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Mechanism of intracranial rebleeding in moyamoya disease
T Iwama1, M Morimoto, N Hashimoto
1Department of Neurosurgery, National Cardiovascular Center, Osaka, Japan.
Abstract:
Intracranial hemorrhage is the major catastrophic event in the natural course of Moyamoya disease, and outcome of the patients with rebleeding is very poor. However, the mechanism underlying intracranial rebleeding is not well elucidated. We retrospectively analyzed 15 patients who bled two times or more among 46 bled patients with Moyamoya disease. The results indicated that there were two different types in the manner of rebleeding. One group consisted of seven cases, which bled two times or more at the same site than the original bleeding site. In four of these seven cases, a ruptured aneurysm was identified at the distal part of collateral vessel or on the major vessel. In the other three cases, no source of bleeding was identified. In all of these cases, rebleeding occurred within 2 months after the initial insult except for one case. Another group consisted of eight cases, which bled repeatedly but at different sites from the initial bleeding site. In any of these cases, neither aneurysms nor other vascular abnormalities were identified. In all of these cases, rebleeding occurred more than 2 months after the initial bleeding. The present result indicated that intracranial bleeding might occur as a result of rupture of a tiny aneurysm at the periphery of collateral vessels. These aneurysms may be blown out after initial bleeding. When they persist after the event, they may rupture again in a fairly short interval. In other cases, bleeding occur at different sites from the initial site. They are considered to be a result of ruptured weak Moyamoya vessels which are forced to act as collateral pathways and are under unusually increased hemodynamic stress.
Insights
Moyamoya disease patients re-bleeding have poor outcomes. Re-bleeding occurs either at the same site, often from ruptured aneurysms within 2 months, or at different sites from weak vessels over 2 months later.
Area of Science:
- Neurology
- Neurosurgery
- Vascular Medicine
Background:
- Intracranial hemorrhage is a severe complication of Moyamoya disease.
- Re-bleeding in Moyamoya disease patients leads to poor outcomes.
- The mechanisms of intracranial re-bleeding remain unclear.
Purpose of the Study:
- To investigate the mechanisms and patterns of intracranial re-bleeding in Moyamoya disease.
- To differentiate types of re-bleeding events based on timing and location.
- To identify potential causes of recurrent hemorrhages in Moyamoya disease patients.
Main Methods:
- Retrospective analysis of 15 patients with multiple intracranial hemorrhages.
- Categorization of re-bleeding based on location (same vs. different site) and timing relative to initial hemorrhage.
- Review of imaging and surgical findings to identify sources of bleeding, such as aneurysms or vascular abnormalities.
Main Results:
- Two distinct patterns of re-bleeding were identified.
- Pattern 1: Re-bleeding at the same site (7 cases), often associated with ruptured aneurysms on collateral vessels, occurring within 2 months.
- Pattern 2: Re-bleeding at different sites (8 cases), linked to weak Moyamoya vessels under hemodynamic stress, occurring after 2 months.
Conclusions:
- Intracranial re-bleeding in Moyamoya disease can result from ruptured peripheral aneurysms on collateral vessels, particularly in early re-bleeding events.
- Late re-bleeding at different sites may be due to the rupture of fragile Moyamoya vessels acting as collaterals under high stress.
- Understanding these distinct mechanisms is crucial for managing re-bleeding risk in Moyamoya disease.