Intracranial middle cerebral artery

EC-IC arterial bypass involves the use of general anesthesia, open craniotomy, and end-to-side anastomosis of the superficial temporal artery to a branch of the middle cerebral artery (MCA) (Fig. 6.1). Currently, this technique is being used primarily in the setting of intracranial aneurysm therapy, moyamoya disease, and... 

FIGURE 6.1 CT angiography of an EC-IC bypass, showing the new intracranial course of the right superficial temporal artery, anastamosed to the middle cerebral artery M2 segment. 

Transcranial Doppler can determine the presence of intracranial sclerosis (e.g., middle cerebral artery stenosis). 

In the past, two different basic mechanisms have been proposed to account for ischemic events in ICA occlusive disease (1) intracranial embolism and (2) a low-perfusion state also referred to as hemodynamic insufficiency. In the post-mortem arteriographic and pathologic study by Rodda and Path (1986), massive infarcts involving two major cerebral artery territories were associated with distal ICA occlusion, middle cerebral artery (MCA) territory infarcts were seen when the ICA was occluded or stenosed, and borderzone infarcts were characterized by ICA disease and limited circle of Willis anastomosis. 

Schwab et al. used mild hypothermia (33-34°C) in 20 patients with acute severe middle cerebral artery (MCA) infarction for 48-72 h and found mild hypothermia to be safe and feasible (38). Schwab subsequently reported a series of 25 patients with severe MCA infarction treated with the same protocol (39). Intracranial pressure (ICP) was monitored for 3-7 d, and was found to decrease with initiation of hypothermia. ICP increased during re warming in several patients, but not to the levels seen prior to induction of hypothermia. Pneumonia was seen in 40% of patients treated with hypothermia in this trial, which is within the expected range of occurrence in patients with prolonged ventilation (40). Shimizu et al. used mild hypothermia (33°C) in five patients with embolic infarctions involving the internal carotid artery and MCA territories. The hypothermia was maintained for 3-7 d (41). It was found to be safe, but the number of patients was too small to report any efficacy. Another acute stroke trial using convection air to induce mild hypothermia without anesthesia was found to be feasible (42). Temperatures in this trial were reduced only to 35.5°C, and shivering... 

Intracranial hemodynamic compromise with low flow In the middle cerebral artery... 

Malignant middle cerebral artery territory infarction is defined as a large middle cerebral artery infarct with marked edema and swelling, leading to raised intracranial pressure and a high risk of coning (Fig. 

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... 

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... 

The study of cerebrovascular disease has advanced markedly in recent years with advances in non-invasive imaging methods such as MR angiography and CT angiography as well as an improved understanding of the immune system in the pathogenesis of atherosclerosis. Atherosclerotic cerebrovascular disease is a common cause of strokes and shows a predilection for sites such as the bifurcation of the common carotid artery into the internal and external carotid arteries and the aortic arch and the major intracranial arteries such as the basilar artery and the middle cerebral arteries. Occlusive atherosclerotic vascular disease of these large extracranial arteries is responsible for as many as 20-30% of ischemic strokes and intracranial steno-occlusive disease causes around 5-10% of ischemic strokes. 

PROACTII <6h 4< <30 but not comatose (except for isolated aphasia or hemianopia) No intracranial tumors, hemorrhage, significant mass effect with midline shift, or acute hypodense parenchymal lesion or effacement of cerebral sulci in >1/3 of the middle cerebral artery (MCA) territory UMI grade 1 of either the Ml segment or an M2 division of MCA... 

Kelly ME, Furlan AJ, FioreUa D. Recanalization of an acute middle cerebral artery occlusion using a self-expanding, reconstrainable, intracranial microstent as a temporary endovascular bypass. Stroke. 2008 39 1770-1773... 

Sensory systems Eyes A 55-year-old woman developed choroidal infarction with permanent visual loss after intracranial irrigation with papaverine 3 ml (30 mg/ml), used to prevent postoperative vasospasm after surgical clipping of a left middle cerebral artery aneurysm [161 ]. 

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. 

Fig. 10.2. a A 59-year old male patient with known colorectal cancer and acute hemiparesis. NECT 1 h after stroke-onset does not show any early stroke signs, hemorrhage or edema, b MIP reconstruction of intracranial CTA scan shows a stop of contrast agent arrows) at the distal main stem of the left middle cerebral artery (MCA), c Dynamic perfusion-CT (PCT) analysis reveals subtotal restriction of cerebral blood flow... 

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). ... 

With modern multislice scanners and optimized protocols," CTA images can provide excellent visualization of the primary intracranial arteries (i.e., the proximal anterior, middle, and posterior cerebral arteries), their smaller secondary... 

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