Absolute Ethanol Embolization of Mandibular Arteriovenous Malformations  Following Direct Percutaneous Puncture Release Coils via Microcatheter

Deming Wang, MD,DDS,PhD, Lixin Su, DDS,PhD, Yifeng Han, MD,  Zhenfeng Wang, MD,  Lianzhou Zheng, MD,  and Xindong Fan, MD,  Shanghai, P.R. China

Department of Interventional Radiology, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China

INTRODUCTION

Approximately 50% of arteriovenous malformations (AVMs) occur in the head and neck region and about 50% of intraosseous AVMs are also found in this region.1AVMs of the mandible are rare but may present a life-threatening hemorrhages spontaneously or after a tooth extraction. Almost all patients presenting with AVMs in the mandible are children or adolescents.2,3

With the improvement of catheter technology, superselective technique, and the use of embolic agents, embolotherapy has emerged as the mainstay for the management of AVMs in the mandible. From 2007, we began to embolize mandibular AVMs with absolute ethanol combined with coils and found that it is technically feasible. Complete and durable obliteration of the nidus is achievable during the follow up period.4 However, a more prolonged follow-up has shown that recurrences occurred in 3 out of 8 cases in a previous cohort study.  

In order to obliterate any compartment of the lesion and achieve the permanent solution for AVMs in the mandible, we made some improvement to our technique of embolization and some progresses were noted in this study. Microcatheter was induced through direct puncture needle and any corner of venous pouch was easily accessible. Here, we report 18 cases of mandibular AVMs that were successfully embolized with absolute ethanol following direct percutaneous transvenous approach release coils via microcatheter.

Endovascular techniques

All procedures were performed with the patients under general anesthesia with nasal intubation. The arterial pressure, electrocardiogram, oxygen saturation, and end-tidal carbon dioxide level were constantly monitored during the injection of absolute ethanol. Foley catheters were inserted after induction of anesthesia to monitor the state of hydration and the presence of hemoglobinuria. Baseline digital subtraction angiography was done in the same fashion as embolization. The high-flow vascular lesion was confirmed on the angiogram for each patient. Selective digital subtraction angiographic images were obtained to delineate the territory of the lesions and the timing of blood flow through the nidus (Fig 3). For the patients who underwent ligation of the external carotid artery in the prior therapies, angiograms of the common carotid artery, the vertebral artery, and the thyrocervical trunk were performed on the same side of the lesions, as well as the external carotid artery on the contralateral side.

Transvenous approach embolization through direct percutaneous puncture was preferred to access the venous pouch. Routes of access to the nidus were chosen according to the initial angiogram and CT scan. Direct percutaneous puncture embolization was indicated in all patients, including those patients who underwent ligation of the external carotid artery.

Direct percutaneous puncture approach was used in all 18 patients. The venous pouch was directly punctured with a 16G needle (Lichtwitz antrum needle; MEDICON, Tuttlingen, Germany). Once the position of the needle into the venous pouch was verified in the direct venogram (Fig 4A), the core needle was removed and a 2.2F microcatheter (Cordis Endovascular, Miami Lakes, Fla) was induced through the needle. With the guidance of a guide wire, the microcatheter was induced as close as possible to the exit of dilated outflow vein (DOV) (Fig 4B). Then electrolytically detachable coils (EDCs) (Acheva, Shanghai, China) were deployed after the verification that there was no migration to lung, which rarely happens but could result in a severe pulmonary or cardiovascular complication. In selected cases, EDCs were retracted and redeployed because of its unfavorable position, unfavorable configuration and instability. In some instance, another percutaneous direct puncture and more than one EDCs were required in that the EDCs deployed was risk of migration to systemic circulation because of high-flow of the draining vein.5 Followed by the deployment of EDCs, 0.018mm NEST coils (Cook, Bloomington, IN, USA) were placed also, resulting in a decrease of arteriovenous shunt flow, and then absolute ethanol was injected through the microcatheter or needle to obliterate the AVMs completely (Fig 4C).

When the flow of AVMs of the mandible was decreased in a significant manner by the coils, repeated injection of absolute ethanol was performed. Ethanol embolization was directed against the nidus itself which means the central section of the abnormal connection and the first section of the adjoining dilated vein, not against the vascular feeders; the goal was to embolize all or part of the nidus until the desired clinical outcomes were achieved (Fig 4D). The amount of ethanol used during embolization was based on the amount required to fill the portion of AVMs being treated. Ethanol was manually injected after several test injections with contrast material to determine the hand pressure required and the amount of ethanol injected. After ethanol injections, we waited for 10 minutes and then acquired an arteriogram to determine whether the therapy was successful. The total amount of absolute ethanol used per session was less than 1 mL/kg of body weight. To minimize swelling, all patients received an intravenous injection of dexamethasone before the procedure, usually 10 mg for adults and 3 to 10mg for children, depending on their body weight. Postoperative management consisted of steroid and intravenous infusion of fluids. Patients with gastrointestinal tract sensitivity to steroids can also be given ranitidine to protect against development of gastric or duodenal ulcer. Patients were usually observed in the intensive care unit overnight. The following medications usually include a tapering dose of corticosteroids for 7 days and ranitidine management to prevent ulcer development, if required.

Evaluation of Clinical Data and Follow-up Result

Two radiologists analyzed by consensus the therapeutic responses to ethanol embolization by comparing the degree of AVMs devascularization (ie, 100%, 76%–99%, 50%–75%, or<50%) between baseline and final angiography. Two oral and maxillofacial surgeons and 1 interventional radiologist evaluated by consensus the clinical outcome of symptoms and signs (that is, resolving completely, improving, no change, or aggravating). Several periodic (1–3 months) follow-up evaluations were performed on the basis of physical examination, panorama, and contrast-enhanced CT. Results of the follow-up evaluation were analyzed by consensus. As a rule, additional embolization was recommended if the symptoms and signs were not relieved or if the AVMs were still present at follow-up. All patients came for follow-up after the last treatment and follow-up times ranged from 8 to 26 months (mean, 15.7 months). We established therapeutic outcomes by evaluating the clinical outcome of symptoms and signs and the degree of devascularization seen on angiography or CT examination. Cure was defined as the resolution of oral bleeding, shrinkage of soft tissue, and obliteration of the expanded external jugular vein, with 100% devascularization of the AVMs on angiography (Fig 5). Partial remission was defined as complete resolution or improvement of the clinical symptoms and signs, with 50% to 99% devascularization of the AVMs on angiography. No remission was defined as improvement or no change of the clinical symptoms and signs, with less than 50% devascularization of AVMs at angiography. Aggravation was defined as an aggravation of the clinical symptoms and signs, regardless of the degree of devascularization of AVMs at angiography. Cure and partial remission were considered effective therapeutic outcomes of ethanol embolization of mandibular AVMs following direct puncture transvenous release coils.

Complications were classified as either major or minor according to standards reported by Society of Interventional Radiology(SIR).6 Major complications included death, permanent adverse sequelae, and requirement of major therapy. Minor complications included any non-permanent adverse sequelae, such as transient nerve injuries or spontaneously healed skin injury. Patients were physically and neurologically examined before and after embolization to assess complications. When complications were observed, we reviewed the angiograms again to find the possible cause of the complications.

RESULTS

In all 18 patients, venous outflow embolization with ethanol and coils was used as the primary treatment technique. Twelve patients were treated electively, and the remaining 6 patients were treated on an emergency basis in which hemorrhage was brought under control by occlusion pressure. Limited blood loss occurred during this procedure. The needle was removed, and manual pressure on the puncture site was applied for 5 minutes until there was no more oozing or bleeding. The acute oral bleeding was controlled just after embolization. Remaining bleeding around the involved tooth occurred after immediate embolization in 6 cases and interdental suture was found to be necessary. The patients’ postoperative recovery was uneventful. Patients exhibited focal swelling in the area of the AVMs after the procedure, which resolved within 2 weeks. During the 22 ethanol embolizations performed, the amount of ethanol that was used ranged from 5 to 50 mL(mean, 25.7 mL) for a single embolization session. When maximal amounts of ethanol were used, the total dose did not exceed 1 mL/kg of body weight. No patients experienced ethanol toxicity. Hemoglobinuria occurred in 8 out of 18 patients for a total of 11 of 22 procedures and disappeared 5 to 6 hours later after continuous infusion of Ringer’s lactate intravenously and no patients showed an elevation in creatinine and urea levels. With regards to the therapeutic outcome of ethanol embolization, 16 of 18 patients were cured, and 2 had partial remission and were waiting for additional sessions of ethanol embolization to treat residual AVMs in the adjacent soft tissues. The number of required embolization procedures varied from patient to patient depending on the volume, the behavior of the lesion, and whether there was involvement of adjacent soft tissue. A single embolization was usually sufficient to achieve cure of intraosseous AVMs in 14 patients, and the involvement of adjacent soft tissue required multistage embolizations in other 4 patients. In the patients who needed 2 procedures, the interval between the procedures ranged from 1 to 3 months. The immediate venogram and control arteriogram after the procedure were both obtained and documented a significant thrombosis of the lesion in all patients. Obvious expansion of the external jugular vein in 15 patients was obliterated after 1 session of ethanol embolization. Satisfactory shrinkage of facial swelling and improvement and/or loss of the pseudo-port-wine stain of the skin were obtained in 5 patients with involvement of adjacent soft tissues. Contrast-enhanced CT and panorama were performed in all the patients, and angiography was used in 7 patients for the follow-up (Fig 6). The amount of coils and ethanol used and outcomes in 18 patients with AVMs in the mandible were summarized in Table 2.

Discussion

Mandibular AVMs is usually a potentially life-threatening hemorrhage at presentation. It needs rapid and efficient treatment by an experienced team.7 With the development of interventional radiology, embolotherapy plays an ever-increasing role in the management of AVMs.4,7-10 Endovascular embolization has proven effective for immediate bleeding control and has to be performed on an emergency basis as the initial treatment of choice. In addition, embolization can preserve functional anatomy and morphology, in contrast to malocclusion or disfiguration which may result from classical surgical excision though some modified surgical techniques have been reported, such as partial resection of the mandible and immediate replantation of the cortical shell or hollowing out of the mandible and cauterization inside the bone after osteotomy. 11-13

The choice of the agent for the embolization of mandibular AVMs depends on several factors: the vascular territory to be treated, the type of abnormality being treated, the possibility of superselective delivery of an occlusive agent, the goal of the procedure and the permanence of the occlusion required. With regards to AVMs, permanence is a significant issue. It has already been documented in the literature that embolization with materials such as polyvinyl alcohol, tissue adhesives and coils are rarely curative but, on the other hand, provides excellent palliation.14,15 The main reason for recanalization and neovascular recruitment is that all of the aforementioned embolic agents do not completely destroy the endothelial cells of the AVMs, which may cause the decreased oxygen tension, release of angiogenesis factors that stimulate neovascular formation, and the chemotactic matters that cause cellular infiltration to carry debris from the vascular channels. Once that happens, the endothelial cell re-endothelializes and recanalization occurs.16

With the use of absolute ethanol, the endothelial cell is denuded from the vascular wall, its protoplasm is precipitated, and a fracture in the vascular wall to the level of the internal elastic lamina is formed, followed by the shrinking of the lesions.17,18 In AVMs, these changes are desirable and responsible for the curative effects and permanence of ethanol embolization.

Even if ethanol, the most powerful embolization agent, is used, single absolute ethanol embolization cannot provide good result in all extracranial AVMs in the head and neck. In some high flow cases with obvious DOV, the injected ethanol may become diluted with blood and may be swept away from the nidus before it causes nidus occlusion. Assuming that the nidus of the AVMs type has a large DOV component like most of AVMs in the mandible, flow occlusion techniques including external pneumatic pressure cuffs and intravascular occlusion balloon catheters or coils embolization of the DOV are sometimes required for achieving effective ethanol embolization of this subset of peripheral AVMs, as described by Jackson, Cho and Yakes.19-21

Another reason we chose absolute ethanol combined with fiber coils to treat AVMs in the mandible is because of the safety and efficiency of induction of clotting when fiber coils were combined with additional injection of absolute ethanol. The volume and flow of the nidus in the mandible were decreased immediately following the placement of the coils, and the endothelial cells of the lesion were destroyed by absolute ethanol. The decreased volume of the nidus with coils makes it possible to treat the AVMs of the mandible in less embolization session within the limit of the maximal amount of ethanol used.

In spite of the fact that absolute alcohol is a known potential embolic agent that produces vascular thrombosis and might inhibit angiogenesis, its effect on hemostasis for high-flow AVMs is not promising because it cannot deliver immediate hemostatic control, while some cases of AVMs in the mandible present with life threatening hemorrhage.22,23

Coils exposure and gingiva dehiscence occurred in some cases and curettage of the extruded material and associated granulation tissue was required in this report. Comparing with the 0.035mm stainless steel coils we used before, 0.018mm platinum fiber coils are softer and have less chance of causing such problems. During embolization of the mandibular AVMs with DOV, it was possible for the 0.018mm NEST coils to migrate due to the fast flow.24-26 After the occlusion of DOV using EDCs, the possibility of coils migration had been decreased. That is the reason we chose to deploy EDCs before the placement of the 0.018mm fiber coils and make sure that no coils could migrate to the lung.

Direct percutaneous access to the intraosseous vein through the thinned bone cortex or the mental foramen allowed for direct delivery of coils either through the 16G needle or sheath. Due to the complicated anatomy structure of mandible and the nidus of AVMs, it is very difficult to reach every “corner” of venous lakes which matter is very important to complete eradicate all AVMs nidus to pursue for a permanent solution. The 2.2F microcatheter through the 16G stainless needle was easily manipulated to the proper site where you decide to place the coils. Based on this technique, the coils can fill every “corner” and the absolute ethanol can get the best effect. Compared with multiple transosseous puncture sites we used before, we can finish most of cases through one site of puncture now. It can also decrease the risk of procedural hemorrhage.

This study has some limitations, although this is an appealing treatment option. First, it is retrospective and the follow-up duration was not long enough. There is a need for a prospective study involving a significantly large patient population, which would permit assessment that is more precise. Second, coils, as foreign bodies, may cause foreign body reactions and interfere with follow-up by computed tomography and magnetic resonance imaging due to ghost images. Third, coils migration to the pulmonary artery rarely occurs and is associated with a high tendency of severe pulmonary or cardiovascular complications.26 Another drawback of the use of EDCs is their high cost versus the cost of stainless-steel coils.

In conclusion, AVMs in the mandible may lead to fatal complications due to dental treatment. The treatment of intraosseous AVMs requires a multidisciplinary team approach. Despite some potential problems with ethanol embolization still exist and a longer period of follow up is needed, we recommend that the varix within the mandible can be appropriately controlled and completely obliterated by the superselective deployment of coils via microcatheter and the injection of absolute ethanol.