Patho Chapter 20

Brain_________________represents a displacement of brain tissue under the falx cerebri or through the tentorial notch or incisura of the tentorium cerebelli.

herniation

Because_______________indicates decreased oxygen levels in all brain tissue, it produces a generalized depressant effect on the brain.

hypoxia

Increased_________________pressure is a common pathway for brain injury from different types of insults and agents.

intracranial

Subdural hematoma

a hematoma located beneath the dura

Intracerebral hematoma

a hematoma located inside the brain

Epidural hematoma

a hematoma located on top of the dura

To what does "global ischemia" refer, and what is the result of global ischemia?

a time when blood flow is inadequate to meet the metabolic needs of the entire brain. The result is a spectrum of neurologic disorders reflecting global brain dysfunction. Unconsciousness occurs within seconds of severe global ischemia, such as that resulting from complete cessation of blood flow, as in cardiac arrest, or with marked decrease in blood flow, as in serious cardiac arrhythmias. If cerebral circulation is restored immediately, consciousness is regained quickly. However, if blood flow is not promptly restored, severe pathologic changes take place. Energy sources, glucose and glycogen, are exhausted in 2 to 4 minutes, and cellular adenosine triphosphate (ATP) stores are depleted in 4 to 5 minutes. When ischemia is sufficiently severe or prolonged, infarction or death of all the cellular elements of the brain occurs. Even if blood flow is restored, if ischemic thresholds for injury were exceeded, then permanent cell death ensues.

Ischemic 2

Neuronal cell injury and death

Unprovoked

No identifiable cause can be determined.

Vasogenic edema

Occurs when integrity of the blood-brain barrier is disrupted

Non-communicating hydrocephalus

Overproduction of CSF

Global and focal brain injuries manifest differently. What is almost always a manifestation of a global brain injury? a. Altered level of consciousness b. Change in behavior c. Respiratory instability d. Loss of eye movement reflexes

a. Altered level of consciousness

Hydrocephalus

An abnormal increase in cerebrospinal fluid volume in any part or all of the ventricular system

Complex partial seizures

Begins in a localized area of the brain but may progress rapidly to involve both hemispheres

______________usually are caused by head injury in which the skull is fractured.

Epidural hematomas

Aphasia

Inability to comprehend, integrate, and express language

What are the two components of consciousness? What are the signs of altered consciousness?

(1) Arousal and wakefulness, and (2) content and cognition. The content and cognition aspects of consciousness are determined by a functioning cerebral cortex. Arousal and wakefulness requires the concurrent functioning of both cerebral hemispheres and an intact RAS in the brain stem. The earliest signs of diminution in level of conscious- ness are inattention, mild confusion, disorientation, and blunted responsiveness. With further deterioration, the delirious person becomes markedly inattentive and variably lethargic or agitated. The person may become obtunded and respond only to vigorous or noxious stimuli.

If Frontal lobe is damaged it affects

-Reasoning -behavior (emotions) -thinking initiation -movement -speaking -memory

If parietal lobe is damaged it affects

-Understanding spatial relationships -knowing right from left -sensation -reading

If cerebellum is damaged it affects

-balance -coordination -fine muscle control

If brainstem is damaged it affects

-breathing -blood pressure -heartbeat -alertness/sleep

If temporal lobe is damaged it affects

-understanding language -behavior -memory -hearing

If occipital lobe is damaged it affects

-vision -color blindness

Normal Intracranial Pressure (ICP)

0 to 15 mm Hg

Bacterial Meningitis

1. Bacteria replicate and undergo lysis in CSF. 2. Release endotoxins 3. Endotoxins initiate inflammatory response. 4. Pathogens, neutrophils, and albumin to move across the capillary wall into the CSF 5. Development of a cloudy, purulent exudate in CSF 6. Vascular congestion and infarction in the surrounding tissues 7. Meninges thicken and adhesions form 8. Adhesions may impinge on the cranial nerves or impair the outflow of CSF.

Normal brain function

10% blood, 80% brain tissue, 10% CSF

Although the brain makes up only 2% of the body weight, it receives 15% of the resting cardiac output and accounts for________________% of the oxygen consumption.

20

How are pupillary reflexes used to evaluate levels of brain function?

A bilateral loss of the pupillary light response is indicative of lesions of the brain stem. A unilateral loss of the pupillary light response may be caused by a lesion of the optic or oculomotor pathways. The oculocephalic reflex (doll's-head eye movement) can be used to determine whether the brain stem centers for eye movement are intact and the oculovestibular may be used to elicit nystagmus.

Circle of Willis

A structure at the base of the brain that is formed by the joining of the carotid and basilar arteries.

Hydrocephalus

Abnormal increase in cerebrospinal fluid (CSF) volume in any part or all of the ventricular system

Non-modifiable risk factors for stroke

Age Sex Race Family history

Central Transtentorial Herniation

Altered level of consciousness, decorticating posturing, roster all-caudal deterioration

What is postconcussion syndrome?

Although recovery usually takes place within 24 hours, mild symptoms, such as headache, irritability, insomnia, and poor concentration and memory, may persist for months. The memory loss usually includes an interval of time preceding the accident (retrograde amnesia) and following the injury (anterograde amnesia).

Brain herniation

Displacement of brain tissue under the falx cerebri or through the tentorial notch or incisura of the tentorium cerebelli

Hypoxic 2

Can be focal or global, with only one part of the brain being under- perfused or all of the brain being compromised

Cerebral edema 2

Cerebral hemispheres become enlarged, and the ventricular system beyond the point of obstruction is dilated. The sulci on the surface of the brain become effaced and shallow, and the white matter is reduced in volume.

The use of____________for brain tumors is somewhat limited by the blood-brain barrier.

Chemotherapy

Generalized onset

Clinical signs, symptoms, and supporting electro- encephalographic (EEG) changes indicate involvement of both hemispheres at onset.

Excitotoxic 2

Clouding of consciousness, bilaterally small pupils (approximately 2 mm in diameter) with a full range of constriction, and mo- tor responses to pain that are purposeful or semi-purposeful (localizing) and often asymmetric.

Tentorium cerebelli

Divides the cranial cavity into anterior and posterior fossae

_______________is the state of awareness of self and the environment and of being able to become oriented to new stimuli.

Consciousness

Hypoxic

Decreased oxygen levels in all brain tissue

Hydrocephalus 2

Depends on the brain's compensatory mechanisms and the extent of the swelling

Hypoxia

Deprivation of oxygen with maintained blood flow

What is the mechanism of toxicity of excitotoxic amino acids?

During prolonged ischemia, the glutamate trans- port mechanisms become immobilized, causing extracellular glutamate to accumulate. Addition- ally, intracellular glutamate is released from the damaged cells. This glutamate excess then drives the uncontrolled opening of N-methyl-d-aspartate (NMDA) receptor-operated channels producing an increase in intracellular calcium. Excess intracellular calcium leads to a series of calcium-mediated processes called the calcium cascade, including the release of intracellular enzymes that cause protein breakdown, free radical formation, lipid peroxidation, fragmentation of DNA, mitochondrial injury, nuclear breakdown, and eventually cell death.

What is the ischemic penumbra of an ischemic stroke, and how does it affect the degree of irreversible damage?

During the evolution of a stroke, there usually is a central core of dead or dying cells, surrounded by an ischemic band or area of minimally perfused cells called the "penumbra." Brain cells of the penumbra receive marginal blood flow, and their metabolic activities are impaired; although the area undergoes an "electrical failure," the structural integrity of the brain cells is maintained. Whether the cells of the penumbra continue to survive depends on the successful timely return of adequate circulation, the volume of toxic products released by the neighboring dying cells, the degree of cerebral edema, and alterations in local blood flow. If the toxic products result in additional death of cells in the penumbra, the core of dead or dying tissue enlarges, and the volume of surrounding ischemic tissue increases.

________________represents a generalized infection of the parenchyma of the brain or spinal cord.

Encephalitis

Excitotoxic

Excessive activity of the excitatory neurotransmitters and their receptor-mediated effects

FAST-G

F: facial asymmetry A: arm drift S: speech T: time to call 911 G: glucose levels (check)

Why do arteriovenous malformations predispose a patient to stroke?

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.

Brain herniation 2

Generalized depressant effect on the brain

Macroneurons

Large cells with long axons that leave the local network of intercommunicating neurons to send action potentials to other regions of the nervous system

Compare the general manifestations of global and focal brain injury.

Global brain injury, whether caused by head trauma, stroke, or other pathologies, is manifested by alterations in sensory, motor, and cognitive function and by changes in the level of conscious- ness. In contrast to focal injury, which causes focal neurologic deficits without altered consciousness, global injury nearly always results in altered levels of consciousness ranging from inattention to stupor or coma. Severe injury that seriously compromises brain function can result in brain death.

Glutamate

Glutamate ---> NMDA receptor----> Opening calcium channels----> calcium cascade----> -Release of intracellular enzymes -Protein breakdown -Free radical formation -Lipid peroxidation -Fragmentation of DNA -Nuclear breakdown

The most frequently fatal stroke is a spontaneous ___________________into the brain.

Hemorrhage

Modifiable risk factors for stroke

Hypertension Smoking Diabetes mellitus Asymptomatic carotid stenosis Sickle cell disease Hyperlipidemia Atrial fibrillation

Increased intercranial volume and pressure

Increase in intercranial tissue causing an increase in intracranial pressure

Ischemic

Interferes with delivery of oxygen and glucose as well as the removal of metabolic wastes.

If they have a gcs of 8

Intubate

________________strokes are caused by an interruption of blood flow in a cerebral vessel, and__________________strokes are caused by bleeding into brain tissue

Ischemic, hemorrhagic

Tonic-clonic

Most common major motor seizure

Absence seizures

Motion takes the form of automatisms such as lip smacking, mild clonic motion (usually in the eyelids), increased or decreased postural tone, and autonomic phenomena.

Tramatic Brain Injury (TBI)

Primary injuries: Axonal injury (axons severed) Focal lesions of laceration Contusion Hemorrhage Secondary injuries: Subsequent brain swelling Infection Cerebral hypoxia

Ischemia

Reduced or interrupted blood flow

Decorticate posturing

Results from lesions of the cerebral hemisphere

Microneurons

Small cells intimately involved in local circuitry

Glasgow Coma Scale (GCS)

The less the number is, the worse it it.

Atonic

These seizures also are known as drop attacks.

_____________ are the most common cause of ischemic strokes, usually occurring in atherosclerotic blood vessels.

Thrombi

Increased intercranial volume and pressure 2

Tissue perfusion be- comes inadequate, cellular hypoxia results, and neuronal death can occur.

Hemineglect

To attend to and react to stimuli coming from the contralateral side

________________seizures usually present with a person having a vague warning and experiencing a sharp tonic contraction of the muscles with extension of the extremities and immediate loss of consciousness.

Tonic-clonic

Explain what watershed infarcts are and why they occur.

Watershed infarcts are concentrated in anatomically vulnerable border zones between the over- lapping territories supplied by the major cerebral arteries, notably the middle, anterior, and posterior cerebral arteries. The overlapping territory at the distal ends of these vessels forms extremely vulnerable areas in terms of global ischemia, called "watershed zones." During events such as severe hypotension, these distal territories undergo a profound lowering of blood flow, predisposing to focal ischemia and infarction of brain tissues. Therefore, global ischemia can result in fo- cal infarcts that occur in the border zones between major vascular territories.

Penumbra

We want to reperfuse the penumbra

Much as with brain death, there are criteria for the diagnosis of a persistent vegetative state, and the criteria have to have lasted for more than 1 month. What are criteria for the diagnosis of persistent vegetative state? Mark all that apply. a. Bowel and bladder incontinence b. Ability to open the eyes c. Lack of language comprehension d. Lack of sufficient hypothalamic function to maintain life e. Variable preserved cranial nerve reflexes

a. Bowel and bladder incontinence c. Lack of language comprehension e. Variable preserved cranial nerve reflexes

Several types of brain injuries can occur. What are the primary (or direct) brain injuries? Mark all that apply. a. Focal lesions of laceration b. Contusion c. Hypoxic d. Diffuse axonal e. Hemorrhage

a. Focal lesions of laceration b. Contusion d. Diffuse axonal e. Hemorrhage

Generalized convulsive status epilepticus is a medical emergency caused by a tonic-clonic seizure that does not spontaneously end or recurs in succession without recovery. What is the first-line drug of choice to treat status epilepticus? a. Intravenous (IV) diazepam b. Intramuscular (IM) lorazepam c. IV cyclobenzaprine d. IM cyproheptadine

a. Intravenous (IV) diazepam

Intracranial aneurysms that rupture cause subarachnoid hemorrhage in the patient. How is the diagnosis of intracranial aneurysms and subarachnoid hemorrhage made? a. Lumbar puncture b. Magnetic resonance imaging (MRI) c. Loss of cranial nerve reflexes d. Venography

a. Lumbar puncture

In many neurologic disorders, various mediators, including excitatory______________, catecholamines, nitric oxide, free radicals, inflammatory cells, apoptosis, and intracellular__________________can cause injury to neurons.

amino acids, proteases

______________malformations are a complex tangle of abnormal arteries and veins linked by one or more fistulas.

arteriovenous

Cerebral___________________has been classically defined as the ability of the brain to maintain constant cerebral blood flow despite changes in systemic arterial pressure.

autoregulation

When the suspected diagnosis is bacterial meningitis, what assessment techniques can assist in determining the presence of meningeal irritation? a. Kernig sign and Chadwick sign b. Brudzinski sign and Kernig sign c. Brudzinski sign and Chadwick sign d. Chvostek sign and Guedel sign

b. Brudzinski sign and Kernig sign

You are the nurse caring for a 31-year-old trauma victim admitted to the neurologic intensive care unit (ICU). During your initial assessment, you find that the patient is flexing arms, wrists, and fingers. There is abduction of the upper extremities with internal rotation and plantar flexion of the lower extremities. How would you describe this in your nursing notes? a. Decerebrate posturing b. Decorticate posturing c. Extensor posturing d. Diencephalon posturing

b. Decorticate posturing

Brain death is defined as the irreversible loss of function of the___________________, including the brain stem.

brain

A number of regulatory mechanisms, including the blood-brain barrier and autoregulatory mechanisms that ensure an adequate blood supply, maintain the_____________electrically active cells.

brain's

Manifestations of brain tumors are focal disturbances in brain function and increased intracranial pressure (ICP). What causes the focal disturbances manifested by brain tumors? a. Tumor infiltration and increased blood pressure b. Brain compression and decreased ICP c. Brain edema and disturbances in blood flow d. Tumor infiltration and decreased ICP

c. Brain edema and disturbances in blood flow

Brain death is the term used when irreversible loss of function of the entire brain occurs. A clinical examination must be done and repeated at least 6 hours later with the same findings for brain death to be declared. What is not assessed in the clinical examination for brain death? a. Blink reflex b. Responsiveness c. Electrocardiographic (ECG) findings d. Respiratory effort

c. Electrocardiographic (ECG) findings

What are some of the possible causes of a seizure?

can be caused by alterations in cell membrane permeability or distribution of ions across the neuronal cell membranes. Another cause may be decreased inhibition of cortical or thalamic neuronal activity or structural changes that alter the excitability of neurons. Neurotransmitter imbalances, such as an acetylcholine excess or γ-aminobutyric acid (GABA, an inhibitory neurotransmitter) deficiency, have been proposed as causes. Certain epilepsy syndromes have been linked to specific genetic mutations causing ion channel defects.

The three metabolic factors affect cerebral blood flow: _______________,________________, and ________________concentration.

carbon dioxide, hydrogen ion, oxygen

Aneurysmal subarachnoid hemorrhage represents bleeding into the subarachnoid space caused by a ruptured______________.

cerebral aneurysm

The specific manifestations of stroke or TIA are determined by the___________________that is affected by the area of brain tissue that is supplied by that vessel and by the adequacy of the collateral circulation.

cerebral artery

____________seizures involve impairment of consciousness and often arise from the temporal lobe.

complex partial

__________________edema involves an increase in intracellular fluid.

cytotoxic

The regulation of cerebral blood flow is accomplished through both autoregulation and local regulation. This allows for the brain to meet its metabolic needs. What is the low parameter for blood pressure before cerebral blood flow becomes severely compromised? a. 30 mm Hg b. 40 mm Hg c. 50 mm Hg d. 60 mm Hg

d. 60 mm Hg

For seizure disorders that do not respond to anticonvulsant medications, an option for surgical treatment exists. What is removed in the most common surgery for seizure disorders? a. Temporal neocortex b. Hippocampus c. Entorhinal cortex d. Amygdala

d. Amygdala

communicating hydrocephalus

decreased absorption of CSF

Cerebral______________is an increase in tissue volume secondary to abnormal fluid accumulation.

edema

A(n)______________stroke is caused by a moving blood clot that travels from its origin to the brain.

embolic

Cerebral ischemia can be_________________, as in stroke, or____________________, as in cardiac arrest.

focal, global

____________________infarcts result from occlusion of the smaller penetrating branches of large cerebral arteries, commonly the middle cerebral and posterior cerebral arteries.

lacunar

___________________refers to short serpiginous segments of necrosis that occur within and parallel to the cerebral cortex, in areas supplied by the penetrating arteries during an ischemic event

laminar necrosis

Transient ischemic attack (TIA) or "_______________" is equivalent to "brain angina" and reflects a temporary disturbance in focal cerebral blood flow, which reverses before infarction occurs, analogous to_______________in relation to heart attack.

ministroke, angina

Myoclonic seizures involve brief, involuntary ____________________induced by stimuli of cerebral origin.

muscle contractions

The effects of traumatic head injuries can be divided into two categories: _______________injuries, in which damage is caused by impact, and secondary injuries, in which damage results from the subsequent brain swelling, infection, or______________.

primary, cerebral hypoxia

A(n)___________________represents the abnormal behavior caused by an electrical discharge from neurons in the cerebral cortex.

seizure

________________seizures usually involve only one hemisphere and are not accompanied by loss of consciousness or responsiveness.

simple partial

Excessive influx of______________during neural ischemia results in neuronal and interstitial edema.

sodium

Seizures that do not stop spontaneously or occur in succession without recovery are called___________.

status epilepticus

___________________is the syndrome of acute focal neurologic deficit from a vascular disorder that injures brain tissue.

stroke

Cerebral edema

swelling of the brain

A subdural hematoma develops in the area between the dura and the arachnoid and usually is the result of a(n)_______________in the small bridging veins that connect veins on the surface of the cortex to dural sinuses.

tear

The functional manifestations of _________________edema include focal neurologic deficits, disturbances in consciousness, and severe intracranial hypertension.

vasogenic

The_______________state is characterized by loss of all cognitive functions and the unawareness of self and surroundings

vegetative

_________________occurs with or without nausea, may be projectile, and is a common symptom of increased intracranial pressure (ICP) and brain stem compression.

vomiting