Strategy for the treatment of arteriovenous malformations

Intraoperative Anatomical and Hemodynamic Analysis of Intracerebral Arteriovenous Malformations by Semi-quantitative Color-coded Indocyanine Green Videoangiography

Objective and Background:

To evaluate possible roles for indocyanine green (ICG)-based FLOW 800 software in surgical treatment of cerebral arteriovenous malformations (AVMs).

Methods:

We perform ICG videoangiography several times for each step of AVM resection to elucidate feeders, drainers, and cerebral perfusion.

Results:

Since 2010, 22 AVM surgeries in our department have been conducted using FLOW 800 intraoperatively. We demonstrated ICG angiograms, color-coded images, and semi-quantitative curves for AVMs. By reviewing all these modalities, we would define vascular structure of the AVM, proceed with resection, and finally recheck for any remnant.

Conclusions:

ICG FLOW 800 software helps the surgeon to recognize feeding and draining vessels of an AVM intraoperatively. Further studies to evaluate semi-quantitative acquired data regarding blood flow and tissue perfusion are warranted.

Safe resection of arteriovenous malformations in eloquent motor areas aided by functional imaging and intraoperative monitoring

BACKGROUND

Arteriovenous malformations (AVMs) proximal to motor cortical areas or motor projection systems are challenging to manage because of the risk of severe sensory and motor impairment. Surgical indication in these cases therefore remains controversial.

OBJECTIVE

To propose a standardized approach for centrally situated AVMs based on functional imaging and intraoperative electrophysiological evaluation.

METHODS

We conducted a retrospective analysis of 15 patients who underwent surgical treatment for AVMs in motor cortical areas or proximal to motor projections. Preoperative assessment included functional magnetic resonance and 3-dimensional tractography. Operations were performed under continuous electrophysiological monitoring aided by direct brain stimulation. We identified critical bloody supply to the motor areas by temporary occluding the feeding vessels under electrophysiological monitoring. Clinical outcome was evaluated with the modified Rankin Scale.

RESULTS

Total resection was achieved in 12 cases, whereas electrophysiology limited total extirpation in 3 cases. A significant reduction of motor evoked potentials by up to 15% of the initial values was associated with good recovery of motor function; in contrast, the disappearance of potentials correlated with long-term impairment. The mean follow-up time was 13 months, and clinical assessments revealed overall functional improvement (P < .05). After surgery, 11 patients were asymptomatic or presented with only minor neurological deficits.

CONCLUSION

Surgical resection of AVMs in eloquent motor areas can be considered a safe option for selected cases when performed in conjunction with a detailed functional assessment. Possible selection criteria for surgical treatment are discussed in light of the presented clinical data.

A prospective, multicenter, randomized trial of the Onyx liquid embolic system and N-butyl cyanoacrylate embolization of cerebral arteriovenous malformations

Object

The Onyx liquid embolic system (Onyx) was approved in the European Union in 1999 for embolization of lesions in the intracranial and peripheral vasculature, including brain arteriovenous malformations (AVMs) and hypervascular tumors. In 2001 a prospective, equivalence, multicenter, randomized controlled trial was initiated to support a submission for FDA approval. The objective of this study was to verify the safety and efficacy of Onyx compared with N-butyl cyanoacrylate (NBCA) for the presurgical treatment of brain AVMs.

Methods

One hundred seventeen patients with brain AVMs were treated with either Onyx (54 patients) or NBCA (63 patients) for presurgical endovascular embolization between May 2001 and April 2003. The primary end point was technical success in achieving ≥ 50% reduction in AVM volume. Secondary end points were operative blood loss and resection time. All adverse events (AEs) were reported and assigned a relationship to the Onyx or NBCA system, treatment, disease, surgery, or other/unknown. The Data Safety Monitoring Board adjudicated AEs, and a blinded, independent core lab assessed volume measurements. Patients were monitored through discharge after the final surgery or through a 3- and/or 12-month follow-up if resection had not been performed or was incomplete.

Results

The use of Onyx led to ≥ 50% AVM volume reduction in 96% of cases versus 85% for NBCA (p = not significant). The secondary end points of resection time and blood loss were similar. Serious AEs were also similar between the 2 treatment groups.

Conclusions

Onyx is equivalent to NBCA in safety and efficacy as a preoperative embolic agent in reducing brain AVM volume by at least 50%.

Combined effects of embolization and hypofractionated conformal stereotactic radiotherapy in arteriovenous malformations of the brain

SUMMARY

There are three major treatment options for cerebral AVMs; surgery, embolization and radiosurgery. Embolization may be effective to reduce the size and density but completely obliterates AVMs only in a minority of cases. Radiosurgery may be an alternative to resection, especially in smaller AVMs. Large AVMs have been considered difficult to treat safely and effectively with single fraction radiosurgery. Hypofractionated conformal stereotactic radiotherapy (HCSRT) alone or in combination with embolization may be an alternative treatment. Embolization may reduce the volume and density of AVMs, followed by HCSRT, allowing a safe delivery of a higher total dose of radiation than possible with a single fraction. Sixteen patients with AVMs were treated with embolization and HCSRT. Embolization was performed in 1-6 (median 2) sessions. HCSRT was delivered in 5 fractions with 6-7 Gy each to the total dose of 30-35 Gy. Cerebral angiographies before and after embolization were digitally compared for calculation of volume reduction and luminescence as a measure of AVM density. The mean AVM volume in 15 patients was reduced from 11.9 +/- 2.1 (1-29, median 10.0) ml to 6.5 +/- 2.0 (0.5-28, median 3) ml by embolization. The luminescence for all AVMs was significantly higher after than before embolization, indicating that all AVMs were less dense after embolization. Thirteen out of 16 patients (13/16, 81%) treated with embolization and HCSRT have so far shown obliteration of their AVMs 2-9 (median 4) years after HCSRT. Three patients experienced neurological sequele after embolization, and three patients developed radionecrosis after HCSRT. Using a new method to compare cerebral angiographies in AVMs we report reduction in density and volume after embolization. The obliteration rate of a combined treatment with embolization and HCSRT seems comparable with single fraction radiosurgery although the AVMs in our series are larger than reported in most series treated with single fraction radiosurgery.

Surgical handling characteristics of an ethylene vinyl alcohol copolymer compared with N-butyl cyanoacrylate used for embolization of vessels in an arteriovenous malformation resection model in swine

OBJECT

There have been significant improvements in neurovascular technology and implants over the past decade. One such material, N-butyl cyanoacrylate (NBCA), is now commercially available for cerebral arteriovenous malformation (AVM) embolization in the US. An ethylene vinyl alcohol copolymer preparation, Onyx, which is currently being evaluated, is approved for use outside North America. Although reports indicate that Onyx may be superior to NBCA from an endovascular perspective, little information exists about its surgical handling characteristics. The purpose of this study was to compare the surgical handling characteristics of Onyx-treated vessels with those of NBCA-embolized vessels in an AVM resection model.

METHODS

Fourteen pigs (two groups of seven) were anesthetized. A femoral artery was cannulated, followed by selective catheterization of the ascending pharyngeal arteries. Nidal rete mirabile (RM) embolizations were performed using either 6% Onyx or 20% NBCA. After angiographically confirmed obliteration of flow in the right RM, microsurgical resection of this structure was performed. Surgical handling characteristics of the embolized RM were rated on a scale of 1 to 5 and blood loss was recorded. Different surgeons performed the embolizations and resections. The surgeon who performed resections was blinded to the embolization agent used, and the data analysis was also performed in a blinded fashion. The surgical handling scores were superior (p < 0.05) in the Onyx-treated group. Although there was also less blood loss in this group, the difference was not significant. Subjectively, the surgeon who performed the resections believed that Onyx was softer and handled better than NBCA.

CONCLUSIONS

Onyx, which may offer endovascular advantages, also seems to provide benefits for the surgeon.

Compartments in arteriovenous malformation nidi demonstrated with rotational three-dimensional digital subtraction angiography by using selective microcatheterization. Report of three cases

Although in several histological studies of arteriovenous malformation (AVM) nidi the presence of compartments has been documented, no clinical study has been published. The present study was conducted to determine the presence of nidus compartments in clinical cases by using a new radiographic method. Two patients with unruptured and one with a ruptured AVM (all Spetzler-Martin Grade III) were studied. A microcatheter was superselectively introduced into each of two or three feeding arteries of the AVMs under three-dimensional (3D) angiographic guidance to obtain 3D images of the nidus by using rotational digital subtraction angiography. On 3D images the different feeding arteries were found to be independent from one another, which allowed the authors to confirm the presence of compartments. On the other hand, separate feeding arteries often had a common draining vessel. Compartments in AVM nidi were demonstrated by a novel rotational 3D angiographic procedure by using superselective microcatheterization, which should be useful for designing treatment strategies for large and complex AVMs.