Sheet 2 Flashcards
(131 cards)
1
Q
What is a significant cause of death and disability?
A
Trauma to the brain and spinal cord
2
Q
What affects the outcome of the brain and spinal trauma?
A
1) Severity
2) Site of injury
3
Q
Injury of several cubic centimeters of brain parenchyma may be:
A
1) Clinically silent (if in the frontal lobe).
2) Severely disabling (spinal cord).
3) Fatal (involving the brain stem)
4
Q
A blow to the head may be:
A
Penetrating (Open) or blunt (closed) injury.
5
Q
The magnitude and distribution of traumatic brain lesions depend on:
A
1) The shape of the object causing the trauma
2) The force of impact
3) Whether the head is in motion at the time of injury
6
Q
True or false:
Severe brain damage can occur only in the presence of external signs of head injury.
A
False; Severe brain damage can occur in the absence of external signs of head injury.
7
Q
True or false:
Severe lacerations and even skull fractures do not necessarily indicate damage to the underlying brain.
A
True
8
Q
In addition to skull or spinal fractures, trauma can cause:
A
1) Parenchymal injury.
2) Vascular injury.
3) Combinations of both.
9
Q
Types of traumatic Parenchymal brain Injuries are:
A
1) Contusions.
2) Laceration.
3) Diffuse axonal injury.
4) Concussion.
10
Q
What is a contusion?
A
A brain injury that occurs from collision of the brain with the skull (1) at the site of impact (a coup injury), or (2) on the opposite side (contrecoup injury) due to the pressure.
11
Q
What causes a contusion?
A
1) Rapid tissue displacement
2) Disruption of vascular channels
3) Subsequent hemorrhage
4) Tissue injury
5) Edema
12
Q
Which part of the brain is most susceptible to contusions? Why?
A
Crests of gyri, because they are the points of impact
13
Q
Which part of the brain is less susceptible to contusions?
A
The cerebral cortex along the sulci
14
Q
The most common locations where contusions occur correspond to:
A
1) The most frequent sites of direct impact
2) Regions of the brain that overlie a rough and irregular inner skull surface
15
Q
What are the regions of the brain that overlie a rough and irregular inner skull surface?
A
1) The frontal lobes
2) The orbital gyri
3) The temporal lobes
16
Q
What is a laceration?
A
Penetration of the brain, either by a projectile such as a bullet or a skull fragment from a fracture.
17
Q
What causes lacerations?
A
1) Tissue tearing
2) Vascular disruption
3) Hemorrhage
4) Injury along a linear path
18
Q
What is a diffuse axonal injury?
A
Widespread injury to axons
within the brain
19
Q
What leads to the disruption of axonal integrity and function?
A
The movement of one region of the brain relative to another
20
Q
What may cause axonal injury and hemorrhage without need for an impact?
A
Angular acceleration
21
Q
What is diffuse axonal injury characterized by?
A
Wide but often asymmetric distribution of axonal swellings that appear within hours of the injury and may persist for much longer
22
Q
As many as 50% of patients who develop coma shortly after trauma, even without cerebral contusions, are believed to have:
A
White matter damage and diffuse axonal injury
23
Q
Where are diffuse axonal injury lesions found most often?
A
1) Near the angles of the lateral ventricles
2) In the brain stem
24
Q
Some neurons may be affected more than others depending on:
A
The force direction
25
What is a concussion?
Reversible altered consciousness from head injury in the absence of
contusion.
26
The characteristic transient neurologic dysfunction in concussions includes:
1) Loss of consciousness
2) Temporary respiratory arrest
3) Loss of reflexes
27
True or false:
| Although neurologic recovery from concussions is complete, amnesia for the event persists.
True
28
What is the pathogenesis of the sudden disruption of nervous activity from concussions?
It is unknown
29
What is vascular injury?
A frequent component of CNS trauma
30
What does vascular injury result from?
Direct trauma and disruption of the vessel wall = hemorrhage.
31
What might treatment for vascular injury do?
Prevent the development of permanent damage to the parenchyma
32
Depending on which vessels rupture, hemorrhage may occur in any of several compartments:
1) Epidural
2) Subdural
3) Subarachnoid
4) Intra-parenchymal
33
Subarachnoid and intraparenchymal hemorrhages most often occur at sites of:
1) Contusions
| 2) Lacerations
34
The dura is normally tightly applied to the inside of the skull fused with __.
The periosteum
35
Which vessel in particular runs in the dura and is therefore vulnerable to injury from skull fractures? (Epidural hematoma)
The middle meningeal artery
36
What could tear a vessel in children in the absence of a skull fracture resulting in an epidural hematoma?
A temporary displacement of the skull bones
37
What can happen once a vessel is torn in an epidural hematoma?
The accumulation of blood under arterial pressure can cause separation of the dura from the inner surface of the skull.
38
The expanding epidural hematoma has a smooth inner contour that:
Compresses the brain surface.
39
Clinically, epidural hematoma patients can be lucid for ___ between the moment of trauma and the
development of neurologic signs.
Several hours
40
What kind of hematoma is expands rapidly and is a neurosurgical emergency requiring prompt
drainage to release pressure?
Epidural hematoma
41
What type of hematoma results from torn bridging veins?
Subdural hematoma
42
What veins are torn during a subdural hematoma?
Bridging veins
43
What artery is torn during an epidural hematoma?
Middle meningeal artery
44
What are bridging veins?
Veins that extend
from the cerebral hemispheres through the subarachnoid and subdural space to empty into dural
sinuses.
45
Where does the bleeding happen if bridging veins are torn?
Subdural space
46
What are the risk factors for a subdural hematoma?
1) Elderly patients with brain atrophy (the bridging veins are stretched out and the brain has additional space for movement) = minor head trauma could cause it.
2) Infants (bridging veins are thin walled).
47
Which syndrome can cause a subdural hematoma in infants?
Shaking baby syndrome
48
Subdural hematomas most often become manifest ___ after injury.
Within the first 48 hours
49
Where are subdural hematomas most common?
Over the lateral aspects of the cerebral hemispheres (bilateral in about 10% of cases).
50
What are the neurological signs of a subdural hematoma?
1) Headache or confusion
2) Slowly progressive neurologic deterioration, rarely with acute
decompensation.
51
Why do we have neurological signs in a subdural hematoma?
Because of the pressure exerted on the adjacent brain
52
Clinical manifestations of neurological signs are:
Usually nonlocalizing, but can be focal.
53
What are Cerebrovascular diseases?
Any abnormality of the brain caused by a pathologic process involving blood vessels.
54
What are the three basic processes of cerebrovascular diseases?
1) Thrombotic occlusion of vessels
2) Embolic occlusion of vessels
3) Vascular rupture
55
___ and ___ cause ischemic injury or infarction of specific regions of the brain, depending on the vessel involved
Thrombosis; embolism
56
Why do thrombosis and embolisms share the same characteristics?
Because their effects on the brain is the same:
| Loss of oxygen and metabolic substrates resulting in brain infarction.
57
Hemorrhage accompanies ___, leading to:
Rupture of vessels;
(1) Direct tissue damage
(2) Secondary ischemic injury
58
What is a stroke?
It's a clinical term that describes the presence of a vascular problem without defining the exact disease.
59
What does the brain require?
Constant delivery of glucose and oxygen from the blood
60
Although the brain accounts for only _-_% of the body weight, it receives _% of the resting cardiac output and accounts for _% of the total body oxygen consumption.
1-2%; 15%; 20%
61
Why does cerebral blood flow remain constant over a wide range of blood pressure and intracranial pressure?
Because of autoregulation of vascular resistance.
62
The brain is a highly __ tissue, with __ being the limiting substance.
Aerobic; oxygen
63
Which cell can't stand the state of hypoxia?
Neurons
64
The brain may be deprived of oxygen by:
1) Functional hypoxia in a setting of:
a) A low partial pressure of oxygen
b) Impaired oxygen-carrying capacity (anemia)
c) Inhibition of oxygen use by tissue
2) Ischemia:
a) Transient
b) Permanent
65
Cessation of blood flow can result from:
1) Reduction in perfusion pressure, as in hypotension
2) Secondary to vascular obstruction
3) Both
66
What is Global Cerebral Ischemia?
Widespread ischemic/hypoxic injury
67
When does Global Cerebral Ischemia occur?
When there is a generalized reduction of cerebral perfusion, usually below systolic pressures of less than 50mmHg
68
What could cause Global Cerebral Ischemia?
1) Cardiac arrest
2) Shock
3) Severe hypotension
69
Which is more sensitive to hypoxia: Glial cells or neurons?
Neurons
70
What is the clinical outcome for mild Global Cerebral Ischemia?
There may be only a transient postischemic confusional state, with eventual complete recovery. However, Irreversible damage of CNS tissue does occur in some individuals who suffer mild or transient global ischemic insults.
71
True or false regarding mild Global Cerebral Ischemia:
| There is no variability in the susceptibility of different populations of neurons in different regions of the CNS.
False; There is variability.
72
List the most susceptible cells to ischemia of short duration.
1) Pyramidal cells of the Sommer sector (CA1) of the hippocampus.
2) Purkinje cells of the cerebellum.
3) Pyramidal neurons in the neocortex
73
What is the clinical outcome for severe global cerebral ischemia?
Widespread neuronal death irrespective of regional vulnerability.
Individuals who survive in this state often remain severely impaired neurologically and deeply
comatose (persistent vegetative state).
74
What is the clinical criteria of brain death?
1) Evidence of diffuse cortical injury (isoelectric, or "flat," ECG).
2) Brain stem damage including absent reflexes and respiratory drive.
75
What happens when brain dead patients are maintained on mechanical ventilation?
The brain gradually undergoes an autolytic process, resulting in "respirator brain."
76
What are border zone ("watershed") infarcts?
Wedge-shaped areas of infarction that occur in those regions of the brain and spinal cord that lie at the most distal fields of arterial perfusion
77
Which area in the cerebral hemispheres is at most risk for border zone ("watershed") infarcts?
The border zone between the anterior and the middle cerebral artery distributions
78
Damage to the border zone between the anterior and the middle cerebral artery distributions results in:
A band of necrosis over the cerebral convexity a few centimeters lateral to the interhemispheric fissure
79
When are border zone infarcts usually seen?
After hypotensive episodes.
80
What leads to focal ischemia? If sustained, what can it then lead to?
Cerebral arterial occlusion; to infarction of CNS tissue in the distribution of the compromised vessel.
81
The size, location, and shape of the focal ischemia infarct and the extent of tissue damage that results are determined by:
Modifying variables such as the adequacy of collateral flow
82
What is the major source of collateral flow?
Circle of Willis
83
Where is partial collateralization provided?
Over the surface of the brain
84
What provides partial collateralization?
Cortical leptomeningeal anastomoses.
85
There is little if any collateral flow for what?
For the deep penetrating vessels supplying structures such as:
1) Thalamus
2) Basal ganglia
3) Deep white matter
86
Occlusive vascular disease of severity sufficient to lead to cerebral infarction may be due to:
1) In situ thrombosis
| 2) Embolization from a distant source
87
Which type of brain infarcts are most common?
Embolic infarcts
88
Where do thrombi usually start?
At rough surfaces (so the inner lining of the circulation is very important)
89
What are some predisposing factors for brain infarctions?
1) Cardiac mural thrombi
2) Myocardial infarct
3) Valvular disease
4) Atrial fibrillation
90
Why are myocardial infarctions a predisposing factor for brain infarcts?
Because of the relaxation of the heart and the stagnation of the blood.
91
Why is atrial fibrillation a predisposing factor for brain infarcts?
Because of the stagnation of the blood.
92
Thromboemboli arise in:
1) Atheromatous plaques within the carotid arteries.
2) Paradoxical emboli particularly in children with cardiac anomalies
3) Emboli associated with cardiac surgery.
4) Emboli of other material (tumor, fat, or air)
93
What are some common sites of embolization?
1) The territory of distribution of the middle cerebral artery (the direct extension of the internal carotid artery)
2) Emboli tend to lodge where vessels branch or in areas of preexisting luminal stenosis.
94
What are the majority of thrombotic occlusions causing cerebral infarctions due to?
Atherosclerosis
95
Atherosclerotic stenosis can develop ___, accompanied by:
Superimposed thrombosis;
1) Anterograde extension
2) Fragmentation
3) Distal embolization
96
What are the most common sites of primary thrombosis?
1) The carotid bifurcation
2) The origin of the middle cerebral artery
3) At either end of the basilar artery
97
Infarcts can be divided into two broad groups based on their macroscopic and corresponding radiologic appearance:
1) Non-Hemorrhagic infarcts
| 2) Hemorrhagic infarcts
98
Which type of brain infarct is related to ischemia?
Non-Hemorrhagic infarcts
99
Non-Hemorrhagic infarcts can be treated with:
Thrombolytic therapies, if identified shortly after presentation
100
What are hemorrhagic infarcts?
Multiple, sometimes confluent, petechial hemorrhages.
101
Why does a hemorrhagic infarct occur?
Secondary to reperfusion of ischemic tissue, either through collaterals
or after dissolution of intravascular occlusions.
102
What is an intracranial hemorrhage?
Hemorrhage within the skull or brain
103
Hemorrhages within the brain itself can occur secondary to:
1) Hypertension or other forms of vascular wall injury
2) Arteriovenous malformation
3) Cavernous malformation
4) Intraparenchymal tumor
104
Subarachnoid hemorrhages are most commonly seen with what?
Aneurysms (berry
| aneurysm)
105
Hemorrhages associated with the dura (in subdural or epidural spaces) are
associated with what?
Trauma
106
Primary Brain Parenchymal Hemorrhage is:
Spontaneous (nontraumatic)
107
Primary Brain Parenchymal Hemorrhages occur most commonly in what ages?
Mid to late adult life, with a
| peak incidence at about 60 years of age.
108
What causes a Primary Brain Parenchymal Hemorrhage?
Rupture of a small intraparenchymal vessel due to hypertension
109
Brain hemorrhage accounts for roughly _% of deaths among individuals with
chronic hypertension.
15%
110
Hypertensive intraparenchymal hemorrhages typically occur in the:
1) Basal ganglia
2) Thalamus
3) Pons
4) Cerebellum
111
What determines the clinical manifestations of a Primary Brain Parenchymal Hemorrhage?
The location and size of the bleed
112
When can an intracerebral hemorrhage be clinically devastating?
When it affects large portions of the
| brain and extends into the ventricular system.
113
Over weeks or months, Primary Brain Parenchymal Hemorrhage will
Gradually resolve.
114
What are the causes of Subarachnoid Hemorrhage and Saccular Aneurysms?
1) Rupture of a saccular (berry) aneurysm. [The most frequent cause of clinically significant subarachnoid hemorrhage]
2) Vascular malformation
3) Trauma
4) Rupture of an intracerebral hemorrhage into the ventricular
system
5) Hematologic disturbances and tumors
115
Rupture can occur at any time, but in about 1/3 of cases it is associated with:
Acute increases in intracranial pressure (as with
| straining at stool).
116
What happens after a rupture in a Subarachnoid Hemorrhage?
Blood under arterial pressure is forced into the subarachnoid space, and individuals are
stricken with a sudden, excruciating headache (classically described as "the worst headache
I've ever had") and rapidly lose consciousness.
117
Between _-_% of individuals die with the first rupture, although those who survive
typically improve and recover consciousness in __.
25-50%; minutes
118
What is common in Subarachnoid Hemorrhage survivors?
Recurring bleeding
119
The prognosis of Subarachnoid Hemorrhages worsens with:
Each episode of bleeding.
120
Aneurysms have a roughly _% per year rate of bleeding.
1.3%
121
The probability of rupture increases with:
The size of the lesion (aneurysms greater than 10 mm have a roughly 50% risk of bleeding per year)
122
About 90% of saccular aneurysms occur in the:
Anterior circulation near major arterial
| branch points.
123
Multiple aneurysms exist in -_-_% of cases
20-30%
124
Subarachnoid Hemorrhages are sometimes called congenital, but are not present at birth. Why do they happen?
They develop over time because of underlying defects in the vessel media. (NOT congenital)
125
In the early period after a subarachnoid hemorrhage, there is a risk of:
Additional ischemic
| injury from vasospasm involving other vessels.
126
What can occur during the healing phase of a subarachnoid hemorrhage?
Meningeal fibrosis and scarring = obstruction of CSF flow as well as interruption of the normal pathways of CSF resorption.
127
What are the most important effects of hypertension on the brain?
1) Massive hypertensive intracerebral hemorrhage
2) Lacunar infarcts
3) Slit hemorrhages
4) Hypertensive encephalopathy
128
Hypertension affects:
The deep penetrating arteries and arterioles that supply the basal ganglia, hemispheric white matter, and the brain stem.
129
Hypertension causes several changes including:
1) Hyaline arteriolar sclerosis in arterioles (weaker and vulnerable to rupture)
2) Development of minute aneurysms in vessels that are less than 300 μm in
diameter (Charcot Bouchard microaneurysms) which can rupture.
130
What is hypertensive encephalopathy characterized by?
Diffuse cerebral dysfunction including:
1) Headaches.
2) Confusion.
3) Vomiting.
4) Convulsions, sometimes leading to coma.
131
Does hypertensive encephalopathy resolve spontaneously?
No, it needs rapid therapeutic intervention to reduce the accompanying increased intracranial pressure
