Abstract
Background Medial sphenoid wing meningiomas (MSWMs) account for approximately 20% of all meningiomas that are known for their critical relation to neurovasculture structures.
Objective The purpose of this study is to examine the relation between the maximum diameter of the MSWM medial to the anterior clinoidal line (AC line) and surgical outcome.
Methods This is a retrospective cohort study investigating all surgically resected MSWM cases at our institution over 10 years. The patients were divided into groups A and B based on the average ratio between the maximum medial extension of the MSWM from the AC line to the maximum diameter of the tumor, that is, value I = 0.42 (group A ≤ 0.42 and group B > 0.42). And into groups C and D based on the average medial extension of the tumor, that is, 14 mm (group C ≤ and D group D > 14 mm). These measurements were correlated with patients' demographics, preoperative symptoms, and postoperative assessment.
Results Among 150 patients, 51patients had MSWM that fulfilled the inclusion criteria. Among them, 76.47% were females with a median age of 48 years (standard deviation [SD] = 47.75 ± 15.11). Also, 92% of the cases were World Health Organization (WHO) grade I. The follow-up period was 0.5 to 10 years. Among them, 40% of group C had gross total resection (GTR), whereas 43% in group D. In group B, 70% had GTR, whereas 48% had GTR in group A. None of the patients developed statistically significant postoperative complications. There is no statistically significant difference in the risk complication with medial extension in all groups.
Conclusion The degree of medial extension of MSWM from the AC line has no statistically significant correlation with major postoperative complications, extent of resection, or clinical outcome.
Keywords: sphenoid wing, meningioma, outcome, anterior clinoid line
Introduction
Medial sphenoid wing meningiomas (MSWMs) account for approximately 20% of all meningiomas. 1 They are notorious for their complicated relation to adjacent structures including the optic apparatus, the internal carotid artery and its branches, the cavernous sinus, and other critical structures. Therefore, gross total resection (GTR) of the tumor is challenging and has significant morbidity ranging from 4 to 18%. 1
Background
There have been several studies on the relation of tumor size to the extent of resection and consequent clinical outcome 2 3 4 ; however, to our knowledge, there are no published studies that show a correlation between the tumor's medial extension and postoperative complications and clinical outcome.
Objectives
Therefore, the purpose of this study is to establish an association between the maximum diameters of the MSWMs medial or lateral to the anterior clinoidal line (AC line) and the postoperative outcome in terms of improvement of preoperative symptoms or development of postoperative complications.
Methods
Study Design and Participants
This is a retrospective cohort study investigating all surgically resected MSWM cases at our institution over the past 10 years. After obtaining the approval of the local institutional review board (IRB), all patients with surgically treated MSWMs, who were aged 18 to 90 years old and who had a follow-up for at least 3 months, were included. Consent was not required as this was an observational study, and steps were taken to ensure the anonymity of the data.
Measurement
We measured the MSWM maximum medial margin, labeled as line A ( Fig. 1 ), and the maximum lateral margin, labeled as line B ( Fig. 1 ), in relation to a line crossing the tip of the AC line ( Fig. 1 ) and parallel to a midline ( Fig. 1 ) that extends between the most caudal edge of the superior sagittal sinus and the most midline structure, such as the rostrum of the sphenoid sinus. The maximum diameters of the tumor were obtained medially and laterally from the coronal plane of the tip of the anterior clinoid using the digital ruler in the picture archiving and communication system (PACS). We divided the patients into two subgroups based on the average of the medial extension of the MSWMs (i.e., line A), which was 14 mm. Group A had a medial extension of 14 mm or less, and group B had a medial extension greater than 14 mm ( Fig. 2 ). A ratio was then generated between the maximum medial margin of the MSWMs to the maximum diameter of the tumor and was labeled as (value I), and a ratio generated between the lateral extension of the MSWM to the maximum diameter of the tumor was labeled as (value II). We divided the patients into two subgroups based on the average of value I, which was 0.42. Group C had an average ratio that was equal to or less than 0.42, and group D had an average ratio that was greater0.42 ( Fig. 2 ). These measurements were then correlated with the patients' demographics; preoperative symptoms, including headache, proptosis, visual impairment, oculomotor nerve palsy, limb weakness, speech involvement, and seizures; and postoperative complications, including worsening of preoperative symptoms, cerebrospinal fluid (CSF) leak, pneumocephalus, hydrocephalus, meningitis or death, as well as the extent of resection using Simpson's grading. The data collected from electronic charts including surgical and clinical follow-up records and imaging studies was recorded in an Excel spreadsheet (Microsoft, Redmond, Washington, United States). All data were entered and analyzed through statistical package SPSS version 22, (IBM Corporation, Armonk, New York, United States). Two different investigators recorded the patients' data and the image measurements to prevent bias.
Fig. 1.
T1-weighted MRI revealing right MSWM. White line: midline, black line: AC line; A: line A medial extension from the AC line to the most medial aspect of the tumor; B: line B lateral extension from the AC line to the most lateral aspect of the tumor. AC, anterior clinoid; MRI, magnetic resonance imaging; MSWM, medial sphenoid wing meningiomas.
Fig. 2.
Patients classification based on line A and value I. AC, anterior clinoid; MSWM, medial sphenoid wing meningiomas.
Data Analysis
All categorical variables, such as sex, diabetes mellitus (DM), and hypertension (HTN), were presented as numbers and percentages. Continuous variables, such as age, length of stay (LOS), and lines A and B, were expressed as mean ± standard deviation (SD). Either Chi-square or Fisher's exact test was performed, according to whether the cell expected frequency was smaller than 5, and was used to determine the significant association among categorical variables. Backward multiple logistics regression analysis was conducted for value I and value II to examine the relationship between the AC line and the study parameters of the patients. A p -value of less than 0.05 was considered as statistically significant. There were no cases with missing data that were eliminated.
Results
Participants and Descriptive Data
A total of 150 meningioma patients were identified. Out of these patients, 51 had MSWM and fulfilled the inclusion criteria; 76.47% were females with a median age of 48 years (range, 10–84 years). Forty-seven (92%) of the cases were World Health Organization (WHO) grade I, and the remaining 4 cases (8%) were WHO grade II. The mean follow-up period was 3 years (range, 0.5–10 years).
We divided the patients based on the average measurements of line A, which is the maximum medial margin of the MSWM, and we correlated each group with the demographics, clinical presentation, and surgical outcome.
Outcome Data
Group A included all patients who had MSWMs with medial extension less than or equivalent to 14 mm, and 24 patients (47%) in group B had a medial extension of more than 14 mm (47%). In group A, 13 patients (48%) presented with seizures ( p < 0.001; Table 1 ) that improved in 9 patients (33%) postoperatively (p = 0.009), whereas 1 patient (4.2%) in group B presented with seizures that improved postoperatively. GTR was achieved in 10 of the patients (41.7%) in group B and in 11 of the patients (40.7%) in group A ( p = 0.947; Table 2 ).
Table 1. Comparative analysis of medial extension of medial sphenoid wing meningiomas with preoperative characteristics.
| Characteristic | Line A | p -Value | ||
|---|---|---|---|---|
| Group A (≤14) n (%) |
Group B (>14) n (%) |
|||
| Gender | Male | 7 (25.92) | 5 (20.8) | 0.363 |
| Female | 20 (74.07) | 19 (79.2) | ||
| Preoperative visual status | No visual loss | 16 (59.3) | 8 (33.3) | 0.064 |
| Partial visual loss | 6 (22.2) | 6 (25.0) | 0.815 | |
| Visual loss of ipsilateral eye | 4 (14.8) | 5 (20.8) | 0.574 | |
| Partial or complete involvement of both eyes | 1 (3.7) | 5 (20.8) | 0.058 | |
| Preoperative limb weakness | Yes | 3 (11.1) | 8 (33.3) | 0.054 |
| No | 24 (88.9) | 16 (66.7) | ||
| Preoperative headache | Yes | 14 (51.9) | 20 (83.3) | 0.017 |
| No | 13 (48.1) | 4 (16.7) | ||
| Preoperative abnormal behavior | Yes | 3 (11.1) | 1 (4.2) | 0.357 |
| No | 24 (88.9) | 23 (95.8) | ||
| Preoperative seizure | Yes | 13 (48.1) | 1 (4.2) | <0.001 |
| No | 14 (51.9) | 23 (95.8) | ||
| Preoperative third cranial nerve involvement | Yes | 0 (0.0) | 2 (8.3) | 0.126 |
| No | 27 (100.0) | 22 (91.7) | ||
| Preoperative proptosis | Yes | 3 (11.1) | 2 (8.3) | 0.739 |
| No | 24 (88.9) | 22 (91.7) | ||
Table 2. Comparative analysis of medial extension of MSWM with postoperative characteristics.
| Characteristic | Line A | p -Value | ||
|---|---|---|---|---|
| Group A (≤14) n (%) |
Group B (>14) n (%) |
|||
| Postoperative visual status | Stable | 26 (96.3) | 23 (95.8) | 0.932 |
| Improved | 1 (3.7) | 1 (4.2) | ||
| Postoperative limb weakness | The same | 21 (77.8) | 19 (79.2) | 0.904 |
| Improved | 1 (3.7) | 1 (4.2) | 0.932 | |
| Worse | 5 (18.5) | 4 (16.7) | 0.863 | |
| Postoperative headache | The same | 15 (55.6) | 14 (58.3) | 0.842 |
| Improved | 12 (44.4) | 9 (37.5) | 0.615 | |
| Worse | 0 (0.0) | 1 (4.2) | 0.284 | |
| Postoperative abnormal behavior | The same | 24 (88.9) | 21 (87.5) | 0.878 |
| Improved | 1 (3.7) | 1 (4.2 | 0.932 | |
| Worse | 2 (7.4) | 2 (8.3 | 0.902 | |
| Postoperative seizure | The same | 17 (63.0) | 22 (91.7) | 0.016 |
| Improved | 9 (33.3) | 1 (4.2) | 0.009 | |
| Worse | 1 (3.7) | 1 (4.2) | 0.932 | |
| Postoperative third cranial nerve involvement | The same | 24 (88.9) | 18 (75.0) | 0.194 |
| Improved | 1 (3.7) | 1 (4.2) | 0.932 | |
| Worse | 2 (7.4) | 5 (20.8) | 0.164 | |
| Postoperative hydrocephalus | Yes | 1 (3.7) | 2 (8.3) | 0.483 |
| No | 26 (96.3) | 22 (91.7) | ||
| Postoperative meningitis | No | 27 (100.0) | 22 (91.7) | 0.126 |
| Yes | 0 (0.0) | 2 (8.3) | ||
| WHO grades of meningioma | Grade I | 27 (100.0) | 20 (83.3) | 0.063 |
| Grade II | 0 (0.0) | 4 (16.7) | ||
| Postoperative Simpson's grades | Grade II | 13 (48.1) | 15 (62.5) | 0.304 |
| Grade III | 0 (0.0) | 2 (8.3) | 0.126 | |
| Grade IV | 14 (51.9) | 7 (29.2) | 0.989 | |
| Postoperative resection | STR | 16 (59.3) | 14 (58.3) | 0.947 |
| GTR | 11 (40.7) | 10 (41.7) | ||
Abbreviations: GTR, gross total resection; MSWM, medial sphenoid wing meningiomas; STR, subtotal resection; WHO, World Health Organization.
In group A, one patient had postoperative trigeminal neuralgia in the distribution of V1 and V2, and one patient had left middle cerebral artery (MCA) infarction, which was managed with decompressive craniectomy. However, he was discharged home with residual right-sided hemiplegia and was lost to follow-up after 10 months.
Furthermore, we have analyzed the databased on the average of value I, which is the ratio of the tumor maximum medial margin of the MSWM from the AC line to the maximum diameter of the whole tumor. The average of value I was found to be 0.42. The value I that was equivalent to 0.42 or less was labeled as group C, comprised of 32 patients (62%), and value I that was more than 0.42 was labeled as group D, comprised of 19 patients (38%). All patients in group C had WHO grade I meningioma, whereas in group D, 17 (81%) had WHO grade I, and 4 (19%) had WHO grade II. On the other hand, 0% of the patients in group C had WHO grade II meningioma. In group C, patients were more likely to present with seizure which was observed in 13 (43%; p = 0.002; Table 3 ) of the patients, with improvement in 69.2% of the patients who presented with seizures, whereas in group D, only 1 patient presented with seizure that improved postoperatively. In group D, almost 20% of the patients had normal vision preoperative in comparison to 67% of group C ( p < 0.05).
Table 3. Association with value I with preoperative characteristics.
| Characteristic | Value I | p -Value | ||
|---|---|---|---|---|
| Group C (≤0.42) n (%) |
Group D (>0.42) n (%) |
|||
| Gender | Male | 10 (33.3) | 2 (9.5) | 0.113 |
| Female | 20 (66.7) | 19 (90.5) | ||
| Preoperative visual status | No visual loss | 20 (66.7) | 4 (19.0) | 0.001 |
| Partial visual loss | 6 (20.0) | 6 (28.6) | 0.478 | |
| Visual loss of ipsilateral eye | 3 (10.0) | 6 (28.6) | 0.087 | |
| Partial or complete involvement of both eyes | 1 (3.3) | 5 (23.8) | 0.056 | |
| Preoperative limb weakness | Yes | 4 (13.3) | 7 (33.3) | 0.086 |
| No | 26 (86.7) | 14 (66.7) | ||
| Preoperative headache | Yes | 18 (60.0) | 16 (76.2) | 0.227 |
| No | 12 (40.0) | 5 (23.8) | ||
| Preoperative abnormal behavior | Yes | 4 (13.3) | 0 (0.0) | 0.081 |
| No | 26 (86.7) | 21 (100.0) | ||
| Preoperative seizure | Yes | 13 (43.3) | 1 (4.8) | 0.002 |
| No | 17 (56.7) | 20 (95.2) | ||
| Preoperative third cranial nerve involvement | Yes | 0 (0.0) | 2 (9.5) | 0.085 |
| No | 30 (100.0) | 19 (90.5) | ||
| Preoperative proptosis | Yes | 2 (6.7) | 3 (14.3) | 0.368 |
| No | 28 (93.3) | 18 (85.7) | ||
Forty percent of group C had GTR, whereas approximately 43% of group D had GTR ( Table 4 ). The most common presentation in all patients was headache, 66.6%.
Table 4. Association with value I with study postoperative characteristics.
| Characteristic | Value 1 | p -Value | ||
|---|---|---|---|---|
| Group C (≤0.42) n (%) |
Group D (>0.42) n (%) |
|||
| Postoperative visual status | Stable | 29 (96.7) | 20 (95.2) | 0.777 |
| Improved | 1 (3.3) | 1 (4.8) | ||
| Postoperative limb weakness | The same | 24 (80.0) | 16 (76.2) | 0.745 |
| Improved | 0 (0.0) | 2 (9.5) | 0.085 | |
| Worse | 6 (20.0) | 3 (14.3) | 0.598 | |
| Postoperative headache | The same | 17 (56.7) | 12 (57.1) | 0.973 |
| Improved | 13 (43.3) | 8 (38.1) | 0.708 | |
| Worse | 0 (0.0) | 1 (4.8) | 0.227 | |
| Postoperative abnormal behavior | The same | 25 (83.3) | 20 (95.2) | 0.194 |
| Improved | 2 (6.7) | 0 (0.0) | 0.227 | |
| Worse | 3 (10.0) | 1 (4.8) | 0.493 | |
| Postoperative seizure | The same | 20 (66.7) | 19 (90.5) | 0.055 |
| Improved | 9 (30.0) | 1 (4.8) | 0.025 | |
| Worse | 1 (3.3) | 1 (4.8) | 0.796 | |
| Postoperative speech involvement | The same | 27 (90.0) | 18 (85.7) | 0.64 |
| Improved | 1 (3.3) | 1 (4.8) | 0.796 | |
| Worse | 2 (6.7) | 2 (9.5) | 0.709 | |
| Postoperative third cranial nerve involvement | The same | 24 (80.0) | 18 (85.7) | 0.598 |
| Improved | 1 (3.3) | 1 (4.8) | 0.796 | |
| Worse | 5 (16.7) | 2 (9.5) | 0.466 | |
| Postoperative hydrocephalus | Yes | 2 (6.7) | 1 (4.8) | 0.776 |
| No | 28 (93.3) | 20 (95.2) | ||
| Postoperative meningitis | Yes | 0 (0.0) | 2 (9.5) | 0.085 |
| No | 30 (100.0) | 19 (90.5) | ||
| WHO grades of meningioma | Grade I | 30 (100.0) | 17 (81.0) | 0.013 |
| Grade II | 0 (0.0) | 4 (19.0) | ||
| Postoperative Simpson's grades | Grade II | 16 (53.3) | 12 (57.1) | 0.788 |
| Grade III | 0 (0.0) | 2 (9.5) | 0.085 | |
| Grade IV | 14 (46.7) | 7 (33.3) | 0.341 | |
| Postoperative resection | STR | 18 (60.0) | 12 (57.1) | 0.838 |
| GTR | 12 (40.0) | 9 (42.9) | ||
Abbreviations: GTR, gross total resection; STR, subtotal resection; WHO, World Health Organization.
In summary, patients with tumors with more medial extension are mostly WHO grade I that are less likely to present with seizures; however, if seizure is present preoperatively, it is likely to improve postoperatively. More medial extension was also correlated to partial or complete visual loss in both eyes, but it was statistically insignificant.
If value II, the average of lateral extension of MSWM, 78 mm, was used as the cut-off to correlate clinical findings, then there would be no statistically significant complication except in patients with lateral extension of 78 mm or more, who had higher risk of presenting with lower limb weakness. In both groups, there were no statistically significant major postoperative complications.
Discussion
MSWM is a benign tumor; however, its location in close proximity to neurovasculature structures can limit its resection and result in postoperative complications. Sphenoid wing meningioma accounts for approximately 20% of supratentorial lesions. 4 5 Resection of this tumor is challenging and has a significant mortality rate (0–16%) due to its proximity to vital structures. 6 7 8 9 10 11 12 13 Visual acuity and visual field deficits that were caused by tumor compression rather than due to ischemia improved post tumor resection in 58% 3 of the patients in one study and in 70% 14 in these studies. In a study by Liu et al, four cases had postoperative deterioration in visual acuity, as well as in the visual field, where only gross changes in the visual field were considered significant and subtle changes were missed. 3 However, in our study, it was not found to be a statistically significant presentation or a complication.
The concept of AC line was coined by the authors to guide surgeons in predicting clinical outcomes and in anticipating surgical complications. Our rationale for using the AC line for measuring the tumor's medial extension is based on the hypothesis that the more medial the tumor to the AC line, the more likely there is invasion of neurovascular structures, and consequently, higher risk for postoperative complications. The current study did not address the relation of critical structures with the extent of resection; however, GTR was achieved in approximately 40% of the patients. We correlated radiological medial extension of MSWMs with the clinical outcome. Medial extension of the tumor did not correlate with seizures as a presenting symptom; however, patients who presented with seizures and a lesser MSWM extension were more likely to have improvement of their seizures postoperatively. Accordingly, any increase in the ratio of tumor diameter medial to the AC line in relation to the tumor as a whole does not necessitate a poor clinical outcome or an increase in postoperative complications.
In several studies, tumor size was found to affect the extent of resection. Liu et al 3 concluded that patients with large tumors have poorer clinical outcomes (vision, Karnofsky's score) and are at greater risk of complications when achieving GTR. That was attributed to the finding that ICA encasement and infiltration were commonly encountered in large tumors, which may significantly limit tumor resection. Goel et al 11 proposed a system for grading AC meningiomas, in which tumor size would predict the extent of resection. GTR was achieved in all tumors measuring less than 3 cm; however, in tumors greater than 3 cm, GTR was limited in 35.3%. In another study, Pamir et al 15 stated that tumor size should be a determinant when classifying clinical and surgical risk because tumor size larger than 2 cm was found to have an unfavorable outcome in terms of the extent of resection and outcome in comparison to tumors smaller than 2 cm due to adherence to neurovascular structures. In our study, medial extension of MSWMs from the AC line had no significant effect on GTR or visual improvement.
Limitations
There are a few limitations of our study. First, it is a retrospective cohort study that was limited to one center, and second, there were confounding factors, including the surgical approach and tumor invasion, to surrounding structures.
Generalizability
However, in our experience, we have learned that the understanding and, hence, management of MSWM has generally evolved despite its anatomical complexity as there were no statistically significant postoperative complications. These findings were contrary to the common belief that the greater the medial extension of the tumor, the greater the risk and complications of the GTR. Defying this concept and achieving GTR may decrease the risk of mortality that is increased by 4.2 folds in subtotal resection as per Kallio et al, as this high risk was attributed to the clinical status of the patients, critical location of the tumor, and the surgical techniques that were used at the time of the study. 14
Conclusion
Surgical management of MSWM continues to be a challenge. Patients with MSWMs with more medial extension (groups B and value II) are more likely to present with headache, abnormal vision, and WHO grade II meningioma. The current study suggests that the degree of medial extension of MSWMs from the AC line has no statistically significant correlation with major postoperative complications, with the extent of resection or with the clinical outcome.
Funding Statement
Funding None.
Conflict of Interest None declared.
Note
Portions of this work were presented in abstract form as an oral presentation in the North American Skull Base Society 28th Annual Meeting, Coronado, California, United States, February 17, 2018.
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