8. Intro To Neuropathology Flashcards
How do microorganisms gain entry to CNS?
Direct spread - e.g. middle ear infection, base of skull fracture
Blood-borne - e.g. sepsis, infective endocarditis
Iatrogenic - e.g. V-P shunt, surgery, lumbar puncture
What are the 2 main bacteria which cause neonatal meningitis?
E.coli
L.monocytogenes
What is the main causative organism of meningitis in 2-5years?
H.influenzae ty B
What is the most common causative organism of meningitis in 5-30years?
N.meningitides
What is the main causative organism of meningitis over 30 years?
S.pneumoniae
What is the causative organism of chronic meningitis?
M.tuberculosis
What are the local complications of meningitis?
Death Cerebral infarction - neurological defect Cerebral abscess Subdural empyema Epilepsy
What happens in prion disease?
PrP aggregates - causes neuronal death and holes in grey matter
What is the definition of dementia?
Acquired global impairment of intellect, reason and personality without impairment of consciousness
What happens pathologically in Alzheimer’s disease?
Loss of cortical neurones - decreased brain weight, cortical atrophy
Due to increased neuronal damage - neurofibrillary tangles, senile plaques
What are neurofibrillary tangles?
Intracellular twisted filaments of Tau protein
Tau normally binds and stabilised microtubules
Tau becomes hyperphosphorylated in AD
What are senile plaques?
Foci of enlarged axons, synaptic terminals and dendrites
Amyloid deposition in vessels in centre of plaque
What are the compensation mechanisms that maintain normal ICP?
Reduced blood volume
Reduced CSF volum
Spatial - brain atrophy
What can increase ICP?
Tumour, haemorrhage, oedema
What happens in a subfalcine herniate on?
Same side as mass
Cingulate gyrus pushed under the free edge of the flax cerebri
Ischaemia of medial parts of the frontal and parietal lobe and corpus callosum due to compression of anterior cerebral artery - leads to infarction
What is a tentorial herniation?
Uncus/medial part of parahippocampal gyrus through the tentorial notch
Damage to oculomotor nerve on the same side
Occlusion of blood flow in posterior cerebral and superior cerebellar arteries
Frequently fatal because of secondary haemorrhage into brainstem
What is a tonsillar herniation?
Cerebellar tonsils pushed into foramen magnum compressing the brainstem
Name a benign primary CNS tumour
Meningioma
Name a malignant primary brain tumour
Astrocytoma - spread along nerve tracts and through subarachnoid space often presents with a spinal secondary
What are the 2 broad categories of stroke?
Cerebral infarction (most common) Cerebral haemorrhage
What are the signs/symptoms of subarachnoid haemorrhage?
Sudden severe headache (thunderclap)
Sentinel headache
Loss of consciousness
Often instantly fatal
