Artery anterior communicating

The anterior cerebral artery passes horizontally and medially to enter the interhemi-spheric fissure it then anastomoses with its counterpart of the opposite side via the anterior communicating artery, curves up around the genu of the corpus callosum and supplies the anterior and medial parts of the cerebral hemisphere. Small branches also supply parts of the optic nerve and chiasm, hypothalamus, anterior basal ganglia and internal capsule. 

The circle of Willis. This is formed by the proximal part of the two anterior cerebral arteries connected by the anterior communicating artery, and the proximal part of the two posterior cerebral arteries, which are connected to the distal internal carotid arteries by the posterior communicating arteries. However, approximately 50% of circles have one or more hypoplastic or absent segments, usually one of the communicating arteries, and atheroma may limit the potential for collateral flow (Fig. 4.2). 

The near-occluded internal carotid artery (ICA) is markedly narrowed, and flow of contrast into the distal ICA is delayed. After selective injection of contrast into the contralateral carotid artery, significant collateral flow can be seen across the anterior communicating arteries with filling of the middle cerebral artery of the symptomatic hemisphere (top). 

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). 

Intracranial aneurysms are not congenital but develop over the course of life. Approximately 10% of aneurysms are familial, and candidate genes identified thus far include those coding for the extracellular matrix. Saccular aneurysms tend to occur at branching points on the circle of Willis and proximal cerebral arteries approximately 40% on the anterior communicating artery complex, 30% on the posterior communicating artery or distal internal carotid artery, 20% on the middle cerebral artery and 10% in the posterior... 

Anosmia is a sequela in almost 30% of patients, particularly after surgery and anterior communicating artery aneurysms. 

The most plausible pathogenetic theory is that they are acquired due to hemodynamic stress on the relatively unsupported bifurcations of cerebral arteries (Timperman et al. 1995). This is supported by the clinical observation that many patients with an anterior communicating artery (Acorn) aneurysm do have one hypoplastic or absent Al segment and thus an increased hemodynamic stress on the AcomA. Other factors than hemodynamics and structural alterations of the vessel wall contributing to the development of saccular aneurysms may be genetic, infection, trauma, neoplasms, radiation or idiopathic. 

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. 

The rupture of an aneurysm at the anterior communicating artery (Acorn) is responsible for approximately 40% of subarachnoid hemorrhages (Kassell et al. 1990a,b). Treatment of these aneurysms is thus a frequent situation and of great importance. In the past. Acorn aneurysms were treated nearly exclu-... 

Levy D1 (1997) Embolization of wide-necked anterior communicating artery aneurysm technical note. Neurosurgery 41 979-982... 

Moret J, Pierot L, Boulin A, Castaings L, Rey A (1996) Endovascular treatment of anterior communicating artery aneurysms using Guglielmi detachable coils. Neuroradiology 38 800-805... 

Fig. 10.1. Correct patient positioning for intracranial scans, light box indicates the scan volume, eye-lenses outside of scan volume. Note the titanium coils after endovascular coil embolization of an aneurysm at the anterior communication artery (ACoA)...

DEATH A case report demonstrated hypotension and subsequent cardiac arrest after instillation of intracistemal papaverine during clipping of an anterior communicating artery aneurysm [67 ]. 

Chowdhury FH, Haque MR. Severe hypotension, cardiac arrest, and death after intracistemal instillation of papaverine during anterior communicating artery aneurysm clipping. A case report. Acta Neurochir February 2013 155(2) 281-2. 

Haematologic Intravenous administration of recombinant tissue plasminogen activator (rtPA), also known as alteplase, is a common component of ischaemic stroke management, but its use is associated with intracranial haemorrhage in 6.4% of patients. A 51-year-old woman who had received IV rtPA for acute left middle cerebral artery thromboembolism later presented with subarachnoid haemorrhage from an acutely ruptured anterior communicating artery aneurysm. The patient xmderwent mechanical thromboembolectomy of the left middle cerebral artery occlusion with recanalization followed by coil embolization of the aneurysm, but she did not improve neurologjcally and ultimately died (32). ... 

Rammos SK, Neils DM, Fraser K, Klopfenstein JD. Anterior communicating artery aneurysm rupture after intravenous thrombolysis for acute middle cerebral artery thromboembolism case report. Neurosurgery June 2012 70(6) 1603-7. 

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