Falx Meningioma

Neurosurgery Department, University General Hospital of Alicante, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), Alicante, Spain

Falx or falcine meningioma, as defined by Harvey Williams Cushing, is a intracranial meningioma arising from the falx cerebri and completely concealed by the overlying cortex 1).

Not involving the superior sagittal sinus.

Falcine meningiomas account for 9% of all intracranial meningiomas.

Falcine meningioma tends to grow predominately into one cerebral hemisphere but is often bilateral, and in some patients the tumor grows into the inferior edge of the sagittal sinus.

The patients with falcine meningiomas with reference to gender had the following ratio of male:female of 1:2.1 and an average age of 55 years.

In the series of Pires de Aguiar et al 1:6 (men:women) relationship, and the mean age was 55.4 years old 2).

They can be divided into anterior, middle, and posterior types, depending on their origin in the falx 3).

The anterior type extends from the floor of the anterior cranial fossa to the coronal suture, the middle type from the coronal suture to the lambdoid suture, and the posterior type extends from the lambdoid suture to the torcular Herophili.

Falx meningioma of the anterior third

Falx meningioma of the middle third

Falcine meningioma of the posterior third.

Yasargil classified falcine meningiomas into outer and inner types. The former arise from the main body of the falx in the frontal (anterior or posterior), central parietal, or occipital regions, whereas inner falcine meningiomas arise in conjunction with the inferior sagittal sinus4).

Zuo et al classified FM into four types, according to tumour growth patterns on coronal MRI: Type I, hemispheroid-shaped tumours invaginating deeply into one hemisphere without shifting the falx (10 patients); Type II, olive-shaped tumours shifting the falx substantially to the contralateral side (six patients); Type IIIA, globular- or dumbbell-shaped tumours extending into both hemispheres, but to different extents (one patient); and Type IIIB, globular- or dumbbell-shaped tumours extending into both hemispheres to approximately equal extent (three patients). An ipsilateral interhemispheric approach was performed for Type I tumours, and a contralateral transfalcine approach for Type II. Type IIIA tumour was approached from the side where the smaller tumour was located. Type IIIB tumours were approached from the non-dominant hemisphere 5).

Das et al. proposed a new classification schema:

Thirty-five patients with FM (mean age, 50.03 years; male/female ratio, 16:19) were classified into unilateral conventional (type I; n = 17), unilateral high (type II; n = 9) and bilateral FM (type III; n = 9) based on the coronal magnetic resonance imaging findings. We excluded the primary parasagittal meningiomas from our analysis.

Type II and III tumors were more common in males (unlike the overall cohort), presented more often with seizures, and were associated with less favorable postoperative outcomes. Preoperative motor weakness was almost exclusively seen with the unilateral tumors (type I/II). Preexisting weakness (P = 0.02) was a strong predictor of the likelihood of postoperative motor power worsening, the major surgical complication in our series (n = 9; 25.7%). New-onset postoperative weakness (n = 2) recovered completely, whereas worsening of the preexisting weakness showed only a partial improvement (n = 6).

The proposed classification scheme characterizes FMs comprehensively. Bilaterality and parasagittal extensions in FMs affect their clinical presentation, increase surgical difficulty, and influence the surgical outcome adversely. Preexisting motor weakness portends a poor postoperative motor outcome 6).

see also cystic falx meningioma.

Symptoms can vary depending upon the location of these tumors along the falx.

Those located in the frontal section may impair higher levels of brain functioning such as reasoning and memory, while those located in the middle section would be more likely to cause leg weakness.

In the series of Chung et al. at presentation, symptom durations were found to vary widely. Twenty-one patients (30%) presented with headache, and eleven (16%) with unilateral motor weakness. Five (7%) patients had a chief complaint of a seizure history. Five (7%) patients presented with personality change and four (6%) were asymptomatic and their brain tumors were detected incidentally 7).

MRI with and without gadolinium helps better to delineate the tumor in relation to the dural sinus, the tumor interface with the cerebral cortex, presence of significant blood supply, and presence of cysts or other intra-tumoral structures that will add to the complexity and malignant potential of the tumor. Good pre-operative evaluation of falcine meningiomas is also important when integrated with neuronavigation protocols to be utilized in the operating room. Furthermore, the junction between tumor and adjacent brain suggests the presence or absence of an accessible arachnoid plane and enables the surgeon to predict the potential degree of neurologic deficit that may follow surgical removal. Gadolinium-enhanced MRI allows demonstration of tumoral or adjancent dural enhancement. The radiological appearance affords a valid predictor of the degree of dural involvement in the region of the sinus and adjacent falx. This may suggest the presence of syncytium of meningeal cells spreading along the falx from the site of major dural attachment.

Multiplanar MRI is the current standard study for the preoperative evaluation of patients with falcine meningiomas. Coronal, sagittal, and axial T1-weighted gadolinium-enhanced sequences help define the anatomical locations, sizes, and medial hemisphere involvements of these tumors.

MR venography in vertex view can be useful for demonstrating nearby parasagittal draining veins, which must be protected 8) , but MRA alone seems to be inadequate in the lack of venous phase of cerebral vasculature around tumors.

Cerebral angiography

Cerebral angiography is necessary in patients with these meningiomas, and the pericallosal artery is often displaced and may actually be engulfed by the tumor. Arterial phase cerebral or MR angiograms should be studied to determine the relationship between tumor and ACA. Anterior falcine meningiomas are usually supplied by the ACA or by a tentorial branch of the ophthalmic artery. Venous phase cerebral angiography is important because it provides significant information about whether a tumor mass has invaded the sagittal sinus. Moreover, it provides information about the courses of many large drainers around a mass, which must be determined to identify trajectory to a falcine mass and to prevent postoperative venous infarction. It is also useful for determining sinus patency and for delineating the anatomical location of the major cortical draining vein. Signs of venous occlusion include the disappearance of a segment of the superior sagittal sinus (SSS), a delay in venous drainage in the area of obstruction, and failure of the cortical vein to reach the sinus.

Falx meningioma differential diagnosis.

see Falx meningioma treatment.

The falcine meningiomas may be present with bleeding as intraparenchymal hematomas, subdural hematomas and subarachnoid hemorrhage, causing a clinical finding of apoplexy in the patients.

Hemorrhages occurring in asymptomatic falcine meningiomas are known beforehand to have been described after the internal use of low-dose aspirin for prolonged period.

During falcine meningioma surgery, we must pay attention to cardiac monitoring due to the risk that the handling of falx and tentorium could provoke cardiac asystole. The mechanical stimulation of the falcine area may result in the hyperactivity of the trigeminal ganglion, thereby triggering TCR.

The dorsal region of the spinal trigeminal tract includes neurons from hypoglossal and vagus nerves, and projections have been seen between the vagus and trigeminal nuclei.

It has been reported that parasagittal meningioma and falx meningiomas recur more frequently than other intracranial meningioma9).

The rate of recurrence of falx meningiomas significantly increases in cases of non-radical resection of tumor. Aggressive surgical treatment obviously may present several hazards and may carry an increased risk of unsatisfactory outcome; however, the risk of recurrence is significantly decreased 10).

Abou Al-Shaar et al. have utilized brachytherapy as a salvage treatment in two patients with a unique implantation technique. Both patients had recurrence of WHO Grade II falcine meningiomas despite multiple prior surgical and RT treatments. Radioactive I-125 seeds were made into strands and sutured into a mesh implant, with 1 cm spacing, in a size appropriate to cover the cavity and region of susceptible falcine dura. Following resection the vicryl mesh was implanted and fixed to the margins of the falx. Implantation in this interhemispheric space provides good dose conformality with targeting of at-risk tissue and minimal radiation exposure to normal neural tissues. The patients are recurrence free 31 and 10 months after brachytherapy treatment. Brachytherapy was an effective salvage treatment for the recurrent aggressive falcine meningiomas in two patients 11).

Parasagittal and falx meningiomas 1970 by P. C Gautier-Smith (Author)

Publisher: Appleton-Century-Crofts (1970) Language: English ISBN-10: 0407352406 ISBN-13: 978-0407352407

Falx meningioma case series.

see Falx meningioma case reports


Cushing H, Eisenhardt L. Their Classification, Regional Behavior, Life History, and Surgical End Results: The chiasmal syndrome, in Meningiomas. Suprasellar Meningiomas. 1938:224–49.
2) , 10)

Pires de Aguiar PH, Aires R, Maldaun MV, Tahara A, de Souza Filho AM, Zicarelli CA, Ramina R. Is sagittal sinus resection in falcine meningiomas a factor of bad surgical outcome? Surg Neurol Int. 2010 Oct 25;1:64. doi: 10.4103/2152-7806.71983. PubMed PMID: 21125007; PubMed Central PMCID: PMC2980903.

Al-Mefty O, Becker DP, Lanman TH. Meningiomas. 1991. pp. 345–356.

Yasargil MG. Microneurosurgery. Vol 4. 1996. Meningioma; pp. 134–165.

Zuo FX, Wan JH, Li XJ, Qian HP, Meng XL. A proposed scheme for the classification and surgical planning of falcine meningioma treatment. J Clin Neurosci. 2012 Dec;19(12):1679-83. doi: 10.1016/j.jocn.2012.01.034. Epub 2012 Oct 6. PubMed PMID: 23047062.

Das KK, Gosal JS, Sharma P, Mehrotra A, Bhaisora K, Sardhara J, Srivastava A, Jaiswal AK, Kumar R, Behari S. Falcine Meningiomas: Analysis of the Impact of Radiologic Tumor Extensions and Proposal of a Modified Preoperative Radiologic Classification Scheme. World Neurosurg. 2017 Aug;104:248-258. doi: 10.1016/j.wneu.2017.04.159. Epub 2017 May 3. PubMed PMID: 28478253.

Chung SB, Kim CY, Park CK, Kim DG, Jung HW. Falx meningiomas: surgical results and lessons learned from 68 cases. J Korean Neurosurg Soc. 2007 Oct;42(4):276-80. doi: 10.3340/jkns.2007.42.4.276. Epub 2007 Oct 20. PubMed PMID: 19096556; PubMed Central PMCID: PMC2588203.

Alvernia J, Sindou M. Preoperative neuroimaging findings as a predictor of surgical plane of cleavage : Prospective study of 100 consecutive cases of intracranial meningioma. J Neurosurg. 2004;100:422–430.

Melamed S, Sahar A, Bellar AJ. The recurrence of intracranial meningiomas. Neurochirurgia. 1979;22:47–51.

Abou Al-Shaar H, Almefty KK, Abolfotoh M, Arvold ND, Devlin PM, Reardon DA, Loeffler JS, Al-Mefty O. Brachytherapy in the treatment of recurrent aggressive falcine meningiomas. J Neurooncol. 2015 Aug 8. [Epub ahead of print] PubMed PMID: 26253325.

Middle cerebral artery M4 segment aneurysm

Middle cerebral artery M4 segment aneurysm

Middle cerebral artery aneurysms, are mainly found in the proximal and bifurcation tracts and only in the 1.1-1.7% of cases they are located in the M4 segment of the middle cerebral artery 1) 2) 3).

Generally, these aneurysms are secondary to traumatic brain injury and inflammatory or infectious diseases and only rarely they have idiopathic origin 4).

At present, only nine cases of ruptured cortical middle cerebral artery aneurysms have been described in literature 5) 6) 7) 8) 9) 10).

The patients are all males, except the case of Ricci et al. 11). The average age of the reported patients is 40 years. The size of the aneurysms is between 1 mm and 10 mm and, in most cases, they are saccular intracranial aneurysms or fusiform morphology. In five patients, the aneurysms present infectious etiology. Usually, they occur with ICH, sometimes associated with subarachnoid hemorrhage (SAH).

The endovascular treatment (EVT) has been performed in four cases, while the surgical treatment has been performed in three cases (two of trapping and one of clipping). In one patient, the infectious aneurysm has resolved spontaneously after antibiotic therapy. In all treatments performed, the patients have improved the neurologic symptoms and no residual aneurysms have been observed in the subsequent neuroradiology follow-up 12). Although surgery remains the main choice in the M4 aneurysms, because of the extremely distal location of them over the motor/somatosensory cortices, 13) Lv et al. 14) propose the use of the EVT in all types of the M4 aneurysms, especially after the surgery, when it is impossible to locate the small ruptured aneurysm.

The main difficulty of the surgery is the precise surgical localization of the small M4 aneurysms 15). An inaccurate localization of these vascular lesions may result in larger craniotomies and unnecessary arachnoid and pial dissections with possible resultant permanent neurological injuries 16).

In cases of aneurysms or arteriovenous malformations located at the sylvian point or at the posterior superior aspect of the insula, especially in dominant hemisphere, to reduce the dissection and open easily sylvian fissure, a logical path would follow the angular artery in the sylvian fissure cutting the arachnoid fibers and retracting only the tissues which are necessary to gain more exposure of the lesion 17).

A case of a ruptured dissecting pseudoaneurysm in the distal Middle cerebral artery (distal M3/proximal M4) prefrontal division in an healthy young patient (<60 years) successfully treated with a Pipeline Embolization Device. The PED was chosen both as the only vessel sparing option in the young patient as well as for its potential as a vessel sacrifice tool if the pseudoaneurysm was felt to be incompletely treated, which in this case was not necessary-though would have leveraged the thrombogenicity of the device as a therapeutic advantage 18).


A 53-year-old female was admitted with a sudden severe headache, nausea, vomiting, and a slight left hemiparesis. The computed tomography (CT) scan showed subarachnoid hemorrhage (SAH) in the left sylvian fissure and intracerebral hemorrhage (ICH) in the left posterior parietal area. The CT angiography (CTA) reconstructed with 3D imaging showed a small saccular aneurysm in the M4 segment in proximity of the angular area. A left parieto-temporal craniotomy was performed, the aneurysm was clipped and the ICH evacuated. The motor deficit was progressively recovered. At 3-month follow-up examination, the patient was asymptomatic and feeling well.

Surgery is the best choice for the treatment of ruptured M4 aneurysms with ICH in the opinion of Ricci et al., because it allows to evacuate the hematoma and to exclude the aneurysm from the intracranial circulation. In addition, we suggest both the use of the neuronavigation technique and of the indocyanine green videoangiography (ICGV) for the aneurismal surgery 19).


A 41-year-old man presented with an infarction manifesting as left-sided weakness and dysarthria. Magnetic resonance angiography revealed a subacute stage infarction in the right MCA territory and complete occlusion of the right ICA. Angiography demonstrated aneurysmal dilatation of the M4 segment of the right MCA. Surgery was performed to prevent hemorrhage from the aneurysm. The aneurysm was proximally clipped guided by Navigation-CT angiography and flow to the distal MCA was restored by superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis 20).


A 20-year-old man with an intracerebral haemorrhage due to a ruptured aneurysm, which arose from a penetrating artery of the distal middle cerebral artery (MCA; M4 segment). Excision of the aneurysm was successfully achieved via a right pterional approach. The follow-up angiogram demonstrated filling of the parent vessel and no residual aneurysm. This report illustrates the angiographical finding of a penetrating artery aneurysm of the distal MCA and summarizes the previous reports to discuss their pathological and clinical characteristics 21).

1) , 4) , 5) , 21)

Ahn JY, Han IB, Joo JY. Aneurysm in the penetrating artery of the distal middle cerebral artery presenting as intracerebral haemorrhage. Acta Neurochir (Wien). 2005 Dec;147(12):1287-90; discussion 1290. Epub 2005 Aug 29. PubMed PMID: 16133768.
2) , 8) , 14)

Lv N, Zhou Y, Yang P, Li Q, Zhao R, Fang Y, Xu Y, Hong B, Zhao W, Liu J, Huang Q. Endovascular treatment of distal middle cerebral artery aneurysms: Report of eight cases and literature review. Interv Neuroradiol. 2016 Feb;22(1):12-7. doi: 10.1177/1591019915617317. Epub 2015 Dec 3. Review. PubMed PMID: 26637241; PubMed Central PMCID: PMC4757379.

Elsharkawy A, Lehečka M, Niemelä M, Billon-Grand R, Lehto H, Kivisaari R, Hernesniemi J. A new, more accurate classification of middle cerebral artery aneurysms: computed tomography angiographic study of 1,009 consecutive cases with 1,309 middle cerebral artery aneurysms. Neurosurgery. 2013 Jul;73(1):94-102; discussion 102. doi: 10.1227/01.neu.0000429842.61213.d5. PubMed PMID: 23615110.

Horiuchi T, Tanaka Y, Takasawa H, Murata T, Yako T, Hongo K. Ruptured distal middle cerebral artery aneurysm. J Neurosurg. 2004;100:384–8.

Lee SM, Park HS, Choi JH, Huh JT. Ruptured mycotic aneurysm of the distal middle cerebral artery manifesting as subacute subduralhematoma. J Cerebrovasc Endovasc Neurosurg. 2013;15:235–40.
9) , 13) , 15) , 16)

Raza SM, Papadimitriou K, Gandhi D, Radvany M, Olivi A, Huang J. Intra-arterial intraoperative computed tomography angiography guided navigation: a new technique for localization of vascular pathology. Neurosurgery. 2012 Dec;71(2 Suppl Operative):ons240-52; discussion ons252. doi: 10.1227/NEU.0b013e3182647a73. PubMed PMID: 22858682.
10) , 11) , 12) , 19)

Ricci A, Di Vitantonio H, De Paulis D, Del Maestro M, Raysi SD, Murrone D, Luzzi S, Galzio RJ. Cortical aneurysms of the middle cerebral artery: A review of the literature. Surg Neurol Int. 2017 Jun 13;8:117. doi: 10.4103/sni.sni_50_17. eCollection 2017. PubMed PMID: 28680736; PubMed Central PMCID: PMC5482160.

Ausman JI, Diaz FG, Malik GM, Tomecek F. A new microsurgical approach to cerebrovascular lesions of the sylvian point: report of two cases. Surg Neurol. 1990 Jul;34(1):48-51. PubMed PMID: 2360163.

Berwanger RP, Hoover MC, Scott JA, DeNardo AJ, Amuluru K, Payner TD, Kulwin CG, Sahlein DH. The Use of a Pipeline Embolization Device for Treatment of a Ruptured Dissecting Middle Cerebral Artery M3/M4 Aneurysm: Challenges and Technical Considerations. Neurointervention. 2022 Apr 7. doi: 10.5469/neuroint.2022.00045. Epub ahead of print. PMID: 35385900.

Lee SH, Bang JS. Distal Middle Cerebral Artery M4 Aneurysm Surgery Using Navigation-CT Angiography. J Korean Neurosurg Soc. 2007 Dec;42(6):478-80. doi: 10.3340/jkns.2007.42.6.478. Epub 2007 Dec 20. PubMed PMID: 19096593; PubMed Central PMCID: PMC2588183.

Foramen ovale

Foramen ovale

Oval opening in the greater wing of sphenoid bone transmitting the mandibular nerve as its major content.

It serves as an important landmark for neurosurgeons in certain procedures as to gain access to trigeminal nerve.

Therefore, its topographic position in relation to adjacent bony landmarks provides useful tool during these procedures.

Morphometric analysis was carried out on 104 foramina ovalia of 52 dry human skulls from South India. Following dimensions of foramen ovale were measured: antero-posterior length, transverse width, distance (d(1)) from tubercle of root of zygoma to the centre of the foramen (CF) and distance (d(2)) from the midline of the base of the skull to CF. Results: The mean antero-posterior length was 7.0±2.17mm on right side and 6.8±1.40mm on left side, mean transverse width was 5.0±0.42mm and 4.70±0.91mm on right and left side respectively. Mean d(1) was 32.58±1.72mm on right side and 32.75±1.76mm on left side. Mean d(2) was 25.83±1.26mm on right side and 25.08±1.31mm on left side. Conclusion: Regional variations in the morphometric measures may be useful in neurosurgical procedures like administration of anaesthesia involving the mandibular nerve 1).

The aim of a study is to objectively describe the shape of the FO and its most likely shape variation. A total of 211 FO were evaluated by geometric morphometric analysis. A consensus shape is presented for the FO. No significant difference was found between the shapes of left- and right-sided FO. The most likely shape variation of the FO occurs as an inverse relationship between the anteromedial-posterolateral and anterolateral-posteromedial aspects of the foramen. The capacity to visualize the average FO shape and understand the most likely shape variance, as illustrated by Zdilla et al., will aid neurosurgeons in their approach to procedures requiring cannulation of the FO 2).

Anatomical variations can occasionally result in unexpected findings on physical examination. McDonough et al. from the Tulane Center for Clinical Neurosciences reported two cases of seemingly unique connections between maxillary nerve (V2, sensory) and mandibular nerve (V3, motor and sensory) branches parts of the trigeminal nerve. In these two cadaveric specimens, at the foramen ovale, small neural connections, confirmed with histology, were identified joining V2 to specifically, the motor root of V3 3).

see Patent foramen ovale.

see Foramen ovale puncture.


Patil J, Kumar N, K G MR, Ravindra S S, S N S, Nayak B S, Marpalli S, L S A. The foramen ovale morphometry of sphenoid bone in South Indian population. J Clin Diagn Res. 2013 Dec;7(12):2668-70. doi: 10.7860/JCDR/2013/7548.3727. Epub 2013 Dec 15. PubMed PMID: 24551606.

Zdilla MJ, Fijalkowski KM. The Shape of the Foramen Ovale: A Visualization Aid for Cannulation Procedures. J Craniofac Surg. 2016 Dec 23. doi: 10.1097/SCS.0000000000003325. [Epub ahead of print] PubMed PMID: 28027173.

McDonough S, Olewnik Ł, Iwanaga J, Dumont AS, Tubbs RS. Connection between V2 and V3 parts of the trigeminal nerve at the internal cranial base. Folia Morphol (Warsz). 2022 Apr 5. doi: 10.5603/FM.a2022.0031. Epub ahead of print. PMID: 35380015.
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