Meningioma embolization with the pressure cooker technique using Squid 12

Abstract

Background

Preoperative meningioma embolization may be performed with microparticles or liquid embolic agents. The pressure cooker technique (PCT) has recently been described for the embolization of brain arteriovenous malformations (AVMs).

Case

We present the case of a 73-year-old woman with a large frontal interhemispheric meningioma that was successfully preoperatively embolized with the PCT using Squid 12, a new ethyl-vinyl alcohol copolymer embolic agent. The PCT presents considerable advantages relative to conventional embolization techniques such as deeper and faster tumor penetration and embolization of tumors with difficult vascular access, and retrograde feeling of pial afferents may be achieved.

Conclusions

The use of the PCT with Squid 12 may potentially increase the effectiveness of meningioma embolization, increase tumor devascularization and improve outcomes of surgical resection.

Introduction

Meningioma embolization is mainly performed by selective injection of polyvinyl alcohol (PVA) microparticles and to a lesser extent by the injection of liquid agents like N-butyl-cyanoacrylate (NBCA) or Onyx (Ev3-Covidien, Dublin, Ireland), an ethylene vinyl alcohol copolymer (EVAC).^1,2 The pressure cooker technique (PCT) has recently been introduced as a technique to maximize the efficiency of Onyx embolization of cerebral arteriovenous malformations (AVMs). It consists of the creation of an anti-reflux plug by trapping the detachable part of an Onyx-compatible microcatheter with coils and glue in order to obtain wedge-flow conditions and allows more comprehensive, forceful and controlled Onyx embolization.³

This is, to our knowledge, the first report of the use of the PCT with Squid 12 (Emboflu, Switzerland), a new EVAC, for the embolization of a meningioma.

Case description

A 73-year-old woman presented to the emergency department after an episode of confusion and fall. Brain magnetic resonance imaging (MRI) demonstrated a large frontal tumoral lesion, presumably a falx meningioma (Figure 1). Preoperative embolization was planned to be followed by complete tumor excision.

Figure 1.

T1-weighted axial post-contrast image shows a large anterior interhemispheric mass with inhomogeneous enhancement.

The PCT consisted of creating a plug of coils between the tip and the detachment zone of a dimethyl sulfoxide-compatible microcatheter, Apollo (EV3-Covidien, Ireland) to enable a continuous injection of Squid 12 while avoiding reflux. To create the plug, a second microcatheter (Magic 1.2 FM, Balt Extrusion, Montmorency, France) was navigated alongside the first in the same feeder. Its tip was positioned between the most distal marker and the detachment zone of the Apollo microcatheter. The plug was then created by pushing through the second catheter one injectable 2*25 mm SPIF flow coil (Balt Extrusion, Montmorency, France). A total of 3 ml of Squid 12 was injected resulting in the complete disappearance of the tumor blush on control injections (Figures 2 and 3). No reflux of Squid 12 was noticed proximal to the SPIF coil. The Apollo microcatheter was easily detached and retrieved at the end of the injection. The patient underwent complete surgical excision seven days later and the neurosurgeon reported complete devascularization of the tumor and no blood loss.

Figure 2.

Selective injection of a left middle meningeal artery branch supplying the tumor.

Figure 3.

Squid 12 cast of the entire tumor at the end of the embolization.

Discussion

Preoperative meningioma embolization with PVA microparticles is a safe, efficient and cost-effective method with few complications.^1,2 Compared to PVA, liquid embolization agents like NBCA or EVACs penetrate deeper into intratumoral capillaries and have a permanent effect. The use of liquid agents might be anticipated in the following situations: when delayed surgical resection is planned or in the case of large unresectable or small meningiomas with the hope of tumor shrinkage or delayed tumor growth.^4,5 The delivery of NBCA has technical constraints that require experience to use it successfully as it may solidify rapidly and microcatheters may get caught or break.⁴ Also large meningiomas, when embolized with PVA or NBCA, usually require the catheterization of multiple tortuous afferents to completely exclude the tumor, which may not always be feasible.

The restricting factors associated with PVA or NBCA embolization may be less of an issue with the newer EVAC agents. These may be delivered in a slower and more controlled manner.⁶ The use of a detachable-tip microcatheter lowers the likelihood of microcatheter retention. Tumor penetration is high and extensive devascularization may be obtained. The lower viscosity of Squid 12 compared to Onyx 18 may allow an even deeper penetration of the tumoral capillary network.

The addition of the PCT appears to bring several advantages to the use of EVACs. The vascular plug needed for copolymer injection is shorter and more predictable, adding to the safety of the technique. The embolization may be carried out by applying pressure to the copolymer mixture, resulting in a deeper and faster penetration of the tumor. Distal large tumors with a difficult tortuous vascular access, not amenable to total exclusion by PVA or NBCA embolization may be efficiently embolized through one afferent vessel only. It has also been observed that Onyx injection with PCT in brain AVMs has the propensity to penetrate arterial feeders in a retrograde fashion, even reaching venous outflow channels.^2,3 However, meningioma embolization with very smaller microparticles that reach deep small feeders has been linked to a higher risk of periprocedural bleeding.² In the case of meningioma embolization with EVAC and PCT, deeper tumor penetration may be an advantage as retrograde feeling and permanent occlusion of pial afferents in conjunction with the permanent occlusion of the larger arterial feeders may actually exclude these two major sources of peri-embolization and surgical bleeding. Thus PCT may maximize preoperative tumor devascularization, facilitating and promoting a better surgical outcome. This could be a major advantage compared to the preoperative use of PVA. As a permanent agent, embolization with Squid 12 may achieve tumor shrinkage after a few weeks and allow easier tumor dissection. However, the PCT may not always be technically feasible. In this case, a simple wedged position of the microcatheter may suffice to obtain some degree of EVAC penetration and reflux control. The importance of these relative properties for the safety and efficacy of the technique remains to be assessed.

This is, to our knowledge, the first report of the PCT with Squid 12 for meningioma embolization. We believe that advantages and disadvantages of the technique need to be verified in a prospective study.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.