This is an overview on the pathology and pathogenesis of aneurysms, focused on the weakness of the tunica muscularis and the existence of a locus minoris resistentiae. In this regard emphasis is brought to alterations of the internal elastic lamina (IEL) and consequently to the decrease of smooth muscle cells. Tears of IEL, endothelial disruption and formation of thrombi are discussed also in relation to the occurrence of apoptosis of smooth muscle cells. In the remodelling of the vessel walls a major role is played by the constituents of extracellular matrix which have been studied especially in experimental conditions. Many examples of the illustrated pathology have been provided from the personal collection of aneurysm surgical material. Since there is little doubt that the susceptibility to develop aneurysms has genetic components, a special attention is paid to genetic studies dealing with genes encoding for proteins of the extracellular matrix.
AndoJKomatsudaTKamyiaA: Cytoplasmic calcium response to fluid shear stress in cultured vascular endothelial cells in vitro. Cell Dev Biol24: 871–877, 1988.
2.
AnidjarSSalzmannH: Elastase-induced experimental aneurysms in rats. Circulation82: 973–981, 1990.
3.
BakerCJFioreA: Serum elastase and apha-1 antitrypsin levels in patients with ruptured and unruptured cerebral aneurysms. Neurosurgery37: 56–61, 1995.
4.
ChyaneDLewisI: Gelatinase activity and the occurrence of cerebral aneurysms. Stroke28: 799–804, 1997.
5.
ConwayHHutchinsGMTamargoRJ: Marfan syndrome is not associated with intracranial aneurysms. Stroke30: 1632–1636, 1999.
6.
FinlayHMWhittakerPCanhamPH: Collagen organization in the branching region of human brain arteries. Stroke29: 1595–1601, 1998.
7.
ForbusW: On the origin of miliary aneurysms of the superficial cerebral arteries. Bull Johns Hopkins Hosp47: 239–281, 1930.
8.
FutamiKYalashitaJHigashiS: Do cerebral aneurysms originate at the site of media defects? Microscopic examination of experimental aneurysms at the fenestration of the anterior cerebral artery in rats. Surg Neurol50: 141–146, 1998.
9.
GaetaniPRodriguez y BaenaRR: Metalloproteases and intracranial vascular lesions. Neurol Res21: 385–390, 1999.
10.
GaetaniPTartaraF: Collagen cross-linkage, elastolytic and collagenolytic activities in cerebral aneurysms: a preliminary investigation. Life Sci63: 285–292, 1998.
11.
HazamaIKataokaH: Early changes of experimentally induced cerebral aneurysms in rats, Light microscopic study. Am J Pathol124: 399–404, 1986.
12.
HedinILDottgerBA: Diverse effects of fibronectin and laminin on phenotypic properties of cultures arterial smooth muscle cells. J Cell Biol107: 307–319, 1988.
13.
KangYHashimotoN: Effect of blood coagulation factor XIII on the development of experimental cerebral aneurysms in rats. J Neurosurg73: 242–247, 1990.
14.
KimSCSinghM: Matrix metalloproteinase-9 in cerebral aneurysms. Neurosurgery41: 642–647, 1997.
15.
KnoxJBSukhovaGK: Evidence for altered balance between matrix metalloproteinases and their inhibitors in human aortic diseases. Circulation95: 205–212, 1997.
16.
KondoSHashimotoN: Apoptosis of medial smooth muscle cells in the development of saccular cerebral aneurysms in rats. Stroke29: 181–189, 1997.
17.
KondoSHashimotoN: Response to Stehbens, Stroke29: 1481–1482, 1998.
18.
KrexDSchaeckertHKSchaeckertG: Genesis of cerebral aneurysms. An update. Acta Neurochir (Wien)143: 429–449, 2001.
19.
MajamaaKSavolainenERMyliylaVV: Synthesis of structurally instable type III procollagen in patients with cerebral artery aneurysm. Biochem Biophys Acta1138: 191–196, 1992.
20.
MitzutaniTYoshimasaM: Proposed classification of nonatherosclerotic cerebral fusiform and dissecting aneurysms. Neurosurgery45: 253–259, 1999.
21.
NakajimaNNagahiroS: Phenotypic modulation of smooth muscle cells in human cerebral aneurysmal walls. Acta Neuropathol100: 475–480, 2000.
22.
NakatomiHSegawaH: Clinicopathological study of intracranial fusiform and dolicoectatic aneurysms. Stroke31: 896–900, 2000.
23.
OstergaardJROxlundH: Collagen type III deficiency in patients with rupture of intracranial saccular aneurysms. J Neurosurg67: 690–696, 1987.
24.
OstergaardJRReskeNielsenEHuhlJ: Deficiency of reticular fibers in cerebral arteries. On the etiology of saccular aneurysms in childhood. Br J Neurosurg3: 113–115, 1989.
25.
PetersDGKassamAB: Molecular anatomy of an intracranial aneurysm. Coordinated expression of genes involved in wound healing and tissue remodelling. Stroke32: 1036–1042, 2001.
26.
RubanyiGMRomeroJCVanhouettePM: Flow-induced release of endothelium-derived relaxing factor. Am J Physiol250: 1145–1149, 1986.
27.
StehbensWI: Histopathology of cerebral aneurysms. Arch Neurol8: 45–76, 1963.
28.
StehbensWI: Etiology of intracranial berry aneurysms. J Neurosurg70: 823–831, 1989.
29.
StehbensWI: Apoptosis and matrix vesicles in the genesis of arterial aneurysms of cerebral arteries. Stroke29: 1478–1480, 1998.
30.
ShievinkWI: Genetics and aneurysm formation. Neurosurg Clin N Am9: 485–495, 1998.
31.
TakenakaKSakaiH: Polymorphism of the endoglin gene in patients with intracranial saccular aneurysms. J Neurosurg90: 935–938, 1999.
32.
YoonSTrompG: Genetic analysis of MMP3, MMP9 and PAL-1 in Finnish patients with abdominal aortic or intracranial aneurysms. Biochem Biophys Res Commun265: 563–568, 1999.
