Pathoma CNS Flashcards
What’s anencephaly? How would the mom present?
Cranial neural tube defect. Fetal absence of skull and brain. Frog like appearance.
Mom: polyhydramnios and ⬆️ AFP
What are neural tube defects associated with and how are they detected in prenatal care?
Low folate levels prior to conception
⬆️ AFP in amniotic fluid and maternal blood
What’s spins bifida? What are the 3 ways it can present?
Caudal neural tube defect of posterior vertebral arch closure
- Meningocele: cystic protrusion of meninges thru defect
- meningomyelocele: cystic protrusion of meninges and spinal cord thru defect
- Spins bifida occulta: dimple or hair patch overlying defect
What embryo structures from the CNS, ventricles/spinal cord canal and PNS?
CNS: wall of neural tube
Ventricles and spinal cord canal: Lumen of neural tube
PNS: neural crest cells
What’s the most common cause of hydrocephalus in newborns?
Cerebral aqueduct stenosis
What’s cerebral aqueduct stenosis?
Congenital stenosis of cerebral aqueduct (drains 3rd ventricle into 4th) ➡️ hydrocephalus & enlarged head circumference
What’s the flow of CSF in the brain?
CSF is produced by choroid plexus ➡️ lateral ventricles ➡️ foramen of monro ➡️ 3rd ventricle ➡️ cerebral aqueduct ➡️ 4th ventricle ➡️ foramen of luschka (2 lateral) and Magendie (1 middle) ➡️ subarachnoid space
What’s Dandy-walker malformation?
Features?
Congenital failure of cerebellar vermis (separates cerebellar halves) to form
Newborn: enlarged 4th ventricle/ posterior fossa, no cerebellum, hydrocephalus
What’s Arnold-Chiari Malformation? Features?
Congenital downward displacement of cerebellar vermis and tonsils thru foramen magnum
Newborn: hydrocephalus; occurs with meningomyelocele and syringmyelia
What tract carried pain and temperature?
Spinothalamic tract (part of anteriolareral tract)
What does the Spinothalamic tract transport and where are the neurons located?
sPinoThalamic: pain and temperature
1st order neuron: peripheral nerve to posterior horn, cell body in dorsal root ganglion
2nd order neuron: arises from post horn, immediately crosses over anterior what commissure & ascends to thalamus
3rd order neuron: thalamus to cortex
What does the dorsal column/medial lemniscus transport and where are the neurons?
PPTV- pressure, proprioception, touch, vibration
1st order neurons: peripheral nerves to medulla via dorsal column. Cell body in dorsal root ganglion
2nd order neurons: at medulla, crosses over, ascends via medial lemniscus to thalamus
3rd order: thalamus to cortex
What does that lateral corticospinal tract transport and where are the neurons?
Voluntary movement
1st order: cortex pyramidal neurons descend, cross over in medulla pyramids & synapse on anterior motor horn of spinal cord (upper motor neuron)
2nd order: anterior motor horn & synapses on muscle (lower motor neuron)
What does the hypothalamospinal tract transport and where are the neurons?
Sympathetic face input
1st order: from hypothalamus, synapse on T1 lateral horn
2nd order: T1 lateral horn to superior cervical ganglion
3rd order: SVG to eyelids, pupil and face skin
What path runs through the anterior horn of the spinal cord?
lateral corticospinal tract (voluntary movement)
What’s syringomyelia? Where does it usually occur? What’s it associated w/ and what’s lost?
cystic degeneration of the spinal cord (usually at C8-T1 - upper extremities) assoc w/ trauma or Arnold-Chiari malformation
Lost: sensory loss of pain and temperature (spinothalamic tract in the anterior white commissure) in the upper extremities (“Cape-like distribution”)
In syringomyelia what senses are lost vs what’s spared and why?
Lost senses: Pain and temperature b/c lesion is in spinothalamic tract’s anterior white commissure
Spared senses: pressure, proprioception, touch and vibration) b/c part of dorsal column
If syringomyelia expands, what other spinal tracts can become involved and how would they present?
- Anterior horn lateral corticospinal tract: muscle atrophy and weakness w/ decreased muscle tone and reflexes (damaged lower motor neurons)
- Lateral horn hypothalamospinal tract at T1: horner’s syndrome (interrupted sympathetic input to the face)
what’s poliomyelitis and how does it present?
poliovirus infection damages anterior motor horn of spinal column.
Presents w/ lower motor neuron signs (decrease in everything): flaccid paralysis w/ muscle atrophy, fasciulations, weakness, impaired reflexes & negative Babinski sign (downgoing toes)
What’s Werdnig-Hoffman Disease?
How does it present?
AR degeneration of anterior motor horn
Floppy baby w/ death w/in few yrs
What’s ALS? How do the 2 degeneration locations present?
ALS - Amyotrophic Lateral Sclerosis
Degenerative disorder of upper and lower motor neurons of the corticospinal tract
1. Anterior horn degeneration: lower motor neuron signs (decreased everything)
2. Lateral corticospinal tract degeneration: upper motor neuron signs (everything’s increased - spastic paralysis w/ hyperreflexia, increased muscle tone & positive Babinski)
What’s an early sign of ALS? Who gets ALS?
Early sign: atrophy & weakness of hands (no sensory loss)
Most ALS is sporadic in middle-aged adults. Familial mutation: Zinc-copper SOD1 mutation (normally converts superoxide to hydrogen peroxide): free radical injury to neurons
What’s Friedreich Ataxia, what causes it and what are some symptoms?
AR disorder from expanded unstable trinucleotide GAA repeat in Frataxin gene leads to degeneration of cerebellum (leads to ataxia) and spinal cord (leads to loss of vibration, proprioception, lower extremity muscle weakness and loss of reflexes)
What’s the function of Frataxin gene. When does Friedreich ataxia present and what’s it associated with?
Frataxin gene is essential for mitochondrial iron regulation, loss leads to iron buildup w/ free radical damage to cerebellum and spinal cord
Presents in early childhood, wheelchair bound w/in few years
Associated w/ hypertrophic cardiomyopathy
What’s meningitis? How does it present?
inflammation of the leptomeninges (pia & arachnoid)
Presents w/ classic triad: headache, nuchal rigidity and fever. May also present w/ photophobia (MC w/ viral infection), vomiting and altered mental status
What’s the MC causes of meningitis in neonates, nonvaccinated infants, kids/teens, and adults/elderly?
Neonates: “GEL” Group B Strep, E. coli & Listeria monocytogenes (from birthing process)
Nonvaccinated infants: H. influenza
Kids/teens: N. menigitidis (thru nares)
Adults/Elderly: Strep pneumoniae
How do yo diagnose meningitis? How do you differentiate the causitive agents?
CSF via lumbar puncture btwn L4 & L5 (iliac crest level)
Bacterial meningitis: neutrophils w/ decreased CSF glucose (bacteria consume glucose). Gram stain & culture for organism
Viral meningitis: lymphocytes w/ norm CSF glucose (norm CSF glucose = 2/3 serum glucose)
Fungal meningitis: lymphocytes w/ decreased glucose (fungi consume glucose)
What type of meningitis are complications seen w/ and what types?
Bacterial meningitis
Death due to herniation from cerebral edema
Hydrocephalus, hearing loss and seizures related to fibrosis
At what level does the spinal cord, subarachnoid space and cauda equina end?
spinal cord: L2
subarachnoid space and cauda equina: S2
What layers need to be crossed during a lumbar puncture?
“Shiny LEDs Are Sexy”
Skin, Ligaments, epidural space, dura, arachnoid, subarachoind space (where CSF is)
PIA IS NOT PIERCED
what are the 2 major categories/causes of cerebrovascular disease?
- Ischemia (85%)
2. Hemorrhage (15%)
what are the 2 major categories of both ischemic and hemorrhagic cerebrovascular diseases?
Ischemic: 1. Global Cerebral Ischemia (GCI) 2. Focal: Ischemic stroke (symptoms > 24 hrs) or Transient ischemic attach (TIA, symptoms < 24 hrs) Hemorrhagic: 1. Intracerebral hemorrhage 2. subarachnoid hemorrhage
what are major causes of global cerebral ischemia and examples of each?
- low perfusion - ex atherosclerosis
- acute decrease in blood flow - ex cardiogenic shock
- chronic hypoxia - ex anemia
- repeat episodes of hypoglycemia - ex insulinoma
what are clinical features and a example of mild global ischemia?
Mild global ischemia - transient confusion w/ prompt recovery. ex: insulinoma, low glucose, pt confused, give glucose feels better
what are clinical features and an example of severe global ischemia?
severe global ischemia: results in diffused necrosis; survival leads to a vegetiative state
what’s clinical features and an example of moderate global ischemia?
moderate global ischemia: leads to infarcts in watershed areas (regions fed by end of circulation) and damage to highly vulnerable regions
Ex: area lying btwn regions fed by anterior and middle cerebral artery
what regions are highly vulnerable to moderate global ischemia? what would each lead to?
- Pyramidal neurons of cerebral cortex (layers 3, 5 & 6): leads to laminar (lines of) necrosis
- Pyramidal neurons of hippocampus in the temporal lobe: leads to long term memory loss
- Purkinje layer of the cerebellum: loss of integration of sensory perception w/ motor control
what’st the function of the hippocampus and where is it located?
transports information to long term memory
location: temporal lobes
what’s an ischemic stroke? what are the 3 subtypes?
focal regional ischemia to the brain that results in focal neuro deficits lasting > 24 hrs
- thrombotic stroke
- embolic stroke
- Lacunar strokes
what’s a thrombotic stroke, where does it usually occur and what does it result in?
Ischemic stroke due to ruptured atherosclerotic plaque (exposed eubepithelial collagen develops thrombus w/ necrotic debris
Usually occurs at branch points (ex: bifurcation of ICA & MCA in circle of willis)
Results in a pale infarct at periphery of cortex
what’s a embolic stroke, where does it usually occur and what does it result in?
Ischemic stroke due to thromboemboli, usu from L heart (a-fib)
Usu occurs in middle cerebral a (MCA)
Results in hemorrhagic infarct bc thromboemboli is eventually lysed at periphery of cortex
what’s a lacunar stroke, where does it usually occur and what does it result in?
ischemic stroke secondary to hyaline arteriolosclerosis (thick vessels w/ small lumen), a complication of HTN or DM
Usu occurs in lenticulostriate vessels off MCA
Results in small cystic areas of infarction, affecting deep structures of the brain
if a pt suffers from a lacunar stroke involving the internal capsule or thalamus, how would they present?
Internal capsule involvement: pure motor stroke
Thalamus involvement: pure sensory stroke
what are the pathology stages seen in an ischemic stroke?
- Early (12 hrs post infarct): red neurons w/ eosinophilic changes in cytoplasm
- 24 hrs: necrosis
- 1-3 days: neutrophil infiltration
- 4-7 days: microglial cells infiltration (brain macrophages)
- 2-3 weeks: gliosis: reactive atrocytes line the fluid filled cystic space –> liquifactive necrosis
what kind of infarct is seem w/ a thrombotic stroke, embolic stroke and lacunar stroke?
Thrombotic stroke: pale infarct
embolic stroke: hemorrhagic infarct
Lacunar stroke: small cystic infarcts in deep brain structures
what’s an intracerebral hemorrhage and what usually causes it?
bleeding into brain parenchyma
Usu due to Charcot-Bouchard microaneurysms (complications of HTN weakens bv wall) of the lenticulostriate vessels. Basal ganglia is MC site
how does an intracerebral hemorrhage present?
severe headache, nauseau, vomiting and eventually coma. often a complication of HTN which leads to Charcot-Bouchard microaneurysms
what’s a subarachnoid hemorrhage and what usually causes it?
what’s a major complication of it?
bleeding into the subarachnoid space (bleed on brain bottom)
Usu due to ruptured berry aneurysm (medial layer of bv fails to form) from trauma. Also caused by AV malformations and anticoagulated states
Major complication is vasospam a few days layer leading to death
how does a subarachnoid hemorrhage present?
“worst headache of my life” w/ nuchal rigidity
how do you diagnose a subarachnoid hemorrhage?
lumbar punction shows xanthochromia: yellow CSF due to bilirubin breakdown)
“worse headache of my life”
what are berry aneurysms? where are they most likely to form and what are they associated with?
thin-walled saccular outpouching that lacks a media layer of the bv, increasing rupture risk leading to subarachnoid hemorrhage
Usu in anterior circle of willis at branch pts of anterior communicating artery
Assoc w/ Marfan Syndrome & AD polycystic kidney disease
what’s an epidural hematoma? what causes it, how does it present on CT?
Collection of blood btwn dura and skull usu due to fracture of temporal bone (trauma) w/ rupture of Middle Meningeal A.
Lens shaped lesion: bleeding separates dura from skull
how would a pt w/ an epidural hematoma present? what’s a lethal complication?
post-trauma (possibly fractured temporal bone)
Lucid internal may precede neuro signs: feels fine, then gets sleep. Ipsilaterally blown pupil & ipsilateral paresis
Lethal complication: herniation a few days later
