LETTERS TO THE EDITOR
|Year : 2022 | Volume
| Issue : 6 | Page : 1217-1218
Aneurysm associated with moyamoya angiopathy: Indian perspective and review of management strategies
Shambaditya Das1, Biman Kanti Ray1, Ritwik Ghosh2, Souvik Dubey1
1 Department of Neurology, Institute of Post Graduate Medical Education and Research, Bangur Institute of Neurosciences, Kolkata, West Bengal, India
2 Department of General Medicine, Burdwan Medical College and Hospital, Burdwan, West Bengal, India
|Date of Submission||26-May-2022|
|Date of Acceptance||14-Jun-2022|
|Date of Web Publication||15-Jul-2022|
Bangur Institute of Neurosciences, 52/1A Shambu Nath Pandit Street, Kolkata-25, West Bengal
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Das S, Ray BK, Ghosh R, Dubey S. Aneurysm associated with moyamoya angiopathy: Indian perspective and review of management strategies. Ann Indian Acad Neurol 2022;25:1217-8
|How to cite this URL:|
Das S, Ray BK, Ghosh R, Dubey S. Aneurysm associated with moyamoya angiopathy: Indian perspective and review of management strategies. Ann Indian Acad Neurol [serial online] 2022 [cited 2023 Jan 29];25:1217-8. Available from: https://www.annalsofian.org/text.asp?2022/25/6/1217/351077
Moyamoya angiopathy (MMA) is a chronic progressive occlusive intracranial vasculopathy characterized by angiographic findings of stenosis or occlusion at the terminal portion of the internal carotid artery or proximal anterior cerebral artery (ACA) and/or middle cerebral artery (MCA) together with the abnormal vascular network (classically appears to be like “puff of smoke”) at the base of the brain. Traditionally, hemorrhagic presentation of MMA is more common in adults and remains a major cause of mortality. The frequency of hemorrhagic presentation is much higher among the Japanese population (62.5%) in contrast to the Caucasian (8.5–15%) and Indian (25%) populations., The two main causes of intracranial bleed include rupture of dilated, fragile Moyamoya vessels (perforating arteries) and rupture of the circle of Willis aneurysms (CoA). The prevalence of intracranial aneurysm in MMA patients ranges from 3 to 18% as compared to 2-3% in general population.,, However, data pertaining to the frequency of intracranial aneurysm in the Indian MMA population is sparse and limited to few case series and case reports.,, We herein report our observation of aneurysm associated with MMA in comparison to other Indian experiences with MMA-associated aneurysm and briefly overview its current management trends.
We encountered 160 angiographically proven MMA patients (85 had adult-onset MMA and 75 had pediatric-onset MMA) in our center over the past 5 years (2016–2021). Among them 130 (81.3%) had ischemic, 18 (11.3%) had hemorrhagic, and 12 (7.5%) had normal brain imaging features. The hemorrhagic presentation was exclusively found in adult-onset MMA. Interestingly, none of our patients harbored the evidence of aneurysm. This is in contrast to the prevalence of intracranial aneurysm in MMA among the Japanese population, which ranges from 3 to 18%. Our results are compatible with other major studies from India by Sadashiva et al. and Srivastava et al., which also had a similar low frequency of aneurysm associated with MMA of 2.9% and 3.8%, respectively. Garg et al. however reported a higher incidence of aneurysm associated with MMA of 25%, but a possibility of referral bias cannot be ruled out. In this study, 91% of the aneurysms involved the posterior circulation and 82% of them were around the circle of Willis.,,,,,
Histological findings of MMA vessels have shown attenuated media and fragmented elastic laminae, reflecting the fragile integrity of the arterial wall. Besides, MMA leads to increased hemodynamic stress in the nonoccluded vessels and collaterals due to altered distribution of intracranial blood flow. Both these factors predispose MMA to spontaneous intraparenchymal hemorrhage and aneurysm formation.,,,
Aneurysm formation in patients with MMA may be classified according to the location into two groups: aneurysms arising from the major arteries in circle of Willis and aneurysms that arise from pathologic Moyamoya vessels, their collateral vessels, or distal perforators (peripheral aneurysm). Aneurysms originating from the circle of Willis account for approximately 39% of the aneurysms associated with MMA. Main trunk aneurysms are mostly true saccular aneurysms arising from the circle of Willis or its tributaries, whereas peripheral artery aneurysms are mainly dissecting aneurysms, becoming pseudoaneurysms after rupture, originating from distal fragile Moyamoya vessels in basal ganglia and choroidal arteries (anterior and posterior).,,,,
There is no consensus on the optimal treatment approach for intracranial aneurysm associated with MMA. The pathophysiology of intracranial aneurysm formation and anatomical location commonly dictates the treatment strategies, and no “one-size-fits-all strategy” can be applied.,,,
Endovascular therapy is ideal for aneurysm around the circle of Willis, and both the posterior circulation aneurysm as well as endovascularly accessible anterior circulation aneurysm with minimal stenosis of large intracranial arteries, alternatively open surgery may be considered. It has been seen that revascularization surgery alone may cause regression or stability in size of posterior circulation aneurysm, explained by decreased hemodynamic stress in the vertebrobasilar system. Some literature also rationalizes the conservative management of unruptured anterior circulation aneurysms because gradual progression of steno-occlusive changes in the proximal ACA, MCA, and distal ACA will finally lead to its spontaneous disappearance. However, variable progression rates of Moyamoya may prolong the time taken for steno-occlusive changes to occur and carry the risk of rebleeding in the interim, especially in previously ruptured aneurysm.,,
Peripheral aneurysm associated with MMA often regresses spontaneously (65.7%), whereas some may experience rapid enlargement and subsequent hemorrhage. The distal choroidal artery aneurysms often rebleed, within days to 4 months following the first rupture. Hence, prompt treatment of accessible peripheral aneurysm is warranted. The fragile nature of the Moyamoya vessels, deeper distal locations, and obstruction in the surgical field due to the abundant collaterals and perforators make interventions technically difficult in this location. Also, the parent arteries are slim; super-selective catheterization is usually difficult to perform, and often, parent artery occlusion (PAO) has to be performed. In such scenarios, pretesting with the amobarbital provocative test to assess the feasibility of PAO tolerance is suggested. Endovascular therapy is considered as the first choice in the treatment of peripheral aneurysm associated with MMA in the setting of favorable aneurysm and parent vessel characteristics. However, revascularization surgery in such patients, by means of decreasing the hemodynamic stress on the fragile Moyamoya vessels and the delicate choroidal arteries, further increases the rate of complete involution of the aneurysm and decreases rupture rates at follow-up. However, due to the small but definite risk of rebleeding during the period between presenting rupture and involution of the aneurysm in this approach, it should be reserved for candidates where the peripheral aneurysm is technically inaccessible for interventions. [Table 1] summarizes the management strategy of the aneurysms associated with MMA.,,,,
To conclude, Indian MMA continues to behave differently in comparison to MMA in other ethnicities. Despite various complications, endovascular therapy can be considered as the first line of treatment for intracranial aneurysms associated with MMA, although individualized case-wise assessment is warranted.
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Conflicts of interest
There are no conflicts of interest.
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