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Stroke and Transient Ischemic Attacks of the Brain and Eye
Published in Philip B. Gorelick, Fernando D. Testai, Graeme J. Hankey, Joanna M. Wardlaw, Hankey's Clinical Neurology, 2020
Most commonly, subarachnoid blood is maximal adjacent to a ruptured saccular aneurysm at the base of the brain (Figure 12.138). Saccular aneurysms are small, thin-walled blisters protruding from the arteries of the circle of Willis or its major branches (Figure 12.139). They are located at bifurcations and branchings: Anterior communicating artery complex: 40%.ICA: 30%: Origin of the posterior communicating artery from the stem of the ICA.Terminal bifurcation of the ICA, into the middle and anterior cerebral arteries.MCA: first major bifurcation (Figure 12.140) is 20%.Posterior circulation: tip of basilar artery is 10%.
Answers
Published in Andrew Schofield, Paul Schofield, The Complete SAQ Study Guide, 2019
Andrew Schofield, Paul Schofield
Strokes are commonly seen in the elderly population, and are often terminal events. The risk factors for cerebrovascular disease are the same as those for cardiovascular disease, such as hypertension, diabetes, hypercholesterolaemia and smoking. Patients with atrial fibrillation are also at an increased risk of stroke due to the formation of thrombus in the left atrium and subsequent embolisation to the cerebral arteries. The arterial network in the brain is called the Circle of Willis. The anterior communicating artery links the two anterior cerebral arteries, and the posterior communicating arteries link the internal carotid arteries to the posterior cerebral arteries. This allows redistribution of blood flow within the brain if it has been compromised.
Cardiac surgery and percutaneous cardiac interventions
Published in John Edward Boland, David W. M. Muller, Interventional Cardiology and Cardiac Catheterisation, 2019
Some authors have suggested the transcarotid approach, but this is reliant on the patient tolerating temporary unilateral carotid artery occlusion and an adequate anterior communicating artery at the Circle of Willis.28 This approach is not widely used, with only a few case series reported.
Type 2 persistent primitive proatlantal intersegmental artery, a rare variant of persistent carotid-vertebrobasilar anastomoses
Published in Baylor University Medical Center Proceedings, 2019
Gagandeep Choudhary, Narendra Adhikari, Jad Chokr, Nishant Gupta
There was a three-vessel aortic arch. The right vertebral artery (VA) was hypoplastic arising from the subclavian artery and ended as a posterior inferior cerebellar artery. The left VA was absent. Both common carotid arteries, carotid bulbs, ICAs, and external carotid arteries were patent. An anomalous artery equal to the caliber of the ICA was seen arising from the proximal left external carotid artery at the origin of the lingual artery at the C2 vertebral level (Figure 1). The anomalous vessel coursed cranially and entered the foramen magnum coursing between the C1 arch and the occiput, without passing through the transverse foramina of the cervical vertebrae. Intracranially, it had a tortuous course and continued as a basilar artery, which terminated in posterior cerebral arteries. The right-sided posterior communicating artery was present but small in caliber, and the left posterior communicating artery was not seen. Both intracranial ICAs and proximal middle cerebral arteries, the anterior cerebral arteries, and the anterior communicating artery were present and unremarkable. The patient did not have any symptoms attributable to this vascular variant. He was discharged in stable condition with a short course of pain medication.
Oculomotor Nerve Palsy Associated with Duplication of Middle Cerebral Artery, Anterior Communicating Artery Aneurysm, and Parietal Meningioma
Published in Neuro-Ophthalmology, 2019
Ayman G. Elnahry, Gehad A. Elnahry
Isolated oculomotor nerve paralysis occurs most commonly due to diabetes mellitus, hypertension, neoplasia, or intracranial aneurysms, particularly a posterior communicating artery aneurysm.1,2 Anterior communicating artery aneurysms have been rarely reported to cause oculomotor nerve paralysis; however, an associated intracranial hematoma was usually present in these cases.2,3 Fetal-type posterior cerebral artery, a relatively common variant of the posterior cerebral circulation in which the posterior cerebral artery directly originates from the internal carotid artery, is another rarely reported cause of oculomotor nerve paralysis that is postulated to compress the oculomotor nerve when it becomes more tortuous with aging and atherosclerosis.4 Meningiomas have seldom been recognized as the cause of oculomotor nerve paralysis, presumably by causing cerebral oedema and increased intracranial pressure.5 Duplicate MCA is a rare variant of the cerebral circulation that has a reported prevalence of 0.2–2.9% and can be smaller or equal in size to the main MCA.6,7 It has not been previously reported to be associated with oculomotor nerve paralysis. MCA fenestration has also been very rarely reported.8 The authors suspect that the oculomotor nerve palsy in the presented case may have been caused by compression of the oculomotor nerve by the tortuous duplicate MCA on two separate occasions. This compression could have been precipitated by the other associated conditions. Intraoperative confirmation is warranted.
Beyond descriptive neurology: Broca, cerebral hemodynamics, and cortical function
Published in Journal of the History of the Neurosciences, 2018
The evaluation of CBF in patients suffering a cerebral ischemic attack, as Broca tried to do with thermometry, is now commonplace. Cerebral angiography performed in patients who have suffered a stroke reveals the site of obstruction, the avascular central area about the Sylvian fissure, and the recruitment of collateral channels across the border zones into the penumbra. The importance of collateral channels at the base of the brain in mitigating the effect of stroke was highlighted by Charles Miller Fisher (1913–2012) in a landmark paper on carotid occlusion (1951): The anterior cerebral arteries on the two sides are connected by the anterior communicating artery, which completes the circle of Willis anteriorly. The two posterior cerebral arteries complete the circle of Willis posteriorly. The size of each of these component arteries is highly variable and determines the adequacy of collateral circulation from one side to the other, as well as between the basilar and the carotid systems. In some cases there are probably small arteries on the surfaces of the hemispheres, which provide important connections between the anterior, middle and posterior cerebral arteries. (Fisher, 1951, p. 348)