Editorial: Radiosurgery for parasagittal and parafalcine meningiomas

Abstract

Ding and colleagues at the University of Virginia review their results after Gamma Knife surgery for parasagittal and parafalcine (PSPF) meningiomas.1 This analysis details outcomes in 65 patients with 90 WHO Grade I tumors with an average imaging follow-up of almost 5 years. The tumor control rate was 85% at 3 years and 70% at 5 years, which is somewhat less than other long-term radiosurgery reports in patients with Grade I meningiomas. This may reflect the fact that cranial base tumors were not included, and indeed may have a more benign course and outcome after radiosurgery. The authors note that the supratentorial tumors may be associated with higher recurrence rates due to more extensive dural tails. However, this remains unproven. The procedure was well tolerated and postradiosurgery edema was noted in only 4 patients, 3 of these sustaining only temporary symptoms. Because management for such patients is so individualized, there is not ever likely to be a randomized trial comparing meningioma resection to radiosurgery.Although the report is about both parasagittal and falcine meningiomas, the two tumor types pose somewhat different clinical challenges. In their discussion the authors link the two together. Of course, the regional venous anatomy is important for both locations. However, falcine tumors are more amenable to complete resection and less likely to have residual tumor after resection. The authors found that parasagittal tumors had a higher control rate (p = 0.031) and discuss that this may be true due to more superficial draining veins. However, it is not clear to me why this would be true, and it is not my own experience.This study and others raise the question of how initially to manage meningiomas in this location. Although some still advocate sagittal sinus resections and repair when the sinus is not completely occluded, this practice has largely been eliminated. Certainly a larger tumor with mass effect should be resected. If residual tumor remains, I favor planned radiosurgery within a few months. At the other end of the clinical spectrum is the younger patient with an incidentally identified and smaller tumor. Should this patient have radiosurgery early while the superior sagittal sinus is open, brain edema has not yet occurred, and regional veins are less compromised? Given the problems that can be caused by such tumors, and a somewhat variable natural history, close observation is certainly warranted and early radiosurgery is reasonable depending on patient goals. For tumors between 2 and 4 cm in maximum diameter, the indications for resection compared to radiosurgery can be debated. Certainly if the goal is to improve symptoms from mass effect more rapidly, then resection is optimal. The conclusion of this report-"Radiosurgery can be used as initial and adjunct therapy for PSPF meningiomas with significant sinus invasion, meningiomas that cannot be completely resected, and patients with minimal to no symptoms"-is an appropriate one. As for all complex meningiomas, the options provided t...

<p>Stereotactic Radiotherapy for Parasagittal and Parafalcine Meningiomas: Patient Selection and Special Considerations</p>

“…Literature data focused on RS and SRT outcomes for parasagittal and parafalcine meningiomas are very limited 8,10,18,19. Five studies were found reporting the lesion outcomes,8,16,19–21 in which only one single dose RS was employed.…”

“…Addressing this issue could provide crucial information on the index of proliferation and neurobiological characteristics associated with the molecular pathways that regulate the apoptotic response of tissue, cellular, and genetic post-irradiation damage 52. With regard to the management of these tumors, some authors suggest be planned RS within a few months if a larger lesion with mass effect has been resected 18. Due to the high recurrence rate reported, even when an apparently total resection is obtained, a multidisciplinary approach is mandatory for parafalcine and parasagittal meningiomas.…”

Intraoperative MRI for the microsurgical resection of meningiomas close to eloquent areas or dural sinuses: patient series

“…Radiosurgery has also a risk of symptomatic imaging-demonstrated changes, which are frequently transient. 36 The risk of such adverse radiation events (AREs) after SRS is mostly related to symptomatic edema or damage to the cranial nerves. In a recent meta-analysis, 43 which included 4229 patients, the overall relative frequency of AREs was 8.1% (range 5.2%–11.5%).…”

“…31,32 Combined Approaches With Planned Subtotal Resection Followed by Radiosurgery During the past years, combined approaches with postoperative adjuvant radiosurgery on the postoperative residual tumors have been proposed, 33 aiming at conserving neurological function. [34][35][36] Such approaches depend mainly on the residual tumor volume to safely perform SRS as an adjuvant therapy. 37 Long-term tumor control after SRS also depends on histology, being as high as 93%-95% for WHO grade I, 50%-60% for WHO grade II, and decreasing to 10%-17% for WHO grade III.…”