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Cerebral Hemispheres and Vacular Supply


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Where are the sensory areas for the faces and hands? What about the leg areas?
The lateral convexities for face and hands; in the intrahemispheric fissure for the leg areas
What brain region is Broca's area in?
In the inferior frontal gyrus - just anterior to the articulatory areas of the primary motor cortex.
Where is Wernicke's area?
In the superior temporal gyrus, adjacent to the primary cortex.
Infarcts of the optic radiations, which pass under the parietal and temporal cortex, cause what symptom?
Visual field deficits.
What can cause seizures following a CVA?
Scar tissue
What % of patients with CVA suffer from depression? What side of the brain is associated with depression?
~30%; typically left CVA's are associated with depression.
Potentially fatal shifts in intracranial structures can be caused by what event following a CVA?
Severe cerebral edema following a CVA.
What is locked-in synrome?
Mute and quadriplegic, but with intact cognitive capacity.
What are anastomes?
Connections between different cerebral arteries on the cortical surface.
What is the function of an anastome?
It allows perfusion between arterial systems to limit extent of cortical damage in stroke. While this protects gray matter, it also creates greater vulnerability in the watershed areas between arteries.
Which are the main blood suppliers to the brain?
Internal carotid arteries and vertebral arteries. The internal carotid supplies most of the diencephalon and cerebral hemispheres.
What are the 3 main arteries supplying blood to the cortex and subcortical structures?
Anterior cerebral artery (arises from internal carotid), middle cerebral artery (from internal carotid), & posterior cerebral artery (from basilar artery).
What are the 2 anastomes in the Circle of Willis?
Anterior communicating artery (anastomes of the anterior cerebral artery) AND posterior communicating artery (connect internal carotids to the posterior cerebral arteries)
What are the two branches of the anterior cerebral artery?
Pericallosal artery and Callosomarginal artery (wrapping around corpus callosum and cingulate region). The ACA supplies most of the cortex on the anterior medial surface - from the frontal to anterior parietal lobes.
The MCA supplies which part of the cortex?
The dorsolateral convexoty of the brain, involving frontal, parietal, and temporal lobes.
The PCA supplies which part of the cortex?
The inferior and medial temporal and occipital cortex (including visual cortex).
The lenticulostriate arteries branch off from which main artery and supply which part of the brain?
They arise from the initial portions of the MCA and supply the basal ganglia and internal capsule.
What can happen to the lenticulostriate arteries in hypertension?
These arteries are prone to narrowing, leading to lacunar infarcts or rupture (hemorrhage).
What main artery does the Recurrent artery of Heubner branch off of?
The ACA.
The Recurrent artery of Heubner supplies which areas of the brain?
The head of the caudate nucleus, globus pallidus, anterior putamen, and internal capsule (it is medial to the lenticulostriate arteries).
The thalamogeniculate arteries and thalamoperforator arteries branch off of which main artery?
Posterior cerebral artery.
The thalamogeniculate arteries and thalamoperforator arteries supply blood to which area of the brain?
The thalamus and sometimes posterior limb of the internal capsule.
The verterbal/basilar system supply blood to which areas?
The midbrain, cerebellum, and portions of the temporal and occipital lobes.
What can happen with in a CVA with total occlusion?
Coma or locked in syndrome.
The internal carotid artery branches to what artery, and where does it supply blood?
Branches to the anterior choroidal artery and supplies to the globus pallidus, putamen, thalamus, and posterior limb of the internal capsule.
Where was the CVA: right face and arm weakness of the upper motor neuron type, and a nonfluent, or Broca's, aphasia. Sometimes there may be right face and arm cortical-type sensory loss?
Left MCA - superior division.
Where was the CVA: Fluent, or Wernicke's, aphasia and a right visual field deficit. There may be right face and arm cortical-type sensory loss. Motor findings are usually absent, and patients may initially seem confused or crazy, but otherwise intact, un
Left MCA - inferior division.
Where's the CVA: left face and arm weakness of upper motor neuron type; left hemineglect; sometime left face & arm cortical-type sensory loss?
Right MCA - superior division.
Where's the CVA: Left homonymous hemianopia; larger infarcts including the thalamus and internal capsule may cause left hemisensory loss and hemiparesis?
Right PCA.
What can occur with a left MCA deep territory CVA?
Right pure motor hemiparesis of the upper motor neuron type; larger infarcts may produce "cortical" deficits as well, such as aphasia.
Where is the CVA: profound left hemineglect; left visual field & somatosensory deficits are often present; motor neglect with decreased voluntary or spontaneouse initiation of movements on the left side can also occur; often a right-sided weakness ma
Right MCA - inferior division.
A CVA of the right MCA deep territory can cause what symptoms?
Left pure motor hemiparesis of the upper motor type. Larger infarcts may produce "cortical" deficits as well, such as hemineglect.
What can be seen in a left ACA CVA?
Right leg weakness of the upper motor neuron type and right leg cortical-type sensory loss; grasp reflex, frontal lobe behavioral abnormalities, and transcortical aphasia may be seen; larger infarcts may cause right hemiplegia.
Where is the CVA: right homonymous hemianopia; extension to the splenium of the corpus callosum can cause alexia w/o agraphia?
Left PCA.
Occlusion of the proximal part of the MCA results in what?
Contralateral hemiparesis, hemi-sensory loss, homonymous hemianopsia, aphasia (w/left hemisphere lesions) and hemi-inattetion, anosagnosia, apraxia, neglect, and dysprosody (w/RH lesions).
What is Angular Gryus Sydrome (and where is the infarct)?
Fluent aphasia, alexia with agraphia, Gerstmann's syndrome, constructional problems - posterior MCA.
Infarcts and ischemic events are more common in the ACA, MCA, or PCA?
MCA, partly because of their relatively larger territory
The deep territory of the MCA includes which areas?
The internal capsule and much of the basal ganglia.
What can be seen in large MCA infarcts, particularly during acute period?
Gaze preference towards side of lesion.
What are lacunes?
Small deep infarcts involving penetrating branches of the MCA or other vessels.
Contralateral lower extremity cortical sensory loss and weakness of of upper motor neuron type can be seen in an infarct in which area?
ACA (uncommon area)
Damage to the supplementary area can lead to which syndrome?
"Alien hand syndrome" - semi-automatic movements of contralateral arm that aren't under voluntary control.
Posterior cerebral artery infarcts typically cause what commone sypmtom?
Contralateral homonymous hemianopsia.
Bilateral occlusion of the ACA can cause what symptoms?
Emotional disturbance with apathy, confusion, and occasional mutism, plus spastic paraparesis.
Hemorrhages most often result from what medical condition?
Hypertension. It tends to affect the basal ganglia, thalamus, pons, and cerebellum.
What can be the cause of a patient presenting with what appears to be a severe migraine, with possible vomiting, diplopia, altered state of consciousness (a non- traumatic cause)?
Subarachnoid hemorrhage, usually from a ruptured berry aneurysm.
What can be readily evacuated and is diagnosed by occipital headaches, gait ataxia, dysarthria and lethargy?
Cerebellar hemorrhage.
Bilateral watershed infarcts in the ACA-MCA and in the MCA-PCA zones can occur with severe drops in blood pressure and in patients with: seizures, carotid stenosis, or congestive heart failure?
Carotid stenosis.
"Man in the barrel" syndrome represents what event?
Watershed infarcts that produce proximal arm and leg weakness.
By definition, how long can a transient ischemic attack last?
Neurologic deficit lasting ess than 24 hours, caused by temporary brain ischemia.
What is the typical duration of a TIA?
10 minutes; those lasting longer than one hour are usually small infarcts.
What are the mechanisms that can cause TIA?
Embolism which dissolves, in situ thrombus formation or vasospasm leading to temporary narrowing of the vessel. It's typically indicative of underlying atherosclerotic cerebrovascular disease and increased risk of sustianing a stroke.
What are the most common causes of transient neurologic episodes?
TIA, migraines, seizures, cardiac arrhythmia or hypoglycemia.
Cardioembolic infarcts occur in which conditions?
Atrial fibrillation (thrombi form in the fibrillating left atrial appendage), myocardial infarction (thrombi form on hypokinetic or akinetic regions of infarcted myocardium), valvular disease (thrombi form on the valve leaflets or prosthetic parts), artery - to - artery emboli.
What is the pathologic process in which small penetrating vessels become occluded?
Lipohyalinosis - in chronic hypertentions.
Contralateral somatosensory deficits can be can be seen in what type of lacune?
Thalamic lacunes.
Name one way a stroke can be produced?
1 - Sudden reduction in blood pressure and blood perfusion
2 - Impaired blood supply as a result of occlusion of stenosis
3 - Obstruction of a vessel by embolus
What is hemorrhagic conversion?
When ischemic strokes cause blood vessels to become fragile and rupture.
What is the most common cause of stroke?
Thrombosis; second is emboli originating in a carotid artery and lodgin in a cerebral artery.
IVH or intraventricular hemorrhage can be seen in....
What is AVM (arterial vascular malformation)?
Congenital malformation leading to poor perfusion, weak areas in the vessels that may bleed, or secondary aneurysm at vessel bifurcations or junctures.
What is the difference between embolic and thrombotic infarcts?
In embolic, a piece of material (e.g., blood clot) is formed in one place and then travels through the blood stream to lodge in and occlude a blood vessel supplying the brain. In thrombotic a blood clot forms on the blood vessel wall.
What brain regions are most vulnerable to ischemic-anoxic insults?
The hippocampus, cerebellum, and cerebral cortex.
On initial CT scans, which are commonly more visible, infarcts or hemorrhage?
What is a "dissections" of the carotid or vetebral arteries?
Head or neck trauma, and sometimes even minor events (e.g., a sneeze) can cause a small tear to form on the surface of the carotid or vertebrate arteries. This allows blood to burrow in the vessel wall, producing dissection.
What can dissection lead to?
Development of a thrombosis or embolism. Some patients report hearing a pop at the onset.
What are the two ways venus drainage occurs?
Through dural sinuses and direct venous return.
Where do the superficial veins drain into?
The superior sagittal sinus and the cavernous sinus.
Where do the deep veins drain?
Into the great vein of Galen.
Where does nearly all venous drainage systems merge?
Internal jugular veins.
Where is CSF reabsorbed into the ventricular system before blood passes out of the brain?
Dura sinuses (between the dura and arachnoid).
Obstruction of venous drainage usually causes elevated intracranial pressure which can cause what?
parasagittal hemorrhages, increased venour pressure (can can decrease cerebral perfusion leading to infarcts), seizures, headaches and papilledema, and depressed levels of consciousness.
What is an empty delta sign?
A defect observed on imaging - the sinuses normally fill uniformly with contrast, so a dark region in the middle suggests a filling defect.
What should be considered if a patient experiences the "worst headache" of their life (until proven otherwise)?
Subarachnoid hemorrhage.
What are the most common locations for aneurysms?
The origins of the ACA, PCA, or bifurcation points of the MCA.
Why can subarachnoid hemorrhage lead to hydrocephalus?
Because of impaired CSF flow in the subarachnoid space.

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