This study received approval from the Institutional Review Board of the Shanghai Ninth hospital, and patient informed consent was acquired. Between January 2017 and June 2018, 10 consecutive patients with AVMs located in the floor of the mouth who underwent ethanol embolization in combination with coil-assisted DOV occlusion were enrolled. The AVMs with DOV were defined as multiple arteriolar components of the nidus shunted into dilated venous components and can be identified as a part of a enlarged outflow vein on an angiogram. Cases with extensive anatomy structure involved who’s both the floor of the mouth and base of the tongue or the oropharyngeal area affected were not included from this series. The risks and advantages of the operation were discussed in detail with all the patients, and written consent for undergoing the operation was obtained. For participants that are minors (age less than 16 years), informed consent had been obtained from parents. All methods were performed in accordance with the relevant guidelines and regulations.
The study group consisted of 10 patients (4 males and 6 females) with a mean age of 32.1 years (range: 13–48 years) during the treatment (Table 1). All the patients exhibited multiple symptoms. The most common symptoms were swelling, pulsation/thrill and hemorrhage (Table 1). The clinicians used the standard staging system described by the Schobinger stage, which was adopted by the International Society for the Study of Vascular Anomalies (ISSVA) for the evaluation of the clinical manifestations of the AVMs(6). 7 patients (70%) had Schobinger stage II AVMs, and 3 patients (30%) had Schobinger stage III AVMs (Table 1). After the clinical investigation, enhanced computed tomography (CT) scan was recommended to evaluate the hemodynamic and anatomic features (Figure 1A, B). The feeding arteries, nidus and drainage veins were defined using superselective digital subtraction angiography (DSA) in all patients before embolization. The clinicians recorded the patients’ sex and age, Schobinger stage, lesion location, and clinical manifestations (Table 1). For the patients with acute torrential hemorrhage, the bleeding portion was sutured for hemostasis.
All the procedures of embolization were performed under general anesthesia via nasal intubation. The oxygen saturation, invasive arterial pressure, electrocardiogram (ECG) and end-tidal carbon dioxide levels were constantly monitored through the procedure.
Occlusion of the DOV
All the patients underwent selective angiography of the related artery (lingual and facial artery) through femoral approach to determine the detailed angioarchitecture of the AVM (Figure 2A). The DOV was identified as obvious dilated outflow vein according to venous phase of selective angiograms. The tortuous arteriovenous components of the nidus (Figure 2B) and DOV were observed in all angiograms (Figure 2C).
Once the DOV identified, it was occluded in the following manner: a 17.8-G needle (Cook, Bloomington, Indiana) was used to puncture the DOV with the guidance of a roadmap percutaneously or transmucosal. After verify the positioning of the needle in the DOV by venogram (Figure 3A), a 2.2-F microcatheter (Asahi, Seto, Japan) was introduced into the dilated venous sac through the needle (Figure 3B). After confirming the correct positioning of the microcatheter, three-dimensional (3D) detachable coils (EV3, Irvine, California) were inserted through the microcatheter (Figure 3C). The external pressure to the submandibular region can be applied manually with a finger of the operator to the proximal end after the insertion of the detachable coil. This pressure stimulates colis to form a 3-D pattern and reduces the risk of coil migration to some extent. After the satisfactory obliteration of the distal end of the draining veins, Nester coils (Cook, Bloomington, Indiana) were released to make a compact obliteration of the DOV. Because of the size and tortuous of DOV in the floor of the mouth, coils with small size and soft physical properties were preferred. The insertion of the coils was stopped once the venogram showed a significant reduction in the outflow from the vein and contrast stain (Figure 3C). The size, type and number of coils were recorded in all the cases.
Absolute ethanol was injected into the nidus through the needle or microcatheter. The volume and rate of ethanol per injection were determined by several venograms from the needle or from the microcatheter before absolute ethanol injected into the nidus. The contrast material should be noted only in the nidus and drainage veins, but not in the feeding arteries. Angiography of the feeding artery was carried out 3-5 minutes after ethanol injection to determine whether the nidus of the AVM was embolized. Repeated ethanol injection was required if the nidus was still noted.
The management after ethanol embolization included intravenous (IV) infusion of a tapering dose of IV methylprednisolone was administered after ethanol embolization for 3–5 days to relieve the swelling. Ranitidine was given to protect against gastric or duodenal ulcer development. The patients were routinely monitored in the intensive care unit (ICU) overnight with nasal intubation to avoid unexpected severe swelling. The nasal intubation was removed in 1–3 days according to the degree of swelling relief.
Evaluation of the clinical data and follow-up results
Follow-up was performed at 1–3-month intervals after the initial treatment. enhanced CT or angiography was recommended when the symptoms and signs of the patients worsened. Additional embolotherapy was required if the AVMs were still observed or clinical symptom remained. For the patients with a complete response to the treatments, a telephone questionnaire at 3-month intervals and physical examination at 1-year intervals were suggested.
The following 4-point grading scale was used to evaluate the clinical symptoms and signs (10): (i) adverse response, AVM became larger or pain was aggravated; (ii) no response, AVM was ≤49% resolved; (iii) partial response, AVM was 50–99% resolved; and (iv) complete response, AVM was 100% resolved. Complete response was defined as the complete resolution of the clinical signs or 100% devascularization on arteriography after more than 12 months of follow-up (Figure 3D). Partial response was defined as the complete resolution or improvement of the clinical symptoms and signs with 50–99% devascularization of the AVMs. No response was defined as no improvement in the clinical signs with ≤49% devascularization. Adverse response was defined as an aggravation of the clinical signs regardless of the degree of devascularization on arteriography. The partial and complete responses were considered as effective therapeutic outcomes.
The complications related to the embolization procedure were classified as minor or major(7). The minor complications included any temporary adverse sequelae, such as transient nerve injury or spontaneous mucosal necrosis and coil exposure heal with minor debridement. The major complications included permanent adverse sequelae, death, and the need for major therapy. The transient pain and swelling of the treated area after the embolization were not judged to be complications.