PATHOPHYSIOLOGY OF STROKE

Transcription

1 PATHOPHYSIOLOGY OF STROKE 2 CONTACT HOURS Reviewed and approved by Dr. Erica Frangione, RN-BC, Stroke Center at Bayonne Medical Center Learning objectives Identify anatomical structures of the brain. Identify anatomical components of cerebral circulation. Differentiate between ischemic and hemorrhagic stroke. Describe the pathophysiology of ischemic stroke. Describe the pathophysiology of hemorrhagic stroke. Introduction It is impossible for healthcare professionals to provide safe and appropriate care for patients who have suffered a cerebrovascular accident (CVA) or stroke unless they have a thorough knowledge of: The anatomical structures of the brain and cerebral circulation. The pathophysiology of ischemic stroke. The pathophysiology of hemorrhagic stroke. The type and extent of the stroke suffered and the specific areas of the brain that are affected dictate the impact of the event. Stroke healthcare management, from emergency intervention through and including rehabilitation, dictates patient outcomes. Essential to that management is comprehension of the pathophysiology of stroke. Anatomical structures of the brain The central nervous system (CNS) is composed of the brain and the spinal cord. The adult brain weighs about three pounds and is responsible for controlling all critical body functions, receiving and interpreting information from the environment, and embodying such intangibles as intelligence, emotion, memory, and creativity. 5 The skull (cranium) The skull is the bony structure that protects the brain from injury. It consists of eight bones that are fused together along suture lines. The bones of the skull are: 5 The frontal bone. Two parietal bones. Two temporal bones. The sphenoid bone. The occipital bone. The ethmoid bone. The interior of the skull is divided into three fossae (hollow areas) called the anterior, middle, and posterior fossae. The arteries, veins, and nerves of the brain exit through holes at the base of the skull. These holes are called foramina. The large hole in the center of the base of the skull is called the foramen magnum. It is the site where the spinal cord exits. 5 The brain The brain consists of the: 1 Cerebrum. Cerebellum. Brain stem. Diencephalon (thalamus and hypothalamus). Limbic system. Reticular activating system. The brain (and spinal cord) are covered and protected by the meninges, which are layers of tissue. These are: 5 Dura mater: The outermost tissue layer that lines the inside of the skull. It consists of two layers called the periosteal and menigeal dura, which are combined and separate only when they form venous sinuses. Arachnoid mater: A thin layer that resembles a web and covers the entire brain. It is composed of elastic tissue. The space between the dura mater and the arachnoid mater is called the subdural space. Pia mater: Clings to the surface of the brain following its folds and grooves. It has many blood vessels that penetrate deep into the brain. The area between the arachnoid mater and pia mater is the subarachnoid space where the cerebrospinal fluid cushions the brain. Nursing.EliteCME.com Page 1

2 The brain contains hollow cavities calledventricles that are filled with fluid. These ventricles contain a structure called the choroid plexus that manufactures the clear, colorless cerebrospinal fluid (CSF). This fluid flows around the brain and the spinal cord. Its job is to cushion the CNS and provide it with protection from injury. There is a careful balance between the constant production and absorption of CSF. If the ventricular system is damaged or blocked there may be an excessive build-up of CSF. This can lead to enlargement of the ventricles or excess fluid in the spinal cord. 5 Cerebrum The cerebrum, which contains the nerve center that controls sensory and motor functions, is the largest part of the brain and consists of right and left hemispheres. The cerebrum is responsible for higher level functions such as intelligence, vision, hearing, speech, learning, emotions, reasoning, interpreting touch, and fine motor control. 1,5 The cerebrum s outer layer, the cerebral cortex, is composed of unmyelinated nerve fibers, or gray matter. The inner lining is white matter or myelinated nerve fibers. Basal ganglia, located in the white matter of the cerebrum, are responsible for motor coordination. 1 The cerebrum is divided into right and left hemispheres that are connected by the corpus callosum, a bundle of fibers that transmit messages from one hemisphere to the other. 5 The cerebrum s surface is made up of various convolutions called gyri and fissures called sulci. 1 The fissure of Sylvius (lateral sulcus) separates the temporal lobe from the frontal and parietal lobes. The fissure of Rolando (central sulcus) separates the frontal lobes from the parietal lobe. The parieto-occipital fissure separates the occipital lobe from the two parietal lobes. 1 The hemispheres do not share all functions. The left hemisphere controls speech, comprehension, writing, and arithmetic. The right hemisphere is responsible for spatial skills, creativity, art, and music abilities. About 92 percent of people are left hemisphere dominant in hand use, meaning they are right handed. 5 Knowledge alert! Each cerebral hemisphere controls the opposite of the body. For example, a stroke that occurs in the right side of the brain may cause weakness or paralysis on the left side of the body. 5 Each hemisphere is divided into four lobes that are named for the cranial bones that cover them. The four lobes of each hemisphere are the: 1,5 Frontal lobe. Temporal lobe. Parietal lobe. Occipital lobe. The lobes do not act in isolation. They function via complex interrelationships with each other and the hemispheres of the cerebrum. 5 Each lobe is, however, responsible for specific functions. 1,5,6 Frontal lobe: Personality, judgment, social behavior, emotions, abstract reasoning, voluntary body movement, intelligence, self-awareness, concentration, speech, and writing (Broca s area). Parietal lobe: Interpretation of language and words, interpretation of the sensations of touch, pain, and temperature, interprets size, shape, distance vibration, and texture, and interprets signals from vision, hearing, motor, sensory, and memory. The parietal lobe of the non-dominant hemisphere is especially critical for the awareness of the shape of the body. Occipital lobe: Responsible for the interpretation of vision including color, light and movement. Temporal lobe: Controls hearing, language comprehension (Wernicke s area), recall of memories stored throughout the brain, organization, and sequencing. Knowledge alert! Here is some more information about language and memory! 5 Broca s area: Located in the left frontal lobe, damage to this area may cause the patient to have trouble moving the tongue or facial muscles that are needed to produce speech. However, reading and comprehension of spoken language is intact. Speaking and writing difficulty under these circumstances is referred to as Broca s aphasia. Wernicke s area: Located in the left temporal lobe, damage to this area causes the patient to have trouble understanding speech. They speak in long sentences that make no sense but are unaware of their mistakes. This is referred to as Wernicke s aphasia. Short-term memory: Occurs in the prefrontal cortex, which stores information for about one minute and is limited to about seven items. Long-term memory: Processed in an area called the hippocampus of the temporal lobe and is triggered when someone wants to memorize something for a long period of time. There is unlimited content and duration capacity. 1. Which cerebral hemisphere is dominant in a lefthanded person? Answer: The right hemisphere is dominant in a left-handed person. Each cerebral hemisphere controls the opposite side of the body. 2. Ability to speak and write is controlled by. Answer: Broca s area of the left frontal lobe. 3. What is the area that allows exit of the spinal cord from the skull is the. Answer: The foramen magnum. Page 2 Nursing.EliteCME.com

3 4. After suffering a stroke, a patient has difficulty comprehending language. What area of the brain has been affected? Answer: Wernicke s area of the temporal lobe. 5. How many items can be processed via short-term memory? Answer: About seven items. 6. The brain is protected by three layers of tissue called. Answer: Meninges. 7. Difficulty interpreting vision occurs when there is damage to what lobe? Answer: The occipital lobe. 8. The clings to the surface of the brain following its folds and grooves. Answer: Pia mater 9. Intelligence and social behavior are functions of the lobe. Answer: The frontal lobe. 10. or. About 92 percent are left hemisphere dominant. Answer: Cerebellum The cerebellum is the second largest portion of the brain. Located in the posterior cranial fossa behind the brainstem, it consists of two lateral hemispheres and a middle section called the vermis. It is linked to the brainstem by three pairs of peduncles (stem-like connections). 6 The cerebellum has an outer cortex consisting of gray matter and an inner core of white matter. The primary functions of the cerebellum deal with coordination of voluntary muscle movement, maintenance of muscle tone, and balance. 5,6 Brain stem The brain stem is located right below the cerebrum and just in front of the cerebellum. It goes from the cerebrum to the spinal cord. The brain stem consists of the midbrain, pons, and medulla oblongata and has three primary functions: 1,5 Serves as a communication center by connecting the cerebrum and cerebellum to the spinal cord. The brain stem produces essential autonomic reactions necessary for survival such as breathing, heart rate, and body temperature. The brain stem is also responsible for wake and sleep cycles, digestion, sneezing, coughing, vomiting, and swallowing. The brain stem is the site of origination of 10 of the 12 cranial nerves. In addition to the preceding functions the brain stem is also responsible for the following actions. 1,6 The midbrain acts as the reflex center for cranial nerves III and IV, papillary reflexes, and eye movements. The pons assists with the regulation of respirations and connects the cerebellum and the cerebrum and links the midbrain to the medulla oblongata. The pons is the reflex center for cranial nerves V through VIII and facilitates taste, secretion of saliva, chewing, hearing, and equilibrium. The medulla oblongata serves as the center for vomiting, coughing, and hiccupping reflexes as well as influencing respiratory, cardiac, and vasomotor activities. Diencephalon The diencephalon is located between the cerebrum and the midbrain. It is composed of the thalamus and hypothalamus, lying deep within the cerebral hemispheres. 1,6 Thalamus The thalamus is one of a pair of large oval nervous structures made of grey matter and forming most of the lateral walls of the third ventricle of the brain and part of the dicencephalon. 6 This structure acts as a sort of communication station, relaying all sensory stimuli (except olfactory or sense of smell) as they move up to the cerebral cortex. 1 The thalamus plays a part in primitive awareness of pain sensation, attention, alertness, memory, and screening of incoming stimuli. 1,5 Hypothalamus The hypothalamus is found in the floor of the third ventricle. It serves as the master controller of the autonomic system, controlling: 1,5 Temperature. Appetite (hunger and thirst). Water balance. Pituitary secretions. Emotions. Sleep and waking cycles. Blood pressure. Sexual response. Nursing.EliteCME.com Page 3

4 Limbic system The limbic system is actually a group of structures located deep within the temporal lobe. It is characterized as a primitive brain center that is responsible for initiating basic drives such as hunger, aggression, and emotional and sexual arousal. 1,5 If the limbic system is not controlled and moderated by other cortical areas of the brain, a person may experience periods of uncontrollable rage. 6 Knowledge alert! Note that several areas of the brain work together to initiate certain drives. For example, the hypothalamus controls the autonomic system for functions such as appetite and sexual response while the limbic system initiates some of these basic drives. 1,5 Other deep structures It is important to mention other structures that are located deep within the brain. These include the basal ganglia, the pituitary gland, and the pineal gland. The basal ganglia are areas of gray matter that are composed mostly of cell bodies and are located deep within each cerebral hemisphere. The major ganglia are the caudate nucleus, the putamen, the substantia nigra, the subthalamic nucleus, and the pallidum. 6 The basal ganglia work in conjunction with the cerebellum to coordinate fine motor movements. 5 The pituitary gland is an endocrine gland located in a small pocket of bone at the base of the skull. It is connected to the hypothalamus by the pituitary stalk. 5 The pituitary is referred to as the master gland and controls other endocrine glands in the body. It secretes the hormones that control sexual development, respond to stress, advance bone and muscle growth, and fight illness. 5 Located behind the third ventricle, the pineal gland helps to regulate the body s circadian rhythms and the body s internal clock. It is also believed to play a part in sexual development. 5 Reticular activating system (RAS) The reticular activating system (RAS) is a disperse network of neurons that fans out from the brain stem and extends through the cerebral cortex. 1 Nerve fibers in the thalamus, hypothalamus, brain stem, and cerebral cortex contribute to the system. 6 The RAS screens incoming sensory information and sends it to proper areas of the brain to be interpreted. It is essential to maintaining consciousness and acts as the arousal system for the cerebral cortex Which part of the brain is primarily responsible for coordination of voluntary muscle movement? Answer: The cerebellum. 2. The site of origination of 10 of the 12 cranial nerves is the. Answer: The brain stem. 3. Abnormal stimulation of may cause uncontrollable vomiting. Answer: The medulla oblongata. 4. Failure of other cortical areas of the brain to moderate the may lead to periods of uncontrollable rage. Answer: The limbic system. 5. In conjunction with the cerebellum, the coordinates fine motor movements. Answer: Basal ganglia. 6. The master gland is the. Answer:The pituitary gland. 7. What area of the brain serves as a communication center by connecting the cerebrum and the cerebellum to the spinal cord. Answer: The brain stem. The cranial nerves The brain is able to communicate with the body via the spinal cord and the cranial nerves. 5 There are 12 pairs of cranial nerves that transmit motor and/or sensory messages, and 10 of the pairs originate in the brain stem. The olfactory and optic nerves originate in the cerebrum. 1,5 The cranial nerves (CNs) are responsible for: 1,5 Cranial nerve I: The olfactory nerve is a sensory nerve and is responsible for the sense of smell. Cranial nerve II: The optic nerve is a sensory nerve and is responsible for the sense of vision. Page 4 Cranial nerve III: The oculomotor nerve is a motor nerve and is responsible for superior, medial, and inferior lateral extraocular movement, pupillary constriction, and elevation of the upper eyelid. Cranial nerve IV: The trochlear nerve is a motor nerve that moves the superior oblique muscles of the eye. Cranial nerve V: Trigeminal nerve has both sensory and motor functions and is responsible for transmitting stimuli from the face and head, and the corneal reflex. Its motor functions include chewing, biting, and lateral movements of the jaw. Nursing.EliteCME.com

5 Cranial nerve VI: Abducens nerve is a motor nerve and is responsible for lateral extraocular eye movement. Cranial nerve VII: Facial nerve has both sensory and motor components. It is responsible for the sense of taste on the anterior two-thirds of the tongue. It is also responsible for facial muscle movement that includes the muscles of facial expression in the forehead and around the mouth and the eyes. Cranial nerve VIII: Acoustic or vestibulocochlear nerve is a sensory nerve that is responsible for hearing and balance. Cranial nerve IX: Glossopharyngeal nerve has both sensory and motor components. Its motor function involves swallowing movements. Its sensory function involves sensations of the throat and taste receptors in the posterior one-third of the tongue. Cranial nerve X: Vagus nerve has both sensory and motor components. Motor functions include movement of the palate, swallowing, gag reflex, thoracic and abdominal viscera activity such as heart rate and peristalsis. Sensory functions include sensations of the throat, larynx, and thoracic and abdominal viscera. This involves sensations of heart, lungs, bronchi, and gastrointestinal (GI) tract. Cranial nerve XI: Spinal accessory nerve is a motor nerve that is responsible for shoulder movement and rotation of the head. Cranial nerve XII: Hypoglossal nerve is a motor nerve that is responsible for tongue movement. 1. A physician notes that a patient s lateral eye movement is abnormal. This may indicate a problem with which cranial nerve? Answer: Abducens nerve (CN VI). 2. The functions of the facial nerve (CN VII) can be assessed by. Answer: Testing taste sensation on the anterior two-thirds of the tongue. Asking the patient to frown. 3. Which cranial nerve is responsible for a person s ability to shrug his shoulders? Answer: Spinal accessory nerve (CN X). 4. A nurse practitioner asks a patient to stick out his tongue. She is assessing the function of which cranial nerve? Answer: Hypoglossal nerve (CN XII). 5. A nurse practitioner asks a patient to differentiate between the smell of flowers and the smell of smoke. She is assessing the function of which cranial nerve? Answer: Olfactory nerve (CN I). The brain s blood supply The brain is supplied with oxygenated blood by two pairs of arteries: Two vertebral arteries and two carotid arteries. The two vertebral arteries join together to become the basilar artery. The basilar artery is the vessel that supplies blood to the posterior brain including the cerebellum, the brainstem, and the underside of the cerebrum. 1,5 The carotid arteries branch out to form the two internal carotid arteries. These internal carotid arteries further subdivide to supply blood to the anterior and middle brain. These arteries communicate and interconnect with each other and with the basilar artery through the Circle of Willis at the base of the brain. 1 The Circle of Willis serves an important function. It ensures that, if one of the major vessels of the brain becomes blocked, it is possible for collateral blood circulation to flow across the Circle of Willis to the brain and prevent brain damage. 1,5 Pathophysiology of stroke Introduction Stroke or cerebrovascular accident (CVA) is an abrupt interruption or impairment of cerebral circulation in one or more blood vessels that supply the brain with blood. This type of event interferes with the brain s oxygen supply and decreases brain tissue oxygenation, which, in turn, can cause significant damage or necrosis of brain tissue. 3,8 Stroke is the fourth most common cause of death in the United States affecting more than 795,000 people every year, and half of these people die. It is also the most common cause of neurologic disability and the primary reason for admission to long-term care facilities. In fact, about 50 percent of stroke survivors are permanently disabled and experience another stroke within weeks, months, or years. Strokes most often occur in persons over the age of 65, but can affect people of any age. The risk of stroke doubles with each decade after the age of Strokes are generally classified as ischemic or hemorrhagic. Ischemic stroke is due to impairment of blood supply to an area of the brain as a result of thrombosis or embolism. 6 Hemorrhagic stroke is due to hypertension or rupture of an aneurysm. 3 Nursing.EliteCME.com Page 5

6 TIA Prior to a discussion of ischemic and hemorrhagic strokes it is important to review what occurs during a transient ischemic attack or (TIA). A TIA is a transient or temporary period of neurologic deficit that lasts from a few seconds to hours and resolves with a return to normal function within 12 to 24 hours. TIAs are widely considered to be a warning of impending thrombotic stroke. Research shows that TIAS have occurred in between 50 percent to 80 percent of patients who suffered a thrombotic stroke. 3,8 The pathophysiology of TIA involves the release of microemboli from a thrombus. These microemboli travel to cerebral arteries where they temporarily interfere with cerebral blood flow and cause symptoms related to the affected artery or arteries. Symptoms (similar to those of stroke) may include vision changes, weakness, slurred speech, and dizziness. 8 Patients who experience a TIA should seek prompt medical assistance. Prompt interventions such as anti-platelet medications or carotid endarterectomy (surgical excision atherosclerotic plaques) of may prevent the occurrence of a stroke. 8 Ischemic stroke Ischemic stroke, generally caused by a thrombus or embolus, can be classified into three main categories. These are thrombotic, embolic, and lacunar. 3 Thrombotic stroke A thrombus is a compilation of platelets, clotting factors, fibrin, and the cellular elements of the blood that attach to the interior wall of arteries or veins. 6 Thrombotic ischemic stroke is the most common cause of stroke in middle-aged and elderly persons. However, it can occur at any age. Atherosclerosis, the deposit of cholesterol and plaque within arterial walls, can expand to the point that the arterial wall narrows and blood flow is reduced. Plaque build-up also interferes with the elasticity of the arterial walls. Atherosclerosis is the most common contributing factor to thrombus development. 3,8 Associated risk factors are hypertension, smoking, diabetes, surgery, and use of hormonal contraceptives. 3,8 Imaging studies have recently been used to further clarify these types of secondary contributors to ischemic injury and to analyze their impact on patient outcomes. A summary of some of the results of imaging studies include the following information from a publication by Moustafa. 7 Hyperglycemia: Exploration of the association between hyperglycemia and outcomes showed that acute hyperglycemia was linked to reduced tissue survival. Higher blood glucose levels were strongly associated with larger infarction sizes and worse functional patient outcomes. Hematocrit: Elevated hematocrit has some association with extension of the infarction size. Inflammation: Inflammation is believed to contribute to neuron cell death. A thrombotic stroke can occur while sleeping, soon after awakening, during surgery, or after a heart attack (myocardial infarction or MI). If the thrombus occurs in cranial vessels blood flow to the cerebral cortex is blocked. The most commonly affected extracranial vessel affected by thrombotic stroke is the carotid artery. 3 Embolic stroke Embolic stroke is the second most common type of stroke and occurs when a piece of thrombus, a fragmented clot, a tumor, fat, bacteria, or air travels through the bloodstream until it becomes lodged in a blood vessel. 3,6 An embolus from the heart or extracranial arteries travels into the cerebral circulation and lodges in the middle cerebral artery or its branches. 3 Knowledge alert! The left middle cerebral artery is the most common site of embolic stroke. 8 Embolic stroke: 3 Develops swiftly (within 10 to 20 seconds) and without warning. Generally occurs during activity. Often begins during atrial fibrillation. An embolic stroke can occur at any age. Risk increases with a history of rheumatic heart disease, endocarditis, posttraumatic valvular disease, or atrial fibrillation or other types of arrhythmias. 8 Lacunar The word lacunar pertains to a hollow area within a structure, especially in bony tissue. A lacunar ischemic stroke is a subtype of thrombotic stroke. With a lacunar stroke: 3 Page 6 Hypertension causes the formation of cavities deep within the white matter of the brain, which affects the basal ganglia, thalamus, and pons. Nursing.EliteCME.com

7 Lipid coating that lines small arteries thickens and causes the arterial walls to weaken, which leads to the formation of micro-aneurysms. Hemorrhagic stroke Hemorrhagic stroke is the third most common type of stroke. It can occur rapidly at any age. 3,8 Causes of hemorrhagic stroke include: 3,4,8 Chronic hypertension. Aneurysms that cause a rupture of a cerebral artery. Knowledge alert! Cocaine use can lead to severe, dangerous hypertension and hemorrhagic stroke. 8 When a hemorrhagic stroke occurs, blood supply supplied by the affected artery is reduced and the surrounding tissue is constricted by an accumulation of blood The most likely cause of stroke is. Answer: Thrombotic ischemic stroke. 2. or false. Hyperglycemia is associated with reduced tissue survival but did not impact significantly on patient outcomes. Answer:. Acute hyperglycemia was linked to reduced tissue survival. Higher blood glucose levels were strongly associated with larger infarction sizes and worse functional patient outcomes. 3. The extracranial vessel that is most commonly affected by thrombotic stroke is. Answer: The carotid artery. 4. What type of stroke often occurs with atrial fibrillation? Answer: Embolic stroke. 5. Hypertension leads to the formation of cavities deep within the white matter of the brain and can lead to what type of stroke? Answer: Lacunar stroke. 6. Cocaine use is associated with what type of stroke? Answer: Hemorrhage stroke. Impact of stroke The clinical impact of stroke varies depending on the affected artery, the areas of the brain it supplies, and the extent of the damage. 3,8 Knowledge alert! However, a stroke that damages cranial nerves causes signs and symptoms on the same side as the damage. 3,8 The body is affected in different ways by different types of stroke. 8 Thrombotic stroke: The affected vessel becomes congested and edematous. Ischemia develops in the tissue of the brain that is supplied by that vessel. Embolic stroke: The embolus halts circulation causing necrosis and edema. An infected embolus can cause infection to spread beyond the affected blood vessel, and encephalitis may develop. Infection within the blood vessel can lead to the formation of an aneurysm, which can cause the artery to rupture or hemorrhage. Hemorrhagic stroke: During a hemorrhagic stroke, an artery bursts, impairing the blood supply to the area of the brain that is supplied by the affected vessel. Blood accumulates and compresses brain tissue. The neurologic deficits of stroke are often grouped according to the artery that is affected by the stroke. Here is a summary of signs and symptoms associated with damage to specific areries. 2,3,8 Anterior cerebral artery Changes in mood and personality (e.g. flat affect). Changes in intellect. Confusion. Coordination impairment. Impaired motor functions. Impaired sensory functions. Incontinence. Numbness on the affected side. Weakness. Carotid artery Aphasia. Bruits over the carotid artery. Changes in levels of consciousness. Drooping eyelids (Ptosis). Dysphasia. Headaches. Sensory changes. Vision problems. Weakness. Middle cerebral artery Aphasia. Cuts in fields of vision. Dysphasia. Dyslexia (difficulty reading). Dysgraphia (difficulty writing or inability to write). Hemiparesis on affected side (Usually more severe in the face and arm rather than the leg). Posterior cerebral artery Blindness due to ischemic damage in the occipital lobe. Nursing.EliteCME.com Page 7

8 Coma. Cuts in fields of vision. Dyslexia. Perseveration (persistent discussion/talking about one topic). Sensory changes/impairment. Vertebrobasilar artery Amnesia. Ataxia. Dizziness. Dysphagia. Incontinence. Lack of coordination. Numbness of the lips and mouth. Nystagmus. Slurred speech. Vision deficits such as diplopia (double vision) and color blindness. Weakness on affected side. 1. Personality changes are associated with damage to. Answer: Anterior cerebral artery 2. A patient who is constantly repeating information about the same topic has most likely experienced a stroke that affects. Answer: Posterior cerebral artery. 3. or : A stroke that damages cranial nerves causes signs and symptoms on the opposite side as the damage. Answer:. A stroke that damages cranial nerves causes signs and symptoms on the same side as the damage. 4. or : Blood accumulation from hemorrhagic stroke causes compression of brain tissue and extends damage. Answer: 5. Ptosis occurs with damage to. Answer: The Carotid Artery. In summary, the type and extent of the stroke suffered and the specific areas of the brain that are affected dictate the impact of the event. The care provided, from emergency intervention through and including rehabilitation, dictates patient outcomes. In order to provide care that helps to maximize patient outcomes, healthcare professionals must have a thorough comprehension of the anatomy of the brain and the pathophysiology of stroke, including the ability to differentiate among the various types of stroke. Also essential is knowledge of the neurologic deficits associated with damage to specific cerebral arteries. A review of the various structures of the brain and the functions that are associated with each area of the brain should help members of the stroke team to anticipate probable deficits and to formulate appropriate plans of care. A knowledge of the 12 pairs of cranial nerves is also important. Damage to these nerves will manifest itself in various ways. Healthcare professionals should know the functions of each CN and recognize how damage to these nerves impact patient outcomes. It is not enough to simply accurately follow medical orders. All members of the healthcare team must understand the rationale behind such orders and associate them with the pathophysiology affecting each patient. The goals of patient care following stroke are to minimize brain damage and neurologic deficit, achieve maximal state of wellness, and prevent stroke recurrence. Knowledge of cerebral anatomy and stroke pathophysiology is as important to achieving these goals as is knowledge of treatments and effective interventions. It is a challenge to all healthcare professionals who work with stroke patients and their families to correlate their knowledge of anatomy and physiology with a treatment regimen that is designed to maximize patient outcomes and help patients achieve the best possible state of health and wellness. References 1. Comerford, K. C. (Ed.). (2013). Anatomy & physiology made incredibly easy (4th ed.). Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. 2. Diehl, T. S. (Ed.). Critical care nursing made incredibly easy (3rd ed.). Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. 3. Eckman, M. (Ed.). (2011). Professional guide to pathophysiology (3rd ed.). Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. 4. Liebeskind, D. S. (2011). Hemorrhagic stroke in emergency medicine. Retrieved October 4, 2012 from 5. Mayfield Clinic. (2011). Anatomy of the brain. Retrieved October 4, 2012 from www. mayfieldclinic.com/pe-anatbrain.htm. 6. Mosby. (2009). Mosby s dictionary of medicine, nursing, & health professions (8th ed.). St. Louis: Mosby Elsevier. 7. Moustafa, R. R., & Baron, J. C. (2008). Pathophysiology of ischemic stroke: Insights from imaging, and implications for therapy and drug discovery. British Journal of Pharmacology online, November 26, Retrieved October 4, 2012 from www. ncbi.nlm.nih.gov/pmc/articles/pmc / 8. Rosto, E. (Ed.). (2009). Pathophysiology made incredibly easy (4th ed.). Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins. Page 8 Nursing.EliteCME.com

9 Pathophysiology of Stroke Final Examination Questions Choose or for questions 1 through 10 and mark them online at Nursing.EliteCME.com 1. The cerebrum, which contains the nerve center that controls sensory and motor functions, is the largest part of the brain and consists of right and left hemispheres. 2. A stroke that occurs in one cerebral hemisphere causes signs and symptoms on the opposite side of the body. 3. The lobe of the brain responsible for interpretation of vision including color, light, and movement is the temporal lobe. 4. Broca s aphasia exists when the patient has trouble producing speech but can comprehend the spoken language. 5. Intelligence and social behaviors are functions of the frontal lobe. 6. The spinal accessory nerve (CN XI) is responsible for the gag reflex. 7. The most common site of embolic stroke is the carotid artery. 8. Ischemic stroke is the result of a ruptured cerebral artery. 9. Hypertension causes the formation of cavities deep within the white matter of the brain as part of the pathophysiology of lacunar stroke. 10. Personality changes are associated with damage to the carotid artery. Nursing.EliteCME.com Page 9