Presentation on theme: "Chapter 37 Disorders of Brain Function"— Presentation transcript:
1Chapter 37 Disorders of Brain Function Essentials of PathophysiologyChapter 37 Disorders of Brain Function
2Research News Migraines Increase Stroke Risk November 18, Pooling results from 21 studies, involving 622,381 men and women, researchers at Johns Hopkins Univ. have affirmed that migraine headaches are associated with more than two-fold higher chances of the most common kind of stroke: those occurring when blood supply to the brain is suddenly cut off by the buildup of plaque or a blood clot.
3Pre lecture quizFTCerebral edema, or brain swelling, is characterized by a decrease in volume secondary to an abnormal fluid accumulation.The brain tissue and interstitial fluid represent the majority of the skull content.Concussions are listed under the category of focal brain injuries.All seizure events are related to epilepsy.Alzheimer disease is characterized by cortical atrophy and loss of neurons.
4Pre lecture quiz Glasgow Hydrocephalus Meningitis Seizure stroke __________________ is defined as an abnormal increase in cerebrospinal fluid (CSF) volume in any part or all of the ventricular system.The ______________ Coma Scale is a method for assessing level of consciousness in persons with brain injury.A ______________ is an acute focal neurologic deficit from an interruption of blood flow in a cerebral vessel due to thrombi or emboli or to bleeding into the brain.______________ is an inflammation of the pia mater, the arachnoid, and the CSF-filled space that can spread rapidly because of CSF circulation around the brain and spinal cord.A ___________ represents the clinical manifestations of an abnormal, uncontrolled electrical discharge from a group of neurons in the cerebral cortex.
5Glasgow coma scalescale that is used to assess the severity of a brain injuryvalues from 3 to 15 obtained by summing the ratings assigned to three variablesdepending on whether and how the patient responds to certain standard stimuli byopening the eyes,giving a verbal response, andgiving a motor response,a low score (as 3 to 5) indicates a poor chance of recoverya high score (as 8 to 15) indicates a good chance of recovery
6QuestionWhat two substances are needed by the mitochondria in order to produce ATP?O2 and CO2Glucose and O2Glucose and fatty acidsProteins and monosaccharides
7AnswerGlucose and O2Rationale: Glucose and oxygen are necessary for ATP production. Without ATP, no physiologic work can be done—the cells, and eventually the organism, will die. When oxygen is not available, anaerobic pathways are used, creating lactic acid that also damages the cell.
8Hypoxia and Ischemia Hypoxia causes ATP depletion or “power failure” Aerobic metabolism stops less ATP is producedNa+/K+ ATPase cannot run fast enoughCell swells up with waterAnaerobic metabolism used lactic acid producedAcid damages cell membranes, intracellular structures, and DNA
9Hypoxia and Ischemia (cont.) Ischemia also interferes with:Delivery of energy stores (e.g., glucose)Damage to blood vesselsVasomotor paralysisVasoconstrictionChanges in bloodDesaturationClottingSludging
10Calcium Cascade Ischemia depolarization Depolarization glutamate releaseGlutamate calcium cascadeCalcium influx depolarizationthe predominant molecular Receptor for controlling synaptic plasticity and memory function
11Intracranial Pressure (ICP) Compartment syndrome in the skullIntracranial pressure greater than arterial blood pressureArteries collapse; blood flow to brain cut offBrain swellingVasogenic: extracellular fluidCytotoxic: intracellular fluidHydrocephalus: cerebrospinal fluidTumors
12Brain HerniationIncreased intracranial pressure pushes the brain out of positionBrain tissue is compressed intothe center of the brain (2),against bone (4) oragainst rigid folds of the dura mater (1, 3)Compression of the oculomotor nerve is an early sign
14QuestionTell whether the following statement is true or false. Increased ICP results in primary brain injury.
15AnswerFalse Rationale: Increased pressure in the brain leads to secondary brain injury (there’s nowhere for the pressure to be released because the brain is encased in bone). Primary brain injury is caused by trauma.
16Hematoma—Broken Blood Vessels Epidural space: meningeal arteriesRapid bleeding; unconsciousness may be followed by brief lucid periodDura materSubdural space: bridging veinsSlower bleeding; gradual development over days or weeks
17Cerebral Blood Flow Carotid arteries branch into: External carotid – facialInternal carotid - brainInternal carotid arteries branch into:Anterior cerebral arteriesMedial and superior surfaces of brain; frontal lobesMiddle cerebral arteriesLateral surfaces of brain: face and arm motor and sensory cortexes, optic radiations, speech centersMiddle cerebral arteryAnterior cerebral arteryBrain (lateral view)Internal carotid artery
18Cerebral Blood Flow (cont.) The basilar artery runs up to the back of the brainIt splits to form the two posterior cerebral arteriesThey supply the medulla, pons, cerebellum, midbrain, occipital lobes, temporal lobes, thalamusPosterior cerebral arteryBasilar artery
19Circle of Willis Anterior communicating artery Connects right and left anterior cerebral arteriesBlood from one carotid can cross over to supply the other side of the brainPosterior communicating arteriesConnect the posterior and middle cerebral arteriesBlood from the basilar artery can run forward and supply the front of the brainBrain: ventral view
20QuestionWhich of the following blood vessels ensures collateral circulation in the brain?Internal carotid arteriesCerebral arteriesBasilar arteriesCircle of Willis
21AnswerCircle of WillisRationale: The circle of Willis connects the right and left anterior cerebral arteries and the posterior and middle cerebral arteries. Blood from one carotid can cross over to supply the other side of the brain; blood from the basilar artery can run forward and supply the front of the brain.
22Stroke Stroke = “brain attack” Ischemic stroke Hemorrhagic stroke Large vessel (thrombotic)Small vessel (lacunar infarct- occlusion of one of the penetrating arteries that provides blood to the brain's deep structures)Cardiogenic embolicHemorrhagic strokeTransient ischemic attacks (“brain angina”)
23Excitotoxicity Neuron firing releases glutamate Causes neighboring neurons to fireSpreading injury across the ischemic area
24DiscussionMr. X has cor pulmonale. Mr. Y has a left ventricular aneurysm.Questions:Which of them is more likely to have a stroke?Which is more likely to have a pulmonary embolism?
25Aneurysmal Subarachnoid Hemorrhage Sudden-onset headache with nausea, vomiting, dizzinessHemorrhageSudden severe headache, neck stiffness, photophobia, vision and motor problemsComplicationsRebleeding, vasospasm and ischemia, hydrocephalus, hypothalamus dysfunction, seizures
26Brain Tumors Focal disturbances Dysfunction of particular brain areas Seizures, hallucinations, weakness or palsies in specific areas, sensory deficitsGeneralized disturbancesIncreased intracranial pressure: headache, vomiting, visual problems
27Seizures Spontaneous nerve firing Provoked seizures Fever Electrolyte imbalances (hypocalcemia, alkalosis)HypoglycemiaCNS infection or damageUnprovoked seizures: cause unknown
28Epileptic Syndromes Partial seizures Begin in one cerebral hemisphere Secondarily generalized seizuresBegin in one hemisphere and spread to otherGeneralized seizuresInvolve both hemispheres
29Kinds of Seizures Absence (petit mal): disturbances in consciousness Atonic: loss of muscle toneMyoclonic: muscles contractTonic-clonic (grand mal): muscle contraction and loss of consciousnessGeneralized convulsive status epilepticus: seizures continue without recovery between them
30QuestionWhich type of seizure affects only one cerebral hemisphere?PartialSecondarily generalizedGeneralizedAll of the above
31AnswerPartialRationale: Partial seizures affect one cerebral hemisphere; secondarily generalized seizures begin in one hemisphere and then spread to the other side; generalized seizures involve both hemispheres.
32DementiasMany dementias are associated with abnormal inclusions in the brainAlzheimer disease: amyloid plaquesPick disease: Pick bodiesPrion diseases: prion proteinsCreutzfeldt-Jakob disease
33Alzheimer Disease (50 – 70 % of Dementia) Amyloid-beta protein-forming plaquesNeurofibrillary tanglesDecreased acetylcholine production
34Alzheimer DiseaseCharacterized by loss of neurons and ventricular enlargement
35Alzheimer Disease Loss of function Normal function Alzheimer function
37A healthy neuron (top right) contrasted with a damaged neuron (note its shriveled state and the presence around the nucleus of neurofibrillary tangles) Tom Dolan, UK Medical Illustrator
38Alzheimer Disease amyloid precursor protein normally soluble amyloid b fragmentsstick togetherto form fibrilsclearedawayamyloidplaques
39Stages of Alzheimer Disease First: short-term memory lossSecond: confusional stageDisorientation, lack of insight, impaired hygiene and language use, sundown syndromeThird: incontinence, inability to recognize family and friends
40Other Causes of Dementia Microinfarcts: vascular dementiaVitamin B12 deficiency: Wernicke-Korsakoff syndromeInherited atrophy of brain structure: Huntington disease
41QuestionWhich cause of dementia is vascular in nature?AlzheimerMicroinfarctsVitamin B12 deficiencyInherited
42AnswerMicroinfarctsRationale: Small infarctions cause blood flow to be cut off to certain areas of the brain, causing tissue death. Depending on the extent of the infarctions, the dementia may be more or less severe.