SUMMARY Moyamoya disease was originally defined as a characteristic syndrome of recurrent headaches, occlusion of the distal internal carotid arteries and the foggy (moyamoya) clusters of collateral vessels at the base of the brain as demonstrated by cerebral angiography. The etiology is unknown and pathobiology is poorly understood. We examined the intracranial arteries in 3 patients to demonstrate characteristic changes and to obtain a better understanding of the basis mechanisms of the disease. Controls were obtained from 3 normotensive patients who died as a result of cancer. Occluded internal carotid arteries were characterized by severe thickening of the intima with a dense luminal array of smooth muscle cells, a deeper less cellular zone, pronounced tortuosity of the internal elastica and thinning of the media. Collateral vessels were arterial in structure and were affected by similar prollferative changes in the intima, thinning of the media, and contorted internal elastica. Stainable lipids were not part of the typical components. Severe contortion of the internal elastica, medial damage and intimal proliferation may result from recurrent and sustained spasticity of the cerebral arteries. The distal lenticulostrlate arteries showed severe medial damage similar to what is termed as a moth-eaten change in hypertensive patients dying of massive cerebral hemorrhage. Stroke Vol 15, No 4, 1984ARTERIAL CHANGES IN MOYAMOYA DIS-EASE, as shown by angiography of the distal internal carotid artery, reveal lipid-free fibromuscular thickening and the development of presumably newly formed collateral vessels at the base of the brain.' These collaterals are so characteristic that the term moyamoya vessels has been applied to them. 2 Occlusion of the internal carotid artery caused by atherosclerosis, is not accompanied by the appearance of collateral vessels and is characterized by the presence of stainable lipids.The term moyamoya disease was coined for the "foggy" collateral channels demonstrable by cerebral angiography.2 The disease is relatively uncommon and shows no relationship to systemic hypertension. This disease was first reported in, but it is not confined to, the Japanese. The condition is frequently familial, and may occur in infants and children as well as in adults.1 4 The pathogenesis is unknown and the possibilities include genetic factors.3 3 Intracerebral and subarachnoid hemorrhages are frequent complications. 6 Moyamoya disease of the juvenile type often manifests itself by transient ischemic attacks, and the adult type usually presents as a massive intracerebral hemorrhage.* Thus moyamoya disease provides an interesting model for studies of arterial disease and its complications. The histologic features and morphometry of arterial changes in 22 patients with moyamoya disease have been reported by others. 7The present study was undertaken to characterize ultrastructural changes of the circle of Willis and collateral moyamoya vessels, and to obtain a better un- derstanding of the basic mechanisms of ...

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An Aa-arginine-141 to serine substitution has been identified in a homozygous dysfibrinogen, fibrinogen Lima, associated with impaired fibrin polymerization. The point mutation created an asparagine-X-serine-type glycosylation sequence, and indeed, extra, mainly disialylated biantennary oligosaccharides have been isolated from Aa asparagine-139 of the patient's fibrinogen. This type of glycosylation sequence is unique for human fibrinogen, because the sequences shown for normal and abnormal fibrinogens are all asparagine-X-threonine types. The terminal sialic acids of the extra oligosaccharides seem to have largely contributed to the impaired fibrin gel formation, as evidenced by its correction to a near normal level by desialylation. Nevertheless, the polymerizing fibrin facilitated tissuetype plasminogen activator-catalyzed plasmin formation in a normal fashion, indicating that the initial two-stranded fibrin protofibrils had been constructed normally. Thus the impaired fibrin gel formation could be attributed to the delay in their subsequent lateral association, most probably because of the repulsive forces generated by the negative electric charge of the extra sialic acids. The substitution of a basic residue arginine to a noncharged residue serine may also have contributed to the impaired function in a similar manner or by steric hindrance in association with bulky extra oligosaccharide chains. (J. Clin. Invest. 1992. 90:67-76.) Key words: amino acid substitutioncongenital homozygous dysfibrinogen * extra asparagine-linked oligosaccharide * fibrin-facilitated plasminogen activation * lateral association of fibrin protofibrils

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