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.

Ruptured aneurysm arising at anterior spinal artery as the collateral circulation with bulbar artery supply to posterior inferior cerebellar artery treated by proximal occlusion and occipital artery-posterior inferior cerebellar artery bypass: a case report and literature review

The cases of aneurysms arising from collateral vessels that supply the posterior inferior cerebellar artery (PICA) are so exceptionally rare that there is no consensus on the optimal treatment. In this report, a patient was presented with subarachnoid hemorrhage caused by a fusiform aneurysm on the right anterior spinal artery, which formed an anastomosis network with bulbar artery and the vessels supplying to the right PICA. We chose to perform proximal occlusion on the anterior spinal and bulbar arteries, using occipital artery-PICA bypass. Our case was the first where proximal occlusion was used concurrently with vascular reconstruction to treat a ruptured aneurysm of collateral vessels supplying to PICA.

Predictive factors of medullary infarction after endovascular internal trapping using coils for vertebral artery dissecting aneurysms

OBJECTIVE The first choice of treatment in cases of vertebral artery dissecting aneurysms (VADAs) is endovascular internal trapping (EIT) of the dissecting segment using coils. However, this procedure carries the risk of medullary infarction, and the risk factors for this complication are not well understood. This study investigated the risk factors causing medullary infarction. METHODS One hundred patients who underwent EIT for VADAs were included in this study. Ninety-three patients presented with subarachnoid hemorrhage. In cases involving the posterior inferior cerebellar artery (PICA), partial internal trapping targeting the ruptured site was performed to preserve the PICA. The VADAs were classified into the distal VA stump group, proximal VA stump group, and entire VA stump group, according to the location of VA segments without adequate flow-out vessels (such as the PICA [VA stump]) at risk of delayed thrombosis. The occurrence of medullary infarction was examined in each group using diffusion-weighted MRI and/or clinical symptoms. Various measurements were performed on digital subtraction angiography, and the risk factors for medullary infarction were analyzed. RESULTS Medullary infarction occurred in 30 patients, affecting the posterolateral medulla in 27 patients and the anteromedial medulla in 3 patients. Medullary infarction occurred in 3 of 47 patients (6%) in the distal VA stump group, 10 of 19 patients (53%) in the proximal VA stump group, and 17 of 34 patients (50%) in the entire VA stump group. The length of trapping was significantly longer in the infarction group than in the noninfarction group but did not differ among the 3 groups. Total length (length of trapping plus VA stump) was a risk factor for medullary infarction in the proximal VA stumps. CONCLUSIONS The primary risk factor for medullary infarction after EIT is not the length of trapping; rather, it is the anatomical location of the VADAs. The risk of medullary infarction is low in cases with distal VA stumps, but the symptoms are severe. Preservation of the origin of the anterior spinal artery can reduce the risk of medullary infarction. The risk of medullary infarction is high in cases with proximal VA stumps, but the symptoms are mild. A shorter length of trapping, although less likely to lead to complications, cannot prevent medullary infarction because the total length depends on the anatomical location of the PICA and not on the surgical technique. Reconstructive therapy should be indicated for patients with ruptured VADAs at high risk of severe ischemic complications (e.g., patients with hypoplasia of the contralateral VA or cases involving the PICA or anterior spinal artery, which are inappropriate for partial internal trapping) or for patients with unruptured VADAs.

Bilateral segmental agenesis of carotid and vertebral arteries with rete mirabile and the prominent anterior and posterior spinal arteries as compensations

Agenesis of carotid or vertebrobasilar arteries with rete formation is rare. The anterior spinal artery or posterior spinal arteries supplying the posterior circulation with steno-occlusion or agenesis of bilateral vertebral arteries is also uncommon. Here, we describe a very rare case of concomitant segmental agenesis of bilateral carotid and vertebral arteries with collateral compensations from the prominent anterior spinal artery and posterior spinal arteries, as well as some transdural arterial networks which were considered a rete mirabile. We discuss its embryological and anatomic significance.

A ruptured aneurysm arising at the leptomeningeal collateral circulation from the extracranial vertebral artery to the posterior inferior cerebellar artery associated with bilateral vertebral artery occlusion

We report an extremely rare case of a small ruptured aneurysm of the leptomeningeal collateral circulation from the vertebral artery (VA) to the posterior inferior cerebellar artery (PICA); this aneurysm was associated with bilateral VA occlusion. A 72-year-old woman with sudden headache, nausea, and subarachnoid hemorrhage (SAH) was admitted to our hospital. On admission, no evidence of cerebral signs or cranial nerve palsy was found. Computed tomography imaging showed SAH predominantly in the posterior fossa, and digital subtraction angiography revealed bilateral VA occlusion and the left VA aneurysm located proximal to the VA union. In addition, a small aneurysm was observed at the leptomeningeal collateral circulation located between the extracranial left VA and the left PICA. The patient underwent radical surgery on the day of the onset of the symptoms associated with SAH. However, the VA aneurysm was unruptured and surgically trapped. The small aneurysm arising at the leptomeningeal collateral circulation was ruptured during the surgery and was electrocoagulated; the collateral circulation was preserved, and no neurologic deficits were observed. The postoperative course was uneventful. SAH with the occlusion of major vessels should be diagnosed with utmost caution to allow preoperative neurologic and radiological assessments.