Cavernous malformations are rare sequelae of stereotactic radiosurgery for brain metastases

Radiation-Induced Cerebral Cavernous Malformations: A Single-Center Experience and Systematic Literature Review

OBJECTIVE

Radiation was first demonstrated to be associated with cavernomagenesis in 1992. Since then, a growing body of literature has shown the unique course and presentation of radiation-induced cavernous malformations (RICMs). This study summarizes the literature on RICMs and presents a single-center experience.

METHODS

A prospectively maintained single institution vascular malformation database was searched for all cases of intracranial cavernous malformation (January 1, 1997-December 31, 2021). For patients with a diagnosis of RICM, information on demographic characteristics, surgical treatments, radiation, and surgical outcomes was obtained and analyzed. A comprehensive literature search was conducted using PubMed, Embase, Cochrane, and Web of Science databases for all reported cases of RICM.

RESULTS

A retrospective review of 1662 patients treated at a single institution yielded 10 patients with prior radiation treatment in the neck or head region and a subsequent diagnosis of intracranial RICM. The median (interquartile range) latency between radiation and presentation was 144 (108-192) months. Nine of 10 patients underwent surgery; symptoms improved for 5 patients, worsened for 3, and were stable for 1. The systematic literature review yielded 64 publications describing 248 patients with RICMs. Of the 248 literature review cases, 71 (28.6%) involved surgical resection. Of 39 patients with reported surgical outcomes, 32 (82%) experienced improvement.

CONCLUSIONS

RICMs have a unique course and epidemiology. RICMs should be considered when patients with a history of radiation present with neurologic impairment. When RICMs are identified, symptomatic patients can be treated effectively with surgical excision and close follow-up.

Early tumor-related hemorrhage after stereotactic radiosurgery of brain metastases: Systematic review of reported cases

OBJECTIVE

Early (within 72 h) tumor-related hemorrhage (TRH) after stereotactic radiosurgery (SRS) of brain metastases (BM) has been reported only occasionally. Systematic review of such cases was done.

METHODS

Literature search was performed through PubMed according to PRISMA guidelines using combination of the following medical subject headings: "hemorrhage," "stereotactic radiosurgery," and "brain metastasis."

RESULTS

In total, 7 case reports and 8 clinical series, which noted early TRH after SRS of BM were identified. Scarce and inconsistent data precluded their precise synthesis and statistical analysis. BM of renal cell carcinoma comprised around one-third of reported cases. In 4 patients with multiple BM, TRH after SRS was noted simultaneously in several irradiated tumors. Considering 17 reported cases overall, in 3 patients TRH occurred during SRS session itself, in 4 within several minutes upon completion of treatment, in 7 within several hours thereafter, and in 3 on the third posttreatment day. Out of 11 reported cases providing detailed outcome, 6 patients died shortly after the ictus, 2 others were severely disabled at discharge, and 3 demonstrated good-to-moderate recovery. Overall, among evaluated series the median rates of early TRH after SRS for BM were 0.8% per patient (range, 0.4 - 1.9%) and 0.3% per tumor (range, 0.05 - 0.8%).

CONCLUSION

Early TRH is very rare, but potentially life-threatening complication of SRS for BM; thus, its risk (while extremely low) and possible consequences should be discussed at the time of obtaining informed consent.

Retiform endothelial hyperplasia mimicking cavernous malformation as a late complication of Gamma Knife radiosurgery

OBJECTIVE

Gamma Knife radiosurgery (GKRS) is a powerful tool for the management of arteriovenous malformations; however, newly formed mass lesions resembling cavernous malformations are a rare late complication of GKRS. In this retrospective study, the authors tried to clarify the unique histological features of these mass lesions.

METHODS

The authors retrospectively reviewed the clinical course of 889 patients who had undergone GKRS for arteriovenous malformations at their institute from 1991 to 2021. Among the 848 patients who had been followed up periodically with neuroradiological imaging, 37 developed a mass lesion mimicking a cavernous malformation and underwent surgical removal of the lesion. The median volume of the original nidus was 3.7 cm3 (range 0.07-30.5 cm3), and the median prescription dose was 21 Gy (range 12-25 Gy). The histological characteristics and radiological and clinical features of the 37 patients were investigated.

RESULTS

Histological examination showed an organized hematoma and a structure termed "retiform endothelial hyperplasia" (RFEH) consisting of endothelium forming multiple lumen-like vascular channels mimicking cavernous malformations but lacking the subendothelial connective tissue that forms the typical vascular wall structure found in cavernous angioma and capillary telangiectasia. RFEH was detected a median of 10.8 years (range 3.2-27.4 years) after GKRS. Neuroimaging showed hematoma surrounded by massive brain edema in all 37 patients. Symptoms caused by mass effect of the lesion and perifocal edema worsened relatively rapidly but completely disappeared after surgery. No recurrence or morbidity occurred after the surgery.

CONCLUSIONS

The delayed formation of RFEH that is mimicking a cavernous malformation neuroradiologically but is histologically distinct from a vascular malformation is a potential complication of GKRS. Its progressive clinical course suggests that surgical removal should be considered for symptomatic patients and/or patients with an apparent radiological mass sign.

Recurrent Radiation-Induced Cavernous Malformation After Gamma Knife Stereotactic Radiosurgery for Brain Metastasis

Cavernous malformations are a rare complication of radiation therapy reported most commonly as a late complication after cranial irradiation for pediatric malignancies. However, cavernous malformations after stereotactic radiosurgery in adult patients are not well characterized. We present a case of a 67-year-old female with metastatic breast cancer who received Gamma Knife stereotactic radiosurgery for brain metastases and developed a cavernous malformation at the site of a treated metastasis 30 months after treatment. She underwent resection and did well until 55 months later, when she developed symptomatic recurrence of cavernous malformation without evidence of tumor recurrence, requiring repeat resection. This represents the first reported case of radiation-induced cavernous malformation treated with stereotactic radiosurgery for brain metastases, who later developed a recurrence of the cavernous malformation. As patients with brain metastases are living longer and are increasingly treated with stereotactic radiosurgery, awareness of cavernous malformation as a potential complication and the risk of recurrence is critical to ensure appropriate diagnosis and management.

Intracranial Hemorrhage in Patients with Anticoagulant Therapy Undergoing Stereotactic Radiosurgery for Brain Metastases: A Bi-Institutional Analysis

Background: Stereotactic radiosurgery (SRS) is a well-established treatment modality for brain metastases (BM). Given the manifold implications of metastatic cancer on the body, affected patients have an increased risk of comorbidities, such as atrial fibrillation (AF) and venous thromboembolism (VTE), which includes pulmonary embolism (PE) and deep-vein thrombosis (DVT). These may require therapeutic anticoagulant therapy (ACT). Limited data are available on the risk of intracranial hemorrhage (ICH) after SRS for patients with BM who are receiving ACT. This bi-institutional analysis aimed to describe the bleeding risk for this patient subgroup. Methods: Patients with ACT at the time of single-fraction SRS for BM from two institutions were eligible for analysis. The cumulative incidence of ICH with death as a competing event was assessed during follow-up with magnetic resonance imaging or computed tomography. Results: Forty-one patients with 97 BM were included in the analyses. The median follow-up was 8.2 months (range: 1.7–77.5 months). The median and mean BM volumes were 0.47 and 1.19 cubic centimeters, respectively. The most common reasons for ACT were PE (41%), AF (34%), and DVT (7%). The ACT was mostly performed utilizing phenprocoumon (37%), novel oral anticoagulants (32%), or low-molecular-weight heparin (20%). Nine BM from a group of five patients with ICH after SRS were identified: none of them caused neurological or any other deficits. The 6-, 12-, and 18-month cumulative bleeding incidences per metastasis were 2.1%, 12.4%, and 12.4%, respectively. The metastases with previous bleeding events and those originating from malignant melanomas were found to more frequently demonstrate ICH after SRS (p = 0.02, p = 0.01). No surgical or medical intervention was necessary for ICH management, and no observed death was associated with an ICH. Conclusion: Patients receiving an ACT and single-fraction SRS for small- to medium-sized BM did not seem to have a clinically relevant risk of ICH. Previous bleeding and metastases originating from a malignant melanoma may favor bleeding events after SRS. Further studies are needed to validate our reported findings.