Vessels Aneurysms

Most arterial aneurysms arise at the bifurcation of major arteries, and this is also true for the intracranial location. Around 85% of all intracranial aneurysms originate from the anterior circulation. The most common location (30%-35%) is the anterior communicating artery (Acorn). However, many of these so-called Acorn aneurysms do have their origin at the A1/A2 junction of the anterior cerebral artery and do not involve the anterior communicating artery. Internal carotid and posterior communicating artery aneurysms account for 30% and middle cerebral artery (MCA) bifurcation aneurysms for 20%. Around 15% of intracranial aneurysms arise at the vertebrobasilar circulation. Half of them develop at the basilar tip (with various degrees of involvement of the PI segments) and the other 50% from other posterior fossa vessels. Aneurysms of the anterior inferior cerebellar artery (AICA) and vertebral artery (VA) aneurysms without involvement of the VA-PICA junction or the vertebrobasilar site are extremely rare. 

Shitrit D, Shitrit AB, Starobin D, et al. Large vessel aneurysms in Wegener s granulomatosis. J Vase Surg 2002 36(4) 856-858. 

Vascular grafts are tubular devices implanted throughout the body to replace blood vessels which have become obstmcted by plaque, atherosclerosis, or otherwise weakened by an aneurysm. Grafts are used most often in peripheral bypass surgery to restore arterial blood flow in the legs. 

Total body hypothermia Repair of vessel disease (brain aneurysm)... 

Szekanecz Z, Shah MR, Harlow LA, Pearce WH, Koch AE. Interleukin-8 and tumor necrosis factor-alpha are involved in human aortic endothelial cell migration. The possible role of these cytokines in human aortic aneurysmal blood vessel growth. Pathobiology 1994 62(3) 134-139. 

Hemorrhagic strokes account for 12% of strokes and include subarachnoid hemorrhage, intracerebral hemorrhage, and subdural hematomas. Subarachnoid hemorrhage may result from trauma or rupture of an intracranial aneurysm or arteriovenous malformation. Intracerebral hemorrhage occurs when a ruptured blood vessel within the brain parenchyma causes formation of a hematoma. Subdural hematomas are most often caused by trauma. 

Hemorrhagic (excessive bleeding from a ruptured blood vessel e.g., ruptured aneurysm)... 

Methamphetamines indirectly cause side effects to many other areas of the body through their actions on the CNS. Concerning the heart, methamphetamine use can cause an increased and/or irregular heart rate heart pains that a user may believe is a heart attack (and may actually be a heart attack) skipped heart beats, or palpitations high or low blood pressure and the bursting of blood vessels in the heart called an arterial aneurysm. 

Aneurysms, while not a good diagnosis, represent a physical means for lowering the tension on a blood vessel. 

The endovascular procedure is most frequently used to treat infrarenal AAAs that are a leading cause of death in the older population, As our population ages, we will encounter AAAs more frequently than ever before. An aneurysm is defined by a size greater than 5 cm or 2.5 times the normal diameter of the native artery. Most aneurysms begin below the renal arteries and end close to the iliac bifurcation. More complicated AAAs exist involving the suprarenal aorta and visceral vessels and extending into the iliac arteries. The prevalence of AAAs is 3% to 10% for patients older than 50 years (I). They occur more frequently in men and reach a peak incidence close to the age of 80 years. AAA rupture is associated with an 80% to 90% mortality rate and therefore the focus of AAA treatment is on intervening before the aneurysm ruptures elective repair has mortality rate of less than 5%. 

Vertebral arteries vary in size and symmetry, where mostly the left vertebral artery is the dominant one. The coincidence of vertebral fenestrations and aneurysms is well known. The anterior spinal artery receives tiny vessels from the vertebral arteries which are physiologically not depicted by MRA due to their size. The posterior inferior cerebellar artery (PICA) as the largest, most important and most variable cerebellar artery however, under normal conditions it is constantly depictable with TOF and CE-MRA. 

Atherosclerosis mainly affects large- and mediumsized arteries. Extracranial manifestations at the carotid bifurcation statistically dominate the intracranial arteries. Besides typical manifestations at the carotid siphon or the vertebrobasilar junction, atherosclerosis is occasionally also found in peripheral intracranial vessel segments. Typical sequelae of atherosclerosis are stenosing plaque formations, ulcerations, dilatations or the evolution of fusiform aneurysms, which can be accompanied by extensive formation of thrombus. 

Fig. 5.20a-d. Subacute thrombus formation in a large fusiforme aneurysm of the basilar artery. Parts of the thrombus are still isoin-tense to brain, while others are moderately hyperintense on spin echo Tl-weighted image (a). Residual flow within the vessel is outlined against thrombus much better on post-contrast Tl-weighted spin echo (c) and post-contrast TOF-MRA (d) than on unenhanced TOF-MRA (b)... 

Some congenital diseases such as Marfan syndrome or Ehlers Danlos syndrome (type 4) can cause arteriopathies of cranial cervical vessels. In Ehlers Danlos syndrome, elongations, dissections, dilatation and aneurysms, as well as fistula in large and mid-size arteries, are found. Cystic medial necrosis (Ueda et al. 1999) leads to aortic dissections which can include supraaortic vessels (Fig. 5.27)... 

Fig. 5.27a,b. Cystic medial necrosis. Due to the high grade proximal stenoses, test bolus measurement prior to CE-MRA failed in this case, leading to superimposition of venous contrast (a). Evaluation is nevertheless possible on original source slices (b), showing stenoses and aneurysms along the proximal supraaortic vessels (arrows)... 

Artwork Description Top Left Panel Neuronal Immunocytochemistry Composite. Top Right Panel Magnetic Resonance Image of an Adult Human Brain. Bottom Left Panel Cerebral Angiogram Highlighting an Aneurysm. Bottom Right Panel Immunocytochemistry Highlighting Blood Vessels and Inflammatory Cells in an Ischemic Brain. Created by Elizabeth Hoyte and Carolina Maier. 

Q1 A stroke involves significant reduction in blood flow to a part of the brain. It can be caused either (i) by an embolus or by intravascular clotting, which blocks blood flow to an area (approximately 85% of strokes), or (ii) by haemorrhage from a ruptured blood vessel, which compresses the brain tissue (approximately 15% of strokes). Patients with extensive atherosclerosis are at risk of intravascular coagulation and blockage of cerebral blood flow, but a vessel can be blocked by a thrombus originating in another part of the circulation. This cause of stroke is common in elderly patients >60 years of age. Aneurysms which rupture suddenly are a more common cause of stroke in younger patients. 

Atherothromboembolism ntracranial small vessel disease Leukoaraiosis Dissection (Table 6.4) Fibromuscular dysplasia Congenital arterial anomalies Moyamoya syndrome Embolism from arterial aneurysms Inflammatory vascular diseases Irradiation... 

Moyamoya seems to be mainly confined to the Japanese and other Asians, and in most cases the cause is unknown (Bruno et al. 1988 Chiu et al. 1998). Some cases are familial (Kitahara et al. 1979) others appear to be caused by a generalized fibrous disorder of arteries (Aoyagi et al. 1996), and a few may result from a congenital hypoplastic anomaly affecting arteries at the base of the brain, or associated with Down s syndrome (Cramer et al. 1996). The syndrome may present in infancy with recurrent episodes of cerebral ischemia and infarction, mental retardation, headache, epileptic seizures and, occasionally, involuntary movements. In adults, subarachnoid or primary intracerebral hemorrhage are also common owing to rupture of collateral vessels. There have also been a few reports of associated intracranial aneurysms (Iwama et al. 1997) and also of cerebral arteriovenous malformations. 

Lamy C, Giarmesini C, Zuber M et al. (2002). Clinical and imaging findings in cryptogenic stroke patients with and without patent foramen ovale the PFO-ASA Study (Atrial Septal Aneurysm). Stroke 33 706-711 Leung SY, Ng THK, Yuen ST et al. (1993). Pattern of cerebral atherosclerosis in Hong Kong Chinese severity in intracranial and extracranial vessels. Stroke 24 779-786 Leys D, Moulin Th, Stojkovic T et al. (1995). Follow-up of patients with history of cervical artery dissection. Cerebrovascular Diseases 5 43-49... 

Primary intracerebral hemorrhage is more common than subarachnoid hemorrhage, and its incidence increases with age (see Fig. 1.1). It is more frequent in Southeast Asian, Japanese and Chinese populations than in whites. The most common causes are intracranial small vessel disease, which is associated with hypertension, cerebral amyloid angiopathy and intracranial vascular malformations (Sutherland and Auer 2006). Rarer causes include saccular aneurysms, hemostatic defects, particularly those induced by anticoagulation or therapeutic thrombolysis, antiplatelet drugs, infective endocarditis, cerebral vasculitis and recreational drug use (Neiman et al. 2000 O Connor et al. 2005). 

The main clinical indications for imaging the cerebral circulation are TIA (e.g. to identify arterial stenosis), acute ischemic stroke (e.g. to identify vessel occlusion), intracerebral hemorrhage (e.g. to identify an underlying vascular malformation) and possible arterial dissection, flbromuscular dysplasia or other arteriopathies, cerebral aneurysm, intracranial venous thrombosis or cerebral vasculitis. 

Neovascular glaucoma is a condition maiked by new blood vessel proliferation on the iris and in the anterior chamber angle usually as a result of retinal or anterior segment ischemia/hypoxia. Neovascularization of the iris usually appears first on the surfece of the iris adjacent to the pupillary border.These vessels are fine in caliber and may have aneurysm-like outpouchings. Gonioscopic evaluation may reveal vessels in the anterior chamber angle even in the absence of iris vessels. 

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