Hemorrhage due to a pseudoaneurysm on a dural-pial anastomosis after decompression for Chiari malformation type I: case report

While intracranial aneurysms rarely develop after neurosurgical procedures, delayed pseudoaneurysm formation after foramen magnum decompression (FMD) has never been reported. A 52-year-old woman presented with an atypical subarachnoid hemorrhage in the posterior fossa 12 years after a FMD for symptomatic Chiari malformation type I was performed. A pseudoaneurysm on a dural-pial anastomosis was identified as the bleeding source and successfully occluded by endovascular means with full clinical recovery of the patient. Injury to the distal posterior inferior cerebellar artery related to surgery and postoperative infection likely caused formation of a dural-pial anastomosis. Additionally, hemodynamic stress or dissection may have contributed to delayed pseudoaneurysm formation and rupture.

Clinical importance of the posterior meningeal artery: a review of the literature

The posterior meningeal artery, which arises from the vertebral artery, is a critical artery in neurological lesions. However, a comprehensive review of the importance of the posterior meningeal artery is currently lacking. In this study, we used the PubMed database to perform a review of the literature on the posterior meningeal artery to increase our understanding of its role in vascular lesions. The posterior meningeal artery provides the main blood supply to the paramedial and medial portions of the dura covering the cerebellar convexity. The posterior meningeal artery is often involved in dural arteriovenous fistulas occurring near the posterior fossa, and the posterior meningeal artery can be the path for transarterial embolisation or a path through which to monitor the degree of dural arteriovenous fistula embolisation. In posterior circulation ischaemia and moyamoya disease, the posterior meningeal artery can form transdural anastomoses with pial arteries at the surface of the brain, and these can help prevent ischemia. The posterior meningeal artery can also develop aneurysms, most of which are traumatic pseudoaneurysms; patients should therefore be treated in a timely manner or followed up carefully in cases of rebleeding. In addition, during a craniotomy, the posterior meningeal artery should be protected intraoperatively to avoid damaging any transdural anastomosis that may be present. In addition, when the posterior meningeal artery is the main feeding artery of an intracranial tumour, that artery is a satisfactory path for preoperative embolisation. Briefly, the posterior meningeal artery is a very important artery in neurosurgery.

Delayed Establishment of Collateral Circulation from Posterior Meningeal Artery After Proximal Occlusion of Posterior Inferior Cerebellar Artery: Case Report and Literature Review

BACKGROUND

A dissecting aneurysm on the posterior inferior cerebellar artery (PICA) is a rare entity, and endovascular embolization is often adopted. During the procedure, if the parent artery is occluded, the distal PICA is usually supplied by the ipsilateral anterior inferior artery or contralateral PICA. In extremely rare circumstances, the distal PICA can establish collateral circulation by transdural anastomosis with the posterior meningeal artery (PMA).

CASE DESCRIPTION

A 29-year-old woman was admitted complaining of thunderclap headache, nausea, and vomiting for 3 hours. Head computed tomography and digital subtraction angiography revealed subarachnoid hemorrhage and a dissecting aneurysm located at the tonsillomedullary segment of PICA. The parent artery distal to the aneurysm had no collateral circulation from the adjacent arteries. Selective endovascular coiling of the aneurysm with preservation of the parent artery was adopted for treatment. The patient experienced an uneventful postprocedural recovery. To our surprise, follow-up digital subtraction angiography 6 months later revealed complete occlusion of the aneurysm and parent artery at the site of aneurysm formation. A rare anastomosis between the distal PICA and PMA was established.

CONCLUSIONS

A report about this rare condition suggested that after occlusion of the PICA trunk, the distal PICA can form collateral circulation with the PMA. A potential collateral circulation may be present in advance between the PICA and PMA. When ischemia occurs in the distal PICA, this collateral circulation may open and could be reconstructed and enlarged to provide blood supply.

Flow diversion for the treatment of posterior inferior cerebellar artery aneurysms: a novel classification and strategies

Background

The pipeline embolization device (PED) is frequently used in the treatment of anterior circulation aneurysms, especially around the carotid siphon, with generally excellent results. However, treatment of posterior inferior cerebellar artery (PICA) aneurysms with flow diversion (FD) has not been specifically described or discussed. While there are reports of treating PICA aneurysms using placement of FD stents in the vertebral artery, there are no reports of treating these lesions by placement of flow diverting stents in the PICA vessel itself. Due to the unique anatomy and morphology of these aneurysms, it requires special attention. We assessed our multi-institutional experience treating these lesions, including the first reported cases of the PED placed within the PICA.

Methods

Institutional databases of neuroendovascular procedures were reviewed for cases of intracranial aneurysms treated with the PED. Patient and aneurysm data as well as angiographic imaging were reviewed for all cases of PICA aneurysms treated with the PED. PICA aneurysms were defined as aneurysms that involved the PICA. Vertebral aneurysms without disease in the PICA were excluded from the study.

Results

10 PICA aneurysms were treated during the study period. These were classified based on their morphology and location into two main types and five total subtypes for consideration of treatment with flow diversion. All aneurysms were successfully treated, with 8/10 completely obliterated and 2 with a partial reduction in size. Three patients had the PED placed entirely in the PICA and no patient suffered from a medullary or cerebellar stroke. All PEDs were patent and all patients were independent at the last follow-up.

Conclusions

The PED may be used successfully to treat select aneurysms of the PICA. We present the first described cases of successful PED treatment of PICA aneurysms with direct placement of the PED in the PICA vessel itself. The proposed classification system aids in that selection.

The Lurking Catastrophic Complication of an Equally Catastrophic Disease: The Lesson Learned

BACKGROUND

Medullary-bridging vein dural arteriovenous fistula (DAVF) is an uncommon type of DAVF with an aggressive clinical course due to direct fistulous shunting into medullary and brainstem veins. Important considerations need to be given to retrograde embolic migration or perforator involvement while treating these fistulas endovascularly with a liquid embolic agent. We report a lateral spinal artery feeding the DAVF, the recognition of which is important to avoid potential catastrophic complications during definitive therapy, and which has not been described before.

OBJECTIVE

To discuss the anatomy of the lateral spinal artery (LSA) and its communications with pial arteries such as the posterior inferior cerebellar artery (PICA) that may have important implications in the management of neurovascular diseases in and around the foramen magnum.

METHODS

A retrospective analysis of cerebral angiograms and 3-dimensional rotational angiograms of a patient with medullary-bridging vein DAVF treated by transarterial embolization under balloon protection was performed after the patient developed lateral medullary syndrome in the postoperative period.

RESULTS

Detailed analysis revealed a dural branch from the LSA feeding the DAVF which anastomosed with rudimentary PICA.

CONCLUSION

LSA has important anastomoses with perforating arteries of the medulla and cervical cord and, hence, it is important to recognize and identify LSA prospectively in the vascular pathologies of the foramen magnum to avoid fatal neurological complications during endovascular therapy. This is especially important while treating neurovascular pathologies using liquid embolic agents such as Onyx or SQUID, because they can percolate retrogradely through the anastomoses into PICA or other vertebrobasilar perforators.

Aneurysm of the posterior meningeal artery embedded within a dorsal exophytic medullary hemangioblastoma: surgical management and review of literature

Hemangioblastomas are World Health Organization (WHO) Grade I neoplasms of the hindbrain and spinal cord, whose management can be complicated by preoperative hemorrhage. We report on a case of a young female in extremis with posterior fossa hemorrhage following rupture of a fusiform posterior meningeal artery aneurysm embedded within a medullary hemangioblastoma. We discuss management options, including operative staging and embolization, and review similar cases of hemangioblastoma associated with aneurysm.

Occipital artery-posterior inferior cerebellar artery bypass for the treatment of aneurysms arising from the vertebral artery and its branches

OBJECTIVE

To report experience with 7 cases of intracranial aneurysms of the vertebral artery (VA) and its branches that were treated with occipital artery (OA)-posterior inferior cerebellar artery (PICA) bypass.

METHODS

Over 4 years, 7 cases of intracranial aneurysms arising from the VA and its branches were treated with OA-PICA bypass. The clinical data, characteristics of aneurysms, and results of treatment were analyzed.

RESULTS

There were 4 aneurysms that arose from the VA-PICA junction, 2 aneurysms that occurred at the distal PICA, and 1 aneurysm that occurred at the collateral artery from the distal end of the occluded VA to the ipsilateral PICA. OA-PICA bypass was performed before obliteration of the aneurysms in all patients. Of the 7 aneurysms, 4 were totally obliterated with surgery, 2 were treated with additional endovascular coiling or trapping, and 1 was partially obliterated by surgery and gradually disappeared during the follow-up period. Postoperative angiography revealed that the patency of the grafts was good in 6 patients. In 1 patient with an occluded bypass graft, multiple infarctions developed in the left cerebellum, but the patient had almost fully recovered after rehabilitation.

CONCLUSIONS

OA-PICA bypass with obliteration of the aneurysm is one of the optimal treatments for intracranial aneurysms that occur at the VA and its branches because it can preserve the perforators and distal blood flow from the PICA.