Seizures After Stereotactic Radiosurgery for Benign Supratentorial Meningiomas: An Uncontrollable Type of Seizure?

Pseudoprogression and peritumoral edema due to intratumoral necrosis after Gamma knife radiosurgery for meningioma

Peritumoral cerebral edema is reported to be a side effect that can occur after stereotactic radiosurgery. We aimed to determine whether intratumoral necrosis (ITN) is a risk factor for peritumoral edema (PTE) when gamma knife radiosurgery (GKRS) is performed in patients with meningioma. In addition, we propose the concept of pseudoprogression: a temporary volume expansion that can occur after GKRS in the natural course of meningioma with ITN. This retrospective study included 127 patients who underwent GKRS for convexity meningioma between January 2019 and December 2020. Risk factors for PTE and ITN were investigated using logistic regression analysis. Analysis of variance was used to determine whether changes in tumor volume were statistically significant. After GKRS, ITN was observed in 34 (26.8%) patients, and PTE was observed in 10 (7.9%) patients. When postoperative ITN occurred after GKRS, the incidence of postoperative PTE was 18.970-fold (p = 0.009) greater. When a 70% dose volume ≥ 1 cc was used, the possibility of ITN was 5.892-fold (p < 0.001) higher. On average, meningiomas with ITN increased in volume by 128.5% at 6 months after GKRS and then decreased to 94.6% at 12 months. When performing GKRS in meningioma, a 70% dose volume ≥ 1 cc is a risk factor for ITN. At 6 months after GKRS, meningiomas with ITN may experience a transient volume expansion and PTE, which are characteristics of pseudoprogression. These characteristics typically improve at 12 months following GKRS.

An Overview of Managements in Meningiomas

Meningioma is the most frequent primary tumor of the central nervous system. Important advances have been achieved in the treatment of meningioma in recent decades. Although most meningiomas are benign and have a good prognosis after surgery, clinicians often face challenges when the morphology of the tumor is complicated or the tumor is close to vital brain structures. At present, the longstanding treatment strategies of meningioma are mainly surgery and radiotherapy. The effectiveness of systemic therapy, such as chemotherapy or targeted therapy, has not been confirmed by big data series, and some clinical trials are still in progress. In this review, we summarize current treatment strategies and future research directions for meningiomas.

Treatment Outcomes of Incidental Intracranial Meningiomas: Results from the IMPACT Cohort

BACKGROUND

Incidental findings such as meningioma are becoming increasingly prevalent. There is no consensus on the optimal management of these patients. The aim of this study was to examine the outcomes of patients diagnosed with an incidental meningioma who were treated with surgery or radiotherapy.

METHODS

Single-center retrospective cohort study of adult patients diagnosed with an incidental intracranial meningioma (2007-2015). Outcomes recorded were postintervention morbidity, histopathologic diagnosis, and treatment response.

RESULTS

Out of 441 patients, 44 underwent treatment. Median age at intervention was 56.1 years (interquartile range [IQR], 49.6-66.5); patients included 35 women and 9 men. The main indication for imaging was headache (25.9%). Median meningioma volume was 4.55 cm³ (IQR, 1.91-8.61), and the commonest location was convexity (47.7%). Six patients underwent surgery at initial diagnosis. Thirty-eight had intervention (34 with surgery and 4 with radiotherapy) after a median active monitoring duration of 24 months (IQR, 11.8-42.0). Indications for treatment were radiologic progression (n = 26), symptom development (n = 6), and patient preference (n = 12). Pathology revealed World Health Organization (WHO) grade 1 meningioma in 36 patients and WHO grade 2 in 4 patients. The risk of postoperative surgical and medical morbidity requiring treatment was 25%. Early and late moderate adverse events limiting activities of daily living occurred in 28.6% of patients treated with radiotherapy. Recurrence rate after surgery was 2.5%. All meningiomas regressed or remained radiologically stable after radiotherapy.

CONCLUSIONS

The morbidity after treatment of incidental intracranial meningioma is not negligible. Considering most operated tumors are WHO grade 1, treatment should be reserved for those manifesting symptoms or demonstrating substantial growth on radiologic surveillance.

Factors Associated with Treatment Failure and Radiosurgery-Related Edema in WHO Grade 1 and 2 Meningioma Patients Receiving Gamma Knife Radiosurgery

BACKGROUND

Before the advent of radiosurgery, neurosurgical treatment of meningiomas typically involved gross total resection of the mass whenever surgery was deemed possible. Over the past 4 decades, though, Gamma Knife radiosurgery (GKRS) has proved to be an effective, minimally invasive means to control the growth of these tumors. However, the variables associated with treatment failure (regrowth or clinical progression) after GKRS and GKRS-related complications, such as cerebral edema, are less well understood.

METHODS

We retrospectively collected data between 2009 and 2018 for patients who underwent GKRS for meningiomas. After data collection, we performed univariate and multivariable modeling of the factors that predict treatment failure and cerebral edema after GKRS. Hazard ratios (HR) and P values were determined for these variables.

RESULTS

Fifty-two patients were included our analysis. The majority of patients were female (38/52,73%), and nearly all patients presented with a suspected or confirmed World Health Organization grade 1 meningioma (48/52, 92%). The median tumor volume was 3.49 cc (range, 0.22-20.11 cc). Evidence of meningioma progression after treatment developed in 5 patients (10%), with a median time to continued tumor growth of 5.9 months (range, 2.7-18.3 months). In multivariable analysis, patients in whom treatment failed were more likely to be male (HR = 8.42, P = 0.045) and to present with larger tumor volumes (HR = 1.27, P = 0.011). In addition, 5 patients (10%) experienced treatment-related cerebral edema. On univariate analysis, patients who experienced cerebral edema were more likely present with larger tumors (HR = 1.16, P = 0.028).

CONCLUSIONS

Increasing meningioma size and male gender predispose to meningioma progression after treatment with GKRS. Increasing tumor size also predicts the development of postradiosurgery cerebral edema.