Presentation on theme: "Carotid Circulation Major regions supplied Carotid Circulation Major regions supplied Lumen ventricle Optic nerves and retina Cortex and deep white matter."— Presentation transcript:
Carotid Circulation Major regions supplied Carotid Circulation Major regions supplied Lumen ventricle Optic nerves and retina Cortex and deep white matter Frontal and parietal lobes Lateral parts of the temporal and occipital lobes Corpus callosum - except splenium (posterior) Most of the basal ganglia (including amygdala) Internal capsule
ACA Key functional areas supplied ACA Key functional areas supplied Lumen ventricle Septal area Primary motor cortex Leg and foot areas Area controlling urinary bladder Motor planning areas in medial frontal lobe, anterior to the precentral gyrus Primary somatosensory cortex for leg and foot Most of corpus callosum except splenium
MCA-superior branches Key functional areas supplied MCA-superior branches Key functional areas supplied Lumen ventricle Primary motor cortex - face / arm areas Pyramidal tract axons from all of the primary motor cortex Primary somatosensory cortex - face / arm areas Frontal eye fields Frontal/parietal - language-dominant hemisphere Broca’s and other areas for language expression Frontal/parietal - nondominant hemisphere areas for 3-D visuospatial concepts of self and world areas for expressing emotions
MCA-inferior branches Key functional areas supplied MCA-inferior branches Key functional areas supplied Lumen ventricle Visual radiations Fibers representing information from contralateral superior quadrants Temporal/parietal- language-dominant hemisphere Wernicke’s and other areas for language comprehension Posterior parietal - nondominant hemisphere areas for 3-D visuospatial perceptions of self and world areas for interpreting emotions
Vertebral-Basilar Circulation Major regions supplied Vertebral-Basilar Circulation Major regions supplied Lumen ventricle Upper cervical spinal cord Brainstem and cerebellum Most of thalamus and hypothalamus Cortex and deep white matter Posterior medial parietal lobes Medial and infrior temporal and occipital lobes Splenium of corpus callosum
PCA Key functional areas supplied PCA Key functional areas supplied Lumen ventricle By long penetrating branches Thalamus, subthalamic nucleus, hypothalamus Midbrain By cortical branches - parietal and occipital lobes Visual radiations and primary visual cortex Splenium of corpus callosum By cortical branches - medial temporal lobe Hippocampal formation and posterior fornix
Common Anastomoses Collateral circulation may prevent ischemia Common Anastomoses Collateral circulation may prevent ischemia Lumen ventricle External-internal carotid via ophthalmic branches Circle of Willis Muscular branches of cervical arteries-vertebral or external carotid arteries Short cortical branches of ACA, MCA, PCA Branches of the major cerebellar arteries
ACA-MCA Border Zone Key functional areas that may be present ACA-MCA Border Zone Key functional areas that may be present Lumen ventricle Hip or shoulder (occasionally arm) regions of primary motor or somatosensory cortex Regions involved in aspects of language production (in the dominant hemisphere) Frontal Eye Fields Motor planning areas in frontal lobe
ACA/MCA-PCA Border Zone Key functional areas that may be present ACA/MCA-PCA Border Zone Key functional areas that may be present Lumen ventricle Visual radiations Foveal representation in the primary visual cortex Inferior temporal lobe cortex for visual recognition Regions for language comprehension and word finding (possibly reading) in dominant hemisphere Regions important for visuospatial perceptions in parietal lobe of nondominant hemisphere
What is a TIA? What is a TIA? Lumen ventricle A Transient Ischemic Attack (TIA) is a brief episode in which neurologic deficits suddenly occur, but then disappear completely Most TIAs last a few minutes to an hour. No neurologic deficits remain once a TIA has ended, because little or no brain tissue is permanently damaged. A TIA is an indicator that the stage is set for an ischemic stroke. Treatment of patients with TIAs can significantly reduce their risk of having a stroke.
Patients commonly describe a gray or black fog or a mist clouding vision in all or part of one eye. Attacks are typically brief (1-5 minutes), and afterwards vision is fully restored. TMB often signals the presence of severe ipsilateral carotid artery disease in older adults. TMB can also be caused by migraine. TMB (also known as amaurosis fugax) occurs when the retina becomes temporarily ischemic. TIAs: Carotid Territory Transient monocular blindness TIAs: Carotid Territory Transient monocular blindness
Two Ideas: 1. Thrombus from ulcerated atherosclerotic plaque at the origin of the internal carotid artery enters ophthalmic artery and plugs retinal vessel. A small embolic particle can produce retinal ischemia or block the central retinal artery. If the embolus (often a platelet-fibrin aggregate) falls apart, blood flow is restored and and vision returns. 2. Low perfusion in the internal carotid artery, putting distal structures like the retina at risk. This mechanism implies presence of severe carotid stenosis that significantly impairs blood flow. TMB: What’s Mechanism? TMB: What’s Mechanism?
One-sided limb weakness, clumsiness or paralysis One-sided numbness, paresthesia, or sensory loss Difficulty with language production or comprehension Inability to articulate words clearly, often described as ‘I slurred my words’ (dysarthria) Partial or complete homonymous visual field defects (patients seldom describe these) Problems typically produced TIAs: Carotid Territory Transient hemispheric attacks TIAs: Carotid Territory Transient hemispheric attacks
Carotid Bifurcation atherosclerotic plaque and thrombus Carotid Bifurcation atherosclerotic plaque and thrombus Plaque Thrombus on plaque surface Thrombus on plaque surface Plaque reduces the diameter of artery
Vertigo or dizziness Unilateral or bilateral weakness or clumsiness Unilateral or bilateral numbness or sensory loss Limb ataxia or coarse tremor, staggering gait Dysarthria Visual field defect, blindness, or diplopia Nystagmus (‘it jumps around when I look at it’) Problems typically produced TIAs: Vertebral-Basilar Various combinations may be present TIAs: Vertebral-Basilar Various combinations may be present
Because the episode of impaired function is brief, patients may not tell you about it unless you ask. Seniors with somewhat impaired memory may simply not recall such brief events. TIAs in carotid territory predict severe atherosclerosis in the proximal internal carotid artery. Tests can determine actual blood flow in the carotid. The odds of stroke in the next 1-2 weeks are great! If severe narrowing is present, surgical and medical treatments can help to reduce stroke risk. Patients may ignore TIAs! Patients may ignore TIAs!