CNS Flashcards
Cause of neural tube defects?
Low folate prior to conception
What is elevated AFP seen in ?
Neural tube defects
What does failure of posterior vertebral arch cause?
Spina bifida
Foramen of monro?
CSF from lateral to third ventricle
Cerebral aqueduct?
Drains 3rd - 4th ventricle
Presentation of aqueduct stenosis?
Enlarging head circumference in infant
Dandy walker?
- Failed cerebellar vermis
- Dilated 4th
- Absent cerebellum
Arnold chiari?
Cerebellar tonsils through foramen magnum
Type 1: asymptomatic
Type 2: obstructed CSF flow
Cause of syringomyelia?
Cystic degeneration of spinal cord from:
- Trauma
- Arnold chiari
Where does syringomyelia usually occur?
C8 - T1
Presentation of syringomyelia?
- Loss of pain and temp
- Intact proprioception
- LMN signs in expands to lower motor horn
- Horner’s if lateral horn knocked out
* **STT knocked out as this crosses in center where syrinx is DCP is preserved as syrinx is not hitting dorsal spinal cord
What occurs is syrinx knocks out lateral horn?
Horner’s
Polio?
Anterior motor horn damage = LMN signs
- Atrophy
- Weakness
- Flaccid paralysis
- Imparied reflexes
What is werdnig hoffman?
“Floppy baby syndrome”
Inherited degeneration of anterior motor horn: presents just like polio buy in baby
What is ALS?
- ## Degenerative UMN and LMN (think ALS is hitting “all the motor horns”)
Destruction of what causes UMN and LMN signs?
LMN: anterior motor horn
UMN: lateral corticospinal tract
What is atrophy / weakness of hands early sign of?
ALS
How to tell ALS form syringomyelia?
In ALS, there is not loss of pain and temperature sensation
Cause of familial ALS?
Zinc-copper superoxide dismutase mutation
What is SOD?
“Superoxide dismutase”
- Converts Oxide to hydrogen peroxide to prevent free radical damage
- Loss of enzyme implicated in familial cases of ALS
What is friedreich ataxia?
- Degeneration of spinal cord and cerebellum:
1. Ataxia: cerebellar
2. Vibratory / proprioceptive loss
3. Lower extremity weakness
4. Absent DTRs
5. HOCM
Cause of freidrichs?
AR: GAA repeat in frataxin gene
- Responsible for iron regulation if out of order leads to ROS via fenton rxn
What are the leptomeninges?
“Light meninges”
- Pia and arachnoid that surround brain - what is inflamed in meningitis
Meningitis in non vaccinated infant?
H flu
Viral meningitis?
Coxsackie
Meningitis presentation?
- Headache
- Neck stiffness
- Fever
- Vomit
- Photophobia
Where is lumbar puncture?
L4-5: iliac crest
- Cord ends at L2 and we dont want to hit this
- Trying to hit subarachnoid that continues lower
What does LP go through?
Skin Ligaments Epidural Dura Arachnoid ***DO NOT pierce pia
LP fluid diagnosis?
Bact: Neuts, low glucose
Viral: Lymph, normal glucose
Fungal: Lymphocytes, low glucose
CV ischemia or hemorrhage more common?
Ischemia
Mild global ischemia?
Transient confusion with complete recovery: seen in insulinoma dropping brain sugar
Severe global ischemia?
- Brain necrosis from ischemia - death or coma
What does moderate global ischemia cause?
Watershed infarct
What are pyramidal neurons?
- Layers 3/5/6 of cortex
- Highly vulnerable to ischemia “cortical laminar necrosis”
Areas vulnerable to moderate global?
- Pyramid 3/5/6 “cortical laminar necrosis”
- Pyramid of hippocampus
- Cerebellar purkinjes
Difference in transient ischemic attack and stroke?
TIA:
Cuase of pale and hemorrhagic infarct in stroke?
Pale: thrombosis
Hemorrhagic: embolism
Most common source of embolic stroke?
Afib LA: to MCA
What is lacunar stroke?
- Hyaline arteriolosclerosis in small vessels of brain
- Most often in lenticulostriate vesicles feeding deep structures of brain
Microscopic progress of ischemic stroke?
Liquefactive necrosis in following steps:
- Red neurons: 12 -24 hours
- Neuts / microglia / granulation tissue (week)
- Fluid cyst surrounded by gliosis (Month)
What is gliosis?
Reactive astrocytes lining cystic space
What are microglials?
Macs in brain
Common cause of intracerebral hemorrhage?
- Rupter of charcot bouchard microaneurysm from HTN
- Usually impact basal ganglia
- Also are occurring in lenticulate from atherosclerosis weakening walls
Most common area impacted by charcot bouchard microaneurysm?
Basal ganglia
Worst headache with xanthochromia on LP?
Subarachnoid
- Usually from berry in anterior willis at branch of anterior communicating artery
What does Berry lack?
Medial layer
2 berry aneurysm associations?
- Marfan’s
2. ADPKD
What is epidural hematoma?
- Collection of blood on top of dura
- From temporal bone fracture and rupture of MMA
- High pressure surface so bleeds fast
- Lense shaped lesion
What is talk and die syndrome?
Epidural hematoma
- Herniation of the hematoma causing this as the artery a is a high pressure circuit
Tonsillar herniation?
- Cerebellar tonsils through magnum compressing brain stem
* Cardiopulmonary arrest
Subfalcine herniation?
Cingulate gyrus herniates under falx cerebri (butt crack of brain) compressing ACA
Uncal herniation?
Uncus of temporal lobe between cerebellum and brainstem causing:
- CN 3 compression: down and out with dilated pupil
- PCA compression: occipital infarct
- Pull on marmedian a.: brainstem hemorrhage
What happens if CN3 compressed?
Down and out dilated pupil
What myelinates axons?
CNS: oligodendrocytes
PNS: Schwann
What happens in demyelinating disorders?
- Preserved axons with destruction of oligos or myelin
- Conduction velocity is greatly impaired
What is leukodystrophy?
- Impairment of enzymes necessary to make myelin
What is metachromatic leukodystrophy?
- Arylsulfatase deficiency: cannot degrade myelin so it accumulates in lysosomes
What is following:
Arylsulfatase deficiency: cannot degrade myelin so it accumulates in lysosomes
Metachromatic leukodystrophy