified according to the presence of C7 laminar fracture. Clinical parameters (neck/arm pain score and neck disability index) and radiologic parameters (C2–7 angle, C2–7 sagittal vertical axis, and C7–T1 angle) were compared between the groups preoperatively and at postoperatively at 3, 6, 12, and 24 months. Risk factors for complications were evaluated, and a formula estimating C7 fracture risk was suggested. @*Results@#: C7 lamina fracture occurred in 32/123 (26%) patients and occurred at the bilateral isthmus in 29 patients and at the spinolaminar junction in three patients. All fractures appeared on X-ray within 3 months postoperatively, but patients did not present any neurological deterioration. The fracture spontaneously healed in 27/32 (84%) patients at 1 year and in 29/32 (91%) at 2 years. During follow-up, clinical outcomes were not significantly different between the groups. However, patients with C7 fractures showed a more lordotic C2–7 angle and kyphotic C7–T1 angle than patients without C7 fractures. C7 fracture was significantly associated with the extent of bone removal. By incorporating significant factors, the probability of C7 laminar fracture could be assessed with the formula 'Risk score = 1.08 × depth (%) + 1.03 × length (%, of the posterior height of C7 vertebral body)', and a cut-off value of 167.9% demonstrated a sensitivity of 90.3% and a specificity of 65.1% (area under the curve, 0.81). @*Conclusion@#: C7 laminar fracture can occur after C7 dome-like laminectomy when a substantial amount of lamina is resected. Although C7 fractures may not cause deleterious clinical outcomes, they can lead to an unharmonized cervical curvature. The chance of C7 fracture should be discussed in the shared decision-making process.

Minimally Invasive Surgery without Decompression for Hepatocellular Carcinoma Spinal Metastasis with Epidural Spinal Cord Compression Grade 2

OBJECTIVE: There is a lack of knowledge regarding whether decompression is necessary in treating patients with epidural spinal cord compression (ESCC) grade 2. The purpose of this study was to compare the outcomes of minimally invasive surgery (MIS) without decompression and conventional open surgery (palliative laminectomy) for patients with hepatocellular carcinoma (HCC) spinal metastasis of ESCC grade 2.METHODS: Patients with HCC spinal metastasis requiring surgery were retrospectively reviewed. Patients with ESCC grade 2, medically intractable mechanical back pain, a Nurick grade better than 3, 3–6 months of life expectancy, Tomita score ≥5, and Spinal Instability Neoplastic Score ≥7 were included. Patients with neurological deficits, other systemic illnesses and less than 1 month of life expectancy were excluded. Thirty patients were included in the study, including 17 in the open surgery group (until 2008) and 13 in the MIS group (since 2009).RESULTS: The MIS group had a significantly shorter operative time (94.2±48.2 minutes vs. 162.9±52.3 minutes, p=0.001), less blood loss (140.0±182.9 mL vs. 1534.4±1484.2 mL, p=0.002), and less post-operative intensive care unit transfer (one patient vs. eight patients, p=0.042) than the open surgery group. The visual analogue scale for back pain at 3 months post-operation was significantly improved in the MIS group than in the open surgery group (3.0±1.2 vs. 4.3±1.2, p=0.042). The MIS group had longer ambulation time (183±33 days vs. 166±36 days) and survival time (216±38 days vs. 204±43 days) than the open surgery group without significant difference (p=0.814 and 0.959, respectively).CONCLUSION: MIS without decompression would be a good choice for patients with HCC spinal metastasis of ESCC grade 2, especially those with limited prognosis, mechanical instability and no neurologic deficit.

Minimally Invasive Surgery without Decompression for Hepatocellular Carcinoma Spinal Metastasis with Epidural Spinal Cord Compression Grade 2

OBJECTIVE: There is a lack of knowledge regarding whether decompression is necessary in treating patients with epidural spinal cord compression (ESCC) grade 2. The purpose of this study was to compare the outcomes of minimally invasive surgery (MIS) without decompression and conventional open surgery (palliative laminectomy) for patients with hepatocellular carcinoma (HCC) spinal metastasis of ESCC grade 2. METHODS: Patients with HCC spinal metastasis requiring surgery were retrospectively reviewed. Patients with ESCC grade 2, medically intractable mechanical back pain, a Nurick grade better than 3, 3–6 months of life expectancy, Tomita score ≥5, and Spinal Instability Neoplastic Score ≥7 were included. Patients with neurological deficits, other systemic illnesses and less than 1 month of life expectancy were excluded. Thirty patients were included in the study, including 17 in the open surgery group (until 2008) and 13 in the MIS group (since 2009). RESULTS: The MIS group had a significantly shorter operative time (94.2±48.2 minutes vs. 162.9±52.3 minutes, p=0.001), less blood loss (140.0±182.9 mL vs. 1534.4±1484.2 mL, p=0.002), and less post-operative intensive care unit transfer (one patient vs. eight patients, p=0.042) than the open surgery group. The visual analogue scale for back pain at 3 months post-operation was significantly improved in the MIS group than in the open surgery group (3.0±1.2 vs. 4.3±1.2, p=0.042). The MIS group had longer ambulation time (183±33 days vs. 166±36 days) and survival time (216±38 days vs. 204±43 days) than the open surgery group without significant difference (p=0.814 and 0.959, respectively). CONCLUSION: MIS without decompression would be a good choice for patients with HCC spinal metastasis of ESCC grade 2, especially those with limited prognosis, mechanical instability and no neurologic deficit.

The Formation of Extragraft Bone Bridging after Anterior Cervical Discectomy and Fusion: A Finite Element Analysis

OBJECTIVE: In addition to bone bridging inside a cage or graft (intragraft bone bridging, InGBB), extragraft bone bridging (ExGBB) is commonly observed after anterior cervical discectomy and fusion (ACDF) with a stand-alone cage. However, solid bony fusion without the formation of ExGBB might be a desirable condition. We hypothesized that an insufficient contact area for InGBB might be a causative factor for ExGBB. The objective was to determine the minimal area of InGBB by finite element analysis. METHODS: A validated 3-dimensional, nonlinear ligamentous cervical segment (C3–7) finite element model was used. This study simulated a single-level ACDF at C5–6 with a cylindroid interbody graft. The variables were the properties of the incorporated interbody graft (cancellous bone [Young’s modulus of 100 or 300 MPa] to cortical bone [10000 MPa]) and the contact area between the vertebra and interbody graft (Graft-area, from 10 to 200 mm²). Interspinous motion between the flexion and extension models of less than 2 mm was considered solid fusion. RESULTS: The minimal Graft-areas for solid fusion were 190 mm², 140 mm², and 100 mm² with graft properties of 100, 300, and 10000 MPa, respectively. The minimal Graft-areas were generally unobtainable with only the formation of InGBB after the use of a commercial stand-alone cage. CONCLUSION: ExGBB may be formed to compensate for insufficient InGBB. Although various factors may be involved, solid fusion with less formation of ExGBB may be achieved with refinements in biomaterials, such as the use of osteoinductive cage materials; changes in cage design, such as increasing the area of polyetheretherketone or the inside cage area for bone grafts; or surgical techniques, such as the use of plate/screw systems.

Methylation Status of the O6-Methylguanine- Deoxyribonucleic Acid Methyltransferase Gene Promoter in World Health Organization Grade III Gliomas

OBJECTIVE: We analyzed the methylation status of the O6-methylguanine-DNA methyltransferase (MGMT) gene promoter in World Health Organization (WHO) grade III gliomas in association with other molecular markers to evaluate their prevalence. METHODS: The samples of a total of 36 newly WHO grade III glioma patients including 19 anaplastic oligodendrogliomas (AO), 7 anaplastic oligoastrocytomas (AOA), and 10 anaplastic astrocytomas (AA) were analyzed. The methylation status of the MGMT gene promoter was confirmed by methylation-specific polymerase chain reaction. The 1p/19q chromosomal deletion status and EGFR amplification were assessed by Fluorescence In-Situ Hybridization. MGMT, EGFR, EGFRvIII, and p53 expression were analyzed by immunohistochemical staining. RESULTS: The MGMT gene promoter was methylated in 32 (88.9%) and unmethylated in 4 (11.2%). Among them, all of the AO and AOA had methylated MGMT gene promoter without exception. Significant associations between MGMT gene promoter hypermethylation and 1p/19q deletion was observed (p = 0.003). Other molecular markers failed to show significant associations between MGMT gene promoter statuses. CONCLUSION: There was extensive epigenetic silencing of MGMT gene in high grade gliomas with oligodendroglial component. Together with frequent 1p/19q co-deletion in oligodendroglial tumors, this may add plausible explanations supporting the relative favorable prognosis in oligodendroglial tumors compared with pure astrocytic tumors.