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107 Cards in this Set
- Front
- Back
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What is the Circle of Wills?
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The spot in the base of the brain where the cerebral arteries meet and divide into penetrating arteres that supply blood flow to the parachyma. The circle assts in regulating differential blood flow to the brain.
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What is ment by"differental blood flow to the brain?"
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If for some reason a carodid artery is occluded the brain can still fuction - the circle of wills can shut blood to make up for the lack of flow - it rerounts blood to the area of the brain that needs it the most.
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What must be considered if someone is on ECMO?
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1.) Have they had ecmo b4 - cant occlude the same caroid twice
2.) If they have a normal Cirlce of Wills - an abnormal Cirlce will just burst, and be unable to regulate ceberal blood flow |
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What metabolic action regulates CBF?
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blood PaCO2, PaO2
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What causes cerebral vasodilation?
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disslocated H+ ions from carbonic acid, ie elevaded Pco2/decreased PaO2 is considered a ceberal diltor, acidodis causes vasodilatoion, lactate or pyruvate dilates cerebral vessles
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T or F
A high metabolic rate without adquate oxygenation delivery triggers decreased blood flow to the cerebral area |
False - causes increased blood flow to meet the metabolic demands on the brain. The Brain is the first "sparing" organ of the body
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What is the underlining rule for metabolic regulation of CBF
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The vessles are going to dilate to deliver oxygen rich blood to the brain
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When a child has ICP, why would you hyperventilate?
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you flood the area oxygen, or you decrease the PaCO2 thus increaseing the PaO2 to decrese CBF, cause constriction to help minimize swelling of the brain
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T or F
Map has no effect on CBF |
False. The CBF resistance changes in responce to MAP inorder to keep the CBF 50-100ml/hr - idealy the MAP should be 60-140 for this to be optimal
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T or F
Children has less ability to autoregulate the CBF |
True. Children up to age 2 have very poor ability to regulate there own CBF in relation to the map
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A 1 year old comes to the ER in shock. The Maps are 33. What type of brain injury witll the child suffer?
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Ischemia of the brain - the CBF does not respond to the changes in blood pressure
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What controls the MAP?
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Sympathetic innerventions from superior cervical ganglua in the neck and receptors in the carotid arteries relay the meddates of map
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T or F
As your map decreases the CBF decreases |
False
As the map decreases the cbf increases |
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T or F
The "glial feet" support capillaries and prevent distention resulting in the blood brain barrier |
Ture
Ther cerebral capillaries (which are more extensive in the gray matter - cell bodies) are less permeable that other capillary beds |
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The impermeablity of the bbb to outside substances is due to what structure of the capillaries
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tight junctions
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Where do you want there to be less tight junctions
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hypothalamus so the gland can sense blood concentrations and control metabolism
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What substances are permeable to the BBB
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H2O, CO2, O2
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What regulates the chemical composition of the CSF
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BBB
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What can not permeate the BBB
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pproteins and lipids
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What is a danger assoicated with dehydration?
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Sagittal sinus thrombosis
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What is the classic setup for a cortical infarction from venous thrombosis
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slight dehydrated and receving chemo - so the clotting factors change
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What is a cortical infarction from venous thrombosis
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what it sounds like - cuased by being dehydrated/chemo
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What are the three types of ischemic brain diseases?
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GLobal cebral ischemia
Focal cerebral ischema Border Zone infarcts |
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What is global cerebral ischemia?
What causes it? |
ischemic/hypoxic encephlopathy - occurs when there is generalized reduction of cerebral perfusouns like in shock, cardiac arrest or sever hypotension
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What is focal cerbral ischemia?
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a stroke - follows a reduction or cessation of blood flow to a local area due to an embolic or thrombotic arteral occlusion
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What are border zone infarts
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water shaped areas of infacart that occur in region of the brain and spinal cord that lie at the most distal fields of the arterial perfusion, usually seen after a hypotensive episode
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T or F
The ventricles are above the brain stem and cerbelleum |
true
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What produces the cerebral spinal fluid?
What absorbes the CSF |
choroid plexus
arachnoid villi |
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Describe the choroid plexus.
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Its a type of cell that covers clood vessles located in the posterior horn of each lateral venrtircle, posterioer portion of third ventricle, and the roof of the fourth ventricle
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What type of transport occurs at the choriod plexus?
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active trasport of glucose across the membrane into csf and active transprot of na with diffusion of cl following and resulting osmosis of water formoing csf
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What is the arachnoid villi?
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microscopic projection of arachonid membranes through the walls of the venous sinuses that are covered with porous epithelium where csf is freely reabsorebed into the benous blood
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What is the flow of CSF?
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Lateral ventricles,third ventricles, aqueduct of sylvius, forth ventricles, foramen of magendie, spinal cord, subarachnoid space, acrachnoid villi
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When do you see hydrocephilis
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if the csf cant drain or if the arachnoid villi cant absorb OR is there is a tumor of the chroid plexus - the overproduction of CSF that can also be productive
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What is hydrocephalus
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the accumiliation of excessive csf within the ventriclar system
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What is hydrocephalus ex vacuo?
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A dilation of the ventricular system with a compensatory increase in CSF due to loss of brain parachemia - its a compensssary reslut no ICP
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Non-communicating hydrocephalus
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flow of csf is obstructed throughtout the chambers of the cetral nervous system
obstructive hydrocephalus |
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What is a Arnold-Chiari malformation, "Chiari malfromation type II"
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Type II, a small posterioer fossa, a misshapen midline cerevellum with downward extension of vermis thorugh the foramen magnum (causing hydrocephalus) and a lumbar myelomeningocele.
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What is a Chiari I malformation?
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low-laying cerebellar tonsils that extend down into the vertebral canal and may cause obstruction of CSF flow and medullary compression that are amenable to neurosurgical intervention
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Describe the structural abnormailty of congenital posterior fossa anamolies?
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forms a hyperacute angle of the foramen of magendie, where it acts as a ball valve occipital depression device. They dont like to change positions - it changes there CSF balance.
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What is the difference between type I and type II chiari malformations?
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Type II has a myelomeningocele. THey both have an abnormal alligment of the occipitable structures of the cranium - the cerebellar tonsils extend down the foramen magnum
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What are the two complications that the chaiari malformations (both one and two share)
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Brain stem compression - central hypventilation syndrome.
Obstructive hydrocephalus |
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What is a syringomyelia
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a CSF filled faulse tract in the spinal colum - associated with the Chiari Malformation
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What is anecephaly
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A neural tube defect that is a malformation of the anterioer end of the neural tube, with the absence of the forebrain. The posterior fossa structures may be spared, depending on the extendt of the skill defect
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What is encephalocele
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CNS tissue that extends through a defect in the cranuim and most offen occurs in the occipital region or in the posterior fossa - or high in the cervial vetebra
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What is a myelomeningocele
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the extension of CNS tissue through a defect in the vetebral colum of nerves and mengines
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What is a meningomyelocele
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extenstion of only menings throughthe veberbral colum.
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T or F
The type 2 chiari malformations have meingomyeloceles associated with them |
false
Myelomeningocele |
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What is the difference between a hydromyelia and a syrinx
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A hydromyelia is a multisegmental expansion of the ependyma lined central canal of the cord and the syrinx is a fluid filledcleft-like cavity in the inner cord
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T or F
syringomyelia and syrinx is the same thing |
T they are synomones for a fluid filled cleft-like cavity in the inner cord
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T or F
Syringobulbia and a syringomyelia are the same thing |
False
A syringobulbia is a cavity that extends into the brainstem |
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What is a dandy-Walker cyst
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An enlarged posterior fossa due to absent or rubimenary anterior cerebellar vermis with a large midline syst that is lined by ependyma - the cyst creates an expanded roofless fourth ventricle in the absence of a normally formed vermis
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What is the end result in a dandy-walker cyst?
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central hypoventilation syndrome - dysplasia of the brain stem nuclei and hydrocephalus (as with all congenital noncommunicating)
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What is communicating hydrocephalus
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All chambers of the ventricular system connect, but absorption at the level of the arachnoid villi is impaired
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What can you assume if you see all dilated ventricles on an head CT?
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that there is communicating hydrocephletis
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What is the subpendymal germinal matrix?
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An area of neuronal and glial precusors in the premature infant that is higly vascular - forms at 24-weeks disapears at 36 weeks - is highly vascular, and there is large amounts of cerebral blood flow. It extends into the ventricles
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What is a intraventricular hemorrhage?
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a hemorrhage in the subependymal germinal matrix that occurs between the 24-36 weeks - can occur due to changes on maps or in changes in osmilarity
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What is preiventricular leukomalacia
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Scar tissue in the ependymional cells from the IVH
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If the bleeding of the subepndymal germinal matrix causes a clot what occurs?
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communicating hydrocephlusis - the reabsorbtion of the cerbral spinal fluid does not occur.
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T or F
Menigitis causes non-communicating hydrocephalus |
faulse
communicating hydrocep. |
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What are the layers of the skull/brain
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Skin, periosteum, bone, epidural space, dura mater, subdural space, arachnoid, subarachnod space, piamatter, gray matter, white matter
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Where are all the places that blood/fluid can accumulate in the brain?
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Above or below the dura
below the arachnoid, or in the paranchyma |
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What does the dura adhear to?
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the skull bone where there are sutures
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what is an epidual hematoma?
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a rupture of the meningeal artery usually associated with skull fracture that leads to accumilation of arterial blood between the dura and the skull. Causes a more dramatic ICP increase, besause it can not spread out - it is confined by the dura's attachment to the sutures
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What is an subdural hematoma?
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a vascular damage that occurs to veins between the brain and the superior sagittal sinus that leads to the accumulation of blood betweenthe dura and the arachnoid . Has more space to fill - not as dramatic ICP increase - slower in apperence
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What kind of hematoma do you see with shaken baby sydrome
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subdural hematomas
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Why would you admit someone to the ICU if they have a small epidual hematoma?
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If the clott of the middle menginal artery ruputers you are in trouble due to the ICP that will occur in the short time span
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What will you see with shaken baby syndrome?
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subdural hematoma from the sudden impact when the body/brain stops jiggling. retinal hemmorhages and eggshell fractures from impact of throwing a kid down
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When will you see intraparachymal hemorrhage?
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An hemorrhagic stroke, an av fistula that ruptures, anyruism
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When does a brain abscess occur?
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When there are direct infection of organisms from extension of adjacent foci, or hematogenous spread
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What foci can contribute to a brain abscess
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mastoiditis, paranasal sinusitis
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What are the "hematogenous" causes of a brain abcess?
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heart lungs or distal bones - the denstishia after a tooth extraction.
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What are the predisposing condtions of a brain abscess
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acute bacterial endocarditis, and cyanotice CHD (R to L shunt where there is a loss of pulmonary filtration of organisms) also immunocompromised people
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What types of organisms cause a brain abscess
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streptococci and staphylococci
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What is a consussion
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a diffuse axonal injury - due to an abrubt change in movement. the neuron becomes sheered whihc results in cytotoxice edema inflamation/puncate hemorrhage and diffues cerebral edema which can be local or global
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How does ceberal edema cause ICP
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The edema increase the water content in the brain - exceeding the point of extra space in the cranium
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What are the two types of ceberal edema
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vasogenic edema and cytotoxic edema
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What is vasogenic edema
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occurs where the bbb is disrupted and there is an increased vasocular permeability, fluid excapes from the intravascular compartment into the intercellular spaces of the brain
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Why can the blood brain barrier absorb extra fluid?
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THe paucity of lymphacities and the close apposition of neuros and glia greatly impars the resorption of the excess extracellular fluid
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Is vasogenic edema localized or generalized?
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both depends on the reason - occurs due to inflmmatory diesase or neoplasms
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What is cytotoxic edema
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Increase in intracellular fluid secondary to neuronal, glial or endothelial cell membrane injury - a generalized hypoxic ischemic insult due to global inflammation or with some intoxocians
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What is the "story" of cebral edema?
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the gyri are flattened and the interventing sulci are narrowed, ventricles are compressed
as the brain expands intracranial pressure increase and herniation of the brain stem may occur |
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What is a cistern
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any opening in the subarachnoid space of the brain created by a separation of the arachnoid and pia mater. These spaces are filled with cerebrospinal fluid. There are many cisterns in the brain
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What is the monroe-kellie principle
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In a fixed container if you incrase the colume you incrase the pressure
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What is subfalcine herniation
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unilateral expansion of a cerebral hemisphere
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What is transtentorial herniation
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cerebral cortex is compresses against the tentorium cerebelli, the third cranial nereve is compressed resulting in pupillary dilation and impariment of ocular movements on the side of the lesion, the posterior artery becomes copressed, hemmorages in the midpreain and pons due to tearing of penetrating veins and arteries
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What is tonsillar hernation
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displacement of the cerebellar tonsials through the foramen magnum causing brainstem compression - chiari malformations
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Signs of elevated ICP
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irritability
depressed LOC behavior changes emesis, ocular movement, stridor, chusing's triad, posturing |
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why would someone have stridor with elevated ICP
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vagal nerve compressed
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What is cushings triad
when do you see it |
hypertension - wide pressure pulses
brady irregualar respirations when the medulla and brainstem is compressed |
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What is brainstem herniation syndrome
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depressed loc
decreased pupil reactivity brain stem dysfunction |
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What is meningoencephalitis?
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Inflamation of the meninges and the brain cells - usually viral but can be bacterial
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What is viral encephalitis
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paraenchymal infection of the brain
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What is encephalomyelitis
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viral encephalitis with involvement of the spinal cord
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What is meningoencepalitis
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viral encephalitis with meningeal inflammation
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Which virus does not lead to meningoencephalitis?
A.) herpes simplex virus 2 B.) Zoster C.) cytomegalovirus D.) Herpes simplex virus 1 |
D
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What is Progressive multifocal leukoencephalopathy PML
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viral encephalitis caused by the JC polyomavirus - infects oligodendrocytes by demyelination. Seen is immuncosuppressed
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What is subacute sclerosing panencephalitis (SSPE)
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a rare progessive clinical syndrome characterized by congnitive decline, spasticyt of limbs and seizues
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Who is at risk for SSPE?
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any one after early age acute infection with mesles
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What are prion dieases
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mutates proteins that can be transmited and look like a bacterial infection
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What kind od disease is creutzfeldt-jakob disease (CJD)
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Prion
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What kind of disease is Gerstmann-Straussler-Scheinker syndrome (GSS)
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Prion
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What kind of disease is fatal familal insomnia
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Prion
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What is bovine spongiform encephalopathy
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Prion - pt gets dementia
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What are mitochondrial Encepalomyopthies
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neuro diseses that cant use O2 for energy so use the pruvaic cycle - have alot of lactic acidemia, psychomotor delays, seziures, extrocoular palsies, weakness with hypotonia
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What is Leigh Syndrome (Subacute Necrotizing Encephalopathy)
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a mitochondrial encephalomypathy
death occurs 1-2 years of life due to brain tissue damage - scar tissue froms |
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What is myoclonic epilepsy and ragged red fibers (MERRF)
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myoclonus seizure disorder, myopathy and ataxia associated with evidence of neuronal loss from the cerebellar system
mytochondrial tRNA involved - affecting mitochondira's protein systhesis Cerebellum becomes attacked |
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What is mitochondrial encephalomyopathy, lactic acidosis, and stroke like episodes (MELAS)
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acute episiodes of neurologic dysfuction congnitive changes and weakness (lactic acidosis)
Blood vessles become involved and spasm - appear stroke like but are reversiable and do not correspond to specific vascular territories |
