Disorders of Brain Function Flashcards
What are the General Principles of Brain Disorders?
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
How does the brain function?
Level of consciousness (LOC)
Cognition and content
Arousal and wakefulness
What is Level of consciousness (LOC) within the brain?
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.
What is Cognition and content within the brain?
Requires a fully functioning cerebral cortex
What is Arousal and wakefulness within the brain?
Requires interaction between cerebral cortex and Reticular activating system
What is Arterial Cerebral Blood Flow?
Internal carotid arteries - anterior brain
Vertebral arteries - posterior brain
What is Venous Cerebral Blood Flow?
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
What is Cerebral Blood Flow?
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
What is Autoregulation?
Autoregulation is an organ’s ability to regulate its blood flow despite peripheral blood pressure and is most sophisticated in the brain.
What is Autoregulation in relation to the brain?
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.
What increases blood flow to the brain?
Increased carbon dioxide: hypercarbia
Decreased pH: acidosis
Decreased oxygen: hypoxemia
What is the Monroe-Kellie Hypothesis?
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
What are the key points regarding the Monroe-Kellie Hypothesis?
The skull is rigid.
Intracranial space is limited.
Increase in volume of any component without decrease in another component causes increase intracranial pressure.
What can cause increase in volume of any of the intracranial components?
Trauma
Stroke
Aneurysm
Hematoma
Lesion - tumor
Infection
Toxins
Hypoxia/anoxia
What is Traumatic Brain Injury (TBI)?
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
Secondary Brain Injury:
How long can it take for neurological injuries to evolve?
Anywhere between hours to days
What is the Central Nervous System Responses in Secondary Injury?
Intracranial hematomas
Cerebral ischemia
Cerebral edema
Increased intracranial pressure
Infection
What is the Systemic Body Responses in Secondary Injury?
Hypermetabolism
Hypercatabolism
Hyperglycemia
Gastroparesis
What is a Concussion?
Temporary neurological dysfunction
IF Loss Of Consciousness - < 5 minutes OR none
What are some signs of a concussion?
Possible amnesia
Headache
Nausea/Vomiting
Cognitive alteration
Visual alteration
Chronic pain
What is a contusion?
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.
What are the signs of a Basilar Skull Fracture?
Raccoon Eyes
Battle’s Sign
Rhinorrhea - nose
Otorrhea - ear
Postnasal drip:
Halo sign on dressing - meningitis risk
What are the different types of Intracranial Hemorrhage/Hematomas?
Epidural-arterial: Bleeds faster
Subdural - venous: Bleeds slower usually
- Acute
- Subacute/chronic - Elders at high risk
Subarachnoid - venous or arterial
What is a Diffuse Axonal Injury (DAI)?
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
How does a Stroke differ from a Brain Attack and Cerebrovascular Accident?
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
What time is greatest for stroke risk?
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” ?
What are some stroke risk factors?
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
What are some manifestations of an acute stroke?
Focal neurological signs
May rapidly evolve
Loss of function depends upon area of the brain involved
What are some manifestations of a TIA?
Temporary blood flow distribution in brain
Signs/symptoms resolve quickly
No permanent loss of function
What are 2 major types of strokes?
Ischemic - clots often originate in areas of artery bifurcation or left side of heart.
-Thrombotic
-Embolic
Hemorrhagic
What is an ischemic stroke?
Brain tissue that is distal to the blood clot will become ischemic or if not reversed, will become infarcted with altered neurological function.
What is a Thrombotic Stroke?
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
What is an Embolic Stroke?
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
How can Atrial Fibrillation be a leading risk factor for a stroke and why?
A clot can form in the blood and then travel up to the brain, causing a stroke.
What’s a Hemorrhagic Stroke?
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
What effects does a stroke have of motor and sensory?
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”
What are some common clinical manifestations for a stroke?
Numbness, tingling of face, extremity
Eye ptosis: eyelid drooping
Contralateral hemiplegia
Emotional outbursts
Loss of bowel/bladder control
Slurred speech
Aphasia
Blurred/double vision
