AVM resection after radiation therapy—clinico-morphological features and microsurgical results

Targeted Stereotactic Radiosurgery for Arteriovenous Malformation Downgrading Followed by Microsurgical Resection: A Case Report and Review of the Literature

BACKGROUND

An unruptured brain arteriovenous malformation (bAVM) is a complex pathological entity with the potential to lead to disabling or fatal intracranial hemorrhage. The treatment approaches for these lesions have included microsurgical resection, endovascular embolization, stereotactic radiosurgery (SRS), and medical management or any combination of these modalities. However, the optimal treatment approach for unruptured bAVMs has not yet been determined. In the present case, we used SRS strategically to downgrade an AVM to allow for improved resectability.

CASE DESCRIPTION

A 28-year-old woman had presented with 10 years of headaches and was found to have a Spetzler-Martin grade IV AVM not amenable to resection. She underwent targeted SRS only of the deep portions of the AVM, resulting in a decrease of the AVM to grade III. Subsequent microsurgical resection was successful in complete removal of the AVM. At the 1-year follow-up examination she had no deficits.

CONCLUSIONS

We have proposed a protocol of using focused SRS to eliminate the portions of the AVM that confer an increased surgical risk. SRS, followed by microsurgical resection, could represent an optimal treatment strategy for high-grade AVMs with difficult surgical anatomy.

Transdural Blood Supply in Cerebral Arteriovenous Malformations: A Systematic Evaluation of Angioarchitecture

BACKGROUND AND PURPOSE

Arterial transdural blood supply is a rare angiographic phenomenon in cerebral AVMs. This study aimed to evaluate angiographic transdural blood supply characteristics and to describe the clinical peculiarities of these lesions.

MATERIALS AND METHODS

A prospective AVM data base of 535 patients, enrolled from 1990 to 2016, was analyzed retrospectively. Clinical information was reviewed through patients' medical charts and radiologic studies. Patients with previous AVM treatment were excluded (n = 28).

RESULTS

Patients with (n = 32, male/female ratio = 10:22; mean age, 46 ± 15 years; range, 13-75 years) and without transdural blood supply (n = 475, male/female ratio = 260:215; mean age, 40 ± 18 years; range, 2-87 years) did not show significant differences in clinical presentation (age, hemorrhage, seizures, chronic headache). The predominant nidus size in patients with transdural blood supply was ≥30 mm, with significantly more patients with large AVMs (>60 mm, P = .001). To describe the transdural blood supply, we used 3 grades based on the angiographic transdural blood supply proportion and intensity of AVM nidus perfusion (I-III). Fifty-seven percent of patients with chronic headache had a strong and substantial transdural nidus perfusion (III) and a high-flow transdural blood supply.

CONCLUSIONS

Cerebral AVMs with transdural blood supply represent a rare and heterogeneous subgroup. Lesions can be graded by quantifying the transdural blood supply of the nidus and by capturing hemodynamic characteristics. The broad spread of angiographic features and comparable clinical patterns of patients with or without transdural blood supply raises questions about the relevance of the transdural blood supply to the natural history risk of an AVM and the intention for treatment.

Decreased calcification of a petroclival meningioma after gamma knife radiosurgery

Stereotactic radiosurgery (SRS) has been well reported in the treatment of certain calcified intracranial lesions such as meningiomas. However, reduction in the calcified portion of the tumour after SRS treatment has not been reported. We present the case of a 76-year-old man with a right petroclival lesion consistent on imaging with a calcified meningioma. The lesion progressed on serial neuroimaging studies, and the patient elected to undergo Gamma Knife radiosurgery. No complications were encountered during the radiosurgery. The patient underwent follow-up imaging at 4 and 8 months, during which the lesion was seen to remain stable in overall size, but with marked decrease in the calcified component. Stereotactic radiosurgery can lead to the reduction of all aspects of meninigomas including the calcified component. The radiobiological effects of high dose ionising radiation may result in bony changes and, thereby, decrease intratumoural calcification of an intracranial tumour.

Prospective evaluation of preoperative stereotactic radiosurgery followed by delayed resection of a high grade arteriovenous malformation

Reports of the utility of preoperative radiation for shrinking large arteriovenous malformations (AVM) in preparation for resection have produced conflicting results, and to our knowledge no prospective studies are available. A 28-year-old man presented with a ruptured right temporal Spetzler-Martin Grade 5 AVM with deep venous drainage, involvement of the internal capsule, deep perforator supply, and a diffuse nidus. He underwent staged embolization, a single Gamma Knife (Elekta AB, Stockholm, Sweden) radiation treatment to the deepest portion of the nidus followed by complete surgical resection 3 years later. He suffered no long-term neurological deficits and has since returned to work symptom-free (modified Rankin Scale score 0). Preoperative radiosurgery is an effective method for downgrading high-grade AVM in preparation for surgery by targeting the deeper portions that abut or involve eloquent territory. To our knowledge this is the first such successful prospective report in the literature.

Stereotactic radiosurgery of cranial arteriovenous malformations and dural arteriovenous fistulas

Cranial arteriovenous malformations (AVM) and cranial dural arteriovenous fistulas (AVF) carry a significant risk of morbidity and mortality when they hemorrhage. Current treatment options include surgery, embolization, radiosurgery, or a combination of these treatments. Radiosurgery is thought to reduce the risk hemorrhage in AVMs and AVFs by obliterating of the nidus of abnormal vasculature over the course of 2 to 3 years. Success in treating AVMs is variable depending on the volume of the lesion, the radiation dose, and the pattern of vascular supply and drainage. This article discusses the considerations for selecting radiosurgery as a treatment modality in patients who present with AVMs and AVFs.

Treatment of Giant Cerebral Arteriovenous Malformation: Hypofractionated Stereotactic Radiation as the First Stage

BACKGROUND:

Treatment of giant cerebral arteriovenous malformations (AVMs) remains a challenge.

OBJECTIVE:

To propose hypofractionated stereotactic radiotherapy (HSRT) as a part of staged treatment, and evaluate its effect by analyzing AVM volume changes.

METHODS:

From 2001 to 2007, 20 AVMs larger than 5 cm were treated by HSRT and followed up using magnetic resonance imaging. Patients' median age was 34 years (8–61 years). Eleven patients presented with hemorrhage and 9 with seizure. Ten patients had previous embolization and radiosurgery had failed in 4. Thirteen AVMs (65%) were classified as Spetzler-Martin grade V and 7 as grade IV. Median pretreatment volume was 46.84 cm3(12.51-155.38 cm3). Dose was 25 to 30 Gy in 5 to 6 daily fractions. Median follow-up was 32 months.

RESULTS:

Median AVM volume decreased to 13.51 cm3(range, 0.55-147.14 cm3). Residual volume varied from 1.5% to 98%. Volume decreased 44% every year on average. We noted that 6-Gy fractions were more effective (P= .040); embolized AVM tended to respond less (P= .085). After HSRT, we reirradiated 4 AVMs, with 3 amenable to single dose and one with fractions. After HSRT, one patient had an ischemic stroke and one had increased seizure frequency. One AVM bled during follow-up (2.06%/year). No complete obliteration was confirmed.

CONCLUSION:

HSRT can turn some giant AVMs manageable for single-dose radiosurgery. Six-Gray fractions were better than 5-Gy and routine embolization seemed unhelpful. There was no increase in bleeding risk with this approach. Future studies with longer follow-up are necessary to confirm our observation.