2Conditions Causing Injury to the Brain TraumaTumorsStrokeMetabolic derangementsDegenerative disorders
3Common Pathways of Brain Damage The effects of ischemiaExcitatory amino acid injuryCerebral edemaInjury due to increased intracranial pressure (ICP)
4Hypoxia and Ischemia Hypoxia A deprivation of oxygen with maintained blood flowIschemiaReduced or interrupted blood flowFocal cerebral ischemia: strokeGlobal cerebral ischemia: myocardial infarction
5The large hemorrhage in this adult brain arose in the basal ganglia region of a patient with hypertension. This is one cause for a "stroke".
6A blood clot is seen over the external surface of the dura A blood clot is seen over the external surface of the dura. Thus, this is an epidural hematoma. Such a location for hemorrhage is virtually always the result of trauma that causes a tear in the middle meningeal artery.
7Injury From Excitatory Amino Acids DefinitionInjury to neurons caused by overstimulation of receptors for specific amino acids that act as excitatory neurotransmittersCausesStrokeHypoglycemic injuryTrauma to chronic degenerative disorders such as Huntington disease and Alzheimer dementia
8The cerebral arterial circulation at the base of the brain is diagrammed here. A berry aneurysm is diagrammed at the final bifurcation of the right internal carotid artery. The most common locations for berry aneurysms are in the region of the anterior communicating and anterior cerebral, at the trifurcation of the middle cerebral, and at the bifurcation of internal carotid with posterior communicating. Vertebral-basilar aneurysms comprise <10% of cases. Multiple aneurysms occur in about 20 to 30% of cases.
9The white arrow on the black card marks the site of a ruptured berry aneurysm in the circle of Willis. This is a major cause for subarachnoid hemorrhage.
10The circle of Willis has been dissected, and three berry aneurysms are seen. Multiple aneurysms are seen in about 20-30% of cases of berry aneurysm. Such aneurysms are "congenital" in the sense that the defect in the arterial wall is present from birth, but the actual aneurysm takes years to develop, so that rupture is most likely to occur in young to middle age adults.
11The subarachnoid hemorrhage from a ruptured aneurysm is more of an irritant producing vasospasm than a mass lesion.
12Another cause for hemorrhage, particularly in persons aged 10 to 30, is a vascular malformation. Seen here is a mass of irregular, tortuous vessels over the left posterior parietal region.
13The intraventricular and intracerebral hemorrhage seen here was due to a ruptured vascular malformation. The hemorrhage from such a lesion (which is most often histologically an arteriovenous malformation--AVM) can be intracerebral or extend into ventricles or subarachnoid space.
14The characteristic location of the hemorrhage in this brain is consistent with a fall backwards resulting in a contrecoup injury to the inferior frontal and temporal lobes. This has resulted in extensive contusions and subarachnoid hemorrhage.
15QuestionWhich of the following is not a common cause of neural injury?Recreational drug useIschemiaExcitatory amino acidsCerebral edemaIncreased intracranial pressure (ICP)
16AnswerRecreational drug use: Drug use can cause damage, but it is not a common cause.IschemiaExcitatory amino acidsCerebral edemaIncreased intracranial pressure (ICP)
17Intracranial Pressure Increased ICP is a common pathway for brain injury.Obstruction of cerebral blood flow, destruction of brain cells, displacement of brain tissue, and damage to delicate brain structuresCranial cavity10% blood, 80% brain tissue, 10% CSFNormal ICP 0–15 mm Hg
18Brain Herniation Cingulate Involves cerebral artery Clinical sign: leg weaknessCentral transtentorialInvolves reticular activating system and corticospinal tractClinical signs: altered level of consciousness, decorticate posturing, rostral-caudal deterioration
20Hydrocephalus Definition An abnormal increase in CSF volume in any part or all of the ventricular systemEnlargement of the CSF compartment occursTypesCommunicatingDecreased absorption of CSFNoncommunicatingOverproduction of CSF
21Cerebral Edema Vasogenic edema Occurs with conditions that impair the function of the blood-brain barrier and that allow transfer of water and protein from the vascular into the interstitial spaceCytotoxic edemaInvolves an increase in intracellular fluidInterstitial cerebral edemaEdema of the central white matter, as in hydrocephalus, affecting the brain
22Classifications of Skull Fractures Simple or linearA break in the continuity of boneComminutedA splintered or multiple fracture lineDepressedBone fragments are embedded into the brain tissueBasilarA fracture of the bones that form the base of the skull
23Types of Brain Injuries Primary or direct injuriesDamage is caused by impact.Include diffuse axonal injury and the focal lesions of laceration, contusion, and hemorrhageSecondary injuriesDamage results from the subsequent brain swelling, infection, cerebral hypoxiaOften diffuse or multifocal, including concussion, infection, and hypoxic brain injury
24A coronal section through the frontal lobes reveals extensive contusions involving the inferior gyri. This was a contrecoup injury from a fall in the bathtub by an elderly person.
25Coup–ContrecoupThe brain floats freely in the CSF. Blunt force to the head accelerates the brain within the skull, and then the brain decelerates abruptly upon hitting the inner skull surfaces.Coup: direct contusion of the brain at the site of external forceContrecoup: rebound injury on the opposite side of the brain
26The orange-brown, scalloped appearance of these lesions is consistent with old contusions. The resolution left behind hemosiderin from the hemorrhage that produces the orange-brown staining.
27Seen here are remote contusions, mainly of the right inferior frontal lobe. The crests of the gyri are most susceptible to the traumatic forces.
28Postconcussion Syndrome Concussion refers to an immediate and transient loss of consciousness accompanied by a brief period of amnesia after a blow to the head.Recovery usually takes place in 24 hours.Mild symptoms may persist for months.HeadacheIrritabilityInsomniaPoor concentration and memory
29Types of Hematomas Epidural hematoma Usually caused by head injury in which the skull is fracturedDevelops between the inner table of the bones of the skull and the duraSubdural hematomaUsually is the result of a tear in the small bridging veins that connect veins on the surface of the cortex to dural sinusesDevelops in the area between the dura and the arachnoid (subdural space)
30The dura has been reflected back (with a small portion visible at the lower right) to reveal a subdural hematoma. Such a blood clot is usually the result of trauma with tearing of the bridging veins.
31Hemorrhages involving the basal ganglia area (the putamen in particular) tend to be non-traumatic and caused by hypertension, which damages and weakens the small penetrating arteries. A mass effect with midline shift, often with secondary edema, may lead to herniation.
32The dura has been reflected above to reveal the bridging veins that extend across to the superior aspect of the cerebral hemispheres. These can be torn with trauma, particularly if there is significant cerebral atrophy that exposes these veins even more.
33Here is a bilateral chronic subdural hematoma Here is a bilateral chronic subdural hematoma. The blood clots are brown to tan because of organization. Since the bleeding is venous, subdurals can form more slowly and insidiously than clots from arterial hemorrhages. Subdurals are most common in the very young and the elderly.
34Types of Hematomas (cont.) Traumatic intracerebral hematomaMay be single or multipleOccurs in any lobe of the brain but is most common in the frontal or temporal lobes
35QuestionRotational acceleration of the head may result in which type of injury?CoupContrecoup
36AnswerCoupContrecoup: Contrecoup injury is rebound injury on the opposite side of the brain.
37Manifestations of Global Brain Injury Alterations in sensory and motor functionChanges in the level of consciousnessRostral-to-caudal stepwise progressionAs the diencephalon, midbrain, pons, and medulla are affected, additional respiratory, pupillary and eye movement reflexes, and motor signs become evident.
38Levels of Consciousness ConfusionDeliriumObtundationStuporComa
39Signs of Diminution in Level of Consciousness Earliest signsInattention, mild confusion, disorientation, and blunted responsivenessWith further deteriorationThe person becomes markedly inattentive and variably lethargic or agitated.The person may progress to become obtunded and may respond only to vigorous or noxious stimuli.
40Medical Documentation of Brain Death Cause and irreversibility of the conditionAbsence of brain stem reflexes and motor responses to painAbsence of respiration with a PCO2 of 60 mm Hg or moreThe justification for use of confirmatory tests and their results
41Criteria for Diagnosis of Vegetative State Absence of awareness of self and environmentAn inability to interact with othersAbsence of sustained or reproducible voluntary behavioral responsesLack of language comprehensionHypothalamic and brain stem function to maintain life
42Criteria for Diagnosis of Vegetative State Bowel and bladder incontinenceVariably preserved cranial nerve and spinal cord reflexesCondition has continued for at least 1 month
43Structures Supplying Blood Flow to the Brain Two internal carotid arteries anteriorlyOphthalmic, posterior communicating, anterior choroidal, anterior cerebral, and middle cerebralVertebral arteries posteriorlyInternal carotid and vertebral arteries communicate at the base of the brain through the circle of Willis.
45Two Main Types of Strokes (Brain Attack) Ischemic strokesCaused by an interruption of blood flow in a cerebral vessel and are the most common type of stroke, accounting for 70–80% of all strokes.Hemorrhagic strokesCaused by bleeding into brain tissue, usually from a blood vessel rupture caused by hypertension, aneurysms, arteriovenous malformations, head injury, or blood dyscrasias
46Warning Signs and Danger Zones Ischemic penumbra in evolving strokeTransient ischemic strokeBrain anginaWatershed zone
47Signs and Symptoms of Cerebral Aneurysms Most small aneurysms are asymptomatic.Large aneurysms may cause chronic headache, neurologic deficits, or both.Other manifestations include signs of meningeal irritation, cranial nerve deficits, stroke syndrome, cerebral edema and increased ICP, and pituitary dysfunction.Hypertension and cardiac dysrhythmias result from massive release of catecholamines triggered by the subarachnoid hemorrhage.
48Aneurysmal Subarachnoid Hemorrhage Bleeding into the subarachnoid spaceCausesCongenital defectAcute increases in ICPCigarette smokingHypertensionExcessive alcohol intake
49Hemodynamic Effects of Arteriovenous Malformations First, blood is shunted from the high-pressure arterial system to the low-pressure venous system without the buffering advantage of the capillary network.The draining venous channels are exposed to high levels of pressure, predisposing them to rupture and hemorrhage.Second, the elevated arterial and venous pressures divert blood away from the surrounding tissue, impairing tissue perfusion.
50Risk Factors and Deficits of Stroke Age, sex, raceFamily historyHypertensionSmokingDiabetes mellitusAsymptomatic carotid stenosisSickle cell diseaseHyperlipidemiaAtrial fibrillationStroke-related deficitsMotor deficitsDysarthria and aphasiaCognitive and other deficits
51Classifications of Infections of the CNS By structureMeninges: meningitisBrain parenchyma: encephalitisSpinal cord, myelitisBrain and spinal cord: encephalomyelitisBy type of invading organismBacterial, viral, or other
52MeningitisInflammation of the pia mater, the arachnoid, and the CSF-filled subarachnoid spaceFever and chills, headache, stiff neck, back, abdominal, and extremity pains, nausea and vomitingAcute lymphocytic meningitisAcute purulent meningitisBacterial meningitisPneumococcusMeningococcusViral meningitis
53Encephalitis Types Viral Herpes simplex virus, West Nile virusBacterialFungalInfection of the parenchyma of the brain or spinal cordLocal necrotizing hemorrhageProgressive degeneration of nerve cell bodiesProminent edemaTransmissionIngestionMosquitoRabid animal
54Classification of Brain Tumors Primary intracranial tumors of neuroepithelial tissueNeurons, neurogliaPrimary intracranial tumors that originate in the skull cavity but are not derived from the brain tissue itselfMeninges, pituitary gland, pineal gland, primary CNS lymphomaMetastatic tumorsBenign vs. malignant
55Types and Symptoms of Brain Tumors EpendymomasMeningiomasPrimary CNS lymphomasIncreased ICPFocal disturbances in brain functionEdemaDisturbances in blood flowTumor infiltrationBrain compression
56Treatment and Evaluation Methods for Brain Tumors MRICT scansElectroencephalogramVisual field and funduscopic examinationInclude physical and neurologic examinationsSurgeryIrradiationChemotherapy
57Seizures and Convulsions Abnormal behavior caused by an electrical discharge from neurons in the cerebral cortexA discrete clinical event with associated signs and symptoms which vary according to the site of neuronal discharge in the brainManifestations generally include sensory, motor, autonomic, or psychic phenomena.ConvulsionSpecific seizure type of a motor seizure involving the entire body