Robbins Ch 29- CNS Disorders Flashcards
Define cerebral edema
excess fluid (increased volume) within or around the brain parenchyma
What are the pathogenesis for cerebral edema?
- Vasogenci edema - bleeding within brain due to BBB fails and others
- Cytotoxic edema = cells swell and die due to hypoxia/ischemia or other
- Interstitial - CSF gets squeezed into brain due to obstructive hydrocephalus , faulure of CSF-brain barrier
- Osmotic - brain sucks the water up due to excess water intake or hyponatremia
morphologically how does cerebral edema appear?
gyri flatten, sulci narrow, ventricles get compressed.
What are the major types of herniations due to raised ICP?
Subfalcine herniation
Transtentorial herniation
Tonsilar herniation
What is subfalcine herniation?
Subfalcine herniation = cingulate gyrus.
- unilateral expansion of cerebral hemisphere displaces the cingulate gyrus under the falx cerebri, compressing pericollosal arteries (arteries of corpus callosum) and anterior cerebral circulation
What is transtentorial herniation and what clinical signs?
Aka uncal herniation. Medial aspect of temporal lobe goes through the tentorium cerebelli. CN III compression = ipsilateral pupil dilation and eye paralysis.
- Compression of PCA = infarc of visual cortex
Compression of contralateral penducle = ipsilateral hemiparesis (relative to herniation); called Kernohan’s notch
what is tonsilar herniation and what are some clinical signs?
Aka cerebellum herniation.
- fatal herniation of cerebellum through the foramen magnum. can compress brainstem and lead to death
what are some causes of hydrocephalus?
- increased production, normal outflow = cancer of choroid plexus
- normal production, decreased outflow = ventricular mass/obstruction
- Normal production, decreased resorption = arachnoid impairment
What is communicating hydrocephalus?
enlargement of all the ventricles. Due to functional impairment of the arachnoid granuloations. Can be due to subarachnoid bleed, meningitis, pacchioni granulation (agnesis)
What is noncommunicating hydrocaphlus?
If not all ventricles enlarged. Due to a functional obstruction, usually hemorrhage or tumor. ventricles proximal to obstruction are enlarged, distal are shrunken . it’s common in foramen of monrue
what is hydrocephalus ex vacuo?
Increased volume of CSF from loss of parenchyma. Basically CSF expands to fill in the space left by surgery/degeneration. Seen in tumor resection, Alzheimer’s and other degenerative disease
Neural tube defect has been linked to deficiency in _ in initial weeks of gestation.
Folate
What is anencephaly?
anterior neural tube defect, no brain. incompatible with life, occurring around day 28 gestation.
replaced by area cerebovascuolsa which is a flattened remnant of brain tissue
What is encephalocele?
protrusion of brain through a defect in skull. Protruding part is destroyed by mechanical disruption or ischemia.
What is Spina bifida?
Most common neural tube defect; failure of closure of caudal aspect usually occurring in the lumbosacral region.
Differentiate between oculta, meningocele and myelomeninogcele.
Occulta = no spine closure, Tuft of hair Meningoele = no spine closure, meninges attah to skin, CSF enlarge and bulges, spinal cord normal Myelomeningocele = no spine closure, meninges attach to ski, SCF enlarge and bulges, spinal cord exposed
What are some examples of forebrain abnormalities?
- Lissencephaly/agyria
- Polymicrogyria
- Mega and micro encephaly
- Holoprosencephaly
- Agenesis of the corpus callosum
What is Lissencephaly/Agyria?
“smooth brain”
Thick cortex with the absence of cortical sulci. Gray matter made of 3 layers instead of normal 6. Leads to pscyhomotor retardation + seizures
What is polymicrogyria?
- excessive number of small gyri. Grey matter is composed of 4 layers or less –> retardation + seizures
- can be induced by localized tissue injury during neuronal migration.
What are some common associated risk factors of microencaphly?
fetal alcohol syndrome, chromosomea abnormalities, HIV.
Migration dependent on chemical and physical signals that can go awry altering size and structure of brain parenchyma. Trapped bundles of migrating nurons is called neuronal heterotopias.
What is Holoprosencephaly?
Failure of cerebral hemisphere to separate = one giant lobe.
- associated with diabetic moms, trisomy 13, sonic hedge hog.
- can produce one ventricle, one nostril and one eye and other less severe events.
What is the cause of agenesis of corpus collaosum and what is the consequence?
- absence of white bundle fibers connecting the hemispheres, replaced by adipose tissue.
- mutation of L1 cell adhesion molecule. (neuronal migration)
- can be radiologically demonstrated as bat-wing ventricles.
What are some diseases associated with posterior fossa malformation?
- Arnold-chiari malformation
2. Dandy-Walker malformation
What is Arnold-chiari malformation?
- small posterior fossa + mishapen cerebellum + vermis of cerebellum extending throguh foramen magnum (herniation)
- associated with hydrocephalus and lumbar myelomeningocele
multple types, type II is the most common
What is dandy-walker malformation?
A type of posterior enlarged fossa malformation + absent ecrebellar vermis + midline cyst. Cyst is expanded 4th ventricle that usually is restricted by vermis. Dysplasia of brain stem is common, pt presents with mental retardation
What is Syringomyelia and hydromyelia?
Either an expansion of the central canal of the cord (hydromeylia) or the formation of a cleft-like cavity in the inner portion of the cord (syringomyelia).
- usually occurring in the cervical vertrbrae these compress and damage nearby nerves, essentially eating a functional hole from the inside out.
- Associated with arnold-chiari malformation, traumatic injuries, spinal tumors.
- symptoms occurring in a cape-like fashion
- destroys the anterior spinal commissure then ascending ALS fibers.
What is the significance of intraparenchymal hemorrhage/Germinal matrix hemorrhage?
Germinal matrix is present only in the fetal and neonatal brain around the ventricles. Hypoxia/ishcmia during delivary can cause bleeding in this region. It’s dividied into 4 grades: G1 = germinal matrix only. G2 = germinal matrix + ventricles w/o hydrocephlaus/dilation
G3= germinal matrix + ventricles with hydrocephalus
G4 = germinal matrix + ventriclces + parenchyma
what is periventricular leukomalacia?
infarcts occurring in white matter near to the ventricles, esp in premature babies.
- chalky yellow plaques consisting of discrete regions of white matter necrosis and mineralization (calcification)
What is multicystic encephalopathy?
Extensive version of periventricular leukomalacia involving both gray and white.
- Large cystic lesions throughout both hemisphere
- peirventricular leukomalacia = white matter only, small lesion
- multicystic encephalopathy = grey and white, large cystic lesions
What is ulegyria?
Ischemic injury occurring in cerebral cortex resulting in thinned-out gliotic gyri termed ulegryia
-Mushroom-shaped gyri
What is status marmoratus?
- basal ganglia and thalamus suffer ischemic injury and result in neuronal loss and reactive gliosis
- Later, with myelination, aberrant and irregular myelin formation gives rise to a marble-like appearance of the deep nuclei
What are some signs and symptoms of a basal skull fracture?
- occurs from occiput or lateral damage (fall of a ladder)
- symptoms = lower CN + cervicomedullary defects
- Get battle sign (swelling and discoloration of the mastoid) and raccoon eyes. (periorbital ecchymosis, aka double black eyes)
Clinical syndrome of altered mental status following a change in the momentum of the head. This is a type of parenchymal injury known as _
concussion
What transient neurologic dysfunction are common with concussion that usually recovers completely.
loss of consciousness, loss of reflexes, and a persistent amnesia
What are two types of direct parenchymal injury?
Contusion - brain bruise
Laceration - penetration of an object into the tissue
what is coup and ontracoup injuries?
they are direct parenchymal injuries such as contusions and laceeration. Coup is injury at the site of impact. contracoup is injury at the opposite of the point of impact. Contracoup injury is usually injury to the brain when the head was in motion.
In epidural hematoma: A. what artery? B. What side of brain? C. how does it appear on CT? D. what is the progression?
A. MMA
B. temporal trauma
C. lens, ellipical
D. Clinically lucid interval just prior to rapid progression to death
In subdural hematoma A. between what laters does it form? B. What vessel is involved? C. Which vessels are at highest risk in elderly? D. how does it appear on CT?
A. between dura and subarachnoid
B. Bridging veins and dural sinuses
C. Superior sagital sinus
D. Crescent
What are some sequelae of brain trauma?
- Post traumatic hydrocephalus from ventricular outflow obstruction
- Post traumatic dementia - comes from repeated, protected injury showing diffuse axonal injury, thinning of corpus callosum, and positive alpha beta fibers (AD)
- Others include epilepsy, tumors, infections and psychiatric disorder
What are the three major categories of causes of cerebrovascular disease?
- Stroke
- Vascular malformation
- HTN changes
What are two main types of stroke?
- Ischemic
2. hemorrhagic
In ischemia, which CNS cells die first?
neurons in the hippocampus CA1
For each of the following signs, indicate whether it’s coma vegetative state or brain death.
- positive reflexes, breathing, EEG, and negative consciousness
- Positive reflexes and breathing, but negative EEG
- negative reflexes, and breathing, but positive heartbeat
- Coma
- Vegetative state
- Brain death
Morphologically, in a global cerebral ischemia indicate the changes seen 12-24hrs, 24hrs- 2weeks, and 2 weeks and beyond.
Early changes: 12-24 horus: red neurons
Subacute changes: 24hrs-2 weeks: necrosis, macrophages, vascular proliferation, gliosis
3. 2 weeks and beyond = removal of necrosis, gliosis completed, loss of CNS architecture
What are watershed infarcts? Give example
- wedge-shaped infarcts at regions distal to vascular supply, often between two areas of perfusion = border zone.
- Particular form of infarct associated with hypoperfusion (opposite to blockage or bleed)
- example is between anterior and middle cerebral zone. There is no collateral circulation between these
During an infarction from obstruction,
A. how long till irreversible cell death?
B. Which receptors are responsible for cell death due to Ca influx after an ischemic event?
C. Which component of CNS is MOST susceptible?
A. 4-6 minutes
B. GLutamate activating NMDA receptors
C. peripheral gray matter
Due to atherosclerosis, Which CNS arteries are most susceptible for thrombosis?
Carotid bifurcation, MCA and Basilar artery
CNS arteritis is associated with which infectious disease?
- symphilis or TB
- oppotunistic infection with CMV, aspergillus, Toxoplasmosis
CNS primary angiitis is due to_
inflammation + giant cells in small to large arteries
What is cerebral amyloid angiopathy?
- Alzheimer’s protein Abeta deposits in vessels which weakens walls and increases risk of hemorrhage. ApoE has been linked to CAA and Alzheimer’s
What are the common causes of Focal cerebral ischmeia?
- Thrombosis - atherosclerosis
- Arteritis - infection
- Primary angiitis - inflammation
- Cerebral amyloid angiopathy - Alzheimers
Cerebral embolism is usually arrived from _
heart, mural embolis.
What are shower emboli?
Fat emboli that disperse and go all over the place, resulting in multiple, diffuse infarcts.
What is the most common cause of intracerebral (intraparenchymal) hemorrhage?
Hypertension. Causes hyaline changes in arterioles, sometimes with frank necrotization of the arterioles.
What is charcot-bouchard Microaneurysm and where do they usually occur?
They are a form of intracranial hemorrhage, minute hemmrhages cuased by HTN, appear in region supplied by small penetrating arteries especially in basal ganglia
Most commonly intracranial hemorrhage originates in what part of the brain?
Putamen
What are some common signs of intracranial hemorrhage?
- increased intracranial pressure
- headache,
nausea
projectile vomitting
-focal lesions
What is the most common cause of subarachnoid hemorrhage?
Rupture of a berry saccular aneurysm.
Subarachnoid hemorrhage due to ruptured saccular aneurysm is highly associated with what other genetic disorders?
- Autosomal dominant polycystic kidney disease
- Marfan’s or Ehler’s Danlos
- Coarctation of aorta
Saccular aneurysm are usually located in what portion of circle of willis?
Anterior circulation
What are some common vascular malformations?
- Arteriovenous malformation
- Cavernous hemangioma
- Capillary Telangectasis
- Venous angiomas (aggregates of venous channels)
What is arteriovenous malformation and what are some signs and symptoms?
It is a form of vascular malformation where arteries are connected to veins without an intervening capillary bed. They resemble a tangled worms with prominent, pulsatile, high flow AV shunt. They cause Seizures and hemorrhages
What is cavernous hemangioma? What are some signs and symptoms
Distended, loosely organized, low flow vasculature with thin collaginized walls devoid of intervening nervous tissue. They usually occur in cerebellum, pons, subcortex.
Causes seizures and hemorrhage.
What were capillary telangectasis usually occur?
Usually in the pons. It’s essentialy hemaniomas with inerveningbrain parenchyma. Usually asymptomatic
What are some common hypertensive vascular diseases?
- Hypertensive cerebral hemorrhage
- Lacunar infarcts
- Slit Hemorrhage?
- Hypertensive encephalopathy
Relating to Lacunar infarcts:
A. what is it caused by?
B. Where they do they usually occur?
A. HTN affecting the blood vessels that supply the basal ganglia and white matter developing arteriolar sclerosis that may become occluded. Forms small, multiple, cavitary infarcts
B. Thalamus, internal capsule, deep white, caudate, and pons. Caused by occlusion of small penetrating arteries in these regions
What is slit hemorrhage?
When HTN causes a hemorrhage due to rupture of small penetrating arteries. Grossly, when the when hemorrhage resolve, they leave slit like cavities. Microscopically they appear with focal tissue destruction, pigment-laden macrophages, and gliosis
What are some signs and symptoms of hypertensive encephalopathy?
- Dementia, loss of function, gait defects
- cerebral dysfunction, headache, confusion, vomitting, coma
Which artery is most vulnerable of embolic cerebral infarcts?
Middle cerebral artery
Which regions of the brain are most affected by hypotensive watershed infarcts?
Deep cortical areas such as hippocampus CA1, cerebellar purkinje, cortical pyramidals
Categorize thrombolic and embolic cerebral infarcts based on morphology
Thrombotic: nonhemorragic/white/pale infacts
Embolic: hemorrhagic/red infarcts
What is the most common artery that is ruptured in subarachnoid hematoma caused by ruptured berry aneurysm?
Anterior communicating artery
A subfalcine herniation can compress anterior cerebral artery causing visual disturbances on which side, Ipsi/contralateral?
Contralateral side.
A patient presents with pupillary dilation and paralysis of extraocular muscles; visual deficits; hemiparesis. On CT small linear of bleeding is seen around midbrain and upper pons. What is the most likely diagnosis?
Transtentorial (uncal) herniation
What are the two main types of acute meningitis?
- Acute pyogenic meningitis = Bacterial
2. Acute aseptic meningitis = viral
What organism is known to cause acute pyogenic meningitis? Categorize by age group
Neonates = E coli, graph B strep Adolescents = N. Meningiditis with possible pandemic spread Elderly = strep pneumo and Lissteria monocytogenes .
Strep Pneumo is most common overall
What are some clinical signs of meningitis?
headache, photophobia, neck stiffness, confusion.
In an acute pyogenic meningitis, describe how spinal tap findings would look.
Cloudy, purulent, increased pressure CSF with neutorphils. INCREASED proteins and decreased glucose
In an acute aseptic meningitis, describe how CSF findings would look
Normal sugar, increased protein, no purulence in CSF.
What is the most common causative agent of aseptic meningitis?
Enterovirus: echovirus, coxsaievirus, nonpralytic polio
What are some common conditions associated with focal supparative infections?
- Brain abscess
- Subdural empyema
- Epidural abscess
Morphologically, how is brain absces described?
descrete lesions with central liquefactive necrosis surrounded by a fibrous capsule found within brain parenchyma.
what are the most common causative agents and route of spread to cause brain abcess?
Most common cause is strep and staph. those cause endocarditis and infects lungs (bronchiectasis) and they can spread to brain. Also can spread due to R–> L shunts
what is subdural empyema and how is it spread?
Emergent collection of pus between dura and arachnoid. infected bones or hair spread to the dural space; arachnoid is spared. Can produce mass effect or spread into veins causing occlusion and infarction.
Epidural abscess is associated with infection of what?
Osteomyelitis. Pott’s Puffy tumor can lead to osteomyelitis.