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STEP COPY > CNS Pathoma > Flashcards

CNS Pathoma Flashcards

1
Q

Neural Crest cells form what?

A

Peripheral Nervous System

Melanocytes

Schwann Cells

Neurons

Osteoblasts/Osteoclasts

Adipocytes

Chondrocytes

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2
Q

Flow of CSF in the brain

A

CSF is produced by the choroid plexus lining the ventricles –> Flows from lateral ventricles into the 3rd ventricle via the interventricular foramen of monro –> from third ventricle to fourth via CEREBRAL AQUEDUCT –> 4th to subarachnoid space via the foramina of Magendie and Luschka

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3
Q

Dandy Walker Malformation

A
  • Congenital failure of the cerebellar vermis to develop.
  • Presents as a massively dilated 4th ventricle (posterior fossa) with an absent cerebellum (often accompanied by hydrocephalus)
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4
Q

Arnold-Chiari Malformation (Type II)

A
  • Congenital downward displacement of the cerebellar vermis and tonsils through the foramen magnum
  • Obstruction of CSF flow commonly results in hydrocephalus
  • Often associated with meningomyelocele (type of spina bifida)
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5
Q

Syringomyelia

A

Fluid filled cavity or cystic degeneration of the spinal cord that can arise with trauma or type 1 Arnold-Chiari Malformation

-Usually occurs C8-T1

Involves loss of anterior commissure so see sensory loss of pain and temp with sparing of fine touch and position with “cape-like” distribution

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6
Q

Poliomyelitis

A

Damage to anterior motor horn due to poliovirus infection. Presents with lower motor neuron signs-flaccid paralysis with muscle atrophy, fasciculations, weakness with decreased muscle tone, impaired reflexes, and negative Babinski sign (downgoing toes)

-leading to asymetric weakness

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7
Q

What three things can effect the anterior horn?

A

1. Poliomyelitis: lower motor neuron signs

2. Werdnig-Hoffman Disease: inherited degeneration of the anterior motor horn. AR. Presents as “floppy baby” Symmetric weakness

3. ALS: see LMN signs due to loss of anterior horn. NOTE that also see UMN signs due to loss of lateral corticospinal tract degeneration

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8
Q

Amyotrophic Lateral Sclerosis (ALS)

A
  • Degenerative disorder of UMN, LMN of corticospinal tract.
  • Atrophy and weakness of hands is an early sign. Lack of sensory impairment distinguishes ALS from syringomyelia
  • Most cases are sporatic, arising in middle age adults. Zinc-copper superoxide dismutase mutation (SOD1) is present in some familial cases that leads to free radical injury in neurons

TX: Riluzole

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9
Q

Friedreich Ataxia

A
  • Degenerative disorder of the cerebellum and spinal cord
  • Sx: Ataxia, Loss of vibratory senses and proprioception, muscle weakness in the lower extremities and loss of DTR

AR, due to expansion of an unstable trinucleotide repeat (GAA) in the frataxin gene on Chromosome 9 (essential for mitochondrial iron regulation, loss of which results in iron buildup with free radical damage)

Also associated with hypertrophic cardiomyopathy

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10
Q

Layers of meninges in brain

A

SKULL

DURA

ARACHNOID

PIA

BRAIN (in this order top to bottom). Can be said that there is a PAD over the brain

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11
Q

Leptomeninges

A

Pia and Arachnoid together

Inflammation of the leptomeninges is what is responsible for meningitis

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12
Q

Most common causes of neonatal meningitis (they all make sense!) (3)

A

Group B Strep (from vaginal canal)

E. Coli (from rectum during birth)

Listeria (from placenta)

**Ceftriaxone and Vancomycin empirically

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13
Q

Most common cuase of children 6months-6 years meningitis (4)

A

Strep Pneumo (MOPS)

Neisseria Meningitis (type B)

H. Influenza (type B) (this has DECREASED greatly due to vaccinations)

Enterovirus

**Ceftriaxone and Vancomycin empirically

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14
Q

Most common cause of meningitis in 6year old-60 year old (4, 2 bacteria 2 virus)

A

Strep Pneumo

Neisseria Meningitidis (#1 cause in teenagers, college age kids)

Enterovirus (esp Coxsackie Virus)

HSV (HSV-1 causing encephalitis)

**Ceftriaxone and Vancomycin empirically

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15
Q

Most common cause of meningitis in >60 year olds (3)

A

Strep Pneumo

Gram - Rods

Listeria (remember very old and very young)

*If listeria is suspected, give Ampicillin for tx*

Ceftriaxone and Vancomycin empirically

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16
Q

CSF findings in bacterial vs fungal vs viral CSF

A

Bacterial: neutrophils with decreased glucose (bacteria eat glucose), and gram stain and culture

Viral: lymphocytes with normal CSF glucose (bacteria NOT eat glucose)

Fungal/TB: lymphocytes with decreased glucose

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17
Q

Overview of cerebral vascular disease

A

Neurologic deficit due to cerebrovascular compromise

85% ischemia

15% hemorrhage

Neurons are dependent on serum glucose as an essential energy source and are susceptible to ischemia (undergo necrosis within 3-5 minutes)

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18
Q

Global Cerebral Ischemia

A
  • From low perfusion (atherosclerosis), acute decrease in blood flow (cardiogenic shock), chronic hypoxia (anemia), repeated episodes of hypoglycemia (insulinoma)
  • Mild: transient confusion with prompt recovery
  • Moderate: leads to infarcts in watershed areas (area lying between regions red by anterior and middle cerebral artery)
  • Severe: diffuse necrosis. survival in vegetative state
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19
Q

Laminar necrosis

A

Pyramidal neurons of the cerebral cortex (layers 3,5,6) leadings to laminar necrosis.

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20
Q

Thrombotic Stroke (subtype of ischemic)

A
  • Due to rupture of atherosclerotic plaque
  • Atherosclerosis usually develops at branch points (bifurcation of internal carotid and middle cerebral artery in the circle of Willis)
  • Results in a pale infarct at the periphery of the cortex
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21
Q

Embolic Stroke (subtype of ischemic)

A
  • Due to thromboemboli
  • Most common source is from the Left Atrium (from AFIB)
  • Usually involves the middle cerebral artery. Results in hemorrhagic infarct in the periphery of the cortex
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22
Q

Lacunar Stroke

A

Occurs secondary to hyaline arteriolosclerosis, a complication of hypertension

Most commonly involves the lenticulostriate vessels, resulting in small cystic areas of infarction

  • Involvement of the internal capsule leads to a PURE MOTOR stroke.
  • Involvement of the thalamus leads to a PURE SENSORY stroke
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23
Q

Necrosis associated with ischemic stroke and the timing (12h, 24h, 1-3d, 4-7,d 2-3w)

A

Liquefactive necrosis

12 hours: RED neurons due to eosinophilic changes in the cytoplasm of neurons

24 hours: NECROSIS

Days 1-3: Neutrophils

Days 4-7: Microglial cells

Weeks 2-3: Gliosis

24
Q

Intracerebral Hemorrhage

A

Bleeding in the brain parenchyma

Classically due to rupture of Charcot-Bouchard microaneurysms of the lenticulostriate vessels

-Complication of HTN

-Basal ganglia most common site

Presents as severe HA/N/V coma

25
Q

Subarachnoid Hemorrhage

A

Bleeding into the subarachnoid space

Presents as sudden “WORST HA OF LIFE” w/ nuchal rigidity

LP shows Xanthochromia (yellow hue due to bilirubin)

85% due to rupture of Berry Aneurysms, or can be AV malformations and an anticoag state

  • Berry aneuryms lack a media layer, which increases risk of rupture
  • Most frequently in anterior circle of willis at branch points of the anterior communicating artery

Associated with Marfan and AD PKD

26
Q

Epidural Hematoma

A

Collection of blood between dura and skull

Classically due to fracture of temporal bone with rupture of middle meningial ARTERY***

The bleeding separates the dura from the skull (need a high force to separate these two)

  • Lens-shaped lesion on CT
  • Lucid interval may precede neurologic signs
27
Q

Subdural Hematoma

A

Collection of blood underneath the dura, blood covers the surface of the brain

Due to tearing of BRIDGING VEINS that lie between the dura and arachnoid. Usually arise with trauma

CRESCENT SHAPED

Presents with progressive neurologic signs.

28
Q

Three types of herniation

A

Displacement of brain tissue due to mass effect or increased ICP

  1. Tonsillar Herniation: displacement of cerebellar tonsils into foramen magnum
  2. Subfalcine Herniation: displacement of cingulate gyrus under the falx cerebri
  3. Uncal Herniation: displacement of temporal lobe uncus under tentorium cerebelli
    - compression of CNIII (down and out eye)
    - compression of posterior cerebral artery leads to infarction of occipital love
    - rupture of paramedian artery leads to Duret (brainstem) hemorrhage
29
Q

Metachromatic leukodystrophy (leukodystrophy = inherited mutation in enzymes nexessary for production or maintenance of myelin)

A

Due to deficiency of arylsulfatase. AR. Most common leukodystrophy

-Sulfatides cannot be degraded and accumulate in the lysosomes of oligodendrocytes (accumulation of cerebroside sulfate)

30
Q

Krabbe Disease

A

Due to deficiency of galactocerebrsidase. AR. Galactocerebroside accumulates in MACROPHAGES

-peripheral neuropathy, developmental delay, optic atrophy, globoid cells

31
Q

Adrenoleukodystrophy

A

X-linked genetic disorder typically affecting males. Disrupts metabolism of very-long-chain fatty acids excessive buildup in nervous system, adrenal gland, testes. Progressive disease that can lead to long-term coma/death and adrenal gland crisis.

-Impaired addition of coenzyme A to long chain fatty acids

32
Q

MS is associated with which HLA

A

HLA-DR2

33
Q

Diagnosis of MS

A
  • Made by MRI and LP
  • MRI reveals plaques (areas of white matter demyelination)
  • LP shows increased lymphocytes, increased immunoglobulins with oligoclonal IgG bands on high resolution electrophoresis
34
Q

Progressive Multifocal Leukoencephalopathy

A

JC virus infection of oligodendrocytes

Immunosuppression (AIDS, Leukemia) leads to reactivation of the latent virus

Presents with rapidly progressive neurologic signs

Happens when CD4<200 (start prophalactic TMP-SMX)

Increased risk associated with natalizumab, rituximab.

35
Q

Alzheimer Disease General Principle

A

APP is a receptor that is cleaved and broken down. If cleaved by alpha, OK. If cleaved by beta, results in AB amyloid that deposits in brain

Results in widened sulci, narrowing gyri, dilation of ventricles (hydrocephalus due to loss of parenchyma)

  1. Neuritic Plaques: AB amyloid from APP (chr 21) that underwent Beta cleavage
  2. Neurofibrillary tangles: intracellular aggregates of fibers composed of hyperphosphorylated tau proteins. Tau is a microtubule-associated protein
  3. Loss of Cholinergic neurons in the nucleus basalis of Meynert
36
Q

Alzheimer Genetics

A

Early or Sporatic

Early: due to familial cases associated with presenilin 1 and 2 mutations. Also seen in Down Syndrome due to chr 21 having APP

Sporatic (95% of cases): risk doubles every 5 years after the age of 60. E4 allele of apolipoprotein (APOE) is associated with increased risk, E2 allele with decreased risk

37
Q

Vascular Dementia

A

Multifocal infarction and injury due to hypertension, atherosclerosis or vasculitis

2nd most common cause of dementia

Step-wise decline in cognitive ability with late- onset memory impairment

*essentially a concequence of moderate global cerebral ischemia*

38
Q

Frontotemporal Dementia (Pick Disease)

A

Degenerative disease of the frontal and temporal cortex, spares the parietal and occipital lobe

  • Characterized by round aggregates of tau protein (Pick bodies) in neurons of the cortex
  • Behavioral and language symptoms arise early
39
Q

Parkinson Disease pathophys

A
  • Degenerative loss of dopaminergic neurons in the substantia nigra of the basal ganglia
  • The nigrostriatal pathway of basal ganglia uses dopamine to initiate movement

Rare cases due to MPTP exposure (illicit drugs)

40
Q

Parkinson Disease treatment

A

Want to get more DA.

BALSA.

Bromocriptine (DA agonist)

Amantadine (decrease reuptake, also used in infleunza)

Levodopa (with carbidopa)

Selegiline (and COMT inhibitors block breakdown of DA)

Antimuscarinics

41
Q

Clinical features of Parkinson

A

TRAP

T: Tremor- pill rolling tremor at rest, not seen with movement

R: Rigidity - cogwheel rigidity in the extremities

A: akinesia/bradykinesia - slowing of voluntary movement, expressionless face

P: postural instability and shuffling gate

42
Q

Histology of parkinson disease

A

-Loss of pigmented neurons in substantia nigra and round, eosinophilic inclusions of alpha-synuclein (Lewy bodies)

43
Q

Huntington Disease

A

Degeneration of GABAergic neurons in the caudate nucleus of the basal ganglia

  • AD Chr 4 expansion of CAG in huntingtin gene
  • Anticipation (due to further expansion of the trinucleotides in spermatogenesis)
  • Presents with chorea that can progress to dementia and depression
44
Q

Normal Pressure Hydrocephalus

A

Increased CSF resulting in dilated ventricles

-Can cause dementia in adults

Classic Triad:

1. Urinary Incontinence

2. Gait instability

3. Dementia

“Wet-Wobbly-Wacky”

45
Q

What happens with spongiform encephalopathy to the prions

A

Normal: in alpha-helical configuration PrPc

Abnormal: conversion to a b-pleated conformation PrPsc

46
Q

Creutzfeldt-Jacob Disease (CJD)

A

most common spongiform encephalopathy

Usually sporatic: rarely can arise due to exposure to prion-infected human tissue (HGH or corneal transplant)

-Presents as RAPIDLY PROGRESSIVE DEMENTIA associated with ataxia and startle myoclonus

Variant CJD: Mad cow disease. exposure to bovine spongiform encephalopathy

47
Q

Basic principles of CNS tumors

A

50% metastatic/50% primary

Lung, Breast, Kidney are common sources

Adults are primarily supratentorial (glioblastoma, meningioma, schwannoma)

Kids are primarily infratentorial (pilocytic astrocytoma, ependymoma, medulloblastoma)

48
Q

Glioblastoma Multiforme (GBM)

A

-Malignant, high-grade tumor of astrocytes

Most common primary malignant CNS tumor in adults

Usually arise in the cerebral hemisphere, characteristically cross the corpus callosum (butterfly appearance)

Regions of necrosis surrounded by tumor cells (pseudopalisading) and endothelial cell proliferation

GFAP +

49
Q

Meningioma

A

Benign tumor of arachnoid cells

MOST COMMON BENIGN CNS tumor in ADULTS

W>M

Present as seizures as tumor compresses cortex (not invade)

Round mass attached to the dura

Whorled Pattern w/w/o psammoma bodies

50
Q

Schwannoma

A

Benign tumor of schwann cells

Invades cranial or spinal nerves within the cranium. Most frequently involves cranial nerve VIII at the cerebellopontine angle (presents as loss of hearing and tinnitus)

Tumors are S-100 + (neural crest)

Bilateral tumors seen in neurofibromatosis type 2

51
Q

Oligodendroglioma

A

Malignant tumor of oligodendrocytes

Calcified tumor in white matter, usually involving the frontal lobe, may present with seizures

Fried-egg appearance of cells on biopsy

52
Q

Pilocytic Astrocytoma

A

Benign tumor of astrocytes

Most common CNS tumor in CHILDREN, usually arise in cerebellum

Imagine reveals a cystic lesion with a mural nodule

Biopsy shows Rosenthal fibers (thick eosinophilic processes of astrocytes)

GFAP+

53
Q

Ependymoma

A

Malignant tumor of ependymal cells (cells that line ventricles), usually seen in children

Most commonly arises in the 4th ventricle, may present with hydrocephalus

Perivascular pseudorosettes are characteristic finding

54
Q

Medulloblastoma

A

Malignant tumor derived from the granular cells of the cerebellum (neuroectoderm)

Usually arise in children

Histology reveals small, round blue cells

Homer-wright rosettes may be present

Poor prognosis. tumor grows rapidly and spreads via CSF via 4th ventricular space

If mets to cauda equina called “drop metastasis”

55
Q

General overview of where the types of CNS tumors originate

A
56
Q

Craniopharyngioma

A

Tumor that arises from epithelial remnants of Rathke’s Pouch (anterior pituitary)

Presents as a supratentorial mass in a young adult. May compress the optic chiasm leading to bitemporal hemianopsia

Calcifications common seen on imaging (derived from tooth-like tissue)

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