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Spontaneous occlusion of the circle of Willis (moyamoya syndrome)
Abstract:
Three young autopsy and four temporal artery biopsy cases with an arteriographically typical moyamoya syndrome were studied by histologic, electron microscopic, and immunofluorescence methods. In all autopsy cases the intracranial segment of the internal carotid arteries showed concentric intimal thickening with severe stenosis or obstruction of the lumen, folding of the internal elastic lamina, and shrinkage of the external diameter of the vessel. Inflammatory infiltration was absent. Abnormal networks of thin-walled vessels, interpreted as secondary collaterals, were seen at the base and on the convexity of the brain. Degenerative changes, including a ruptured coronary aneurysm in one case, were also noted in the coronary and temporal arteries. In both the intra- and extracranial arteries repeated endothelial damage was indicated by the presence of redundant subendothelial basement membrane-like material. Lipid or calcium deposits were exceptional, and no evidence for the presence of immunoglobulins or components of the complement could be obtained by immunofluorescence. These pathologic alterations, distinct from atherosclerosis, fibromuscular dysplasia, and the established types of arteritis, seem to be identical in children and adults, in spite of different clinical manifestations of the moyamoya syndrome in these age groups. We suggest that a humoral factor, associated with infections, may induce repeated endothelial damage and intimal thickening in the intracranial arteries of genetically predisposed children in analogy with recent observations made in the coronary arteries of young subjects.
Insights
Moyamoya syndrome involves artery thickening and narrowing, distinct from other vascular diseases. This study suggests a potential humoral factor, possibly infection-related, causes endothelial damage in genetically susceptible individuals.
Area of Science:
- Neurology
- Vascular Biology
- Pathology
Background:
- Moyamoya syndrome is a rare cerebrovascular disorder characterized by progressive stenosis of the intracranial arteries.
- Pathological mechanisms underlying moyamoya syndrome remain incompletely understood, particularly regarding endothelial involvement.
- Distinct clinical presentations exist between pediatric and adult moyamoya syndrome patients.
Purpose of the Study:
- To elucidate the histopathological features of moyamoya syndrome.
- To investigate the role of endothelial damage and potential causative factors in moyamoya syndrome.
- To compare pathological findings in pediatric and adult cases.
Main Methods:
- Histological examination of intracranial arteries and temporal artery biopsies.
- Electron microscopy to assess ultrastructural changes.
- Immunofluorescence studies to detect immune deposits.
Main Results:
- Intracranial arteries showed concentric intimal thickening, lumen stenosis, internal elastic lamina folding, and reduced vessel diameter.
- Absence of inflammatory infiltration, lipid, or calcium deposits; no immunoglobulin or complement detected.
- Evidence of repeated endothelial damage with subendothelial basement membrane-like material in both intra- and extracranial arteries.
- Degenerative changes, including coronary artery aneurysm, were observed in some cases.
- Pathological findings were consistent across autopsy and biopsy cases, and appeared similar in children and adults.
Conclusions:
- Moyamoya syndrome exhibits distinct pathological alterations, differing from atherosclerosis, fibromuscular dysplasia, and arteritis.
- The findings suggest a potential role for a humoral factor, possibly infection-induced, in triggering repeated endothelial damage and intimal thickening.
- Genetic predisposition may play a role in the development of moyamoya syndrome, particularly in children.