Patho Chapter 52

Front 1

By definition, what is the difference between hypoxia and ischemia?

Back 1

• Hypoxia is a deprivation of oxygen with maintained blood flow • Ischemia is greatly reduced or interrupted blood flow

Front 2

What are the 2 general types of ischemia?

Back 2

• Focal ischemia ( ex. stroke) where collateral circulation can provide blood to uninvolved areas • Global ischemia (ex. cardiac arrest) where no collateral circulation exists

Front 3

Name and describe the 2 types patterns of global ischemia injury

Back 3

• Watershed infarcts are located in overlapping areas supplied by the major cerebral vessels (ACA, MCA, PCA) • Laminar necrosis occurs in areas suppled by the penetrating arteries derived from the Pia Mater

Front 4

What is the principal excitatory neurotansmitter in the brain?

Back 4

Glutamate

Front 5

Explain how excess glutamate can contribute to cell injury

Back 5

• Glutamate, when bound to a particular receptor (NMDA), causes opening of calcium channels • Open calcium channels leads to a series of calcium-mediated processes called the calcium cascade • Activation of the calcium cascade leads to release of intracellular enzymes that cause cell death

Front 6

How can an increased intercranial pressure (ICP) cause brain injury?

Back 6

Excessive ICP can: • obstruct cerebral blood flow • destroy brain cells • displace brain tissue as in herniation • damage delicate brain structures

Front 7

What are the 3 parts that contribute to intracranial volume?

Back 7

• blood (10%) • brain tissue (80%) • CSF (10%)

Front 8

What is the Monro-Kellie hypothesis?

Back 8

small increases in the volume of one component can be compensated for by a decrease in the volume of either one or both of the other two compartments

Front 9

What is one of the earliest and most reliable signs of increased ICP?

Back 9

• a decrease in LOC • can deteriorate from alertness to confusion, lethargy, obtundation, stupor, and coma

Front 10

What is the Cushing reflex?

Back 10

• a late reflex see with a marked increase in ICP • triggered by ischemia of the vasomotor center in the brain stem • characterized by 3 signs: 1) marked increase in mean arterial BP (270 mm Hg) 2) widened pulse pressure 3) slowing of heart rate

Front 11

What is the falx cerebri?

Back 11

a septum that divides the two hemispheres

Front 12

What are the 2 broad catergories of brain herniations?

Back 12

supratentorial and infratentorial

Front 13

What is cerebral edema?

Back 13

• brain swelling • an increase in tissue volume secondary to abnormal fluid accumulation

Front 14

Name the 2 types of cerebral edema

Back 14

• Vasogenic edema • Cytotoxic edema

Front 15

Describe vasogenic edema

Back 15

• occurs from an impaired function of the blood-brain barrier • water and protein are transferred from the vasculature to the interstitial space • manifests as focal neurologic deficits, disturbances in consciousness, & severe intracranial hypertension

Front 16

Describe cytotoxic edema

Back 16

• involves the actual swelling of brain cells due to increased intracellular fluid • can be caused by hypoosmotic states, impairment of Na+/K+ pump

Front 17

What is Hydrocephalus?

Back 17

an abnormal increase in CSF volume in any part of the ventricular system that causes enlargment of the CSF compartment

Front 18

What are the 2 causes of hydrocephalus?

Back 18

• decreased absorption of CSF • overproduction of CSF

Front 19

Name the 2 types of hydrocephalus

Back 19

• Noncommunicating • Communicating

Front 20

Describe noncommunicating hydrocephalus

Back 20

• occurs when an obstruction in the ventricular system prevents teh CSF from reaching the arachnoid villi • can be caused by congenital malformation, tumors, inflammation, or hemmorhage

Front 21

Describe communicating hydrocephalus

Back 21

• results from impaired reabsorption of CSF from the arachnoid villi into the venous system

Front 22

What are pathologic patterns that occur with hydrocephalus?

Back 22

• enlarged cerebral hemispheres • dilated ventricular system • gyri on brain surface becomes less prominent • reduced volume of white matter

Front 23

Which type of hydrocephalus is more likely to manifest with increased ICP, acute-onset or slowly developing hydrocephalus?

Back 23

Acute onset

Front 24

What are symptoms of acute-onset hydrocephalus?

Back 24

symptoms of increased ICP such as headache, vomiting, papilledema, or lateral rectus palsy

Front 25

What are the 2 categories of traumatic head injuries?

Back 25

• Primary (or direct) injuries: damage is caused by impact • Secondary injuries: samge results from subsequent brain swelling, infection, or cerebral hypoxia

Front 26

What is the most common cause of secondary brain injury?

Back 26

ischemia

Front 27

What is the definition of a concussion?

Back 27

a momentary interruption of brain function with or without LOC

Front 28

What is the most common cause of a epidural hematoma?

Back 28

• usually caused by a skull fracture • usually results from a tear in an artery, most often the middle menigeal

Front 29

What is the typical presentation of a persion with an epidural hematoma?

Back 29

• presents with a history of head injury and brief period of LOC, followed by a lucid period, followed by rapid progression to unconsciousness • if untreated, progressed to increased ICP, tentorial herniation, and death

Front 30

What is the usual cause of a subdural hematoma?

Back 30

a tear in the small bridging veins that connect veins on the surface of the cortex to dural sinuses

Front 31

What are key clinical signs from injury to the diencephalon?

Back 31

• impaired consciousness • small reactive pupils • intact oculocephalic reflex • decorticate posturing • Cheyne-Stokes respirations

Front 32

What are key clinical signs of injury to the midbrain?

Back 32

• coma • fixed, midsize pupils • impaired oculocephalic reflex • neurogenic hyperventilation • decerebrate posturing

Front 33

What are key clinical signs of injury to the pons?

Back 33

• coma • fixed, irregular pupils • dysconjugate gaze • impaired cold caolric stimulation • loss of corneal reflex • hemi/quadriparesis • decerebrate posturing • apneustic respirations

Front 34

What are key clinical signs of injury to the medulla?

Back 34

• coma • fixed pupils • flaccidity • loss of gag and cough reflexes • ataxic/apneic respirations

Front 35

What is consciousness?

Back 35

• the state of awareness of self and the environment and of being able to become oriented to new stimuli • two components: 1) arousal and wakefulness 2) content and cognition • requires the concurrent functioning of both cerebal hemispheres and reticular activating system

Front 36

Where is the reticular formation located?

Back 36

• it extends from the medulla through the pons to the midbrain

Front 37

What is the oculocephalic reflex?

Back 37

aka doll's-head eye movement

Front 38

What is the oculovestibular test?

Back 38

• aka cold caloric test • cold water is instilled in the ear to elicit nystagmus

Front 39

Decorticate posturing indicates a lesion in what area?

Back 39

the cerebral hemisphere or internal capsule

Front 40

Decerebrate posture occurs from lesions in this area

Back 40

lesions in the diencephalon that extend to the midbrain and upper brain stem

Front 41

What are 3 metabolic factors that affect cerebral blood flow?

Back 41

carbon dioxide, hydrogen ion, and oxygen concentration

Front 42

What are some causes of hemorrhagic stroke?

Back 42

blood vessel rupture due to: • hypertension • aneurysms • AV malformations • head injury

Front 43

What are the 5 stroke subtypes and their frequency?

Back 43

• large artery atheroscelerotic disease (20%) • small vessel or penetrating artery disease (lacunar stroke) (25%) • cardiogenic embolism (20%) • cryptogenic stroke (ie. undetermined cause) (30%) • other, unusual causes (5%)

Front 44

What is a penumbra?

Back 44

• an ischemic band or area of minimally perfused cells that surrounds a centro core of dead or dying cells • occurs during the evolution of a stroke

Front 45

What are common sites of plaque formation which can cause ischemic strokes?

Back 45

larger vessels of the brain including: • the origins of the internal carotid and vertebral arteries • junctions of the basilar and vertebral arteries

Front 46

Describe a small vessel stroke (lacunar infarct)

Back 46

• small infarcts located in the deepe, noncortical parts of the brain or brain stem • found in single deep penetrating arteries supplying the internal capsule, basal ganglia, or brain stem • during healing, infarcts leave behind small cavities, or lacunae (lakes)

Front 47

What are the six basic causes of lacunar infarcts?

Back 47

• embolism • hypertension • small vessel occlusive disease • hematologic abnormalities • small intracerebral hemorrhages • vasospasm

Front 48

What causes an embolic stroke?

Back 48

a moving blood clot that travels from its origin to the brain

Front 49

What is the most frequent site of embolic strokes?

Back 49

middle cerebral artery

Front 50

What are some cardiac conditions that predispose to formation of an emboli?

Back 50

• rheumatic heart disease • A Fib • mobile aortic arch atheroma • recent MI • ventricular aneurysm • bacterial endocarditis • patent forman ovale (for paradoxial venous emboli in arterial system)

Front 51

What are the most common predisposing factors for hemorrhagic stroke?

Back 51

advancing age and hypertension

Front 52

List stroke-related deficits, from most common to least common

Back 52

• Motor deficits (most common) • Language • Sensation • Cognition

Front 53

What are the most common cerebral aneurysm?

Back 53

small saccular aneurysms called berry aneurysms

Front 54

What are some manifestations of a subarachnoid hemmorhage?

Back 54

• worst headache of my life • vomiting • LOC • meningeal symptoms (nuchal rigidity, photophobia) • stroke syndrome • cerebral edema and increased ICP • pituitary dysfunction • hypertension & dysrhythmias

Front 55

What are complications of aneurysmal rupture?

Back 55

• rebleeding & vasospasm (most serious & most difficult to treat) • hydrocephalus (due to plugging of arachnoid villi from blood) • hypothalamic dysfunction • seizure activity

Front 56

What is the definitive diagnostic tool for detecting an aneurysm?

Back 56

conventional catheter angiography

Front 57

What are arteriovenous malformations?

Back 57

• a complex tangle of abnormal arteries and veins linked by one or more fistulas • these vascular networks lack a capillary bed

Front 58

What are the hemodynamic effects from AV malformations?

Back 58

• venous channels are exposed to high-pressure blood flow due to the absence of capillaries (predispositions to rupture & hemorrhage • elevated venous & arterial pressures divery blood away from surrounding tissue, impairing tissue perfusion

Front 59

True/False: Stoke is the number two leading cause in death in the US, behind CAD

Back 59

Stroke is the third leading cause in death in the US The correct answer is: False

Front 60

What are the 2 types of acute infectious meningitis?

Back 60

• acute purulent meningitis (usually bacterial) • acute lymphocytic meningitis (usually viral)

Front 61

What are common bacterial causes of meningitis?

Back 61

• Streptococcus Pneumoniae (ie pneumococcus) (most common) • H. Flu • Neisseria meningitidis • group B streptococcus (in neonates)

Front 62

Name and describe the 2 assessment test to evaluate for meningitis

Back 62

• Kernig's sign is resistance to extension of the knee while the person is lying with the hip flexed at a right angle • Brudzinski's sign is elicited when flexion of the neck induces flexion of the hip and knee

Front 63

How is viral meningitis different from bacterial meningitis?

Back 63

• the course of illness is less severe • presence of lymphocytes in fluid instead of neutrophils • acute viral meningitis are self-limited and require only symptomatic treatment

Front 64

What are some viral etiologies of viral meningitis?

Back 64

• Enteroviruses (coxsackie, poliovirus, echovirus) • Epstein-Barr virus • mumps • herpes simplex virus (HSV) • West Nile virus

Front 65

What is encephalitis and what usually causes it?

Back 65

• Enceohalitis is a generalized infection of the parenchyma of the brain of spinal cord • usually caused by a virus (ie arbovirus, poliovirus, or rabies virus)

Front 66

How is the presentation of patient with encephalitis different from a patient with meningitis?

Back 66

• both are characterized by fever, headache, and nuchal rigidity • encephalitis more often presents with neurologic disturbances (lethargy, disorientation, seizrues, focal parlyisi, delirium, & coma)

Front 67

What are the 3 basic types of brain tumors?

Back 67

• primary intracranial tumors of neuroepithelial tissue • primary intracranial tumors that originate in the skull cavity, but not derived from brain tissue • metastatic tumors

Front 68

What are the 2 main categories of glial tumors?

Back 68

• astrocytic • oligdendroglial

Front 69

What are the 2 sub-categories of astrocytic tumors?

Back 69

• fibrillary astrocytic tumors - account for 80% of primary adult brain tumors; more common in middle age • pilocytic astrocytomas - usually occurs in children & young adults

Front 70

What are characteristics of Primary CNS lymphomas?

Back 70

• deep, periventricular, diffuse tumors common in immunocompromised patients • associated with Epstein-Barr virus and derived from large B cells

Front 71

Name and describe the two broad categories of seizures

Back 71

• Partial seizure - the seizure beings in a specific area of one cerebral hemisphere • Generalized seizure - begin simultaneously in both cerebral hemispheres

Front 72

What type of siezure usually involve only one hemisphere and does not involve LOC?

Back 72

Simple partial seizure

Front 73

What are the different types of simple partial seizures?

Back 73

Different types of simple partial seizures include those: • with motor symptoms • with sensory symptoms • with autonomic symptoms • with psychic symptoms

Front 74

What is a Jacksonian seizure?

Back 74

When motor movement spreads to other cortical areas with sequential involvement of body parts

Front 75

What are characteristics of complex partial seizures?

Back 75

• involve impairment of consciousness and often arise from the temporal lobe • often accompanied by automatisms (repetitive, nonpurposeful activity)

Front 76

Describe a secondarily generalized partial seizure

Back 76

focal seizure at onset but then become generalized, involving deeper structures of the brain, such as the thalamus & reticular formation

Front 77

What are characteristics of generalized-onset seizures?

Back 77

• most common type in young children • symptoms include unconsciousness and bilateral symmetric motor responses

Front 78

What are the 4 types of generalized-onset seizures?

Back 78

• Absence seizures • Atonic seizures • Myoclonic seizures • Major Motor (Grand Mal or Tonic-Clonic)

Front 79

What are characteristics of Absence seizures?

Back 79

• generalized, non-convulsive epileptic events expressed as disturbances in consciousness • typically occur in children • characterized as a blank, stare, motionlessness, and unresponsiveness

Front 80

Describe an atonic seizure

Back 80

• a sudden, split-second loss of muscle tone • causes slackening of the jaw, drooping of limbs, or falling to the ground • aka drop attachs

Front 81

What are characteristics of a myoclonic seizure?

Back 81

• involves brief involuntary muscle contractions caused by stimuli of cerebral origin • involves bilateral jerking of muscles, generalized or confined to the face, trunk, or one or more extremities

Front 82

What is status epilepticus?

Back 82

seizures that do not stop spontaneously or occur in succession without recovery