Chapter 7 Acute Neuro Flashcards
1
Q
Structures of the Brain (2)
A
- Cerebrum
- Cerebellum
2
Q
What is cerebrum consist of?
A
- Right and left hemisphere
- Divided into 4 lobes
3
Q
What are the 4 lobes of cerebrum?
A
- Occipital
- Parietal
- Temporal
- Frontal
4
Q
What is the function of cerebellum?
A
Coordinates voluntary movements and maintains posture
5
Q
What is contralateral processing?
A
- Left hemisphere receives inputs from the right side of the body and vice versa.
6
Q
What is optic chiasm
A
- crossing of optic nerves in the brain
- Forms an X
7
Q
What are the structures of the Brain?
A
- Brain Stem
- Hypothalamus
- Thalamus
8
Q
What is the function of the brain stem?
A
- Regulates cardiac and respiratory function
9
Q
What is the function of Hypothalamus (3)
A
- Controls body temp
- CNS to endocrine
- Smooth muscles, HR, bladder contractions etc
10
Q
What is the function of Thalamus
A
- Sorts information and passes it on the cerebral cortex where it can initiate and coordinate movements in response to the sensations
11
Q
What are ventricles
A
Four cavities within the brain, filled with cerebrospinal fluid (CSF), that connects with one another and with the spinal canal.
12
Q
What is Cerebrospinal Fluid (CSF)
A
- Clear, colourless fluid that circulates within the subarachnoid space that surrounds the brain, brain steam and spinal cord.
- Provides cushioning for the brain and the spinal cord; allows fluid shifts from cranial cavity to spinal cavity; and carries nutrients.
13
Q
What is the other use of CSF?
A
- CSF provides useful diagnostic info relating to certain nervous system disease.
14
Q
Where is CSF Absorbed?
A
Arachnoid Villi
15
Q
what are the 3 protective layers that surrounds the brain and spinal cord called? what are the 3?
A
Meninges
1) Dura Mater
2) Arachnoid
3) Pia mater
16
Q
where is dura mater located
A
Outer most layer that is closest to the skull
17
Q
where is Arachnoid located?
A
Middle layer, delicate impermeable membrane
18
Q
Where is pia matter located?
A
Delicate and adhere to the surface of the brain and spinal cord.
19
Q
where is CSF located?
A
CSF is found in the subarachnoid space ( between arachnoid and pia matter )
20
Q
What is inter-cranial pressure
A
sum of all the pressure within the three components
21
Q
what are the 3 components of inter-cranial pressure
A
- Brain Tissue - 80%
- Blood - 10%
- Cerebrospinal Fluid - 10%
22
Q
Why cant the total volume cannot change
A
- The skull is a rigid and protective covering of the brain.
23
Q
What is the “Monro-Kellie doctrine”
A
A change in 1 component requires a change in another.
24
Q
Factors that influence ICP under normal circumstances are changes in (6) :
A
1) Blood pressure
2) Cardiac function
3) Intra-abdominal and intra thoracic pressure
4) Body position
5) Body temp
6) blood gases, particularly CO2 levels
25
Normal brain function depends on..
- consistent supply of blood ( for oxygen & nutrients/ glucose)
- Brain relies on healthy heart & lungs for perfusion
26
Disease that cause increase ICP (4)
- Brain trauma
- Brain Tumour
- Brain Infections
- Brain Hemorrhage
27
what is the normal ICP pressure
5-15 mmHg
28
What is the pressure of increased ICP
>20 mmHg
29
What is the normal CPP
70 to 100 mmHg
30
what is the minimum CPP
50 - 60 mmHg necessary for adequate cerebral perfusion
31
CPP of <50mmHg is associated with?
cerebral ischemia
32
What is cerebral perfusion pressure (CPP) ?
net pressure gradient that drives oxygen delivery to cerebral tissue. Pressure needed to ensure adequate brain tissue perfusion.
33
Formula for CPP?
MAP - ICP = CPP
34
What are the 3 compensatory mechanisms?
1) CSF Volume
2) Autoregulation
3) Carbon dioxide (PaCO2), Oxygen (PaO2), pH
35
Explain compensatory with CSF volume
Displacement of CSF into the spinal subarachnoid space or the basal subarachnoid cistern and to lesser degree, by altering CSF production and absorption rates.
36
Explain compensatory with Autoregulation
- Brain has an ability to regulate its own blood flow in response to its metabolic needs despite the systemic blood flow.
- By dialating and constricting cerebral blood vessels, the brain can ensure constant blood flow.
37
what is the purpose of autoregulation
- To ensure adequate CBF to meet metabolic needs of the brain tissue and to maintain cerebral perfusion pressure within normal limits
38
Autoregulation fails when?
When theres extreme hypertension and hypotension
39
Explain compensatory with carbon dioxide, oxygen, pH
- increase in CO2 (decrease O2) relaxes the smooth muscles, dilates cerebral vessels, decrease cerebrovascular resistance, and increases CBF to bring more O2
- decrease in CO2 ( increase O2) reverse this process and decreases CBF
- if CO2 is not raised, anaerobic metabolic begins, resulting in an accumulation of lactic acid. As lactic increases and hydrogen ions accumulates, the cerebral environment becomes more acidic. With acidic environment further vasodilation occurs in continue to attempt to increase blood flow.
40
What are the 3 main components of skull that makes up our intracranial pressure?
- Tissue - 80%
- Blood - 10%
- CSF - 10%
41
Summarize the 3 compensatory mechanisms to maintain cerebral blood flow
See notes..
42
What can increased ICP in brain tissue
- Tumor
- Abscess
- Edema
- Contusion ( Bruise )
43
What can increased ICP in Blood?
- Inter-cranial hemorrhage
| - Intracranial hematoma
44
What can increased ICP in CSF (2)
- Hydrocephalus
| - Meningites
45
Consequences of high ICP (9)
- Cerebral Edema
- Compression of brain vessels, tissue, ventricles
- Decreased blood flow
- Tissue hypoxia
- Death of brain cells
- Acidosis
- Impaired Autoregulation
- Brain stem compression
- Brain herniation
46
Explain the cascade of events from insult to the brain to death
Insult to brain > Tissue edema> increase ICP< compression of blood vessels> low cerebral flow
> Low O2 with death of brain cells> edema around necrotic tissue> Increase ICP with compensation of brain stem and respiratory centre > accumulation of CO2> Vasodilation > increase ICP resulting from increase blood volume > death
47
What is brain herniation
Shifting of brain tissue from one space in the brain to another through various openings.
48
Is Brain herniation an emergency?
YES
49
Clinical Manifestations of Increased ICP (6)
- Change in level of consciousness
- Changes in vital signs
- Ocular signs
- Decrease in motor functions
- Headache
- Vomiting
50
What is the earliest sign on increase ICP?
Level of consciousness
51
Increase ICP Manifestation: Level of Consciousness (4)
- Early sign of increased ICP
- Related to decrease in cerebral flow
- Affects brain stem --> specifically RAS
- Can lead to coma if state unrelieved
52
If level of consciousness is unrelieved then what can it lead to?
Can lead to coma state
53
What does RAS control?
Controls conciousness
54
What is the deepest state of unconsciousness?
comatose
55
who regulates temperature?
Hypothalamus
56
Who regulates HR and respiratory?
Brainstem
57
what is the late sign of high ICP?
Vital signs
58
Increase ICP Manifestation: Changes in Vital signs are caused by?
Increasing pressure on the thalamus, hypothalamus, pons, and medulla
59
What are the 3 cushings triads?
1) Increase Blood pressure
2) Decrease HR
3) Irregular respiratory rate, periods of apnea --> Cheyne Stokes
60
changing in vital signs means..
Close to reaching hernation
61
cushings triad: Explain increase BP
- increase in systolic pressure (widening pulse pressure)
- Body tries to regulate due to decrease in blood flow which results in vasoconstriction in the whole body and causes increase in BP
62
cushings triad: Decrease HR (bradycardia)
- Baroreceptors (Aortic Arc) sense the increase in BP and initiates the PSN to kick in and decrease the HR due to body thinking that it already have good CO and BP. This results in decrease HR
63
cushings triad: Irregular RR
- As ICP worsens, the pressure on Brainstem increases and it leads to irregular respiratory pattern and periods of apnea.
- Maybe present but often do not appear until ICP has been increased for some time or suddenly and markedly increases (ex. head trauma)
64
Cushing's Triad is...Med..
Medical emergency!!
65
Cushing Triad an early or late sign?
Late sign
66
Increase ICP Manifestation: Changes in Vital signs such as changes in temperature is caused by?
Associated pressure on the hypothalamus
67
What does Cranial Nerve 3 do? (3)
- Allow movement of the eyes and eyelids
- Motor and sensory function
- Pupil constrictions and response to light
68
Is ocular sign an early or late sign?
Late sign
69
Why is ocular affected?
Cranial nerve exits on top of the brainstem. It becomes compressed when someone has high ICP
70
Compression of oculomotor nerve (Cranial 3) results in? (5)
- Dilation of pupil ipsilateral (same side) to mass or lesion.
- Sluggish
- no response to light
- Inability to move the eye upward
- ptosis of eyelid
71
Ocular signs can be
bilateral or unilateral
72
ocular signs is the result of
shifting of the brain from the midline, a process that compresses the trunk of CN 3, paralyzing the pupil spincter.
73
other cranial nerve that is affected
CN 2 - optic
CN 4 - trochlear
CN 6 - abducens
74
Signs of other CN affected
- Blurred vision
- Diplopia
- Changes in extraocular movement
75
Increase ICP Manifestation: Decrease Motor Function (3)
- Contralateral hemiparesis or hemiplegia
- Decorticate Posturing
- Decerebrate Posturing
76
What is hemiparesis
- Mild or partial weakness on one side or half the body
77
Hemiplegia
- Severe paralysis of one side of the body
78
What decorticate posturing? Where is the damage
- Damage occurred to the cerebral hemisphere. The thalamus and the midbrain. Less severe compared to decerebrate.
- Flexor
79
Decerebrate Posturing? Where is the damage
- Result of brain stem damage which means pressure is compressing the brainstem and pushing down and reaching herniation
- extensor
80
Posturing indicates
- can indicate that brain herniation is occurring or is about to occur (for both)
81
Posturing (4)
- Bad sign of brain injury
- Can occur on its own
- Can be elicited using painful stimuli
- Happens from result of brain herniations or immolate herniation
82
which one is "better" decorticate or decerebrate
Decorticate is better than decerebrate because decerebrate means they're reaching herniation and will die.
83
Increase ICP Manifestation: cause of Headache
- Caused by compression of vessels and nerves in the brain
84
Increase ICP Manifestation: Headache is described as?
- Described as continuous
85
ncrease ICP Manifestation: What aggrevates Headache
Aggravated by moving and straining ( increases more pressure in the brain)
86
What is the non specific sign of increase ICP
Vomiting
87
Increase ICP Manifestation: Vomiting
- Usually occurs without nausea
- Related to direct pressure on vomiting centre (medulla)
- Projectile
88
Explain how high ICP affects the brain cells
- high ICP affects the brain cells through lower cerebral flow caused by compressions due to high ICP it can lead to tissue death/ cell death.
89
Define brain herniation
Brain herniation is when tissues moves from one space in the brain to another through various openings.
90
Describe Cushing's Triad
- Late symptoms of ICP
- increase Systemic BP - due to decrease flow
- Bradycardia - Baroreceptor sense increase in BP so decrease the HR
- Irregular RR - Brain stem compressed leading to dysfunction in respiratory.
91
Which cranial nerve is associated with high ICP? provide rationale
- Cranial nerve number 3
| - Cranial nerve 3 exits on top of the brain stem so it becomes compressed when someone has increase ICP.
92
what is the cause traumatic Brain Injury
- Fall
- Motor Vehicle Accident
- Struck by object
- Sports
93
What is one of the leading cause of death in Canada?
- TBI
94
Traumatic Brain Injury
- Broad term to describe an injury caused by a force outside the brain
95
TBI can be (3)
- Open vs close
- Diffuse vs Focal
- Primary vs Secondary
96
Laceration
a cut or skin wound. Non of the skin is missing
97
Hematoma
A collection of blood
98
Hemorrhage
- profuse bleeding from a vessel
| - Active bleeding not clotting
99
Contusion
bruise to the brain tissue within a focal area
100
Coup
damage occurring at the site of direct impact of the brain or skull
101
Countercoup
Damage occurring on the opposite side away from the injury
102
What is open head injury
object enters the brain through the skull ( bullet, knife, etc) damage is done through penetration of the brain tissue.
103
Closed
- Blow to the head which result in the brain moving and shaking within the skull
- Brain bounce against side of the the skull and causes more damage (ex. coupcontrecoup damage)
104
Diffuse vs Focal (4) each
Diffuse
- Widespread area of damage
- Difficult to view with diagnostics
- Results from acceleration/ deceleration ( shifting and rotating)
- Example: Diffuse axonal injury, hypoxia, meningitis, concussions
Focal
- localized to one area
- Easier to visualize with diagnostics (CT scan)
- Results from blunt and penetrating trauma
- Examples: Lacerations, skull fractures, contusions, hematomas
105
What is primary Injury (2)
- Occurs during the initial insult
| - Related to the injury at the time of trauma --> for example, contusion, damage to blood vessels, axonal shearing
106
what is secondary injury (4)
- Indirect result of injury
- Hours to days after the initial injury
- Most facilities are due to secondary injury
- Complications such as cerebral edema, cerebral hypoxia, ischemia, increased intracranial pressure.
107
explain the cascade of events for secondary starting from injury to edema
- Cerebral edema > Increase ICP > decrease blood flow> tissue hypoxia > increase co2 and Decrease pH > increase flow of blood > increase ICP > hypoxia and cell death > cell death leads to cytotoxic chemicals released which damages more.
108
What is basilar skull fractures
- Fractures that occurs on the base of the skull
| - Risk of CSF leak into sinuses close to the injury
109
Basilar Skull Fractures manifestations (4)
- Bilateral Periorbital Ecchymosis (Raccoon eyes)
- Postauricular Ecchymosis (Battle sign)
- CSF rhinorrhea
- CSF otorrhea
110
Leak of CSF is risk for
meningitis
111
Basilar Skull Fractures complication (5)
- Meningitis
- intracranial infections
- hematoma
- brain tissue damage
- hemorrhage
112
What is TBI complications
Hematomas
113
What is hematomas
collections of blood between meninges
114
Types of Hematoma (4)
1) Epidural Hematoma
2) Subdural Hematoma
3) Intraparenchymal hematoma
4) Subarachnoid hematoma
115
What is risk factors of hematoma? (4)
- Older age
- alcohol
- anticoagulants
- antiplatelets
116
What is subdural hematoma? (3)
- found between dura mater and arachnoid layer of the brain
- It is venous in origin, the hematoma is much slower to develop into a mass large enough to produce symptoms
- caused by traumatic Brain Injuries
117
3 types of subdural hematoma
1) Acute
2) Subacute
3) Chronic
118
explain acute hematoma
- manifestations occurs within 48hours of the injury
| - Immediate deterioration
119
What is subacute hematoma
- 2-14 days of injury
- alterations in mental status as hematoma develops; progression depends on site and location
-
120
Chronic hematoma(3)
- weeks to months to develop
- more common in older adults (50's to 60's)
- Non-specific, non-localizing progression; progressive alteration in LOC.
121
Is bacterial meningitis medical emergency
yes
122
what is bacterial meningitis
acute inflammation of the meninges (pia mater, arachnoid mater, and dura mater)
123
bacterial meningitis occurs to who? (3)
- infants
- older adults
- high risk population
124
when is bacterial meningitis more prevelent? why?
- winter or spring
| - because its secondary to viral respiratory diseases
125
what virus causes bacterial meningitis
1) pneumococcus meningitis
2) meningococcal meningitis
* H. Influenza used to be common cause but vaccine decreased meningitis r/t this organism
126
bacterial meningitis: massive inflammatory response leads to? explain
- cerebral edema
- The inflammatory response to the infection of the meninges and CSF may increase CSF production, while exudate accumulation leads to blockage of the arachnoid villi causing obstruction of CSF absorption. The resulting hydrocephalus may cause an increase in ICP. The purulent secretions that are produced spread quickly to other areas of the brain through the CSF. If this process extends into the brain parenchyma or if concurrent encephalitis is present, cerebral edema and increase ICP become more of a problem.
127
Why must patient be observed closely if they have bacterial meningitis
- Observe closely for manifestations of increase ICP which is thought to be result of swelling around the dura, and increased CSF volume.
