Stroke & Cerebral Vascular Syndromes Independent Study Module PDF (Ana G. Méndez University)

NMDP-706: Neuroanatomy | 2025 Ana G. Méndez University, Gurabo Campus Naturopathic Medicine Program Stroke & Cerebral Vascular Syndromes Independent Study Module I. Stroke or Cerebrovascular Accident (CVA) A stroke is rapid loss of brain function(s)...

NMDP-706: Neuroanatomy | 2025 Ana G. Méndez University, Gurabo Campus Naturopathic Medicine Program Stroke & Cerebral Vascular Syndromes Independent Study Module I. Stroke or Cerebrovascular Accident (CVA) A stroke is rapid loss of brain function(s) due to disturbance in the blood supply to the brain. It is characterized by an acute onset of neurologic deficit lasting for at least 24 hours. A stroke can be caused by blockage of blood vessels (occlusive stroke) or by bleeding from vessels (hemorrhagic stroke). A. Important Definitions: Occlusive strokes = generally caused by atherosclerotic lesions or thrombosis in blood vessels supplying the brain, thus resulting in ischemia. Hemorrhagic strokes = generally caused by long-standing high blood pressure or aneurysms in the vessels supplying the brain. Extraparenchymal Hemorrhage = when bleeding occurs at the surface of the brain (e.g., rupture of an aneurysm causing subarachnoid hemorrhage). Intraparenchymal Hemorrhage = when bleeding occurs in an artery inside the brain tissue. The hemorrage may form a hematoma (blot clot) within the brain tissue that could obstruct blood flow to the adjacent brain tissue. Brain ischemia = insufficient blood flow to the brain; oxygen and glucose delivery to the brain tissue is reduced. In addition, toxic metabolites, such as lactic acid, cannot be removed efficiently due to reduced blood flow. Brain anoxia = brain tissue deprived from oxygen delivery only. Syncope = Brief loss of consciousness caused by generalized cerebral ischemia due to insufficient flow of oxygenated blood to the brain. Transient Ischemic Attack (TIA) = focal ischemia that causes symptoms to last for short periods of time (usually 5-30 min, but less than 20 hrs); caused by emboli dislodged from ulcerated atherosclerotic plaque. If untreated, may developed in permanent cerebral infarction. Prepared By: Dr. Nietzell Vázquez Acevedo  B. Treatment Drugs that prevent or reduce platelet aggregation (e.g., aspirin, clopidogrel, and tirofiban) Anticoagulants (e.g., heparin and warfarin) Thrombolytic agents (e.g., streptokinase, urokinase, and tissue plasminogen activator). Carotid Endarterectomy – vascular surgical procedure beneficial in patients with marked stenosis (greater than 70%) of carotid artery o The common carotid artery and a portion of the external carotid artery are split open by a longitudinal cut, and atherosclerotic plaques are removed. o Risk: Post-operative stroke due to dislodging of thrombi formed at the site where surgery is performed. II. Cerebral Vascular Syndromes The cerebral cortex is supplied by the following arteries: anterior cerebral artery, middle cerebral artery & posterior cerebral artery. The anterior cerebral artery: This artery and its branches supply blood to the medial and dorsal aspect of the frontal and parietal lobes of the cerebral hemisphere, including the postcentral gyrus (which is concerned with the processing of sensory information from the contralateral leg) and precentral gyrus (from which motor control of the contralateral leg originates). The regions of the cerebral cortex supplied by the anterior cerebral artery are shown in Figure 1. The middle cerebral artery: This artery and its branches supply blood to the precentral gyrus (primary motor area), premotor region, the somesthetic and auditory areas, and the integrative association areas of the parietal lobe. The cerebral cortical areas supplied by the middle cerebral artery are shown in Figure 1. The posterior cerebral artery: This artery supplies most of the midbrain and thalamus as well as the subthalamic nucleus. After this artery passes around the midbrain, three major branches arising from it (i.e., anterior and posterior temporal and parieto-occipital branches) supply the temporal and inferior occipital lobes of the cortex. A branch of the posterior cerebral artery, called the calcarine artery, supplies the primary visual cortex. Prepared By: Dr. Nietzell Vázquez Acevedo  Fig. 1: The coronal section through cortex showing the territories supplied by the anterior cerebral (blue), middle cerebral (red), and posterior cerebral (green) arteries. From Siegel & Sapru. (2015). Essential Neuroscience (3rd Edition), Fig. 27-7. The following syndromes are caused by the interruption of the blood flow in the above the mentioned arteries: A. Anterior Cerebral Artery Syndrome Caused by interruption of blood flow in the trunk of one of the anterior cerebral arteries, which damages the precentral gyrus and results in contralateral paralysis (contralateral hemiplegia), mainly of the leg. Occlusion of both anterior cerebral arteries produces bilateral paralysis, which is pronounced in the lower limbs. Ischemic damage to the postcentral gyrus results in impaired sensation, mainly to the leg. B. Middle Cerebral Artery Syndrome Caused by occlusion of the main trunk of this artery, which results in contralateral hemiplegia predominantly in the upper extremities and face because the upper limb region is represented in a lateral position of the precentral gyrus. A contralateral sensory loss characterized by inability to discriminate between intensities of different stimuli may also occur. If the left hemisphere is involved, aphasia (disturbances in speech) may occur because the speech centers are located laterally in this hemisphere. C. Posterior Cerebral Artery Syndrome Caused by interruption of the calcarine branch of the posterior cerebral artery, which supplies both the upper and lower banks of the visual cortex, which results in contralateral homonymous hemianopia. Prepared By: Dr. Nietzell Vázquez Acevedo