Disorders of Brain Function

Question 1

What are the General Principles of Brain Disorders?

Answer 1

Cerebral hemispheres are most susceptible to injury.

Neurological dysfunction worsens as lower brain areas are more involved.
-Motor function
-Pupils
-Eye movements
-Vital signs
-Respirations

Question 2

How does the brain function?

Answer 2

Level of consciousness (LOC)

Cognition and content

Arousal and wakefulness

Question 3

What is Level of consciousness (LOC) within the brain?

Answer 3

Is there a disorder in a focal (small) or global (widespread) brain area?

Is the individual able to recognize and respond to stimuli?

LOC alterations range from inattention to coma.

Question 4

What is Cognition and content within the brain?

Answer 4

Requires a fully functioning cerebral cortex

Question 5

What is Arousal and wakefulness within the brain?

Answer 5

Requires interaction between cerebral cortex and Reticular activating system

Question 6

What is Arterial Cerebral Blood Flow?

Answer 6

Internal carotid arteries - anterior brain

Vertebral arteries - posterior brain

Question 7

What is Venous Cerebral Blood Flow?

Answer 7

Venous blood from the brain circulates into the internal jugular vein, then the superior vena cava to return to the right side of the heart.

Because veins in the brain do not have valves, flow is related to gravity and pressure in venous sinuses

Question 8

What is Cerebral Blood Flow?

Answer 8

About 750 milliliters/minute of Arterial blood circulates into the brain but more of the brain blood is in the veins.

Local metabolic cellular demands influenced by carbon dioxide, blood ph, and oxygen:

-Increased carbon dioxide - causes vasodilation
-Decreased blood pH (acidosis) - causes increased cerebral blood flow
-Decreased oxygen -causes increased cerebral blood flow

Question 9

What is Autoregulation?

Answer 9

Autoregulation is an organ’s ability to regulate its blood flow despite peripheral blood pressure and is most sophisticated in the brain.

Question 10

What is Autoregulation in relation to the brain?

Answer 10

The brain has the most efficient autoregulation of any organ.

Autoregulation is assumed intact to some degree when MAP 60-140mm Hg.

Autoregulation is associated with the brain’s ability to utilize oxygen normally.

Question 11

What increases blood flow to the brain?

Answer 11

Increased carbon dioxide: hypercarbia

Decreased pH: acidosis

Decreased oxygen: hypoxemia

Question 12

What is the Monroe-Kellie Hypothesis?

Answer 12

To maintain steady intracranial pressure, when there is an increase in one component, there must be a decrease in another component. These components include:

Cerebrospinal fluid

Cerebral blood volume

Intracellular/extracellular fluid volume

Question 13

What are the key points regarding the Monroe-Kellie Hypothesis?

Answer 13

The skull is rigid.

Intracranial space is limited.

Increase in volume of any component without decrease in another component causes increase intracranial pressure.

Question 14

What can cause increase in volume of any of the intracranial components?

Answer 14

Trauma

Stroke

Aneurysm

Hematoma

Lesion - tumor

Infection

Toxins

Hypoxia/anoxia

Question 15

What is Traumatic Brain Injury (TBI)?

Answer 15

TBI is the most severe injury that can occur other than burns!

Primary injury: The initial impact event that leads to damage within the brain

Secondary injury: The central nervous system affects such as brain swelling, infection and hypoxia with systemic alterations that occurred due to primary injury

Question 16

Secondary Brain Injury:

How long can it take for neurological injuries to evolve?

Answer 16

Anywhere between hours to days

Question 17

What is the Central Nervous System Responses in Secondary Injury?

Answer 17

Intracranial hematomas

Cerebral ischemia

Cerebral edema

Increased intracranial pressure

Infection

Question 18

What is the Systemic Body Responses in Secondary Injury?

Answer 18

Hypermetabolism

Hypercatabolism

Hyperglycemia

Gastroparesis

Question 19

What is a Concussion?

Answer 19

Temporary neurological dysfunction

IF Loss Of Consciousness - < 5 minutes OR none

Question 20

What are some signs of a concussion?

Answer 20

Possible amnesia

Headache

Nausea/Vomiting

Cognitive alteration

Visual alteration

Chronic pain

Question 21

What is a contusion?

Answer 21

Possible laceration of brain tissue/structures

The brain floats in the cerebrospinal fluid that provides some mechanical protection

Bruising of brain tissue

Manifestations can be similar to concussion but with more severe neurological effects such as coma, paralysis, and cerebral swelling.

Question 22

What are the signs of a Basilar Skull Fracture?

Answer 22

Raccoon Eyes

Battle’s Sign

Rhinorrhea - nose

Otorrhea - ear

Postnasal drip:
Halo sign on dressing - meningitis risk

Question 23

What are the different types of Intracranial Hemorrhage/Hematomas?

Answer 23

Epidural-arterial: Bleeds faster

Subdural - venous: Bleeds slower usually
- Acute
- Subacute/chronic - Elders at high risk

Subarachnoid - venous or arterial

Question 24

What is a Diffuse Axonal Injury (DAI)?

Answer 24

Most severe forms of traumatic brain injury

Can include tension, stretching, and shearing nerve fibers due to:

Trauma

Rotational forces

Acceleration-deceleration

*Look for the “H-shape” of the cerebral ventricles

Question 25

How does a Stroke differ from a Brain Attack and Cerebrovascular Accident?

Answer 25

Inadequate perfusion to areas of brain Injury to brain tissue and altered cerebral metabolism occurs due to lack of blood perfusion and/or bleeding within the brain. Ischemia - leads to changes in central nervous system and systemic metabolism. - Potentially reversible Infarction -causes death of brain cells. - Not reversible

Question 26

What time is greatest for stroke risk?

Answer 26

Following a transient ischemic attack (TIA) "Mini Stroke" Up to 50% have stroke within 3 months Following a "minor" cerebrovascular accident (CVA) At what time was the person last KNOWN to be "normal" ?

Question 27

What are some stroke risk factors?

Answer 27

Risk increases with age Male incidence higher than female and at younger age compared to females Hypertension Prior stroke Family history Smoking Diabetes mellitus Cardiac disease Hypercholesterolemia Hypercoagulability

Question 28

What are some manifestations of an acute stroke?

Answer 28

Focal neurological signs May rapidly evolve Loss of function depends upon area of the brain involved

Question 29

What are some manifestations of a TIA?

Answer 29

Temporary blood flow distribution in brain Signs/symptoms resolve quickly No permanent loss of function

Question 30

What are 2 major types of strokes?

Answer 30

Ischemic - clots often originate in areas of artery bifurcation or left side of heart. -Thrombotic -Embolic Hemorrhagic

Question 31

What is an ischemic stroke?

Answer 31

Brain tissue that is distal to the blood clot will become ischemic or if not reversed, will become infarcted with altered neurological function.

Question 32

What is a Thrombotic Stroke?

Answer 32

Thrombosis is the most common cause of ischemic stroke. Older age is a common factor Atherosclerosis and/or peripheral artery disease. Hypercoagulability Barin cortex often affected: - Aphasia - Visual fields defects - Temporary blindness in one eye

Question 33

What is an Embolic Stroke?

Answer 33

A clot moved through the arterial circulation and lodged in the brain arterial circulation, sites where vessels bifurcate are often involved. Common sources of embolism include: - A-fib - Intra-operative embolus - Recent myocardial infarction - Bacterial endocarditis High fatality Sudden onset and widespread deficits

Question 34

How can Atrial Fibrillation be a leading risk factor for a stroke and why?

Answer 34

A clot can form in the blood and then travel up to the brain, causing a stroke.

Question 35

What's a Hemorrhagic Stroke?

Answer 35

The most frequently fatal type of stroke is due to spontaneous rupture of a blood vessel in the brain. Common risks are advancing age and hypertension Onset is often when the person is active Headache and vomiting related to an increased intracranial pressure. Rapid progression to coma and fatality

Question 36

What effects does a stroke have of motor and sensory?

Answer 36

Motor tracts originate in cortex and cross-over in the medulla in the lower brain (the region of the neck) Sensory tracts originates in the periphery and cross over in the spinal cord Ipsilateral means "same side" Contralateral means "opposite side"

Question 37

What are some common clinical manifestations for a stroke?

Answer 37

Numbness, tingling of face, extremity Eye ptosis: eyelid drooping Contralateral hemiplegia Emotional outbursts Loss of bowel/bladder control Slurred speech Aphasia Blurred/double vision