Aneurysm, cerebral, rupture

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. 

Oral nimodipine is recommended in subarachnoid hemorrhage to prevent delayed cerebral ischemia. Delayed cerebral ischemia occurs 4 to 14 days after the initial aneurysm rupture and is a common cause of neurologic deficits and death. A meta-analysis of 12 studies was conducted and concluded that oral nimodipine 60 mg every 4 hours for 21 days following aneurysmal SAH reduced the risk of a poor outcome and delayed cerebral ischemia.40... 

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. 

A ruptured middle cerebral artery aneurysm originating from the site of anastomosis 20 years after extracranial-intracranial bypass for moyamoya disease case report. Surgical Neurology 64 261-265... 

Approximately 85% of spontaneous SAHs are caused by ruptured aneurysm 10% are perimesencephalic and the remainder are caused by rare disorders (van Gijn and Rinkel 2001). The pattern of bleeding on CT is a clue to the underlying cause. Blood in the interhemispheric fissure suggests an anterior communicating artery aneurysm and in the sylvian fissure suggests internal carotid artery or middle cerebral artery aneurysm (Fig. 30.1). 

Fig. 30.1. These CT brain scans from a patient with a burst right middle cerebral artery aneurysm (arrow) show widespread subarachnoid blood, and rupture into the right cerebral hemisphere and the ventricular system.

Ruijs AC, Dirven CM, Algra A et al. (2005). The risk of rebleeding after external lumbar drainage in patients with untreated ruptured cerebral aneurysms. Acta Neurochirurgie 147 1157-1161... 

Gill JS, Zezulka AV, Horrocks PM. Rupture of a cerebral aneurysm associated with nifedipine treatment. Postgrad Med J 1986 62(733) 1029-30. 

Iwatsuki N, Kuroda N, Amaha K, Iwatsuki K. Succinylcholine-induced hyperkalemia in patients with ruptured cerebral aneurysms. Anesthesiology 1980 53(l) 64-7. 

Cerebral aneurysms treated by traditional endovascular methods using noble metal (platinum) -based coils have a tendency to be unstable, due to chronic inflammation, compaction of coils, or growth of the aneurysm. In addition, with physical limitation, mechanical mismatch between hard metal and the thinned, weakened wall, aneurysms exhibit a potential for rupture. Maitland et al. addressed this issue and developed a new filling... 

Intracranial aneurysms, also known as brain or cerebral aneurysms, are balloon-like bulges in the arteries in the brain and are caused by a weakening of the vessel. If ruptured, bleeding into the brain will occur, leading to a subarachnoid hemorrhage, which can in turn lead to hemorrhagic stroke, brain damage, and death. Approximately 2% of the population will develop an intracranial aneurysm with a rupture rate of 0.7% [51]. 

The course of infectious aneurysms is unpredictable. Under antibiotic or antimycotic therapy they may shrink, or completely disappear. However, enlargement during treatment has also been reported (Brust et al. 1990). Septic aneurysms can be obliterated surgically or by endovascular treatment (Chapot et al. 2002 Phuong et al. 2002 Steinberg et al. 1992). The theoretical assumption that implantation of foreign material - like platinum coils - into an infectious lesion might worsen the problem is not true for infectious intracranial aneurysms. Mortality due to rupture of bacterial cerebral aneurysms is reported to be up to 60% (Barrow and Prats 1990 Bohmfalk et al. 1978 Clare and Barrow 1992). 

Fig. 5.14. Right temporal lobe intracerebral hemorrhage due to a ruptured MCA aneurysm. Beside basal subarachnoid hemorrhage CT reveals brain edema, compression of the basal cisterns and the cerebral peduncle...

Fig. 5.20. Acutely ruptured fusiform posterior cerebral artery aneurysm before and after endovascular treatment. Overlay of 3D vessel anatomy on cross-sectional CT-like images showing extensive SAH...

The primary treatment goal of cerebral aneurysms is prevention of rupture. Surgical clipping has been the treatment modality of choice for both ruptured and unruptured cerebral aneurysms for decades. Just over 20 years ago endovascular treatment was mainly restricted to those patients with aneurysms unsuitable for clipping due to the size or location, or in whom surgical clipping was contraindicated... 

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