Sphenoid Wing Meningioma: Proposing Modification to Cushing Classification System Based on Results of 29 Consecutive Patients

Abstract

Introduction

Cushing and Eisenhardt first classified globoid sphenoid wing meningiomas (SWM) into medial, middle and lateral groups. The authors examined 29 consecutive patients with globoid shape SWMs that were surgically treated by the senior author (NG). Based on our results, we would like to modify Cushing's classification system of globoid SWM.

Methods

All patients who had undergone surgery at two hospitals between 2000 and 2017 were identified. All data from different tumor locations along the sphenoid ridge were compared to determine whether these tumors had different behaviors in presenting symptoms, surgical observation and post-op surgical outcomes.

Results

All 29 consecutive patients with globoid shape of SWM underwent microsurgical resection during this period. The rates of cavernous sinus (CS) invasion (medial 46.1%, lateral 0%, pterional 0%; p 0.01) and vascular encasement (medial 76.9%, lateral 36.3%, pterional 0%; p 0.008) were all highest in medial SWMs. Gross total removal (GTR) was found less in medial SWMs (medial 23%, lateral 63.6%, pterional 100%; p 0.008). Complication rate was higher in medial SWMs (medial 53.8%, lateral 18.1%, pterional 20%, p 0.04). Visual impairment was higher in medial SWMs (medial 92.3%, lateral 36.3%, pterional 40%; p 0.01).

Conclusion

The authors report different entities of meningiomas located along the sphenoid wing, including the presenting symptoms, imaging studies, microsurgical observation, extension of surgical resection, surgical outcome and surgical complication. Our results support the idea to modify Cushing's classification system.

Resumo

Introdução

Cushing e Eisenhardt classificaram inicialmente os meningiomas da asa do esfenóide (MAE) globoides em grupos medial, médio e lateral. Os autores examinaram 29 pacientes consecutivos com MAE globoides que foram tratados cirurgicamente pelo autor sênior (NG). Com base em nossos resultados, propomos modificar o sistema de classificação de Cushing para MAE globoides.

Métodos

Todos os pacientes submetidos à cirurgia em dois hospitais entre 2000 e 2017 foram identificados. Os dados de todos os tumores localizados ao longo da crista do esfenóide foram comparados para determinar se esses tumores apresentavam comportamentos distintos em relação aos sintomas, observação cirúrgica e resultados pós-operatórios.

Resultados

Todos os 29 pacientes consecutivos com MAE globoides foram submetidos à ressecção microcirúrgica durante esse período. As taxas de invasão do seio cavernoso (SC) (medial 46,1%, lateral 0%, pterional 0%; p 0,01) e de envolvimento vascular (medial 76,9%, lateral 36,3%, pterional 0%; p 0,008) foram todas maiores nos SWMs mediais. A remoção macroscópica total (RMT) foi menos frequente nos SWMs mediais (medial 23%, lateral 63,6%, pterional 100%; p 0,008). A taxa de complicações foi maior nos SWMs mediais (medial 53,8%, lateral 18,1%, pterional 20%, p 0,04). A deficiência visual foi maior nos SWMs mediais (medial 92,3%, lateral 36,3%, pterional 40%; p 0,01).

Conclusão

Os autores relatam diferentes entidades de meningiomas localizados ao longo da asa do esfenoide, incluindo sintomas de apresentação, achados de imagem, observação microcirúrgica, extensão da ressecção cirúrgica, resultados cirúrgicos e complicações cirúrgicas. Nossos resultados apoiam a ideia de modificar o sistema de classificação de Cushing.

Keywords

central nervous system neoplasms - meningioma - meningeal neoplasms - sphenoid wing

Palavras-chave

neoplasias do sistema nervoso central - meningioma - neoplasias meníngeas - asa do esfenoide

Introduction

Sphenoid wing meningiomas (SWMs) are one of the most common intracranial meningiomas.[1] Cushing and Eisenhardt first classify SWM into three categories: 1) meningiomas of the deep or clinoid third or medial sphenoid meningioma, 2) middle-ridge meningioma, 3) lateral/pterional meningiomas, which are differentiated into en plaque pterional meningiomas and globoid pterional meningiomas.[2]

Since then, many modifications of Cushing's classification system were proposed.[1] [3] [4] [5] Abdel Aziz et al.,[6] considered globoid pterional meningiomas as convexity meningiomas with significant hyperostosis. Fohanno and Bitar simply divided globoid sphenoid ridge meningiomas into two groups: medial tumors arising from the inner third of the sphenoid ridge and lateral which arise from lateral two thirds.[4] On the basis of surgical outcomes following modern surgical technique for SWM, Sughrue et al. [1] divided globoid SWM in two distinct types: medial globoid and lateral globoid tumors. These two distinct groups had different surgical challenges for neurosurgeons. The medial sphenoid wing region seem to be more difficult because the presence of important neurovascular structures such as optic and cranial nerves coursing to superior orbital fissure (SOF), cavernous sinus (CS), internal carotid artery (ICA) and its branches.[1] [7] In contrary, lateral SWMs gives mass effect and shift the sylvian fissure to the medial. Therefore, optic nerve and other neurovascular structures are less at risk.[1] Bonnal et al.[3] reported invading meningiomas of sphenoid ridge, and divided them into three groups: Group A, deep or clinoidal or sphenocavernous meningiomas en masse; Group B, invading en plaque of the sphenoid wing/pterional tumors en plaque; and Group C invading en masse which combined features of Group A and B. This classification included both en plaque and globoid tumors. Russel et al. [5] modified Cushing's classification into three groups: Group I, global medial ridge, Group II, global lateral ridge and Group III, hyperostosing en plaque. They also included both en plaque and globoid tumors.

Due to discrepancy of classification system and divergent clinical and radiological findings, comparing results across SWM studies is difficult. In our series, we only included globoid tumor of SWM with or without hyperostosis. On the basis our results, we would like to modify Cushing's classification system of globoid SWM.

Methods

This is a retrospective cohort study including patients with globoid SWM who had undergone microsurgical resection performed by senior author (NG) between 2000 and 2017 at our institution. We excluded sphenopetroclival, en plaque sphenoid wing, anterior clinoid, primary CS and optic nerve sheath meningioma. All samples had been provided informed consent and this study had been approved by local ethical committee.

Magnetic resonance imaging (MRI) with T1 and/or T2-weighted sequences with or without contrast was obtained preoperatively to identify tumor extension. The T2 sequence displayed the arachnoid plane around the tumor which can give clue adherence to the neurovascular structure. We did not perform preoperative embolization. Bone invasion was examined with bone window computed tomography (CT) scan.

Standard microsurgical technique was performed. The surgical exposure was achieved through standard pterional or frontotemporal approach and frontoorbitozygomatic approach. Hyperostotic bone was removed, allowing an ample of working space leaving minimal brain tissue retraction. The bone flap was replaced following tumor debulking and/or removal and the scalp was reapproximated.

Clinical pre- and post-operative data were retrospectively collected using medical records, radiological and pathological data from our institution. Clinical assessments were executed by senior neurosurgeon (NG). Tumor location and its classification were confirmed using T1-weighted MRI sequences with contrast preoperatively.

In this study, we classified SWMs globoid meningioma into two categories, which were medial and lateral SWMs. We defined medial SWMs as meningioma involving medial third of the sphenoid ridge and represents medial posterior to anterior projecting segment most adjacent to the anterior clinoid process. Lateral SWMs was defined as meningioma involving the external two thirds of the sphenoid ridge with the pterion closed to its lateral end. Pterional meningioma was defined as globoid tumors with hyperostosis that originate from pterion spreads to temporal bone, to the superficial temporal region. We considered pterional meningiomas convexity meningioma.

Tumor grading was assessed by a neuropathologist at our institution using the 2016 World Health Organization (WHO) classification system of Central Nervous System (CNS) Tumor. Tumor grade was classified into grade I to grade III. Radicality of resection was analyzed based on the Simpson grading scale. Simpson grade I and II were considered gross total removal (GTR). All this information was obtained from intraoperative assessment and was confirmed with post-operative MRI imaging. The definition of CS invasion was tumor infiltration into the CS. Vascular encasement was defined as 180 degrees of ICA, anterior cerebral artery (ACA), and middle cerebral artery (MCA) encasement by tumor mass. Complication was defined as new neurological deficit or other unexpected findings postoperatively and described descriptively. Visual impairment was defined as decreased visual acuity less than 6/6. Data were collected in electronic database and were analyze statistically after confirmation of accuracy.

Continuous data were presented as mean ± SD (standard deviation) and comparation was done using independent sample t-test. Categorical data was compared using Chi-square test. The statistical results were considered significant when p < 0.05.

Results

Twenty-nine patients who had undergone microsurgical resection of globoid SWMs were included in the study. The demographic data can be seen in [Table 1]. In this series, there were 13 cases of medial SWMs, 11 cases of lateral SWMs, and 5 cases of pterional meningiomas. In [Table 2], we can see that visual impairment was the highest presenting symptom in our series and mostly in medial SWMs. Other common presentations include behavioral changes and headache.

Tabel 1 Summary of characteristic of SWM with our modified classification

Characteristic	Value			%			p-value
	Medial	Lateral	Pterional	Medial	Lateral	Pterional
Mean age in yrs	48.5 ± 7.9	42.8 ± 10.9	50.4 ± 12.8				NS
Gender
Male	0	6	0	0	54.5	0
Female	13	5	5	100	45.5	100
Tumor grade
WHO I	12	8	4	92.3	72.7	80	NS
WHO II	0	3	1	0	27.2	20
WHO III	1	0	0	7.6	0	0
Radicality
GTR	3	7	5	23	63.6	100	0.008
STR	10	4	0	76.9	36.3	0
CS invasion	6	0	0	46.1	0	0	0.01
Vascular encasement	10	4	0	76.9	36.3	0	0.008
Complication	7	2	1	53.8	18.1	20	0.04
Visual impairment	12	4	2	92.3	36.3	40	0.01
Total cases	13	11	5	100	100	100

NS: Not significant; GTR: Gross total removal; STR: Subtotal removal; CS: Cavernous sinus

Tabel 2 Presenting symptoms and signs of sample

Symptoms and signs	Value				%
	Medial	Lateral	Pterional	Total	Medial	Lateral	Pterional	Total
Visual impairment	11	5	2	18	84.6	45.4	40	62
Behavioral changes	2	4	4	10	15.3	36.3	80	34.4
Ocular paresis	3	0	0	3	23	0	0	10.3
Hemiparesis	0	3	1	4	0	27.2	20	13.7
Headache	2	9	2	13	15.4	81.8	40	44.8
Seizure	0	1	0	1	0	9	0	3.4
Motoric aphasia	1	0	1	2	7.6	0	20	6.8
Proptosis	1	0	0	1	7.6	0	0	3.4

The average age of samples and tumor grade according to the WHO were not different statistically. GTR was found less in medial SWMs with 23% of GTR, compared to lateral and pterional meningioma, with 63.6% and 100%, respectively (p 0.008). As can be seen in [Table 3], GTR in lateral and medial SWMs cannot be achieved mainly because of hyperostotic bone and cavernous sinus invasion, respectively.

Tabel 3 Factors affecting radicality of tumor removal

Factor	n
Lateral SWMs
Hyperostotic bone	4 cases
Vessel encasement	1 case
Subtotal removal	4 cases
Medial SWMs
Cavernous sinus invasion	6 cases
Bone invasion	3 cases
Vessel encasement	4 cases
Subtotal removal	10 cases

The rates of CS invasion and vascular encasement were all highest in medial SWMs. In this study, we only found CS invasion in medial SWMs (medial 46.1%, middle 0%, lateral 0%; p = 0.01). Vascular encasement was found higher in medial compared to lateral SMWs with 76.9% and 36.3%, respectively (p = 0.008). We did not find vascular encasement in pterional meningioma.

The complication rate was higher in medial SWMs compared to lateral SWMs with 53.8% and 18.1%, respectively (p = 0.04). In [Table 4], we can see the complications occurring in medial SWMs include ptosis, oculomotor nerve palsy, numbness, motor paresis, and cerebrospinal fluid (CSF) leak.

Tabel 4 Postoperative complication and neurological deficit

Medial	Lateral	Pterional
Ptosis	Oculomotor nerve palsy	None
Oculomotor nerve palsy	Hydrocephalus
Numbness
Motor paresis
CSF leak

Discussion

Modification of Classification of SWMs

Cushing and Eisenhardt first classified SWM into four categories: 1) meningiomas of the deep or clinoid third or medial sphenoid meningioma, 2) middle-ridge meningioma, 3) en plaque pterional meningiomas, and 4) globoid pterional meningioma. These categories are based on the clinical manifestation, intraoperative findings, and postmortem examinations.[1] Although Cushing's classification remains the most valid, modification that incorporates information and experiences obtained from presenting symptoms, imaging studies/MRI, microsurgical observation and surgical outcomes were warranted.

Based on the 17 years of experience of our senior author (NG) who have surgically treated 29 patients with globoid SWMs, we proposed a modification of Cushing's classification system. In this modification we only included globoid tumors with or without bone invasion, excluding en plaque hyperostosis masses. Based on clinical presentations, MRI findings, microsurgical observation, extend of resection and postoperative complications of 29 consecutive patients, we divided the SWMs into two major groups: Group I, globoid medial tumor; and Group II, globoid lateral tumors ([Figs. 1] and [2])

Fig. 1 Preoperative axial T1W MRI imaging with gadolinium contrast (A) Pterional meningioma; (B) Lateral SMWs; (C) Medial SWM with cavernous sinus invasion.

Fig. 2 Preoperative T1W MRI imaging with gadolinium contrast of medial SWM without cavernous sinus invasion. (A) coronal section, and (B) axial section.

Three modifications of Cushing's classification system were made. First, Cushing's globoid pterional group (group IV of Cushing's classification) is removed because these tumors are mimicking convexity meningioma according to clinical manifestation, surgical management and radicality.[1] [6] From an anatomical point of view, lateral end of the sphenoid ridge flares out and joins the frontal, parietal, and temporal bone which is called the pterion.[4] [8] At the end, some globoid tumors of lateral SWM are considered convexity meningiomas.[1] Abdel azis et al. [6] also considered pterional meningiomas to be convexity meningiomas with significant hyperostosis. We redefined pterional meningioma as globoid tumors with hyperostosis/bone invasion that originate from pterion spreads to temporal bone, to the superficial temporal region ([Fig. 1A]). After removing all hyperostotic bone from pterion to temporal bone, we transform the pterional meningioma into convexity one.

The clinical presentations of pterional meningiomas in our series are significantly different from those of medial and lateral groups, which mostly caused brain tissue compression by tumor mass ([Table 2]). Imaging findings and confirmed by surgical observation, none of the pterional meningiomas in our series encased major vessels ([Fig. 3C]). The hyperostosis of these tumors did not involve the skull base structures. With regards to the extent of resection, pterional meningiomas in our series 100% was GTR, and this is significantly different from those of medial and lateral groups of our modified classification ([Figs. 3] and [4]). Guduk et al. [2] reported 100% GTR of lateral sphenoid meningiomas in their cases. Postoperative complication of pterional meningioma in our series was significantly lower compared to medial and lateral groups ([Table 1]).

Fig. 3 Intraoperative photograph of pterional meningioma showing that after removing all of hyperostotic bone, the tumor changes to convexity meningioma. (A) Hyperostotic bone was being removed. (B) The dura mater was clearly exposed after removal of hyperostotic bone. (C) The tumor was completely removed and there was no involvement of neurovascular structure.

Fig. 4 Imaging of pterional meningioma. (A) Preoperative T1W MRI with gadolinium contrast and (B) Postoperative head CT scan.

Second, Cushing's globoid middle group also was removed, and it was replaced by globoid lateral group, involving the external two third of the sphenoid ridge with lateral end just close to the pterion (not including the pterional region of the cranial vault) ([Fig. 1B]). This lateral group is in agreement with Fahanno and Bitar division who define lateral as two third lateral of the sphenoid ridge.[4] With regards to surgical radicality, Guduk et al. [2] reported similar GTR rate between lateral and middle SWM. This finding supported our idea to remove the middle group from SWM. Based on imaging findings and surgical observation, lateral globoid tumors present with hyperostosis spreading distally and invading all part of sphenoid greater wing and could extend beyond their limits to middle skull base. They also could encase major blood vessels. In our series, 4 of 11 cases encased the major anterior cerebral vessels.

Third, we divided medial globoid tumors into two subgroups: IA, globoid medial tumor without CS invasion (7 cases) ([Fig. 2]) and IB, globoid medial tumors with CS invasion (6 cases) ([Fig. 1C]). This subgroup was generated because different surgical treatment regarding CS invasion. In CS invasion tumor, often only intradural tumor was removed and leaving remnant in the CS, which was usually observed or radiated. Tumors without CS invasion were mostly gross total removed. Nakamura et al. [7] also divided medial SWM into two subgroups based on CS invasion. Other study by Russel et al.[5] also divide medial SWM into two subgroups in their report.

In agreement with Cushing's classification, we defined a globoid medial SWM as meningioma arising from the medial third of the sphenoid ridge and represents the medial posterior to anterior projecting segment most adjacent to the anterior clinoid process ([Fig. 1C]).[1] This globoid tumor encases the ICA (partially or completely) and its main branches, which differentiate them from other parasellar meningioma.[1] In our cases, 10 of 13 medial group (76.9%) encased ICA and its main branches. Furthermore, the location medial SWMs is close to the important neurovascular structure including oculomotor, trochlear, and ophthalmic nerve coursing to superior orbital fissure or the lateral wall of CS. Therefore, postoperative cranial nerve palsies were higher compared to lateral. In our series, 5 patients in the medial group presented with ocular paresis.

Al-Mefty reported that anterior clinoid meningiomas must be grouped separately from medial SWM because they have a unique behavior.[9] However, Risi et al. still included anterior clinoid meningioma into medial SWM with 3 subgroups; pure clinoidal, clinoidal with lateral extension, and clinoidal with CS invasion.[10] Lee et al. also included their pure anterior clinoid meningioma into medial SWM.[11] We did not classify the anterior clinoid meningioma as medial SWM, because our observation and experience delineated that medial SWM somewhat differed from the anterior clinoid meningioma. We also excluded optic canal meningioma, primary cavernous sinus meningioma with large global component displacing the intradural vascular structure and tumor on anterior fossa skull base involving superior aspect of the sphenoid ridge.

Presenting Symptoms

Importantly, medial SWMs are known for its location which close to ipsilateral optical nerve and apparatus. Therefore, visual compromise is predominantly a feature of the medial group and decrease in frequency in lateral SWMs.[1] [7] [12] As the tumor origin moves laterally, symptoms become less visual and was more the result of of mass effect causing brain compression.[1] Our series also demonstrates that medial tumors predominate visual impairment ([Table 1]). Twelve of 13 cases of medial tumors presented with moderate to severe visual deterioration (nonlight perception), while in lateral tumors, four of 11 cases presented with light to moderate visual impairment ([Table 1]). Al-Mefty et al. reported 86% of visual impairment in anterior clinoid meningioma.[9] Risi et al. reported 59% of preoperative visual impairment in medial SWMs.[10] Nakamura et al. reported 66.7% of visual impairment in medial SWMs without CS involvement and 60.9% with CS involvement.[7] Russel et al. [5] reported 30 of 35 (86%) globoid medial sphenoid meningioma presents with decreased visual acuity and/or visual field loss. Chaichana et al. [12] reported 55% visual declining in 65 patients with globoid SWM. Ocular motor paralysis also commonly occurred in medial tumors.[7] In our series, 3 (50%) ocular paresis occurred in medial tumor with CS invasion. Nakamura et al.[7] reported 30.4% ocular paresis occurred in the medial group with CS invasion compared with only 5.1% without CS invasion.

Factors Affecting Extent of Resection

Each tumor that arises along the sphenoid ridge has its own surgical challenges. The surgical challenges of medial SWMs present the most surgical problem for neurosurgeons because of their relation to the optic apparatus, vascular structure (anterior circulation), optic canal and CS.[1] [2] [13] In contrast, lateral SWMs shift the sylvian fissure and provide less risk to the optic nerve.[1]

The resection of medial SWM involving CS is associated with high mortality and morbidity, because of damaging blood vessel and cranial nerve.[13] [14] [15] The involvement of CS has been reported the main factor of removing the tumor subtotally.[1] [2] [3] [7] [16] Nakamura reported the rate of GTR of medial SWM was 92.3% without CS involvement and 14.5% with CS involvement.[7] Russel reported only 1 (9%) of 11 patients had GTR of medial SWM with CS invasion and 79% had GTR in pure intradural tumor.[5] Abdel et al.[6] reported 38 cases of large medial SWMs involving the cavernous sinus. They recommend that total resection of this tumor should not be attempted, specifically when there is invasion of CS. This recommendation is made to reduce the morbidity and use the efficacy of salvage radiotherapy. Skull base meningiomas is reported recur more frequently than convexity one. However, Russel et al.[5] reported that conservative approach in managing CS tumor extension in medial SWM did not lead to poor outcome in the long term (average 12.8 years). The surgical management of CS meningioma invasion has been continuously debated and remains controversial. In our series, 6 of 13 medial tumor invaded the CS and only the intradural tumor part was removed, not the intracavernous portion.

Major vessel encasement is also a surgical challenge for neurosurgeons because they increase the risk of vascular injury.[1] [2] [7] [14] [15] McCracken described a deadly triad which include complete encasement of the supraclinoid ICA, M1 and A1 segments. The deadly triad represents a definitive indication for subtotal removal and leave tumor remnant to prevent vessel injury.[15] Therefore, vessel encasement was also a factor of incomplete tumor removal. Nakamura reported 71.8% and 91.3% vessel encasement in the medial group tumor with and without CS invasion respectively.[7] Arachnoid planes between tumor and adjacent vessels has been shown to be an important factor affecting complete removal of meningiomas with vessel encasement ([Fig. 5A]).[15] Therefore, our strategy in vessel encasement cases was explore the presence of arachnoid plane so it can be easily removed from the vessels ([Fig. 5B]). When there is a lack of arachnoid plane between the vessel and the tumors, shave down the residual tumor to leave tumor remnant as small as possible. Four of 10 medial tumors with vessel encasement had a lack of arachnoid plane. Therefore, small remnant tumor was left behind ([Fig. 5A]). Sughrue et al. hypothesize that many of these tumor remnants were undergoing growth resting and remain dormant for long time.[16] Another group report vascular injury exceeding 20% when effort was made to dissect the adherent tumor from encased vessels.[14] McCracken reported 76% of some degree of ischemic change to infarct on 75 patients with SWMs with vessel encasement.[15] As the degree of vessel encasement is increased, the risk of vascular injury would also increase and lead to worsened surgical outcome secondary to ischemia.[15] Therefore, it is a wise decision to keep small tumor remnant to avoid vascular injury.[4] [16]

Fig. 5 The Difference in GOS-E Scores Between the Treatment and Control Groups Intraoperative microscopic view (A) A small remnant tumor that strongly attached to ACA in a patient with medial SWM was left behind. (B) Vessel encasement of ACA, ICA, and MCA were well preserved and free from residual tumor in a patient with medial SWM. (C) With delicate manipulation during surgical procedure, the third nerve was well exposed and preserved and free from residual tumor. NII: optic nerve, NII: oculomotor nerve, ICA: internal carotid artery, MCA: middle cerebral artery, ACA: anterior cerebral artery.

Hyperostosis or bone invasion could be occurred in all types of SWMs, including globoid, en plaque, lateral and tumor with CS invasion.[2] [3] [7] [13] Bone invasion has an impact on the surgical extension. Complete resection of SWMs with bone infiltration is even more challenging because adjacent periorbita, dura sheath of optic nerve and superior orbital fissure were also invaded.[13] Roser et al. [13] observed GTR was 38% of SWMs with osseous involvement and 46% without osseous involvement. On the other side, the removal of hyperostosis bone provides an ample of additional space for removing globoid intradural tumor and control of arterial feeders extradurally.[6] [17] Our strategy for hyperostotic bone was selective removal of the sphenoid wing, opening optic canal, SOF and in some cases opening the rotundum, ovale and spinosum foramina. Unfortunately, in medial and lateral tumors, not all hyperostotic bone can be grossly removed, because some tumors also infiltrate dural sheath of optic canal and SOF. In our series, hyperostosis was also a factor to subtotally removed this tumor (medial and lateral groups).

Extent of Resection Postoperative Complication

The total resection rate for medial tumors ranges from 23 to 50%.[7] The presence of CS invasion had been identified as the main factor of lower rate of GTR.[2] [6] [7] Nakamura et al.[7] reported the rate of GTR was 92.3% in medial SWMs without CS invasion vs 14.5% with CS invasion. Similar result was reported by Russel and Benjamin.[5] The rate of GTR in medial tumors in our series was 23.0% (3/13). This lower rate was due to combination of CS invasion (6 cases), vessel encasement (4 cases), and bone invasion (3 cases). In lateral tumors, GTR was 63.5% (7/11 cases). Partial removal was due to hyperostotic bone (4 cases) and vessel encasement (1 case).

Postoperative Complication

Sughrue et al. reported postoperative neurological deficit was higher in medial third tumors even in the modern surgery.[1] Our strategy to minimize this morbidity is to use less cautery at the tentorial junction in the entry site of oculomotor nerve to oculomotor triangle ([Fig. 5C]). Although with this precaution and avoiding CS, we observed 20.6% permanent third nerve palsies in our cases and they all occur in medial third tumors. Similar rates have been reported by other authors. Abdel Azis et al. reported 16% cranial nerve palsies in their series.[6] Langevin et al. [18] observed 15.8% diplopia in their cases. These similarities suggest that understanding of the tumor relationship with tentorium and lateral wall of CS is needed to reduce the rates of third nerve palsies in more difficult cases.

Conclusions

Our results support the idea to modify the globoid sphenoid wing meningioma classification into 2 major distinct groups, rather than 3. Group I, globoid medial tumors; Group 2, globoid lateral tumors. The medial group was further divided into two subgroups: Group IA, Globoid medial tumor without CS invasion; Group IB, Globoid medial tumors with CS invasion. This modified classification should be used as guidance during informed consent and surgical planning of tumor resection.

Conflict of Interest

There is no conflict of interest to disclose.

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Publication History

Received: 06 September 2025

Accepted: 10 November 2025

Article published online:
29 December 2025