Role of the Cervical Anterior Spinal Artery in the Endovascular Treatment of Vascular Diseases: Bystander, Accomplice, Victim, or Friend?

The cervical anterior spinal artery (ASA) is a very important artery arising from the intracranial vertebral artery (VA). It can play different roles in endovascular treatment (EVT) of spinal vascular diseases. The current understanding of these roles is incomplete; therefore, we performed this review. We found that cervical ASA can be involved in many spinal vascular diseases, such as arteriovenous fistula (AVF), arteriovenous malformation (AVM), and aneurysm, and can serve as a collateral channel in proximal VA occlusion. In AVF and AVM, when the cervical ASA is involved, it often plays the role of an accomplice or victim because it acts as the feeder or as a bystander that does not provide blood flow to the AVF and AVM. In cervical ASA aneurysm, the ASA is a victim. During EVT of VA aneurysms or stenoses, the cervical ASA ostia can be covered or occluded, resulting in ASA ischemia. In this situation, the ASA is a victim. In VA occlusion or the subclavian steal phenomenon, the cervical ASA can serve as a collateral channel to provide blood flow to the posterior circulation. In this case, the ASA plays the role of a friend. According to the role of the cervical ASA in spinal vascular diseases, EVT should be determined “case by case.” Most importantly, when EVT is performed to treat these diseases, the cervical ASA axis must be preserved. Therefore, understanding the role of the cervical ASA in spinal vascular diseases is crucial.

Combined surgical and endovascular approach to treat a ventrally located perimedullary arteriovenous fistula

Perimedullary arteriovenous fistulae (PMAVFs) (also called type IV spinal cord arteriovenous malformations) are rare lesions. They are located in the subarachnoid space or just under the pia. The shunt occurs between the anterior spinal artery (ASA) and/or posterior spinal artery (PSA) and a network of perimedullary veins. The aim of the treatment, surgical or endovascular, is to occlude the fistula. This article presents a unique treatment strategy of a demanding strictly ventral PMAVF in the lower thoracic cord. A posterior surgical approach with spinal cord rotation followed by direct puncture of a distally located arterial feeder was achieved. Precise identification of the fistula with superselective contrast injections was obtained and accurate catheterization of the venous pouch with a microcatheter was performed. Complete occlusion of the PMAVF was achieved with coils.

Microsurgical or endovascular strategy for complete obliteration of spinal arteriovenous shunts in a single-institute 10-year retrospective study

The objective of this retrospective study is to more fully understand the optimal strategy to manage spinal arteriovenous (AV) shunts. This study included a cohort of 35 patients with a diagnosis of spinal AV shunts who were treated over the past 10 years at a single institute. Angiographic diagnosis of intramedullary AV malformations (IM-AVM), perimedullary AV fistulas (PM-AVF), dural AV fistulas (D-AVF), or epidural AV fistulas (ED-AVF) was carefully made, and the microsurgical or endovascular strategy for them was determined at the interdisciplinary meeting consisting of neurospinal surgeons and endovascular specialists. Endovascular surgery was first considered whenever safely possible. Microscopic direct surgery using intraoperative image guidance was considered for cases in which endovascular access was challenging or not safely possible. Combined treatment was another option. The clinical condition was assessed using the modified Rankin scale (mRS). Seventeen of 35 cases were treated with microscopic direct surgery, 13 cases with endovascular surgery, and the remaining five cases with the combination. Complete angiographic obliteration was achieved in 30 of 35 cases (85.7%). Although residual AV shunts was recognized in 3 cases of IM-AVM, 1 case of PM-AVF and 1 case of ED-AVF, no angiographic recurrence was present with an average postoperative follow-up period of 44 months. The average mRS before surgery was 2.37 and significantly improved to 1.94 at the most recent follow-up. Interdisciplinary collaboration between neurospinal surgeons and endovascular specialists should be standard to achieve safe and successful outcomes in treating such rare and difficult spinal disorders.

Pediatric perimedullary arteriovenous fistula: clinical features and endovascular treatments

Objective

Pediatric spinal perimedullary arteriovenous fistula (PMAVF) is rare but may cause permanent disability. We aim to summarize the clinical features of pediatric PMAVFs and our clinical experience in their treatment and to evaluate the effect of endovascular treatment in a large cohort.

Methods

From 2008 to 2017, 51 PMAVFs in pediatric patients (<14 years' old) treated with endovascular techniques were retrospectively reviewed, including 24 type IVb (47.1%) and 27 type IVc (52.9%) lesions. Clinical features, radiological findings, treatment, and outcomes were evaluated.

Results

Thirty-eight boys and thirteen girls were included, and the mean age at presentation was 5.6±4.1 years. Acute neurological deterioration was identified in 33 patients, and 21 of those patients (63.6%) suffered from bleeding. The annual bleeding rate before treatment was 2.55%. After transarterial embolization with coils and glue, 46 PMAVFs (90.2%) were completely occluded, and five (9.8%) were obliterated by supplementary microsurgery. During a follow-up period of 6 to 119 months (mean 58.4±16.7 months), the patients’ clinical states were improved in 42 cases (82.4%), stationary in nine cases (17.6%), and aggravated in none. Type IVc patients had a longer preoperative period, more chronic symptoms, a lower cure rate by embolization, and less improvement of symptoms than type IVb patients had (P<0.05).

Conclusions

Pediatric PMAVF is a special subgroup of intradural arteriovenous shunt that should be treated early. Endovascular embolization is safe and effective in the treatment of pediatric PMAVFs.

Study and therapeutic progress on spinal cord perimedullary arteriovenous fistulas

Spinal cord perimedullary arteriovenous fistulas (PMAVFs) are rare and belong to type IV spinal cord arteriovenous malformations (AVMs). Little is known regarding the treatment and prognosis of spinal cord PMAVFs. In the present study the relevant literature from PubMed was reviewed, and it was found that these fistulas can occur at all ages but are more common in children. In children, most spinal cord PMAVFs are large and with high flow, begin with bleeding and are frequently associated with hereditary hemorrhagic telangiectasia. However, in adults, most spinal cord PMAVFs are small and with low flow and begin with progressive spinal cord dysfunction. The early diagnosis of spinal cord PMAVFs is generally difficult, and symptoms can be very severe at the time of diagnosis. Digital subtraction angiography remains the gold standard; however, computed tomography angiography and magnetic resonance angiography are also promising. Spinal cord PMAVFs can be treated by endovascular embolization, surgical removal or a combination of the two methods. Most spinal cord PMAVFs show good outcomes after the appropriate treatment, and the prognosis is primarily associated with the blood flow of the PMAVF. For high-flow spinal cord PMAVFs, endovascular embolization is more effective and can lead to a good outcome; however, for low-flow spinal cord PMAVFs, surgical removal or the combination with endovascular embolization is the optimal choice. The prognosis for low-flow types is slightly worse than for high-flow spinal cord PMAVFs in children, but the outcome is acceptable.

Cervical perimedullary arteriovenous shunts: a study of 22 consecutive cases with a focus on angioarchitecture and surgical approaches

BACKGROUND

Reports of cervical perimedullary arteriovenous shunt (PMAVS) are limited, and treatment strategies have not been established.

OBJECTIVE

To describe angioarchitecture and optimal treatment strategies for cervical PMAVS.

METHODS

We treated 22 patients with cervical PMAVS between 2000 and 2012 (8 women and 14 men; age, 9-80 years). According to the classification, our patients included type IVa (4 patients), type IVb (16 patients), and type IVc (2 patients). Seventeen patients presented with subarachnoid hemorrhage.

RESULTS

A total of 41 shunting points were localized in 22 patients, of which 34 points were located ventral or ventrolateral to the spinal cord. The anterior spinal artery (ASA) contributed to the shunts in 16 patients. Aneurysm formation was identified in 8 patients. Endovascular treatment was attempted in 3 patients, resulting in complete obliteration in 1 patient (type IVc). Overall, 21 patients underwent open surgery. An anterior approach with corpectomy was elected for 2 patients; the other 19 patients underwent the posterior approaches using indocyanine green videoangiography, intraoperative angiography, endoscopy (8 patients), and neuromonitoring. Twenty patients were rated as having a good recovery at 6 months after surgery. No recurrence was observed in any patients during the follow-up (mean, 59.7 months).

CONCLUSION

Shunting points of the cervical PMAVS were predominantly located ventral or ventrolateral to the spinal cord and were often fed by the ASA. Even for ventral lesions, posterior exposure assisted with neuromonitoring and endoscopy, and intraoperative angiography provided a view sufficient to understand the relationships between the shunts and the ASA and contributed to good surgical outcomes.

Spinal Pial (Type IV) Arteriovenous Fistulae

BACKGROUND:

Demographics, hemorrhage risk, and results of surgical and endovascular treatment of spinal pial (type IV) arteriovenous fistulae (AVFs) across a large patient group have not been previously reported.

OBJECTIVE:

To report demographics, hemorrhage rates, and treatment results for these AVFs.

METHODS:

We performed a pooled analysis via the PubMed and Embase databases through November 2012. Individualized patient data were extracted and analyzed using Cox proportional hazards regression to obtain hazard ratios for hemorrhage risk factors and pooled for baseline demographics and treatment results.

RESULTS:

We extracted information on 213 patients from 28 studies. Only 1% of lesions were incidental; 93% of patients presented with neurologic deficits and 36% with hemorrhage. Patients with type IVa lesions were significantly older (mean age, 46.9 years) and demonstrated a male sex predilection (68% male). Patients with type IVc lesions were significantly younger (mean age, 18.7 years), had no sex predilection, and had the highest prevalence of syndromic conditions (29% of cases). The annual hemorrhage rate was 2.5% (95% confidence interval [CI]: 1.4%-4.7%), increasing to 5.6% for hemorrhagic fistulae (95% CI: 3.0%-10.7%; hazard ratio: 6.31; 95% CI: 0.69-57.4; P = .10). Patient sex, fistula location, and fistula subclass were not significant risk factors for hemorrhage. The surgical obliteration rate was 88%; 68% of patients improved, 26% were the same, and 6% were worse. The endovascular obliteration rate was 74%; 75% of patients improved, 14% were the same, and 11% were worse.

CONCLUSION:

We demonstrate the utility of the Anson-Spetzler a-c subclassification and underscore the efficacy of surgical and endovascular spinal AVF treatment.