Effect of dural detachment on long-term tumor control for meningiomas treated using Simpson grade IV resection

POLR2A Mutation is a Poor Prognostic Marker of Cerebellopontine Angle Meningioma

BACKGROUND AND OBJECTIVES

Recent molecular analyses have shown that the driver genetic mutations of meningiomas were associated with the anatomic location. Among these, POLR2A mutation is common among lesions in the skull base, mainly in the cerebellopontine angle (CPA). The objective of this study was to investigate the efficacy of POLR2A mutation as a prognostic marker for CPA meningiomas.

METHODS

We retrospectively analyzed the clinical data of 70 patients who had World Health Organization grade I CPA meningiomas. Somatic DNA was analyzed by Sanger sequencing and microsatellite array to examine for NF2 , AKT1 , KLF4 , SMO , and POLR2A mutations and 22q loss. Genetic and clinical parameters were analyzed to identify the factors related with tumor recurrence.

RESULTS

We detected clearly the clinical features of the CPA cases with POLR2A mutation. Compared with cases without POLR2A mutation, cases with POLR2A mutation had more meningothelial type ( P = 6.9 × 10 -4 ), and higher rate of recurrence ( P = .04). We found that the poor prognostic factors associated with the recurrence of CPA meningiomas were POLR2A mutation ( P = .03, hazard ratio [HR] 9.38, 95% CI 1.26-70.0) and subtotal resection (STR) ( P = 5.1 × 10 -4 , HR 63.1, 95% CI 6.09-655.0). In addition, in the group that underwent STR, POLR2A mutation was a poor prognostic factor associated with tumor recurrence ( P = .03, HR 11.1, 95% CI 1.19-103.7).

CONCLUSION

POLR2A mutation and STR were the poor prognostic markers associated with the recurrence of CPA meningioma. For CPA meningioma cases that underwent STR, only POLR2A mutation was a poor prognostic factor. Detecting POLR2A mutation may be a cost-effective, easy, and useful marker for prognostication.

Simpson's Grading Scale for WHO Grade I Meningioma Resection in the Modern Neurosurgical Era: Are We Really Asking the Right Question?

The Simpson grading scale for the classification of the extent of meningioma resection provided a tremendous movement forward in 1957 suggesting increasing the extent of resection improves recurrence rates. However, equal, if not greater, movements forward have been made in the neurosurgical community over the last half a century owing to improvements in neuroimaging capabilities, microsurgical techniques, and radiotherapeutic strategies. Sughrue et al proposed the idea that these advancements have altered what a "recurrence" and "subtotal resection" truly means in modern neurosurgery compared with Simpson's era, and that a mandated use of the Simpson Scale is likely less clinically relevant today. A subsequent period of debate ensued in the literature which sought to re-examine the clinical value of using the Simpson Scale in modern neurosurgery. While a large body of evidence has recently been provided, these data generally continue to support the clinical importance of gross tumor resection as well as the value of adjuvant radiation therapy and the importance of recently updated World Health Organization classifications. However, there remains a negligible interval benefit in performing overly aggressive surgery and heroic maneuvers to remove the last bit of tumor, dura, and/or bone just for the simple act of achieving a lower Simpson score. Ultimately, meningioma surgery may be better contextualized as a continuous set of weighted risk-benefit decisions throughout the entire operation.

Grading meningioma resections: the Simpson classification and beyond

Technological (and also methodological) advances in neurosurgery and neuroimaging have prompted a reappraisal of Simpson's grading of the extent of meningioma resections. To the authors, the published evidence supports the tenets of this classification. Meningioma is an often surgically curable dura-based disease. An extent of meningioma resection classification needs to account for a clinically meaningful variation of the risk of recurrence depending on the aggressiveness of the management of the (dural) tumor origin.Nevertheless, the 1957 Simpson classification undoubtedly suffers from many limitations. Important issues include substantial problems with the applicability of the grading paradigm in different locations. Most notably, tumor location and growth pattern often determine the eventual extent of resection, i.e., the Simpson grading does not reflect what is surgically achievable. Another very significant problem is the inherent subjectivity of relying on individual intraoperative assessments. Neuroimaging advances such as the use of somatostatin receptor PET scanning may help to overcome this central problem. Tumor malignancy and biology in general certainly influence the role of the extent of resection but may not need to be incorporated in an actual extent of resection grading scheme as long as one does not aim at developing a prognostic score. Finally, all attempts at grading meningioma resections use tumor recurrence as the endpoint. However, especially in view of radiosurgery/radiotherapy options, the clinical significance of recurrent tumor growth varies greatly between cases.In summary, while the extent of resection certainly matters in meningioma surgery, grading resections remains controversial. Given the everyday clinical relevance of this issue, a multicenter prospective register or study effort is probably warranted (including a prominent focus on advanced neuroimaging).

Long-Term Outcomes of Stereotactic Radiosurgery for Postoperative World Health Organization Grade I Skull Base Meningioma: Utility of Ki-67 Labeling Index as a Prognostic Indicator

BACKGROUND

Gross total resection, without causing neurological deficits, is challenging in skull base meningioma (SBM). Therefore, stereotactic radiosurgery (SRS) is an important approach for SBMs; however, it is difficult to predict the long-term prognosis.

OBJECTIVE

To identify the predictive factors for tumor progression after SRS for World Health Organization (WHO) grade I SBMs, focusing on the Ki-67 labeling index (LI).

METHODS

In this single-center retrospective study, factors affecting progression-free survival rates (PFSs) and neurological outcomes in patients undergoing SRS for postoperative SBMs were evaluated. Based on the Ki-67 LI, patients were classified into 3 groups: low (<4%), intermediate (4%-6%), and high LI (>6%).

RESULTS

In the 112 patients enrolled, the cumulative 5- and 10-year PFSs were 93% and 83%, respectively. The PFSs were significantly higher in the low LI group (95% at 10 years) compared with the other groups (intermediate LI, 60% at 10 years, P = .007; high LI, 20% at 10 years, P = .001). Multivariable Cox proportional hazard analysis demonstrated that the Ki-67 LI was significantly associated with the PFSs (low vs intermediate LI; hazard ratio, 6.00; 95% CI, 1.41-25.54; P = .015; low vs high LI; hazard ratio, 31.90; 95% CI, 5.59-181.77; P = .001).

CONCLUSION

Ki-67 LI may be a useful predictor of long-term prognosis in SRS for postoperative WHO grade I SBM. SRS provides excellent long- and mid-term PFSs in SBMs with Ki-67 LIs <4% or 4% to 6%, with a low risk of radiation-induced adverse events.

Preoperative tumor embolization prolongs time to recurrence of meningiomas: a retrospective propensity-matched analysis

BACKGROUND

Meningiomas are often embolized preoperatively to reduce intraoperative blood loss and facilitate tumor resection. However, the procedure is controversial and its effects have not yet been reported. We evaluated preoperative embolization for meningiomas and its effect on postoperative outcome and recurrence.

METHODS

We retrospectively reviewed the medical records of 186 patients with WHO grade I meningiomas who underwent surgical treatment at our hospital between January 2010 and December 2020. We used propensity score matching to generate embolization and no-embolization groups (42 patients each) to examine embolization effects.

RESULTS

Preoperative embolization was performed in 71 patients (38.2%). In the propensity-matched analysis, the embolization group showed favorable recurrence-free survival (RFS) (mean 49.4 vs 24.1 months; Wilcoxon p=0.049). The embolization group had significantly less intraoperative blood loss (178±203 mL vs 221±165 mL; p=0.009) and shorter operation time (5.6±2.0 hours vs 6.8±2.8 hours; p=0.036). There were no significant differences in Simpson grade IV resection (33.3% vs 28.6%; p=0.637) or overall perioperative complications (21.4% vs 11.9%; p=0.241). Tumor embolization prolonged RFS in a subanalysis of cases who experienced recurrence (n=39) among the overall cases before variable control (mean RFS 33.2 vs 16.0 months; log-rank p=0.003).

CONCLUSIONS

After controlling for variables, preoperative embolization for meningioma did not improve the Simpson grade or patient outcomes. However, it might have effects outside of surgical outcomes by prolonging RFS without increasing complications.

Diagnostic value of MRI in coexistence of schwannoma and meningioma mimicking a single dumbbell-shaped tumor in high cervical level. Case series and literature review

CONTEXT

Concurrent schwannoma and meningioma arising in the high cervical level mimicking a single dumbbell-shaped tumor is significantly rare, most of them were found during the surgeries or postoperative histological findings unexpectedly. The specific feature of schwannoma and meningioma coexistence in high cervical level on MR images has not been clearly described yet.

FINDINGS

We presented four cases of concurrent extradural schwannoma and intradural meningioma mimicking a single dumbbell-shaped tumor arising in the high cervical level. There was no interconnection between intradural and extradural masses in any case. In MRI reviews, the signal intensity between intradural lesions and spinal cord was similar on T2 weighted MR images. However, on contrast-enhanced MR images, the intradural lesions were more enhanced than spinal cord and presented as crescent-shaped intradural minor lesions adjacent to the more significantly enhanced extradural major tumor. These MRI findings could not be easily identified without meticulous observation preoperatively. Postoperative pathological findings confirmed the discrete tumors arising in the same cervical level.

CONCLUSION

The comparison of signal intensity changes among the spinal cord, intradural tumor and extradural tumor between T2 weighted and contrast-enhanced MR images may be helpful to predict coexistent schwannoma and meningioma in the high cervical level preoperatively. Intradural exploration is highly recommended when less enhanced crescent-shaped intradural minor lesion was observed adjacent to the significantly enhanced dumbbell-shaped major tumor in preoperative MRI findings.

Clinical significance of NF2 alteration in grade I meningiomas revisited; prognostic impact integrated with extent of resection, tumour location, and Ki-67 index

NF2 alteration is the most commonly-found genetic abnormality in meningiomas and is known to initiate events for aggressive-type meningiomas. Whereas the prognosis of meningiomas differs depending on their epigenomic/transcriptomic profile, the effect of NF2 alteration on the prognosis of benign meningiomas is not fully elucidated. This study aimed to probe the importance of NF2 alteration in prognosis of WHO grade I meningiomas. A long-term retrospective follow-up (5.3 ± 4.5 years) study involving 281 consecutive WHO grade I meningioma patients was performed. We assessed tumour recurrence in correlation with extent of resection (EOR), histopathological findings, tumour location, and NF2 alteration. "NF2 meningioma" was defined as meningiomas with presence of NF2 mutation and/or 22q loss. Overall, NF2 meningioma per se was not a predictor of prognosis in the whole cohort; however, it was a predictor of recurrence in supratentorial meningiomas, together with EOR and Ki-67. In a striking contrast, NF2 meningioma showed a better prognosis than non-NF2 meningioma in infratentorial lesion. Supratentorial NF2 meningiomas had higher Ki-67 and forkhead box protein M1 expression than those of others, possibly explaining the worse prognosis in this subtype. The combination of NF2 alteration, high Ki-67 and supratentorial location defines subgroup with the worst prognosis among WHO grade I meningiomas. Clinical connotation of NF2 alteration in terms of prognosis of WHO grade I meningioma differs in an opposite way between supratentorial and infratentorial tumors. Integrated anatomical, histopathological, and genomic classifications will provide the best follow-up schedule and proactive measures.

The Simpson Grading: Is It Still Valid?

The Simpson Grade was introduced in the era of limited resources, outdated techniques, and rudimentary surgical and imaging technologies. With the advent of modern techniques including pre- and post-operative imaging, microsurgical and endoscopic techniques, advanced histopathology and molecular analysis and adjuvant radiotherapy, the utility of the Simpson Grade scale for prognostication of recurrence after meningioma resection has become less useful. While the extent of resection remains an important factor in reducing recurrence, a subjective naked-eye criteria to Grade extent of resection cannot be generalized to all meningiomas regardless of their location or biology. Achieving the highest Simpson Grade resection should not always be the goal of surgery. It is prudent to take advantage of all the tools in the neurosurgeons’ armamentarium to aim for maximal safe resection of meningiomas. The primary goal of this study was to review the literature highlighting the Simpson Grade and its association with recurrence in modern meningioma practice. A PubMed search was conducted using terms “Simpson”, “Grade”, “meningioma”, “recurrence”, “gross total resection”, “extent of resection” “human”. A separate search using the terms “intraoperative imaging”, “intraoperative MRI” and “meningioma” were conducted. All studies reporting prognostic value of Simpson Grades were retrospective in nature. Simpson Grade I, II and III can be defined as gross total resection and were associated with lower recurrence compared to Simpson Grade IV or subtotal resection. The volume of residual tumor, a factor not considered in the Simpson Grade, is also a useful predictor of recurrence. Subtotal resection followed by stereotactic radiosurgery has similar recurrence-free survival as gross total resection. In current modern meningioma surgery, the Simpson Grade is no longer relevant and should be replaced with a grading scale that relies on post-operative MRI imaging that assess GTR versus STR and then divides STR into > or <4−5 cm3, in combination with modern molecular-based techniques for recurrence risk stratification.

Residual Tumor Volume and Tumor Progression after Subtotal Resection and Observation of WHO Grade I Skull Base Meningiomas

Objective This study investigated the impact of residual tumor volume (RTV) on tumor progression after subtotal resection and observation of WHO grade I skull base meningiomas.

Study Design This study is a retrospective volumetric analysis.

Setting This study was conducted at a single institution.

Participants Patients who underwent subtotal resection of a WHO grade I skull base meningioma and postsurgical observation (July 1, 2007–July 1, 2017).

Main Outcome Measure The main outcome was radiographic tumor progression.

Results Sixty patients with residual skull base meningiomas were analyzed. The median (interquartile range) RTV was 1.3 (5.3) cm3. Tumor progression occurred in 23 patients (38.3%) at a mean duration of 28.6 months postsurgery. The 1-, 3-, and 5-year actuarial progression-free survival (PFS) rates were 98.3, 58.6, and 48.7%, respectively. The Cox multivariate analysis identified increasing RTV (p = 0.01) and history of more than 1 previous surgery (p = 0.03) as independent predictors of tumor progression. In a Kaplan–Meier analysis for PFS, the RTV threshold of 3 cm3 maximized log-rank testing significance between groups of patients dichotomized at 0.5 cm3 thresholds (p < 0.01). The 3-year actuarial PFS rates for meningiomas with RTV ≤3 cm3 and >3 cm3 were 76.2 and 32.1%, respectively. When RTV >3 cm3 was entered as a covariate in the Cox model, it was the only factor independently associated with tumor progression (p < 0.01).

Conclusion RTV was associated with tumor progression after subtotal resection of WHO grade I skull base meningioma in this cohort. An RTV threshold of 3 cm3 was identified that minimized progression of the residual tumor when gross total resection was not safe or feasible.

The Simpson grade: abandon the scale but preserve the message

The Simpson grading scale, developed in 1957 by Donald Simpson, has been considered the gold standard for defining the surgical extent of resection for WHO grade I meningiomas. Since its introduction, the scale and its modifications have generated enormous controversy. The Simpson grade is based on an intraoperative visual assessment of resection, which is subjective and notoriously inaccurate. The majority of studies in which the grading system was used were performed before routine postoperative MRI surveillance was employed, rendering assessments of extent of resection and the definition of recurrence inconsistent. The infiltration and proliferation potential of tumor components such as hyperostotic bone and dural tail vary widely based on tumor location, as does the molecular biology of the tumor, rendering a universal scale for all meningiomas unfeasible. While extent of resection is clearly important at reducing recurrence rates, achieving the highest Simpson grade resection should not always be the goal of surgery. Donald Simpson's name and his scale deserve to be recognized and preserved in the historical pantheon of pioneering and transformative neurosurgical concepts. Nevertheless, his eponymous scale is no longer relevant in modern meningioma surgery. While his message of maximizing extent of resection and minimizing morbidity is still germane, a single measure using subjective criteria cannot be applied universally to all meningiomas, regardless of location. Meningioma surgery should be performed with the goal of achieving maximal safe resection, ideally guided by molecularly tagged fluorescent labeling and assessed using objective criteria, including postoperative MRI as well as molecularly tagged scans such as [68Ga]-DOTATATE-PET.

A Novel Scoring System Based on Preoperative Routine Blood Test in Predicting Prognosis of Atypical Meningioma

Purpose

The aim of this study was to explore the correlation and clinical significance of preoperative fibrinogen and neutrophil-lymphocyte ratio (F-NLR) scoring system with 3-year progression-free survival (PFS) of patients with atypical meningioma.

Materials and Methods

Clinical, pathological, radiological, and laboratory variables were collected to analyze their correlation with 3-year PFS in the training set with 163 patients. Patients were classified by different F-NLR scores (0, 1, or 2). External validation for the predictive value of F-NLR scoring system was performed in the validation set with 105 patients.

Results

Overall, 37.3% (100 of 268) of the enrolled patients were male. The scoring system showed good performance in predicting 3-year PFS (AUC = 0.872, 95%CI = 0.811–0.919, sensitivity = 66.1%, specificity = 93.3%, and Youden index = 0.594). DeLong’s test indicated that the AUC of F-NLR scoring system was significantly greater than that of fibrinogen level and NLR (Z = 2.929, P = 0.003; Z = 3.376, P < 0.001). Multivariate Cox analysis revealed that tumor size (HR = 1.39, 95%CI = 1.10–1.76, P = 0.007), tumor location (HR = 3.11, 95%CI = 1.60–6.95, P = 0.001), and F-NLR score (score of 1: HR = 12.78, 95%CI = 3.78–43.08, P < 0.001; score of 2: HR = 44.58, 95%CI = 13.02–152.65, P < 0.001) remained significantly associated with 3-year PFS. The good predictive performance of F-NLR scoring system was also demonstrated in the validation set (AUC = 0.824, 95%CI = 0.738–0.891, sensitivity = 62.5%, specificity = 87.9%, and Youden index = 0.504).

Conclusion

Our study confirmed the correlation and clinical significance of preoperative F-NLR scoring system with 3-year PFS of patients with atypical meningioma. A prospective and large-scale study is required to validate our findings.

The Simpson grading in meningioma surgery: does the tumor location influence the prognostic value?

In meningiomas, location-specific differences of the prognostic value of the Simpson classification are sparsely investigated but can influence strategy of surgery. We therefore compared the prognostic value of the Simpson classification in different tumor locations. Progression was compared with Simpson grade in 826 meningioma patients (median age 58 years, female:male ratio 2.4) in location-specific uni- and multivariate analyses. Simpson grade strongly correlated with tumor location (p < .001). Within a median follow-up of 50 months, recurrence was observed in 107 of 803 patients (13%). In general, increasing Simpson grade (p = .002) and subtotal resection (STR, ≥grade III) were correlated with tumor recurrence [hazard ratio (HR): 1.87; p = .004]. In 268 convexity meningiomas, frequency of tumor recurrence correlated with Simpson grade (p = .034). Risk of recurrence was similar after grade I and II resections, tended to increase after grade III (HR: 2.35; p = .087) but was higher after grade IV resections (HR: 7.35; p = .003). Risk of recurrence was higher after STR (HR: 4.21; p = .001) than after gross total resection (GTR, ≤grade II). Contrarily, increasing Simpson grade and STR were not correlated with progression in 102 falx, 38 posterior fossa and nine intraventricular meningiomas. In 325 skull base lesions, risk of recurrence was similar after GTR and STR (p = .198) and was only increased after grade IV resections (HR: 3.26; p = .017). Simpson grading and extent of resection were not equally prognostic in all locations. Lower impact of extent of resection should be considered during surgery for skull base, posterior fossa and falx meningiomas.

Surgical Management of Lateral Tentorial Meningiomas

OBJECTIVE

Tentorial meningiomas represent a heterogeneous group of tumors. Most of the published series deal with either a small number of patients or consider different locations as a whole, making indications for treatment and prognosis difficult to drawn. We analyzed the surgical management of the lateral tentorial meningiomas, a homogenous and rare subgroup.

METHODS

Fifty-two later tentorial meningiomas were operated on between 1990 and 2010. Clinical and radiologic features and surgical management of these patients were reviewed. Tumors were further subcategorized in to posterior/intermediate and in to supra-/infratentorial subgroups. Surgical outcome, long-term results, and prognostic factors are described.

RESULTS

Mean age was 57 years (41 female, 11 male). Mean tumor size was 46 mm; most had an infratentorial location (36 vs. 16). Prevailing presenting symptoms were headache (n = 28), vertigo/gait disturbances (n = 25), and confusion and visual disturbances (n = 16). The infratentorial group presented with a poorer clinical condition before as well as after operation. Extent of tumor resection was Simpson I in 10 patients, II in 26, III in 6, and IV in 10. Subtotal resection was statistically correlated with sinus invasion and tumor size. There was no surgical mortality. Permanent complications occurred in 3 patients. At latest follow-up (mean, 119 months) 42/46 had resumed their normal daily activity. Six cases recurred and remained stable after radiosurgery.

CONCLUSIONS

Lateral tentorial meningiomas are a homogeneous entity characterized by simple surgical approaches and favorable outcome (no mortality and low overall morbidity). Infratentorial location was more frequent and was characterized by poorer outcome. The limiting factors for surgical removal were tumor size and sinus invasion. The latter point strengthens the rationale for their classification into posterior and intermediate.

Recurrent Atypical Meningiomas: Combining Surgery and Radiosurgery in One Effective Multimodal Treatment

OBJECTIVE

Owing to their rarity and proteiform pathologic features, the clinical behavior of atypical meningiomas is not yet well characterized. Though the extent of resection is believed to be a key determinant of prognosis, limited data exist regarding optimal management of patients with recurrent disease.

METHODS

In this 20-year retrospective case series, we reviewed the medical records of 46 patients with recurrent atypical meningiomas (185 lesions, 89 of which were local, 78 marginal, and 18 distant recurrences); treatment was radiosurgery (n = 60), surgery (n = 56), or both (n = 8). The median follow-up period was 53 months. Outcome measures were length of overall survival and disease-free intervals and prognostic factors for survival.

RESULTS

Overall, the median progression-free survival was 26 months at the first recurrence and 100 months thereafter (the sum of the later intervals). Multivariate analysis showed that no treatment-related factors influenced prognosis, whereas recurrence at the skull base was a significant tumor-related factor limiting further treatment. Irrespective of treatment type, the recurrence-free interval was increasingly shorter during the clinical course, with a higher occurrence of marginal and distant lesions migrating to the midline and to the skull base. In sporadic cases, disease-free intervals were longer after wide craniotomy, tumor and dural resection with tumor-free margin.

CONCLUSIONS

The disease-free interval was substantially similar after surgery and radiosurgery for treating recurrent disease in patients with atypical meningiomas. Surgery is the mainstay for prolonging survival, while radiosurgery can be an adjuvant strategy to gain time for clinical observation and planning aggressive surgical treatment.

Current Status of Endoscopic Endonasal Surgery for Skull Base Meningiomas: Review of the Literature

Endoscopic endonasal approach (EEA) is expected to be ideal for the paramedian ventral skull base meningiomas, allowing wide access to the ventral skull base regions and realizing early devascularization of the tumor without retraction of the brain. We searched clinical reports of EEA for skull base meningiomas, written in English language, published before October 2014, using the PubMed literature search on the website. Skull base meningiomas are subdivided by the site of occurrence, olfactory groove (8 articles including 80 cases), tuberculum sellae (14 articles, 153 cases), cavernous sinus (2 articles, 8 cases), petroclival region (4 articles, 10 cases), and craniofacial region (2 articles, 5 cases), and the surgical outcomes of EEA were analyzed. In anterior skull base regions, EEA contributed to effective improvement of the symptoms in small and round-shaped meningiomas, but 25% of the patients had postoperative cerebrospinal fluid rhinorrhea. In cavernous sinus and petroclival regions, successful surgical removal largely depended on tumor consistency, and the extent of the surgical resection proportionally increased the risks of serious complications. Thus, judicious endoscopic resection with adjuvant radiotherapy or radiosurgery remains to be the most reasonable treatment option. To decrease the risks of surgical complications, the surgeons must master the closure techniques of dural defect and meticulous microsurgical procedure under endoscopic vision. Further progress will depend on the progresses of surgical technique in neurosurgeons engaging this potentially “minimally invasive” surgery.

Is Simpson grade I removal necessary in all cases of spinal meningioma? Assessment of postoperative recurrence during long-term follow-up

It is generally accepted that the first choice of treatment for spinal meningiomas is “radical” surgical removal. However, Simpson grade I removal is sometimes difficult, especially in cases with ventral dural attachment, because of the risk of spinal cord damage or the difficulty of dural repair after radical resection. In addition, there is no consensus on a surgical strategy for radicality, whether or not Simpson grade I resection should be performed in all cases of spinal meningioma. In this study, we retrospectively analyzed clinical and radiological data of surgically treated 14 patients with spinal meningioma, to assess the influence of the Simpson grade to tumor recurrences during long-term follow-up (median 8.2 years, 1.3–27.9). The number of patients in Simpson grades I, II, III, and IV were 2, 8, 0, and 3, respectively; Simpson grading was not applicable to one patient with non-dura-based meningioma. No postoperative permanent neurological worsening was encountered. The recurrence rate was 21.4% (3 out of 14 cases). Of these 3 recurrent cases, 1 was a case of non-dura-based meningioma and another was a case of neurofibromatosis type 2 (NF2); both of them are known as risk factors for recurrence after surgical removal of spinal meningiomas. Considering this background of these two recurrences, the clinical results of the present study are consistent with previous results. Therefore, we propose that surgeons do not always have to achieve Simpson grade I removal if dural repair is complicated and postoperative cerebrospinal fluid (CSF) leakage or neurological worsening are estimated after resection of dural attachment and repair of dural defect.