Not involving the superior sagittal sinus.
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).
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.
Falcine meningioma of the anterior third
Falcine 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 sinus. 4).
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).
see also cystic falx meningioma.
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.
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 6) , but MRA alone seems to be inadequate in the lack of venous phase of cerebral vasculature around tumors.
Although rare, marginal zone B-cell lymphoma must be considered in the differential diagnosis of an extra-axial enhancing mass 7).
A 43-year-old man arrived at the emergency department following a syncopal episode. Computed tomography and magnetic resonance images demonstrated a small interhemispheric, anterior parafalcine mass that mimicked a meningioma. Surgical excision and subsequent pathologic evaluation revealed an angioleiomyoma and the patient recovered without incident 8).
Cushing and Eisenhardt used a transcortical incision to expose most falcine meningiomas. However, current microsurgical techniques and methods have improved intracranial compliance, including cerebrospinal fluid drainage, mannitolization, and hyperventilation, and a transcortical approach is rarely required 9).
The dura is opened to I to 2 cm from the midline, with the exposure planned in relation to the cortical veins draining to the sagittal sinus. Arachnoid and pacchionian granulation attachments are divided. It is only necessary to retract the medial cerebral cortex I to 2 cm from the falx to expose the tumor. In some cases a bridging vein can be freed from the cortex for a few millimeters to give the required exposure without sacrificing the vein. A selfretaining retractor is placed. In the anterior third it is usually possible to take the draining veins and the sagittal sinus if necessary to complete the resection.
The key to the operation is to carry out an extensive internal decompression of the tumor with the ultrasonic aspirator and gradually draw the capsule into the area of decompression. Sometimes the tumor is transected parallel to the falx so the capsule can be more easily mobilized. In some patients a bilateral exposure is required. At some point in the operation, depending on the size and configuration of the tumor, the falx is divided well away from the tumor attachment. The inferior sagittal sinus can be occluded. Great care must be taken not to injure the pericallosal and callosomarginal arteries.
Spektor et al described a purely endoscopic removal of an atypical parasagittal meningioma in a patient who could not undergo standard craniotomy due to severe scalp atrophy following childhood irradiation for tinea capitis 10).
For treating a patient with multiple falcine and parasagittal lesions, Yamaguchi et al. believe that it is beneficial to resect the maximum possible number of lesions during one operation, even if some lesions are asymptomatic. This practice can potentially reduce the total number of operations during a patient’s lifetime 11).
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.
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 13).
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 14).
Publisher: Appleton-Century-Crofts (1970) Language: English ISBN-10: 0407352406 ISBN-13: 978-0407352407.
Mean tumor volume was 42 cc and ranged from 4 to 140 cc. In 58 of the 68 patients tumors were totally removed. Additional surgery for recurrence was performed in 6 patients over 15 years. Of these 6 patients, only two patients underwent gross total tumor resection at first operation; the other four underwent subtotal tumor resection. Based on pathologic reports, the largest tumor subtype was transitional. There were four patients with a high grade tumor-three atypical and one anaplastic meningioma. Of the 68 patients, 59 achieved a good outcome (no neurological deficit or recurrence), six had temporary complications, two suffered new permanent postoperative deficits, and the remaining one died due to severe brain swelling despite postoperative intensive care. Extent of surgical resection was found to be significantly related to tumor recurrence.
Falcine meningioma accounted for 8.5% of intracranial meningiomas and the transitional meningioma was the most common subtype of falcine meningioma. Gross total resection of tumor was the single most important predictor of an improved surgical outcome 16).