Cerebral Revascularization for the Management of Symptomatic Pure Arterial Malformations

Intracranial pure arterial malformations

Pure arterial malformations (PAMs) are rare vascular lesions often detected incidentally on brain imaging. They are characterised by a mass of arterial loops containing arteries that are tortuous, overlapping and dilated without any associated arteriovenous shunting. The incidence of PAMs have been rising due to the increasing use of non-invasive angiographic imaging for the diagnosis of neurovascular disorders. This article will present the clinical course of two cases of PAM, both of which demonstrated a stable appearance on surveillance imaging despite the lack of surgical or endovascular intervention.

A Hybrid Approach for the Treatment of a Pure Arterial Malformation Located at an Accessory Middle Cerebral Artery. Cerebral Revascularization Followed by Endovascular Occlusion Using nBCA: Case Report

BACKGROUND AND IMPORTANCE

Pure arterial malformations (PAMs) are rare vascular lesions with unknown natural history. Described in 2013 and initially considered benign, recent evidence of ruptured cases and progressive angioarchitectural changes may support the need for interventional treatment for selected patients. We present the first case of an accessory middle cerebral artery PAM successfully treated using a hybrid approach, including microsurgical revascularization and endovascular occlusion using Glubran2/Lipiodol.

CLINICAL PRESENTATION

A 58-year-old woman with a history of spontaneous basal ganglia hemorrhage 2 years before presented to our clinic with a dilated, multilobulated, and overlapping lesion located at a dominant left accessory middle cerebral artery, compatible with the diagnostic criteria of a PAM. The lesion was near the previous bleeding site, and since perforating and cortical vessels arose from its distal lobule, a safeguarding superficial temporal artery-MCA bypass was considered necessary before the successful endovascular embolization of the malformation using nBCA (Glubran2/Lipiodol).

CONCLUSION

PAMs can be associated with intracranial bleeding; thus, active treatment is warranted for selected patients. A hybrid microsurgical-endovascular approach is feasible and can be considered the optimal treatment for specific complex anatomies.

Microneurosurgical treatment of a small perimesencephalic pure pial arterial malformation: an under-recognized etiology of angiographically occult subarachnoid hemorrhage. Illustrative case

BACKGROUND

Pial arterial malformations (PAMs) are rare vascular lesions consisting of dilated tortuous arteries without venous drainage. Current PAM understanding is limited by the lesion's rarity, limited anatomopathological studies, and frequent misclassifications.

OBSERVATIONS

A 23-year-old male experienced two spontaneous subarachnoid hemorrhages (SAHs) over 6 months with initially unremarkable diagnostic cerebral angiograms. Magnetic resonance imaging (MRI) and angiography after the second SAH revealed a small perimesencephalic ovoid lesion within the left crural cistern, between the left superior and posterior cerebral arteries, appearing to be an exophytic cavernoma, a thrombosed aneurysm, or a hemorrhagic tumor. Microsurgical resection was achieved with a pterional craniotomy and anterior clinoidectomy. The resected lesion was characteristic of a pure PAM arising from superior cerebellar arterial branches.

LESSONS

Small pure PAMs can be deceitfully dynamic lesions causing episodes of hemorrhage, complete thrombosis (angiographically occult), recanalization, and rehemorrhage. Small thrombosed vascular malformations or aneurysms should be included in differential diagnoses of angiographically occult SAH. MRI can be diagnostic, but the true angioarchitecture can only be elucidated with microneurosurgery. The only definitive cure is removal. The microneurosurgical strategy should account for worst-case scenarios, provide adequate skull base exposures, and include bypass revascularization options when thrombosed aneurysms are encountered.

Endovascular treatment of a ruptured pure arterial malformation and associated dysplastic middle cerebral artery dissecting aneurysm: illustrative case

BACKGROUND

Pure arterial malformations are characterized as unique cerebrovascular lesions with a dilated, coil-like appearance and tortuous arteries without early venous drainage. Historically, these lesions have been described as incidental findings with a benign natural history. However, pure arterial malformations can rarely demonstrate radiographic progression and develop associated focal aneurysms with an unclear risk of rupture. Whether radiographic progression of these lesions or the presence of an associated aneurysm warrants treatment remains controversial.

OBSERVATIONS

A 58-year-old male presented with sudden-onset left hemiparesis. Computed tomography revealed a large, acute, right frontotemporoparietal intraparenchymal hemorrhage with underlying irregular curvilinear calcifications. Diagnostic cerebral angiography revealed a dysplastic right middle cerebral artery dissecting aneurysm along the M2 segment associated with a pure arterial malformation, which was treated with endovascular flow diversion in a delayed fashion.

LESSONS

Pure arterial malformations with associated focal aneurysms may not exhibit a benign natural history as once thought. Intervention should be considered for ruptured pure arterial malformations to mitigate the risk of rerupture. Asymptomatic patients with a pure arterial malformation with an associated aneurysm should at least be followed closely with interval radiographic imaging to evaluate for malformation progression or changes in aneurysmal morphology.

Subarachnoid and Intraventricular Hemorrhage in a Patient with a Pure Arterial Malformation and Two Associated Aneurysms in the Posterior Inferior Cerebellar Artery: A Case Report and Literature Review

INTRODUCTION

Pure arterial malformations (PAMs) are rare vascular abnormalities defined as dilated, tortuous arterial loops without any associated venous compartment. PAMs are thought to be benign developmental anomalies that can be safely managed conservatively.

METHODS

We present a case of life-threatening hemorrhage in a patient with a PAM associated with two aneurysms and review the literature describing hemorrhages associated with PAMs.

RESULTS

A 65-year-old female presented with subarachnoid and intraventricular hemorrhage. A digital subtraction angiography revealed a posterior inferior cerebellar artery PAM associated with two saccular aneurysms, which were subsequently microsurgically clipped. At the 1-year follow-up, the patient was neurologically intact. In our literature review, we identified 21 papers describing a total of 37 PAMs. Patients were predominantly female (64.9%) and their median age was 35 years. Almost half (48.6%) of PAMs were associated with aneurysms. In the group of PAMs that were not associated with an aneurysm, the intracranial hemorrhage rate was 15.8%, while in cases of coexisting PAM and aneurysm it was 44.4% (p = 0.0789).

CONCLUSIONS

PAM natural history remains unknown, particularly in cases of coexistence with aneurysms. Patients so affected require careful observation. The description of PAMs as benign vascular malformations should be revised. Surgical management of hemorrhagic PAMs coexisting with aneurysms is possible and should be considered.